Leading Edge Slats on the Me-109

[Redroach]

Hmm, well, I'm really uncertain about the Slats on the various Bf-109 models.
I've never seen them moving, optically, so the tendency might be that they still don't work, do they?
I'm not especially familiar with the Me-109 precisely because of that reason, and as long as they won't work, I'm not getting into an 109 cockpit in earnest.
Soo... do they actually work now?

[notafinger!]

Yes, as your speed drops below 300 kmh or so they will pop out. Unfortunately, there is no noise as many accounts say they came out with quite a loud bang that would startle a novice pilot.

[Redroach]

Ah okay, thank you!

[lonewulf]

The slats were spring loaded and extended or retracted depending on the amount of air pressure being exerted on the leading edge. If you suddenly stalled one wing the slat on that wing might extend suddenly but typically they would extend gradually as airspeed dropped below 200k.

Because the slats could extend asymmetrically, this could result in an uneven airflow over the wings.

[Nephris]

Nevertheless I dont have the impression the slats work liable as it did in Il2 1946. Means I cant observe the slats extracting each time i am below 240kmh or even 210kmh.
Even if the slats extract, I cant notice the effect, imho the feature isnt implemented to its final state.

[41Sqn_Banks]

IMHO the easiest way to test the FM effect of leading edge slats is to compare the Tiger with locked and unlocked slats.

[Nephris]

Didnt notice the Tiger got some :confused:

[Kurfürst]

The slats were spring loaded and extended or retracted depending on the amount of air pressure being exerted on the leading edge. If you suddenly stalled one wing the slat on that wing might extend suddenly but typically they would extend gradually as airspeed dropped below 200k.

Because the slats could extend asymmetrically, this could result in an uneven airflow over the wings.

Hi,

There is no spring in the Me 109 slats, they are sucked out by air pressure. AFAIK they are more actuated by the angle of attack of the wing and designed that if it reaches crticial angle, they would deploy. That's why they are working independent, i.e. if they deploy assimetrically, it means that one of the wings have reached a critical angle of attack, the other did not. The uneven airflow is a cause and not an effect of their deployment (if they would not deploy on that wing, the wing would detach the airflow stall).

The very reason of their employment is to make sure that once the wing is near stalling, the slats, by their deployment would keep the outer portion of the wing from stalling, so that ailerons would be still effective.

[Flanker35M]

S!

As Kurfürst said, the slats on Bf109 have no springs. They are on rails sliding forth and back depending on AoA. Moved them on the Finnish Bf109G-6 in Tikkakoski.

[Redroach]

Mh there still seem to be doubts... optically, some confirm that they work, but functionally?
My personal, albeit not extensive, experience, is that the Me-109s are VERY flimsy at slow speeds, when compared to its IL-2 1946 incarnations. Every remotely hard aileron/rudder input could lead into a spin imho - that's why I was asking.

[bongodriver]

slats don't prevent spins

[lonewulf]

I clipped the following info from the wikipedia on the subject of leading edge slats to back up my comments:

Leading Edge Slats
"Types include:
Automatic - the slat lies flush with the wing leading edge until reduced aerodynamic forces allow it to extend by way of springs when needed.
Fixed - the slat is permanently extended. This is sometimes used on specialist low-speed aircraft (these are referred to as slots) or when simplicity takes precedence over speed.
Powered - the slat extension can be controlled by the pilot. This is commonly used on airliners."

"During World War II German aircraft commonly fitted a more advanced version that pushed back flush against the wing by air pressure to reduce drag, popping out when the airflow decreased during slower flight. Notable slats of that time belonged to the German Fieseler Fi 156 Storch. These were similar in design to retractable slats, but were fixed non-retractable slots. The slotted wing allowed this aircraft to take off into a light wind in less than 45 m (150 ft), and land in 18 m (60 ft). Aircraft designed by the Messerschmitt company employed leading-edge slats as a general rule."

If someone has some conflicting information to backup their views that the 109s LES weren't spring actuated, I'd be interested to see it.

[Al Schlageter]

If someone has some conflicting information to backup their views that the 109s LES weren't spring actuated, I'd be interested to see it.

http://109lair.hobbyvista.com/techref/systems/control/slats/slats.htm

[swiss]

Hmm, well, I'm really uncertain about the Slats on the various Bf-109 models.
I've never seen them moving, optically, so the tendency might be that they still don't work, do they?

The effect has to be in the code, it doesn't matter whether they move or not.
It's not like Clod modeled the airflow the wing, there's a reason we don't have vortexes....

[Random_Nonsense]

If someone has some conflicting information to backup their views that the 109s LES weren't spring actuated, I'd be interested to see it.

I've pushed the slats in and out on a Buchon . No springs on them and they are pretty similar to a 109 ;)

[lonewulf]

Well, on the basis of the info supplied by Schlageter and Random Nonsense it appears that I was wrong about the slats. I withdraw and apologize.

[Redroach]

Can one, for once, have a clear answer on the original subject, please? It seems to be a tough task...

[Random_Nonsense]

Well they visually move.

No idea how to test if they have an effect on the flight model though. Anyone a good enough shot to only shoot the slats off a 109?

[macro]

Atag modelled control surface to fall off on limited plane types maybe they could do this with the slats?

[5./JG27.Farber]

I clipped the following info from the wikipedia

Wikipedia is by far the worst source for any information. You might as well ask a stranger in the street. ;) You can actually find contradictions on the same page on most things on wiki if you look hard enough.... Sometimes not even that hard.

Like you, I also found this out the hard way. :-P

[Al Schlageter]

Well, on the basis of the info supplied by Schlageter and Random Nonsense it appears that I was wrong about the slats. I withdraw and apologize.

You might want to ponder why in some photos the slats are out, in other photos the slats are in and in other photos one side is in and the other side is out.

[zipper]

Yepper, on the ground they will either stay out or stay retracted. I've played around with the real thing, too, and they are springless Handley Page slats all the way. (The very first versions of HP slats did use small springs.)

[JtD]

Wikipedia is by far the worst source for any information.That's just not true, on average it's a great free source of accurate information. It is, as with any other source, still advisable to double check against another source.

WRT the slats, the flight model and the slat animation are not necessarily linked. You can have the full benefit of the slats in terms of stall speed and handling, without ever seeing them move. Other way round is also possible. You can most easily check if they are in the FM by determining the maximum power off lift coefficient.

[Redroach]

Would you please get out of this thread with that silly nitpick dispute?

To re-formulate the original question: Do the Leading Edge Slats work properly in CoD or not?

[IIIJG52_Otto_+]

I think the aerodynamic effect of Bf-109´s slats, is bad modeled in CloD.

I was watching the Bf-109 flying in Berlin last September, and he did very fast maneuvers without going into stall, or spins.
It´s a very beautifull airplane :cool:

You can see the video here:
http://www.youtube.com/watch?v=QTxGDI2-wDs

[bongodriver]

Slats do not prevent stalls or spins they simply delay a stall and allow a higher angle of attack, just because an aircraft has slats it does not mean you can just pull it around without penalty.

The 109 in the video didn't stall or spin because the pilot didn't take it to the limits.

[Redroach]

yes, bongodriver, good news, we're all positive now about that fact, and how slats work (and were for some time, I think.).

Back to my original question: I tested a little bit in an E-4B and, besides seeing the slats actually moving for the first time, I noticed (subjectively, of course) a somewhat improved handling at slow speeds. So, to answer my own question: Yes, perhaps the LES are probably working now. If they are properly tuned to reflect RL-Performance, I do not know, however.

[bongodriver]

yes, bongodriver, good news, we're all positive now about that fact, and how slats work (and were for some time, I think.).

Back to my original question: I tested a little bit in an E-4B and, besides seeing the slats actually moving for the first time, I noticed (subjectively, of course) a somewhat improved handling at slow speeds. So, to answer my own question: Yes, perhaps the LES are probably working now. If they are properly tuned to reflect RL-Performance, I do not know, however.

You don't need to take my post personally, I'm sure you can see I'm explaining it to some who don't understand these things, as to your original question it has already been shown that in order to find out if slats are working you need to compare it against performance without operative slats.....how to do it is the tricky part.

[IIIJG52_Otto_+]

Slats do not prevent stalls or spins they simply delay a stall and allow a higher angle of attack, just because an aircraft has slats it does not mean you can just pull it around without penalty.

The 109 in the video didn't stall or spin because the pilot didn't take it to the limits.

I agree with you on that first .. but I'm sure that with a Bf-109E in the CloD, you can not do some maneuvers as in reality, (such as, closed scissors, or Immelmann turn) at speeds flight from reality, because the aircraft enters itself in a spin unreal and unrecoverable.
We need to improve the Bf-109 FM more accurately.

[bongodriver]

the FM's of all the aircraft need improving.

[Kurfürst]

I agree with you on that first .. but I'm sure that with a Bf-109E in the CloD, you can not do some maneuvers as in reality, (such as, closed scissors, or Immelmann turn) at speeds flight from reality, because the aircraft enters itself in a spin unreal and unrecoverable.
We need to improve the Bf-109 FM more accurately.

I agree. The hideous stalling characteristics of the 109 are the most important aspect of the 109-FM that needs improved upon. The real 109 was an almost foolproof plane in the air with gentle stall characteristics (and was so in Il-2FB), compared to the thing we have in the sim doing wild things for seemingly no reason.

[Redroach]

The hideous stalling characteristics of the 109 are the most important aspect of the 109-FM that needs improved upon. The real 109 was an almost foolproof plane in the air with gentle stall characteristics (and was so in Il-2FB), compared to the thing we have in the sim doing wild things for seemingly no reason.

And this, I think, after recently testing in an E-4, has improved somewhat, with the slats actually working now. But, still, this is a highly subjective point of view and probably still doesn't compare favourably to RL.

[Crumpp]

slats don't prevent spins


No, they only make it exponentially harder to enter a spin

[Crumpp]

The hideous stalling characteristics of the 109 are the most important aspect of the 109-FM that needs improved upon.

After that, the stability and control. The Bf-109 was one of the best shooting platforms of the war.

[*Buzzsaw*]

I agree. The hideous stalling characteristics of the 109 are the most important aspect of the 109-FM that needs improved upon. The real 109 was an almost foolproof plane in the air with gentle stall characteristics (and was so in Il-2FB), compared to the thing we have in the sim doing wild things for seemingly no reason.

There are a lot of myths about slats, and a lot of misunderstandings.

The 109's slats do not prevent stalls or automatically give the 109 a stall speed lower than other aircraft. The 109E stalled at speeds higher than the Spitfire I or Hurricane I. A stall is a stall, a loss of effective control of the aircraft by the pilot and a subsequent loss of height.

What the slats do is resist, not prevent the typical right or left wing drop and potential entry into a spin at the stall you see with other non-slat equipped wings, the typical level flight, power off 109 stall is a simple loss of control and gentle nose drop which allows for a quick recovery.

But the pilot still loses control. The aircraft stalls.

And, in accelerated power on stalls under G, the 109 could drop a wing, just like any other aircraft. The chances of this was less, but the slats did not exclude this possibility.

[Kurfürst]

And, in accelerated power on stalls under G, the 109 could drop a wing, just like any other aircraft. The chances of this was less, but the slats did not exclude this possibility.

I agree, of course it should stall and yes, the stall speed was a bit higher. The slats practically do the same thing as washout would do on a slat-less aircraft, making the outer wing section stall later (at higher AoA) than the inner wing, thus maintaining aileron control longer.

The problem is how how this stall happens - from everything what I have read I'd expect the 109 to be pushed fairly far in a turn (partly because of the slats, party because of the elevator's characteristics), the ailerons would snatch a bit when the slats are opening (at least on the 109E), and when it would stall, gently start to sink, none of the violent flick overs, flat spins and other rubbish we have the sim.

"When doing tight turns with the Me.109 leading at speeds between 90 m.p.h. and 220 m.p.h. the Spitfires and Hurricanes had little difficult in keeping on the tail of the Me. 109. During these turns the amount of normal g recorded on the Me. 109 was between 2½ and 4 g. The aircraft stalled if the turn was tightened to give more than 4 g at speeds below about 200 m.p.h. The slots opened at about ½ g before the stall, and whilst opening caused the ailerons to snatch ; this upset the pilot's sighting immediately and caused him to lose ground. [b]When the slots were fully open the aircraft could be turned quite steadily until very near the stall. If the stick was then pulled back a little more the aircraft suddenly shuddered, and either tended to come out of the turn or dropped its wing further, oscillating meanwhile in pitch and roll and rapidly losing height ; the aircraft immediately unstalled if the stick was eased forward. Even in a very tight turn the stall was quite gentle, with no tendency for the aircraft to suddenly flick over on to its back and spin. The Spitfires and Hurricanes could follow the Me.109 round during the stalled turns without themselves showing any signs of stalling."

[Robo.]

Kurfurst I suggest you talk to the 109 pilots who are in perfect control of their aircraft and never stall it even in very aggressive maneuveurs (that someone here claimed to be impossible). It is in a good match with real life records - 109 expert can really really push harder and even outturn not so capable RAF pilot.

I also fly the 109 very often and I don't have this problem (unless I make a pilot mistake like too much foot or ). The aircraft is controllable even in very aggressive maneuveurs and last second corrections like full rudder deflection shots. You will get into high speed stall by doing that incorrectly but that's not aircrafts fault. I wonder if FF helps, I am using MSFF2 joystick and I can really 'feel' the aircraft.

Hurricane's stall behaviour is much worse than 109s btw, with droping the wing if you're not careful.

[Varrattu]

Just out of curiosity ... ...

Has anyone of you experience flying a real BF109E?

Regards

[bongodriver]

Care to expand on that?

Not really, it's pretty self explanatory.

[Crumpp]

Even in a very tight turn the stall was quite gentle, with no tendency for the aircraft to suddenly flick over on to its back and spin.

Right.

Obviously folks do not understand how the LE devices work. Many people would benefit from reading chapter 19 of a book called "Stick and Rudder" by Wolfgang Langewiesche.

It would eliminate all the stupid arguments on these boards.

http://www.amazon.com/Stick-Rudder-Explanation-Art-Flying/dp/0070362408

Handley Page automatic slats equipped aircraft have unique and non-traditional stall characteristics as a result.

The stall was quite gentle because of the LE Slats. The effect of the slats is to increase the angle of attack the stall occurs at by energizing the boundary layer behind the slat.

The slats on the outboard and the inboard wing is not slotted. This means the inboard portion will ALWAYS stall at a lower Angle of Attack. With the inboard wing stalled, it no longer produces the lift required to raise the nose and increase the outboard portion of the wing that is slotted to the stall Angle of Attack.

It acts like training wheels, automatically countering an asymmetrical stall so that depending on the CG location, no amount of rudder input at the stall point will cause a spin.

Today, slats for spin proofing have fallen out of favor and given way to cuffed wing designs. The aerodynamic effect is the same but the cuffs offer the advantage of a constant drag picture without the complexity of the automatic slat. Drag forces increase with the slat deployment as lift and drag are connected linked by a fixed relationship.

http://img856.imageshack.us/img856/5310/spinresistance.jpg (http://imageshack.us/photo/my-images/856/spinresistance.jpg/)

http://img846.imageshack.us/img846/4238/spinresistance2.jpg (http://imageshack.us/photo/my-images/846/spinresistance2.jpg/)

[bongodriver]

Even in a very tight turn the stall was quite gentle, with no tendency for the aircraft to suddenly flick over on to its back and spin


Right.....nothing remarkeable


The Spitfires and Hurricanes could follow the Me.109 round during the stalled turns without themselves showing any signs of stalling


What?!!!! but these aircraft don't have magic slats

Anyway what some people don't appear to grasp is the fact that the effect slats have is not 'infinite', they can only give a fixed amount of increased alpha before stall and what do you think happens after that?
if your elevators remain effective then you have the ability to go beyond maximum AoA and stall.......and dare I say it spin too, after all if one magic slated wing exceeds max AoA before the other then it will flip.

let's not forget the reason the 109 got slats was to improve it's 'low speed' handling......much like any other aircraft with slats (no coincidence slats feature heavily on STOL aircraft) and was nothing to do with making it better at turning, simply it was to prevent that very skittish high-speed, high-loading wing from killing pilots at approach speeds.

[*Buzzsaw*]

Just out of curiosity ... ...

Has anyone of you experience flying a real BF109E?

Regards

Salute All

Already posted this on the ATAG forum.

This is from Rob Erdos. He is a former Canadian Armed Forces military pilot, and now is a senior test pilot with the National Research Council's Flight Research Laboratory in Ottawa. (Canada's equivalent of NASA) He is also the manager of Warbirds at VINTAGE WINGS, a non profit society in Ottawa Canada which operates quite a number of Warbirds, including a Spitfire XVI, P-51D, Hurricane II and IV, KittyHawk III, (P-40N), Corsair ID, Lysander, F-86 Sabre, Harvard and Tiger Moth, as well as other vintage civilian aircraft. He also occasionally is invited to fly other Vintage Warbirds, including the only regularly flown 109E in the world, which is based in southern Ontario Canada, the aircraft is "White 14", recovered in Russia and rebuilt.

You may have seen videos of this aircraft, here is another one: (not being flown by Rob this time)

http://www.youtube.com/watch?v=jNUNJ5wdBZc

And here is Rob's evaluation. Note that this aircraft does not have weapons or ammunition, or armour, and the original radio has been replaced by a lighter modern one. So it is approx. 250 kg lighter than the original fully equipped 109E.

http://www.vintagewings.ca/Portals/0/Vintage_Stories/Erdos8.jpg

Flying the Messerschmitt Bf-109E - by Rob Erdos, Vintage Wings of Canada

“Achtung Spitfire”, I heard in a ridiculous German accent. I smiled. The voice was my own. My head swivelled within the tight confines of the Bf-109 cockpit, looking for the attacker. There it was, above and behind, waiting to pounce upon me from out of the sun! This particular “Spitfire” (pronounced Schpitfire)looked like an unassuming summer cumulus cloud, but I turned to meet the attack nonetheless. An intense and terrifying dogfight ensued, as the Bf-109 twisted and turned to pursue the advantage. The enemy was cunning, but within minutes a particular southern Ontario cumulus cloud had been reduced to wispy shreds, and I had gained a much better understanding of the renowned Messerschmitt Bf-109.

May 2008 found me at Niagara South airfield, the base of the Russell Aviation Group, operators of the pristine and lovely Bf-109E, registered C-FEML, and at that time the only “Emil” flying in the world. In addition to the Messerschmitt, Russell Aviation operates a Spitfire Mk IX and Hurricane XII. The air display season was fast approaching, and the Russell folks needed maintenance test flights performed on all of their aeroplanes. As a happy outcome of my work with Vintage Wings of Canada, I was already familiar with the British fighters. The Messerschmitt was new to me, but I understandably relished the opportunity to sample the flying qualities of the “other side” of the Battle of Britain. It’s a single-seater. You check yourself out. With the concurrence of the nice folks at Russell Group, I went to work.

The cockpit of the Bf-109 was a tight fit, even in comparison to the snug dimensions of the Spitfire cockpit. The seating position was semi-reclined, indicating either that Dr. Messerschmitt appreciated the importance of g-tolerance, or that he was trying hard to reduce my frontal area. As an outcome of both the reclined seating position and being tightly wrapped by the airframe, the forward field of view was nearly non-existent; a characteristic unfortunately common to this vintage of fighters. In stark comparison to the semi-random layout of British cockpits of this era, the Bf-109 instrument panel was arrayed in a thoughtful, almost modern manner. That was when my eyes caught upon the instruments: the airspeed indicator was labelled in kilometers per hour, oil pressure in “kilograms per square centimetre”, power was indicated in “ATA”. An apparently important instrument, devoid of other markings read, “Luftschraube Stellungsanzeige”. Hmm. This was getting interesting.

Returning to the cockpit with my German-English dictionary and a calculator, I took note of the controls. The small control stick fell comfortably to hand, although full displacement seemed to use most of the space in the cockpit. The pedals, oddly situated more ahead than below me in the reclining cockpit, incorporated a metal strap for negative ‘g’ restraint. The throttle was a small stub mounted on the left cockpit sidewall. A larger throttle would have hit my thigh as I advanced it. I scowled at the tailwheel locking mechanism mounted beneath the canopy rail directly under my left elbow. I had already knocked that lever several times, but I mustn’t do it again. Performing a take-off or landing with the tailwheel unlocked was guaranteed to have an unpleasant outcome. Wearing a parachute and helmet, I tried to close the heavy side-hinged canopy, finding that it rested atop my helmet with about two inches to spare before closing. I am 5 feet 9 inches tall. The helmet was reluctantly left behind. Have I mentioned that the cockpit was tight?


Notable in their absence were any further engine controls. Mixture was automatic. The propeller control was truly unusual, consisting of a rocker switch mounted on the inside of the throttle lever. The switch manually controlled the pitch of the propeller, via an electric motor mounted on the engine crankcase, and indicated on a clock-like instrument. (Aha! I think I know what “Luftschraube Stellungsanzeige” must mean!) I could hardly believe the implications of this installation: the Bf-109E had only a controllable pitch propeller. It did not have a propeller governor! I would have thought automated propeller speed control essential for an aeroplane with a 400 knot speed range. Indeed, such systems were fitted to later Bf-109 variants. I noticed that this particular aeroplane incorporated a small electrical switch on the floor, marked “Prop: Auto/Manual”, but it was wired to the Manual position. I was later told that this aeroplane never flew operationally with the system operative. The lack of propeller governing aroused my suspicions about the workload associated with dogfighting in the aeroplane.

The most innovative and interesting feature in the cockpit were two large concentric wheels situated on the left sidewall, aft of the throttle. The outer wheel actuated the flaps and inner wheel controlled the pitch trim by changing the incidence of the horizontal stabilizer. Since the flaps inevitably affect the pitch trim, the pilot could ostensibly maintain trim during flap deployment by actuating both wheels simultaneously. An ingenious mechanism within the wing allowed the ailerons to droop for further lift as the flaps reached full extension. The wings incorporated roughly half-span leading edge slats. These actuated independently under the influence of aerodynamic and inertial forces. In all, this was a very complicated wing, and one designed to squeeze as much lift as possible from each square foot of area. That’s good because another thing became evident about the Bf-109’s wing: there wasn’t much of it. The wing loading of the Bf-109E was almost 50% higher than the Spitfire. This too would be factor in air combat performance, and I would need to keep it in mind if I were ever attacked by a cumulus cloud.

Once my preparations were complete and all requisite German-English translations were made, it was time to go flying. Starting the rare Daimler-Benz DB601 engine was relatively straight forward, although the staccato note of the powerplant initially took me by surprise. I have always found something reassuring in the deep sonorous thrum of the Merlin; a sound akin to standing behind a dozen self-satisfied tenors. The Daimler engine, by comparison, struck me as clattering and harsh, more like a barrel full of hammers rolling down a staircase. I flashed a look of concern at the Russell Group’s Chief Engineer, Gerry Bettridge. His cheerful grin seemed to confirm that this cacophony was not unusual.

Taxiing is the Messerchmitt’s opportunity to get you alone and to whisper a warning in your ear. There is a grotesquely high download on the tailwheel in the Bf-109; a situation made evident by the requirement for full rudder, hard braking, forward stick and a blast of power to effect a turn. Try that in a Spitfire and the propeller will chew dirt! While odd, it at least gave reassurance that even aggressive braking would be unlikely to result in a nose-over. Unfortunately it also meant that the center of gravity was very far aft of the main wheels. That is not a good thing. Recalling my misadventures in once trying to steer a shopping cart backwards down a hill, I made a mental note that the tail might try to pass me during the landing.

The geometry of the undercarriage is perhaps the most unusual feature of the Bf-109. A digression is in order to appreciate how its characteristics would manifest themselves during take-off or landing. Some sources claim that between 15-25% of the Bf-109s ever built were damaged or destroyed during take-off or landing accidents. I find this a remarkable figure for a combat aeroplane – especially one that served on the losing side of the war! Most contemporary histories of the Bf-109 attribute this to the narrow undercarriage track, however this misses the point. (The Spitfire’s undercarriage is just as narrow, and it doesn’t have any of the Bf-109’s quirks. It has its own quirks – but that’s another story.) Dr. Messerschmitt faced a challenge in the design of his first fighter. In the interest of simplifying transport and repair of the aeroplane, it was designed with the undercarriage attached to the fuselage, such that the wings could be completely removed with the aeroplane resting on its wheels. The undercarriage struts were attached to a complicated forging at the firewall aft of the engine mount. The narrow width of the fuselage structure necessitated installing the undercarriage legs splayed outwards. This feature became the aeroplane’s Achilles heel.

Imagine that you have a bicycle wheel in your hands. Roll the wheel with the axle parallel to the ground. It goes straight. Now roll the wheel such that the axle is not parallel to the ground. The wheel turns. Let’s return to the Bf-109. Both of the tires are mounted “crooked”, rolling with a camber angle of about 25°. Consequently both wheels want to turn inwards under the aeroplane. When the aeroplane is rolling with an equal download on both wheels, symmetry prevails; both wheels fight to a stand-off, and the aeroplane rolls straight. Now imagine that something causes the download on the wheels to momentarily become unequal. In that case the rolling friction of the tires becomes uneven and the turning tendency of the “heavy” tire asserts itself. What might do this? Well, crosswinds. Or torque from engine power. However, the most dangerous culprit is turning. With the aeroplane’s centre of gravity situated high above the tires, a swerve will set loose large centrifugal forces that cause the aeroplane to try to roll over the tires. This is true of any aeroplane, but in this scenario the unusual camber of the Bf-109’s tires creates strong directional instability, requiring a different type of control strategy for take-offs and landings. Tight heading control or aggressive tracking of the runway centerline can set off abrupt directional divergence. Better for the pilot to relax, merely dampen heading changes, and accept small heading errors. Funny, I didn’t feel relaxed.

These thoughts ran through my mind as I taxied for take-off at the Niagara South airfield. “Don’t fight with the aeroplane. Accept any heading you get and roll straight”, I told myself as I took position for take-off. The Daimler engine responded by growling at me, as I applied a final stab of power to turn onto the runway centerline. Okay, pause. I checked that the flaps were set to 20°, set the trim to one degree UP, set the propeller pitch to “11:30” on the weird clock indicator, and then locked the tailwheel. Then I checked the tailwheel lock. Then I double checked. Looking straight ahead I took note of the 3-point attitude: completely blind, save for two small strips of horizon visible at the edges of the windscreen. Mentally noting the 3-point attitude wasn’t enough. I would need to quickly re-establish this view when it came time to land, so I took out my secret weapon. Using a black grease pencil I drew the meagre horizon line on the inside of the windscreen.

I opened the throttle slowly. Directional control authority quickly felt quite positive, although I recalled my commitment to use it judiciously. A fairly strong push on the stick was required to gently lift the tail as the airspeed passed 60 km/hr; an act that was further destabilizing, however things were quickly improving as the airspeed increased. With a gentle skip, the Bf-109 became airborne around 110 km/hr. I retracted the undercarriage and immediately turned into a climbing orbit overhead the airfield while I confirmed that the engine indications were stable.

Power was set at 1.15 ATA (atmospheres of manifold pressure) at the recommended climb speed of 250 km/hr. Propeller speed was sensitive to airspeed changes, so a slight pitch reduction was required to stabilize at 2300 RPM. The Daimler engine sounded much smoother in flight. My initial impressions of the aeroplane were mixed. The field of view was poor, necessitating continuous clearing turns in the climb. The greenhouse canopy structure seemed to be slightly obtrusive no matter where I looked. Control response in the climb was satisfyingly light and crisp, with good harmony between pitch and roll control forces. Directional stability was clearly inadequate. Every roll input required conscious pedal coordination. The absence of rudder trim proved a considerable annoyance during the protracted climb. In the interest of “calibrating” my aileron-rudder coordination, I tried a few aggressive roll reversals in the climb and received an unpleasant surprise. The application of full aileron caused the aeroplane to shudder and buffet in a manner that, to my overactive imagination, seemed like I was receiving machine gun fire. I rolled level and breathed. Subsequent investigation showed that the onset of buffet occurred at large aileron displacements, and was associated with a very slight lightening of the aileron control forces and a distinct high-frequency “hammering” in the stick. I had seen that before. Aileron stall! It was becoming clear to me. Dr. Messerschmitt kindly provided me with powerful mechanical leverage to actuate the ailerons against the aerodynamic forces, and that explained why the stick forces were so pleasantly light. That is certainly not the case in the Spitfire, where the ailerons stiffen terribly at high speeds. In the Bf-109 I unfortunately had enough leverage under some conditions to deflect the aileron to the point of airflow separation. The results were a bit disappointing. In spite of the light control feel, the roll rate achievable in the Bf-109 was no better than the Spitfire.

I levelled off above the airfield and went to work. My test card began with an investigation of the slow flight and stall characteristics, in order to prepare myself early for the eventual landing.

The power was reduced to just above idle, and the aeroplane decelerated for a clean stall. I was fascinated to watch as the leading edge slats automatically extended themselves into the airflow. The effect was smooth and transparent, however I noted that the rate of deceleration increased as the slats extended. I made note of this effect, intending further investigation during air combat scenarios. The clean stall occurred at 125 km/hr indicated airspeed, preceded by a 3-5 knot band of mild buffeting. That’s 68 knots. I wasn’t sure if I was impressed or skeptical. The stall was marked by a mild pitch and right roll break; cues so mild that they were hardly inhibiting. I continued to explore increasing angles of attack until I was happily flying along with full aft stick. No sweat. In the clean configuration, the Bf-109 retained its lateral control effectiveness without any tendency to depart - even tolerating mild sideslips at full aft stick.

Next I investigated the stall characteristics in the landing configuration. The undercarriage and flaps were extended, the power reduced to idle, and a gradual deceleration was performed. Roll control response became sluggish once the ailerons drooped with full flap selection, and it exhibited considerably more adverse yaw. Again a mild buffet preceded a gentle pitch break, this time at 88 km/hr. 88 km/hr!? That’s 47 knots indicated airspeed. Now I was definitely skeptical. There was simply no way that this modest wing area was holding this mass of aeroplane aloft at 47 knots. I recalled the location of the pitot-static probe, mounted close under the left wing, and knew with certainty that it was lying. Nevertheless, the low-airspeed and stalling characteristics of the Bf-109 were extremely benign and forgiving; a highly desirable characteristic in a fighter.

While the undercarriage and flaps were extended, I took the opportunity to do a few landings – in the clear air at 6000 feet above the airfield. I did a simulated final turn to parallel the runway and flared to the 3-point attitude, with the objective of “landing” my altimeter exactly at the 6000 foot mark. The final turn in a fighter typically involves a gradual turning deceleration to the runway. I found that controlling speed and descent gradient during the turn were hardly demanding, however the forward field of view was gradually disappearing. No surprise there. Elevator response was suitably precise to capture the 3-point attitude without difficulty. Overshoot from the pseudo-landing was easy – at least for a high-performance fighter. The Bf-109E is powerful, however propeller effects were easily managed. Chalk up one advantage of having low directional stability.

Now that I felt I could land it, I was eager to pursue my curiosity about the Bf-109’s qualities as a fighter. I set cruise power setting (1.0 ATA manifold pressure, 2300 RPM), stabilizing at 415 km/hr at 5500 feet. That equates to a modest 225 knots indicated airspeed, but it wasn’t my engine. The aeroplane felt comfortable in cruise, exhibiting weak but positive speed stability, as evidenced by the gentle, progressive elevator forces required to maintain off-trim speeds. A gentle sustained sideslip gave evidence of both weak directional stability and weak lateral stability, at least by modern standards. The rudder forces seemed very light. The sideslip also induced a gentle nose-down pitch response, indicative of possible elevator blanking. All this talk about weak stability doesn’t imply criticism of its qualities as a fighter. The flip side of low stability is often high agility. Nevertheless this wouldn’t be my first choice of an aeroplane for instrument flying.

The next order of business was to become familiar with manoeuvring the machine. I performed a wing-over and was immediately reminded of the benefits of propeller speed governing. Lacking such amenities, the propeller speed on the Bf-109 decayed terribly as the speed reduced, reaching as low as 1600 RPM at the top of the manoeuvre. The result was a slightly laboured sound from the engine, as it struggled with high torque at low speed. The effect was not unlike taking your foot off your car’s clutch from a standstill in fifth gear. Ouch. Not good for the engine, and not good for performance. I noted that the peak of the wing-over had been about 1700 feet above my starting altitude. I repeated the manoeuvre, this time maintaining a constant propeller speed using the rocker switch on the throttle. The engine sounded happier, if the growling Daimler could be described as “happy”, and this time the top of the manoeuvre managed to achieve 2300 feet of altitude gain. Clearly any pilot wishing to obtain maximum performance from the Bf-109E would need to carefully regulate propeller speed. Unfortunately, this draws the pilot’s attention into the cockpit, rather than allowing him to focus outside where the dangers lurk. I was left wondering whether the young lads who flew the Bf-109E in combat really applied that degree of finesse, or whether the circumstances of combat necessitated cruder engine handling.

Once familiar with coordination of propeller pitch with speed changes, the Bf-109 and I performed some gentle aerobatics together – strictly for technical investigation, you understand. Loops were enlightening. The low directional stability could result in comically large heading variations unless careful rudder coordination was applied. I was reminded of a long-ago instructor of mine, who remarked upon seeing my aerobatics, “Nice loop. Now do one to the right.” It was easily mastered with practice. Multiple manoeuvres seemed to result in a notable decay in speed, particularly whenever the leading edge slats deployed; a stark contrast to the Spitfire, whose elliptical wings retain energy nicely under sustained ‘g’. The Messerschmitt was paying the price for its high wing loading.

It was at this point that I was pounced upon by that dastardly cumulus. “Fine”, I thought, “let’s see what this aeroplane can do”. I climbed steeply and turned to bring the guns to bear upon the target. Field of view through the greenhouse canopy was again a hindrance as I looked over my shoulder to gauge the turn. The cumulus turned and dove steeply to flee (bear with me for a moment…). A deflection shot would be required to engage from long range, however the limited field of view down over the nose would make this difficult. The Bf-109 built speed rapidly in a dive, however the necessity to attend to propeller speed proved a distraction as I closed quickly upon the target. Pulling out of the dive, I discovered that the Bf-109’s elevators became distressingly heavy at high speed. I had read wartime accounts of Spitfire pilots taking Bf-109s into steep high-speed dives, knowing that the Bf-109 would be unable to pull out. This was a convincing demonstration, requiring a two-handed pull to achieve a 3.5 ‘g’ recovery at 450 km/hour. I flashed past my adversary like it was standing still. With a gallant salute, I disengaged. After less than an hour, the fuel gauges were telling me that it was time to return to Niagara South.

The circuit procedures were familiar from my rehearsals at altitude, but this time it was for keeps. A standard overhead break was performed, but delayed until well past the upwind end of the runway. Extension of the flaps required about 30 quarter-turns of the flap wheel; a time-consuming process. The downwind leg was entered at 200 km/hour, decreasing to 150 km/hour as the undercarriage and flaps were extended. The numbers on the airspeed indicator seemed high, and I had to keep telling myself that they were “only kilometers”. From abeam the touchdown point on downwind, a continuous decelerating turn was performed to the flare. With virtually no forward field of view, a straight-in final approach leg was definitely to be avoided. I entered the flare at 125 km/hour, maintaining a trickle of power. I can’t claim to have been completely at ease, but within seconds the wheels began to gently rumble across the grass. The Bf-109 was home from another mission.


Note his comments about the rollrate of the 109E not being any better than the Spitfire are based on his own experience in flying later model Spitfires with metal ailerons, the Spit I had fabric ailerons, thus not as good a rollrate.

His comments about taxing, taking off and landing in the 109E are particularly relevant. The game 109E has none of these characteristics, in fact it is just as prone as the Spitfire and Hurricane to tipping over on its nose, not accurate at all. Neither are the directional issues apparent in the game aircraft. Other characteristics which are absent or muted are the precessional, yaw and trim effects at high throttle/low speed, as well as the sideslip characteristics at various other speeds.

Another video of the same plane, this one in HD:

http://www.youtube.com/watch?v=0cLmBZWDyBM&playnext=1&list=PL6901DDBAE6002821&feature=results_main

[NZtyphoon]

Just out of curiosity ... ...

Has anyone of you experience flying a real BF109E?

Regards

Nope, but it is interesting to read the reports of pilots who have (http://www.vintagewings.ca/VintageNews/Stories/tabid/116/articleType/ArticleView/articleId/124/language/en-CA/Bouncing-Clouds--Flying-the-Messerschmitt-Bf-109.aspx). (also cited by Buzzsaw)

Once familiar with coordination of propeller pitch with speed changes, the Bf-109 and I performed some gentle aerobatics together – strictly for technical investigation, you understand. Loops were enlightening. The low directional stability could result in comically large heading variations unless careful rudder coordination was applied. I was reminded of a long-ago instructor of mine, who remarked upon seeing my aerobatics, “Nice loop. Now do one to the right.” It was easily mastered with practice. Multiple manoeuvres seemed to result in a notable decay in speed, particularly whenever the leading edge slats deployed; a stark contrast to the Spitfire, whose elliptical wings retain energy nicely under sustained ‘g’. The Messerschmitt was paying the price for its high wing loading.


The 109 needed slats to compensate for its high wing loading and lack of washout, which lots of other other fighters had; eg: Spitfire, Fw 190. Slats were simply another way of changing the stall characteristics of a highly loaded wing. They were not the miraculous device that some seem to think.

[Crumpp]

the miraculous device

No miracle required....just basic physics.

;)

[Kurfürst]

Kurfurst I suggest you talk to the 109 pilots who are in perfect control of their aircraft and never stall it even in very aggressive maneuveurs (that someone here claimed to be impossible).

*sigh* point me in the direction of these experience pilots. Besides you do not seem to get the point - the problem is not that the 109 stalls (it should) neither that it does not outturn RAF planes (it shouldn't though getting near to it's turn limit SHOULD be easier than on those) but HOW it stalls. Stalls are extremely violent on this aircraft and spins occur often.

And apparently it's not just my problem. And dear Sir, I fly the 109 since original Il-2 beta - I have never had the problem with it like it's in Il2, well, except for something was extremely badly sc***d up with the G-6's FM.

"Word came from the Luftwaffe out of Antwerp early in the spring of 1943 that many pilots had experienced spin problems with the Me109 G and had to bail out. Numerous airplanes had been lost. Karl Baur's first reaction: "This is almost a foolproof airplane. How do these guys accomplish that?" The Me 109 had a relatively high wing loading (32.2 lb/sq ft) and therefore stalled readily under heavy G forces but the stall was gentle and the aircraft exhibited good control under G forces. If the stick was eased forward the aircraft immediately unstalled with no tendency to flick over on its back and spin. While not totally spin proof it took a fairly ham fisted pilot to get into trouble in the Me 109.

It took Karl several nerve wracking flights before he was able to get a Me 109 into a spin. Finally, after he had tried every possible dog fight maneuver, he had it figured out. It was during those split seconds before going into a vertical dive that it was possible to get this airplane to spin. Only rough flying inexperienced pilots were able to do it. Karl's solution to the problem was very simple. He advised: "Drop the landing gear boys, and the spin will end immediately." The dropped landing gear would appear to lower the airspeed and reduce the severity of the yaw (the movement around the normal axis of the aircraft, i.e. direction stability). Once the aircraft is not spinning (yawning) around its center of gravity the aircraft being in a nose down attitude accelerates and becomes unstalled.

p.86 of: A Pilot's Pilot, Karl Baur - Chief Test Pilot for Messerschmitt by Isolde Baur

I wonder if FF helps, I am using MSFF2 joystick and I can really 'feel' the aircraft.

Maybe, but I do not have a FFB joystick. I tried it once at a friends, but it behaved very weird in CLOD.

Hurricane's stall behaviour is much worse than 109s btw, with droping the wing if you're not careful.

Yes, the Hurri definietely sucks in this regard - but I do not know how the Hurris stall characteristics were.

[*Buzzsaw*]

Salute

Kurfurst is quite correct in noting the game 109 is quite difficult to recover from spins. I have often seen game 109's spinning to their destruction from considerable heights.

This is quite clearly an incorrect modelling of the real aircraft, which was in fact easy to recover from spins or stalls, one would have to be quite ham handed to maintain a spin in the historical aircraft. Not impossible mind you, given a pilot doing all the wrong things, but given a pilot with the training, recovery should be prompt and with a relatively minor altitude loss.

As far as the historical Spitfire stall characteristics were concerned, there was definitely the possibility of a violent flick and spin if the aircraft was pulled into a high G Stall, however, the Spitfire had a characteristic which allowed experienced pilots to know exactly how far to take it. At a point just before the stall, the aircraft would begin to shudder slightly, this was the warning. Experienced pilots learned to ride this edge, as the shudder happened, and maintain it just at that point.

Unfortunately, this vibration or shudder is not present in the game either.

[JtD]

If the 109 had the elevator authority of a Spitfire, it would certainly be possible to send it into a flick or spin easily as well. Stalling characteristics and control characteristics are related, but still a different pair of shoes.

Hurricane stalls/spins were more problematic than the Spitfires, but it didn't have the sensitive elevator.

Recovery from spins shouldn't be hard in any of the three, but easiest in the 109.

[NZtyphoon]

Right.

Obviously folks do not understand how the LE devices work. Many people would benefit from reading chapter 19 of a book called "Stick and Rudder" by Wolfgang Langewiesche.

It would eliminate all the stupid arguments on these boards.



Obviously slats are merely another aerodynamic device which help improve flight characteristics, as are fixed slots, saw-tooths, flap blowing etc etc - nothing magic, nothing worth making a song and dance routine over. One wonders what the 109 would have been like to fly without the slats.

[KG26_Alpha]

Leave the personal attacks out of this thread please.

OK

Seems neither of them take heed of what's been asked of them

Posts removed and both of them on a short holiday together.

[Glider]

Salute

Kurfurst is quite correct in noting the game 109 is quite difficult to recover from spins. I have often seen game 109's spinning to their destruction from considerable heights.

This is quite clearly an incorrect modelling of the real aircraft, which was in fact easy to recover from spins or stalls, one would have to be quite ham handed to maintain a spin in the historical aircraft. Not impossible mind you, given a pilot doing all the wrong things, but given a pilot with the training, recovery should be prompt and with a relatively minor altitude loss.

As far as the historical Spitfire stall characteristics were concerned, there was definitely the possibility of a violent flick and spin if the aircraft was pulled into a high G Stall, however, the Spitfire had a characteristic which allowed experienced pilots to know exactly how far to take it. At a point just before the stall, the aircraft would begin to shudder slightly, this was the warning. Experienced pilots learned to ride this edge, as the shudder happened, and maintain it just at that point.

Unfortunately, this vibration or shudder is not present in the game either.

Can I just say that I found this to be a very good summary of the situation and post 44 is one of the best descriptions I have seen of flying the Me 109.

Thanks for both

[Crumpp]

One wonders what the 109 would have been like to fly without the slats.


It would have been rather bad in the stall characteristics.

The wing would have stalled all at once instead of root first and the tips receiving an energized boundary layer to keep the flow attached.
The entire wing stalling would be violent and uncontrollable.
Same thing the Spitfire would do without the twist. Major difference being twisting the wing does not energize the boundary layer so the ratio of turbulent to laminar flow remains the same.
The slats increase the amount of turbulent flow over the wing. The turbulent flow portion of the boundary layer is the high energy, high lift portion.

[Crumpp]

nothing to do with making it better at turning

Obviously, this comment is an effort to troll because it is contrary to the physics behind the slats.

The slats are a very practical method of allowing the pilot to quickly, precisely, and safely achieve CLmax.

They act as training wheels allowing the pilot to maximize performance of the aircraft without fear of losing control.

[CWMV]

Oberleutnant Erwin Leykauf said, ‘For us, the more experienced pilots, real
manoeuvring only started when the slats were out.'

From Messerschmitt Bf 109 at War. Pretty common statement. Ive seen interviews with Rall where he said the same thing.

[*Buzzsaw*]

The slats are a very practical method of allowing the pilot to quickly, precisely, and safely achieve CLmax.

Actually your comments are an exaggeration.

What the slats do is allow a pilot the confidence that if he pulls too much G and stalls his aircraft, the likelyhood of a violent spin is diminished and the knowledge he should be able to recover relatively easily.

The slats in themselves do not give any guarantee of a stall not occurring, they merely make the event, when it occurs, less violent.

The pilot still must be able to judge whether or not his aircraft is about to depart, and how many G's he is able to pull before departure may occur.

The slats opened prior to the stall, by RAF estimation, approx. 1/2 a G, and in pulling further G's and in order to avoid a stall, the pilot had to know the further signs of a stall approach, in the same way a Spitfire or Hurricane pilot was required to monitor his aircraft's behaviour.

In addition, the installation of the slats was not without penalty. As noted, the slats by deploying, increased the lift generated by the outer section of the wing, but they also generate more drag and reduce the speed of the aircraft. For earlier models of the 109, in particular the E, the chances of the slats deploying assymetrically in a turn was a factor, which was noted to cause aileron snatching and which could cause the aircraft to change direction without the pilot's intention.

[NZtyphoon]

Actually your comments are an exaggeration.

What the slats do is allow a pilot the confidence that if he pulls too much G and stalls his aircraft, the likelyhood of a violent spin is diminished and the knowledge he should be able to recover relatively easily.

The slats in themselves do not give any guarantee of a stall not occurring, they merely make the event, when it occurs, less violent.

The pilot still must be able to judge whether or not his aircraft is about to depart, and how many G's he is able to pull before departure may occur.

The slats opened prior to the stall, by RAF estimation, approx. 1/2 a G, and in pulling further G's and in order to avoid a stall, the pilot had to know the further signs of a stall approach, in the same way a Spitfire or Hurricane pilot was required to monitor his aircraft's behaviour.

In addition, the installation of the slats was not without penalty. As noted, the slats by deploying, increased the lift generated by the outer section of the wing, but they also generate more drag and reduce the speed of the aircraft. For earlier models of the 109, in particular the E, the chances of the slats deploying assymetrically in a turn was a factor, which was noted to cause aileron snatching and which could cause the aircraft to change direction without the pilot's intention.

From what I have read 109 pilots did have concerns about the slats banging open, causing a jolt because of aileron snatching and sometimes upsetting the pilot's aim. Fact is that all designs are a compromise in one way or t'other - like I keep saying slats were no better nor worse at aiding control than other aerodynamic aids. In the end it was the pilot's skills and experience that made a real difference; learning how to get the best out of the aircraft was a great survival technique.

[Crumpp]

Actually your comments are an exaggeration

Let's be specific and point exactly what you think I "exaggerated" otherwise your post is simple trolling and bait attempt to define me as being "red vs blue".

Buzzsaw, you state exactly the same thing I have without any change.

:rolleyes:

[Crumpp]

4.4. Stalling Tests

We find that under all conditions tested, the Bf-109 has:

no tendency to spin.

http://kurfurst.org/Tactical_trials/109E_UKtrials/Morgan.html

[Glider]

Oberleutnant Erwin Leykauf said, ‘For us, the more experienced pilots, real
manoeuvring only started when the slats were out.'

From Messerschmitt Bf 109 at War. Pretty common statement. Ive seen interviews with Rall where he said the same thing.

The key of course are the words 'the more experienced pilots'. As the war went on the proportion of experienced pilots fell dramatically.

[CWMV]

With respect that has nothing to do with the purpose/effect of the slats. They did what they did, up to the pilot to exploit it.

[Robo.]

no tendency to spin.

The in-game 109 has not any unusal tendency to spin - you will stall her of course when you do a mistake and lose control. That is a very good match with the 'us experienced pilots'. I would say that the problem lies in the spin recovery, e.g. once the a/c enters the spin, it is more difficult to recover than it should be.

[Crumpp]

you will stall her of course when you do a mistake and lose control

Again, they act like training wheels on a bicycle. In otherwords, it should be EXTREMELY difficult to spin the aircraft and very easy to recover.

once the a/c enters the spin

The advantage of the slats is in preventing spins. Find a report on the spin characteristics of the Bf-109.

There is an engineering reason there is not one.

[Robo.]

So are you saying that the 109 was unspinnable? Even if the pilot made a mistake?

I see the point that the a/c in game is now too difficult to recover and I agree it should be addressed.

[SlipBall]

So are you saying that the 109 was unspinnable? Even if the pilot made a mistake?

I see the point that the a/c in game is now too difficult to recover and I agree it should be addressed.


I find it easy to recover, trick being to act very fast with opposite rudder, & pitch throttle, to protect the engine

[NZtyphoon]

Again, they act like training wheels on a bicycle. In otherwords, it should be EXTREMELY difficult to spin the aircraft and very easy to recover.



The advantage of the slats is in preventing spins. Find a report on the spin characteristics of the Bf-109.

There is an engineering reason there is not one.

Interesting in light of the fact that one of the reasons the 109 was chosen over the He 112 was because test pilot Hermann Wurster was able to demonstrate a series of spins, 21 to port, 17 to starboard, before a group of Luftwaffe officials. Clearly the 109 was easy to recover from spins - the E probably a little more difficult than a Jumo engined prototype - but the slats were not some miracle cure for spins.

http://i91.photobucket.com/albums/k304/Major_Sharpe/1-CCF06122012_0000-page-001.jpg

[Crumpp]

Hey check it out......the slots resulted in far superior stall characteristics such that with the CG loaded fully aft, the airfract was spun in a tail heavy load safely!

Wow, that is good information. We I teach spins, the CG must be as far forward as possible for a very good reason.

Normally, a rearward CG spin is extremely dangerous and something to be avoided. To intentionally load the aircraft to its rearward limits and then spin it speaks volumes of the confidence in the slat operation.

Entry into a spin is much easier at any aircraft rearward CG limit but recovery is much more difficult if not impossible because the spin will flatten.

The aircraft showed no tendency to flatten the spin even at a rearward CG.

That pretty much says it all and proves the value of the LE slats.

[Robo.]

Hey check it out......the slots resulted in far superior stall characteristics such that with the CG loaded fully aft, the airfract was spun in a tail heavy load safely!

Wow, that is good information. We I teach spins, the CG must be as far forward as possible for a very good reason.

Normally, a rearward CG spin is extremely dangerous and something to be avoided. To intentionally load the aircraft to its rearward limits and then spin it speaks volumes of the confidence in the slat operation.

Entry into a spin is much easier at any aircraft rearward CG limit but recovery is much more difficult if not impossible because the spin will flatten.

The aircraft showed no tendency to flatten the spin even at a rearward CG.

That pretty much says it all and proves the value of the LE slats.

So in your opinion, what exactly is wrong with the Bf 109 we have in game regarding slats operation and spin recovery?

[Crumpp]

It is way too easy to enter a spin and the stall behavior is too violent.

The account Nztyphoon only relates the aircraft being spun at only at the most aft CG location.

Willy Radinger and Walter Schick's books on the Bf-109 development and testing go into some detail on the spin testing of the Bf-109.

Spin entry and normal recovery was a requirement in the RLM specification for a new fighter that the Bf-109 was designed under. They actually modified the Bf-109V1 for this purpose.

The testing experimented with different size slats as well as pilot deployable and retractable slats. It was a very expensive test because of the modifications required to meet the specification

CG location not only changes stall speeds in any aircraft, it effects both spin entry and recovery. At the forward limits, the aircraft is most difficult to spin and recovers the easiest. Aft CG limit is the opposite, easy to spin and difficult to recover.

Once more, we have two basic categories of CG limits. It is just like the difference between an Aircraft Flight Manual and Pilots Operating Handbook.

When the Pilots Operating Handbook covers only a particular model or type of the aircraft, the Aircraft Flight Manual is very specific to the aircraft.


http://www.differencebetween.net/miscellaneous/difference-between-afm-and-poh/

On every aircraft type there is a CG limits range published in the Type Certificate that covers the particular model or type. Each specific aircraft has a weight and balance sheet the cover the specific limits of that serial number aircraft. Like the Aircraft Flight Manual, that weight and balance is part of the airworthiness of that serial numbered aircraft.

So while a production type will have a set range, not every aircraft in that type will have the same CG limits.



My first airplane had LE slats and it was a hot topic on the owners forums on who could get their airplanes to spin. I had the airplane for 3 years and during that time I got it to spin only three times. It was work each time with the airplane just doing a normal stall. Each time, it was summer time (high density altitude), aft CG, and hard stomping on the rudder to get a spin out of it.

That is normal behavior for LE slats. They just won't spin depending on the CG location and conditions. That is why slats are used as an anti-spin device by engineers!

The Bf-109 exhibits the same normal behavior for LE Slats. It is difficult at best to get it to spin under normal operating conditions

[Crumpp]

I even tried spinning it - according tp the POH it was possible, but
despite several attempts I never managed a convincing spin which was
quite re-assuring!.


http://groups.yahoo.com/group/Rallye/message/2974

LE Slats equipped aircraft are very pedestrian in the stall / spin behavior department by design.

[taildraggernut]

Entering stalls/spins from a gentle deceleration in level flight is a very different affair from an accelerated stall.

[Crumpp]

Entering stalls/spins from a gentle deceleration in level flight is a very different affair from an accelerated stall.


The results of both coordinated and uncoordinated accelerated stall behavior are documented in the RAE report.

See:

4.4. Stalling Tests.

The Bf-109 exhibits typical LE slat equipped behaviors.

When the slots were fully open the aircraft could be turned quite steadily until very near the stall. If the stick was then pulled back a little more the aircraft suddenly shuddered, and either tended to come out of the turn or dropped its wing further, oscillating meanwhile in pitch and roll and rapidly losing height ; the aircraft immediately unstalled if the stick was eased forward. Even in a very tight turn the stall was quite gentle, with no tendency for the aircraft to suddenly flick over on to its back and spin.

When the Me.109 was following the Hurricane or Spitfire, it was found that our aircraft turned inside the Me.109 without difficulty when flown by determined pilots who were not afraid to pull their aircraft round hard in a tight turn. In a surprisingly large number of cases, however, the Me. 109 succeeded in keeping on the tail of the Spitfire or Hurricane during these turning tests, merely because our Pilots would not tighten up the turn suficiently from fear of stalling and spinning.


http://kurfurst.org/Tactical_trials/109E_UKtrials/Morgan.html

[macro]

The second quote you put in there only depends on the pilots not the aircraft.

The 109 does spin out far too easily in game. From what iv read it should drop its nose and wing if in a turn, and not be able to gain speed or height until the stick is returned or pushed foward to regain speed to get the inward parts of the wing out of the stall and return airflow to normal. Should feel like its floating but actually in a controlled fall. Is that right?

[Crumpp]

That is pretty much stall behavior in an LE slat equipped high aspect ratio wing, macro!

The second quote you put in there only depends on the pilots not the aircraft.

Yes, it depends on the pilots human reaction to the behavior of the aircraft at the stall point.

[taildraggernut]

That is pretty much stall behavior in an LE slat equipped high aspect ratio wing, macro!



Yes, it depends on the pilots human reaction to the behavior of the aircraft at the stall point.

But the second quote does not suggest the Spits or Hurries were actually in the stall, rather it suggests the Spit/hurri pilots should have pulled harder like in the first part of the same quote...

it was found that our aircraft turned inside the Me.109 without difficulty when flown by determined pilots who were not afraid to pull their aircraft round hard in a tight turn

that second quote is continuously used out of context, to translate it in simple terms it just means that 'a surprisingly large number of cases' which reads as less than a majority of the time and perhaps even very few times and only when the pursued Spits/Hurries were being flown by less determined pilots then the 109 managed to keep on their tail......why else would they be 'surprised' about it.

So what? the 109 didn't have vicious stall characteristics, it seems apparent that in a 109 you just shouldn't be messing around in that regime of flight due to a being completely disadvantaged in relative turn performance against Spits and Hurries, as Crumpp has confirmed an aircraft with LE slats is unable to maintain performance in tight turns due to high drag.

[macro]

So yes yes spit/hurri turns inside 109 as 109 would stall when trying to turn with the when flying "on the edge" (planes edge not pilots!) but the stall would be a smooth drop of the nose/wing/speed and height. Not a flip over and flat spin which is what we see in game.

Seems simple enough to me and i know jack all about aerodynamics.

In game though, i think the real stall would bemore dangerous than the one they have now. Shooting a 109 floating down would be alot easier than shooting one goin into a spin and overshooting them! 109 pilots use the spin to advantage at the moment as a last resort to get out of gun site.

[raaaid]

109 pilots use the spin to advantage at the moment as a last resort to get out of gun site.

i hate that manouber when im about to shoot someone

its amazing hhow we online rediscovered this techniques

[taildraggernut]

So yes yes spit/hurri turns inside 109 as 109 would stall when trying to turn with the when flying "on the edge" (planes edge not pilots!) but the stall would be a smooth drop of the nose/wing/speed and height. Not a flip over and flat spin which is what we see in game.

Seems simple enough to me and i know jack all about aerodynamics.

In game though, i think the real stall would bemore dangerous than the one they have now. Shooting a 109 floating down would be alot easier than shooting one goin into a spin and overshooting them! 109 pilots use the spin to advantage at the moment as a last resort to get out of gun site.

not quite, as reports show the 109 did drop a wing slightly in a gentle stall (about 10degrees) this is likely to be amplified in a high speed accelerated stall so it is possible to flip, but the spin should not be 'flat', the 109 has a good forward CoG and is likely to be quite easy to recover.

[macro]

not quite, as reports show the 109 did drop a wing slightly in a gentle stall (about 10degrees) this is likely to be amplified in a high speed accelerated stall so it is possible to flip, but the spin should not be 'flat', the 109 has a good forward CoG and is likely to be quite easy to recover.

So if you yanked on the stck and kept it there at high speeds it will flip? Forgive me not up to speed on terminology. Seems like you'd have to do this on purpose for it to happen.

At present, planes are flipping over at low speeds as well as high speeds which according to the reports is wrong.

[macro]

but inline with that, i thought 109 elevators were very heavy at high speeds so this yanking would be impossible?

[taildraggernut]

but inline with that, i thought 109 elevators were very heavy at high speeds so this yanking would be impossible?

in real life yes the elevator was apparently heavy, but how are we able to simulate that? the inputs made on game controllers will be proportional irrespective of speed and you can make full deflection, until they make FF that really simulates control stiffening properly that's going to be a problem, I don't think a software solution that limited deflection at speed would be ideal.

it was only rumoured to be impossible to pull hard on the stick at the very highest speeds if you read the annecdotes about allied pilots forcing 109's to fly into the ground in dives.

[macro]

in real life yes the elevator was apparently heavy, but how are we able to simulate that? the inputs made on game controllers will be proportional irrespective of speed and you can make full deflection, until they make FF that really simulates control stiffening properly that's going to be a problem, I don't think a software solution that limited deflection at speed would be ideal.

it was only rumoured to be impossible to pull hard on the stick at the very highest speeds if you read the annecdotes about allied pilots forcing 109's to fly into the ground in dives.

It seems that without ff for everyone limitimg the elevator movement in game would be the only solution for this. I fly a 109 sometimes and at very fast speeds the elevator has less effect already i think? So is it already modelled? Maybe just needs tweaking?

[Robo.]

My number two said, 'I think you're going to get somebody on your tail,' so I told number one to break away - every man for himself. I went into a steep right-hand turn and then a 109 spun in while chasing me round in the right-hand bend. I was going quite slowly and he tried to get in front of me to shoot and he spun in. He pulled it too hard and he spun in so I put him down. I couldn't claim him because I didn't shoot him.

Above quote from 'Last of the few' by Max Arthur, combat report of a pilot of the 64th Squadron RAF, F/O Michael Wainwright.

[WTE_Galway]

Actually your comments are an exaggeration.


In addition, the installation of the slats was not without penalty. As noted, the slats by deploying, increased the lift generated by the outer section of the wing, but they also generate more drag and reduce the speed of the aircraft. For earlier models of the 109, in particular the E, the chances of the slats deploying assymetrically in a turn was a factor, which was noted to cause aileron snatching and which could cause the aircraft to change direction without the pilot's intention.

Hence the often quoted anecdotal comments by Luftwaffe veterans that the "better" 109E pilots would deliberately alternate between slats in and out, using the slats temporarily to tighten the turn or pull lead and then almost immediately easing on the stick to regain lost speed.


- Erwin Leykauf, German fighter pilot, 33 victories. Source: Messerschmitt Bf109 ja Saksan Sotatalous by Hannu Valtonen; Hurricane & Messerschmitt, Chaz Bowyer and Armand Van Ishoven:

http://www.virtualpilots.fi/feature/articles/109myths/

"The Bf 109s also had leading edge slats. When the 109 was flown, advertently or inadvertently, too slow, the slats shot forward out of the wing, sometimes with a loud bang which could be heard above the noise of the engine. Many times the slats coming out frightenened young pilots when they flew the Bf 109 for the first time in combat. One often flew near the stalling speed in combat, not only when flying straight and level but especially when turning and climbing. Sometimes the slats would suddenly fly out with a bang as if one had been hit, especially when one had throttled back to bank steeply. Indeed many fresh young pilots thought they were pulling very tight turns even when the slats were still closed against the wing. For us, the more experienced pilots, real manoeuvring only started when the slats were out. For this reason it is possible to find pilots from that period (1940) who will tell you that the Spitfire turned better than the Bf 109. That is not true. I myself had many dogfights with Spitfires and I could always out-turn them.
One had to enter the turn correctly, then open up the engine. It was a matter of feel. When one noticed the speed becoming critical - the aircraft vibrated - one had to ease up a bit, then pull back again, so that in plan the best turn would have looked like an egg or a horizontal ellipse rather than a circle. In this way one could out-turn the Spitfire - and I shot down six of them doing it. This advantage to the Bf 109 soon changed when improved Spitfires were delivered."

[Crumpp]

they also generate more drag and reduce the speed of the aircraft

Right....

What you don't understand is that speed reduction reduces radius and improves turn performance until Va is reached.

The airplane that slows down the fastest to Va will win the instantenous turn fight.

Hence the often quoted anecdotal comments by Luftwaffe veterans that the "better" 109E pilots would deliberately alternate between slats in and out, using the slats temporarily to tighten the turn or pull lead and then almost immediately easing on the stick to regain lost speed.

Exactly.

He is flying a yo-yo and not a constant altitude turn. By combining the climb advantage of the Bf-109 at low speed climbs with the advantage of the slats, Erwin Leykauf is defeating the constant altitude turn performance advantage of the Spitfires he is fighting.

In most cases this steep climb at low airspeed was the only manceuvre whereby the Me.109 pilot could keep away from the Hurricane or Spitfire.

http://kurfurst.org/Tactical_trials/109E_UKtrials/Morgan.html

The Bf-109 and Spitfire are about as equal a match of dogfighters as one can get.

Above quote from 'Last of the few' by Max Arthur, combat report of a pilot of the 64th Squadron RAF, F/O Michael Wainwright.

Are you fishing and this is bait?

What was the condition of the Bf-109 and the pilot? Was the aircraft damaged? Was the pilot wounded? Was it a real spin or did the pilot pass out??

In otherwords, it is an interesting story but without the details definately does not contradict the findings of the RLM or the RAE.

[Al Schlageter]

What was the condition of the Bf-109 and the pilot? Was the aircraft damaged? Was the pilot wounded? Was it a real spin or did the pilot pass out??

Would a pilot in a damaged a/c or being wounded not try to 'get the heck out of Dodge' and not be the aggressor in combat?

Must have been one heck of a G he was pulling to pass out, especially in a 109.

[NZtyphoon]

Would a pilot in a damaged a/c or being wounded not try to 'get the heck out of Dodge' and not be the aggressor in combat?

Must have been one heck of a G he was pulling to pass out, especially in a 109.

The first is a hard one to answer; that really depends on individuals and - in some cases - their indoctrination. Japanese pilots, for example often attacked when wounded or in damaged aircraft; one example was an A6M pilot during the Pearl Harbor attacks who tried to "body crash" a hanger because his aircraft was damaged and (I think) he was wounded(?). Nicholson, who won the V.C during the B of B, is another example of a pilot who chose to attack, albeit he was presented with the opportunity, while in desperate circumstances.

[Robo.]

Are you fishing and this is bait?

What was the condition of the Bf-109 and the pilot? Was the aircraft damaged? Was the pilot wounded? Was it a real spin or did the pilot pass out??

In otherwords, it is an interesting story but without the details definately does not contradict the findings of the RLM or the RAE.

No I am not fishing :o I was just reading that book and came across several instances of 109 pilots spinning in while trying to follow the RAF fighters in a tight turn.

Of course it does not say anything about the skill of the pilot(s) or state of the pilot and the plane. Maybe the plane wasn't a Bf 109 at all. Just remembered this thread and thought it was an interesting find - especially how you claim it was pretty much unspinnable because it had slats. I believe they helped a great deal but you'd have to be in perfect control of your plane. Same in the game - if you're in control and have experience in 109, you won't spin her. Good 109 pilots can be often seen maneuvring with Spitfires, all that you describe - yo-yos and use of vertical maneuvers - is already possible in the sim. I agree the Emil as too hard to recover but I don't find it too easy to spin. You can tell if your opponent is good and in control of his plane if he flies clean and makes tight turns (e.g. scissors / hammerheads) and does not drop his wing and loses control every now and then. I find that very good actually and in match with combat reports. 109 is not easy to master and requires experienced pilot to be flown to its full potential. RAF planes are easier but also, obviously, you need experience to fly them on the very edge.

[taildraggernut]

Right....

What you don't understand is that speed reduction reduces radius and improves turn performance until Va is reached.

The airplane that slows down the fastest to Va will win the instantenous turn fight..

Right

which still puts the Spitfire at advantage (which you have confirmed yourself) having extensively reminded us of how longitudinaly unstable the Spit is and how easy it was to put load on due to it's sensitivity in pitch it is going to be the best at bleeding off that energy quickly, like you said before the 109 really must keep speed up in order to have a turn advantage over the Spit.



Exactly.

He is flying a yo-yo and not a constant altitude turn. By combining the climb advantage of the Bf-109 at low speed climbs with the advantage of the slats, Erwin Leykauf is defeating the constant altitude turn performance advantage of the Spitfires he is fighting.

Yes....assuming the Spitfire remains in a level turn, in which case the Spitfire is simply making a mistake rather than suffering a disadvantage, the Spit has the option to extend away by split 's' and dive and wait for the 109 to chase and pull him into another attempt at turning.


Are you fishing and this is bait?

What was the condition of the Bf-109 and the pilot? Was the aircraft damaged? Was the pilot wounded? Was it a real spin or did the pilot pass out??

In otherwords, it is an interesting story but without the details definately does not contradict the findings of the RLM or the RAE.

it seems overly paranoid of you to view this with such scepticism, it is simply an account of a 109 making a piloting mistake and spinning, nothing sinister.

[Crumpp]

taildraggernut


Trolling??

[Crumpp]

especially how you claim it was pretty much unspinnable because it had slats.


Spin resistant is not the same as unspinnable.

Spin resistant is a specific term in aeronautical engineering. The problem is not my language but the fact it is being interpretated without the realization it is a defined measured condition.



At the applicant's option, the airplane may be demonstrated to be spin resistant by the following:

(i) During the stall maneuver contained in § 23.201, the pitch control must be pulled back and held against the stop. Then, using ailerons and rudders in the proper direction, it must be possible to maintain wings-level flight within 15 degrees of bank and to roll the airplane from a 30 degree bank in one direction to a 30 degree bank in the other direction;

(ii) Reduce the airplane speed using pitch control at a rate of approximately one knot per second until the pitch control reaches the stop; then, with the pitch control pulled back and held against the stop, apply full rudder control in a manner to promote spin entry for a period of seven seconds or through a 360 degree heading change, whichever occurs first. If the 360 degree heading change is reached first, it must have taken no fewer than four seconds. This maneuver must be performed first with the ailerons in the neutral position, and then with the ailerons deflected opposite the direction of turn in the most adverse manner. Power and airplane configuration must be set in accordance with § 23.201(e) without change during the maneuver. At the end of seven seconds or a 360 degree heading change, the airplane must respond immediately and normally to primary flight controls applied to regain coordinated, unstalled flight without reversal of control effect and without exceeding the temporary control forces specified by § 23.143(c); and

(iii) Compliance with §§ 23.201 and 23.203 must be demonstrated with the airplane in uncoordinated flight, corresponding to one ball width displacement on a slip-skid indicator, unless one ball width displacement cannot be obtained with full rudder, in which case the demonstration must be with full rudder applied.

http://www.law.cornell.edu/cfr/text/14/23.221

[taildraggernut]

Trolling??

explain?

[Robo.]

Spin resistant is not the same as unspinnable.

Spin resistant is a specific term in aeronautical engineering. The problem is not my language but the fact it is being interpretated without the realization it is a defined measured condition.

Ok, but you didn't use the term spin resistant in your post (No 61 for instance.) :)

Again, they act like training wheels on a bicycle. In otherwords, it should be EXTREMELY difficult to spin the aircraft and very easy to recover.

The advantage of the slats is in preventing spins. Find a report on the spin characteristics of the Bf-109.

There is an engineering reason there is not one.

There were obviously quite a few 109 pilots who didn't know their aircraft was spin resistant and spun in making a piloting mistakes.

[Crumpp]

There were obviously quite a few 109 pilots who didn't know their aircraft was spin resistant and spun in making a piloting mistakes.


Where is that proof and in comparison to what?

No 61 for instance

Is absolutely true, did you read the spin testing by Mtt? Did you read the RAE evaluation on flying qualities?

What is the problem? Is something difficult to interpret?

[Robo.]

What is the problem?

That's what I am asking - what is the problem exactly with the 109 in game? How much different should it be? Which maneuveurs do you find difficult to complete and you spin. Which situations exactly make you spin your 109.

I agree to the characteristics posted by you or Kurfurst, the 109 should be stable and easy to fly in general, but you need to be in good control. Good 109 pilots in this sim only very rarely spin their ride, the not so good one do sometimes. It works pretty well. It is actually easy to fly if you know what you're doing, you won't spin her, simple as that.

Once the mistake is made (e.g too much foot in the wrong moment) the spin can be violent (but not always) and it's difficult to recover unles you're in good control of your 109. If you are you, won't spin her to start with. Maybe it's really the matter of FF as I can 'feel' the a/c and the spin coming. I don't know... All I see in the game is experienced 109 pilots won't spin at all.

To me it seems you were saying the 109 would not spin even if the pilot made a mistake. I was not so sure about that. Of course I've read all the reports, no worries.

[zipper]

I'll just jump in here and say stalls for all aircraft are easily the least realistic part of the game in that they always drop instantly into a spin, and the subsequent spin is almost always unrealistically difficult to recover from. This includes the P-39. With effort one might stop the spin from going too far but this is hardly realistic. Individual stall/spin characteristics are also missing.

[Crumpp]

To me it seems you were saying the 109 would not spin even if the pilot made a mistake.

I think you are just trolling.

Honestly, slats are an anti spin device.

So what do you think an airplane equipped with an anti-spin device would require good flying to prevent a spin?

Or do you think the training wheels would work to keep the bicycle upright so it does not tip over and fall?

:rolleyes:

[Robo.]

I think you are just trolling.

Honestly, slats are an anti spin device.

So what do you think an airplane equipped with an anti-spin device would require good flying to prevent a spin?

Or do you think the training wheels would work to keep the bicycle upright so it does not tip over and fall?

:rolleyes:

I am not sure what you mean with me 'trolling' - could you please describe maneuveurs you do in the Bf 109 that you find it difficult not to spin her?

I completely understand what you're saying and I know what the slats do. The plane would still spin if you make a piloting mistake though - and that's what I see most of the time online - 109 suddenly turning too tight (attacking or breaking) and spinning in. 109 climbing, realising there is a threat behind them and pulling hard a lot and too quickly - spin. Sometimes you can tell he's looking back at you and makes a mistake with the rudder. Or 109 attacking at high speed, I break hard, he tries to get guns on me with plenty of rudder = flips wing. Beautiful high speed stall, but if he's good he regains control very quickly, although that piloting error will cost him lots of E.

I fly the 109 in this sim very often and I honestly don't find it being 'unforgoving' or going into 'violent spin' without warning as some say. I wonder why is that, my guess would be FF joystick or simply the fact I am flying her smoothly. There is lots of warning - FF, buffeting acompanied with specific sound. If someone pulls the stick like it's a toilet plunger of course he will spin her.

So if you could describe maneuveurs where the 109 spins while it shouldn't that would be great. I am not 'trolling', I am simply very interested.

[Al Schlageter]

do you think the training wheels would work to keep the bicycle upright so it does not tip over and fall?

:rolleyes:

Back in the day my brother had training wheels on his bicycle and he tipped it over and fell many times.

[taildraggernut]

I think you are just trolling.

Honestly, slats are an anti spin device.

So what do you think an airplane equipped with an anti-spin device would require good flying to prevent a spin?

Or do you think the training wheels would work to keep the bicycle upright so it does not tip over and fall?

:rolleyes:

I really can't believe you typed this publically, slats are NOT I repeat NOT anti spin devices, slats are not anti-anything devices, they simply allow you to hang on to laminar flow air at slightly higher angles of attack but if you exceed that angle a slatted wing is stalled just like any other and subject to the same pitfalls.

[NZtyphoon]

Image removed.

Please leave the thread if want to troll like that.


++Moderated++

[Crumpp]

they simply allow you to hang on to laminar flow air

Experts....have fun

:rolleyes:

[taildraggernut]

Experts....have fun

:rolleyes:

So.....how exactly does the fact that the venturi effect caused by the 'slot' created by an open slat which re-energises the boundary layer of air over the wing maintaining smooth flow (sometimes called laminar http://en.wikipedia.org/wiki/Laminar_flow ) prevent you from understanding what I meant?

While we're discussing this so civilly perhaps you could explain to us all this magical phenomenon that prevents a slatted wing from stalling once it has gone beyond its allowable angle of attack?

[Crumpp]

I really can't believe you typed this publically, slats are NOT I repeat NOT anti spin devices, slats are not anti-anything devices, they simply allow you to hang on to laminar flow air at slightly higher angles of attack but if you exceed that angle a slatted wing is stalled just like any other and subject to the same pitfalls.

While we're discussing this so civilly

You are not discussing anything civilly...you are just making insults.

So.....how exactly does the fact that the venturi effect caused by the 'slot' created by an open slat which re-energises the boundary layer of air over the wing maintaining smooth flow

First of all, you do not understand the fundamentals of LE slat aerodynamics.

Quit using wikipedia as your source. It is not credible and in this case is just plain wrong as the author does not understand boundary layer mechanics.

In boundary layer mechanics, we have two portions, laminar and turbulent.

Laminar flow is the last thing you want on the outboard portion in a stall. Laminar flow is low energy. That is why it is low drag AND subsequently, low lift.

Slats work by increasing turbulent flow not laminar flow. Turbulent flow portion of the boundary layer is high energy and high lift!

Flow separation from the top of the airfoil, i.e., stall, results from the loss of the kinetic energy in the boundary layer due to viscous shear and an adverse pressure gradient. A turbulent boundary layer is better able to delay flow separation than a laminar boundary layer because of the higher energy associated with the turbulence. For this reason it is better to have a turbulent boundary layer over the airfoil. Vortex generator are put on the top surface of a wing for the purpose of forcing the early transition of the boudary layer to turbulent.

optfly.iaa.ncku.edu.tw/aftdesgn/lect16.pdf

The laminar flow is not the purpose of the slats, it is the increase in turbulent flow boundary layer which delays the onset of the stall.

No stall = NO SPIN! Hence, the spin resistance found in slats and the reason engineers used them as an early anti-spin device.

http://imageshack.us/a/img856/5310/spinresistance.th.jpg (http://imageshack.us/photo/my-images/856/spinresistance.jpg/)

http://imageshack.us/a/img846/4238/spinresistance2.th.jpg (http://imageshack.us/photo/my-images/846/spinresistance2.jpg/)


They are spin resistant because they allow for control inputs that would normally result in a spin. One can easily see this in the RAE report.

[Glider]

No stall = NO SPIN! Hence, the spin resistance found in slats and the reason engineers used them as an early anti-spin device.

While there are a number of devices that delay the stall, in the end if you push it too far, you will stall.

Of course a stall by itself doesn't result in a spin.

It is very, very rare to find an aircraft of any type that cannot spin. I only have experience of one type of Glider that could fit that bill and am confident that aircraft of the 1930/40 era would have to be specially designed.
The Me 109 isn't one of those aircraft. I don't disagree when people say that it was a difficult aircraft to spin and that the model is wrong, but go to the extream and it will depart.

[taildraggernut]

You are not discussing anything civilly...you are just making insults.

I am being very civil, if you have taken insult from that then I believe you are a touch over-sensitive......I believe that comes with instability ;)


First of all, you do not understand the fundamentals of LE slat aerodynamics.

Now that is an insult. :rolleyes:

Quit using wikipedia as your source. It is not credible and in this case is just plain wrong as the author does not understand boundary layer mechanics.

Oh come now, that 'Stop using Wikipedia as a source' is too cliche, used as a cheap attempt at discrediting in many internet debates, there is nothing wrong with that article.

In boundary layer mechanics, we have two portions, laminar and turbulent.

Laminar flow is the last thing you want on the outboard portion in a stall. Laminar flow is low energy. That is why it is low drag AND subsequently, low lift.

Slats work by increasing turbulent flow not laminar flow. Turbulent flow portion of the boundary layer is high energy and high lift!.

optfly.iaa.ncku.edu.tw/aftdesgn/lect16.pdf

The laminar flow is not the purpose of the slats, it is the increase in turbulent flow boundary layer which delays the onset of the stall..

http://history.nasa.gov/SP-4103/app-f.htm

I suggest you read this article, it will help you understand boundary layers and the effect of skin friction and subsequent separation due to turbulence.

Extracts from the article......I hope NACA are a more credible source for you rather than wikipedia.

The flying qualities of wings can be enhanced in two ways, and boundary-layer control can help in both. The first is to decrease drag; the second is to increase lift. The most desirable way to decrease drag is to maintain laminar flow within the boundary layer and prevent a transition to turbulent flow.

Over a normal wing, the boundary layer remains laminar over only a small portion of the wing chord before breaking up into turbulent flow. The area of turbulent flow experiences significantly greater skin-friction drag than the laminar flow.3

Finally, however, the boundary layer on the upper surface breaks free of the wing altogether, reducing lift drastically. This is known as stalling. If the boundary layer can be kept from separating, the maximum lift of the aircraft can be increased, an important consideration in increasing takeoff-weight capacity and reducing landing speed. Furthermore, the same energizing of the boundary layer that delays separation can also help to maintain the boundary layer in fast laminar flow, increasing total lift even at low angles of incidence.


No stall = NO SPIN! Hence, the spin resistance found in slats and the reason engineers used them as an early anti-spin device.

They are spin resistant because they allow for control inputs that would normally result in a spin. One can easily see this in the RAE report.

Spin resistance is not anti-spin.....anti would suggest there is complete protection and that is simply not the case.

in case you were doubtfull that slats are a boundary layer control device heres more stuff from NACA..

http://history.nasa.gov/SP-367/chapt4.htm

Slots.- The maximum coefficient of lift may be increased through the use of a slot formed by a leading-edge auxiliary airfoil called a slat. Figure 63(a) illustrates the operating principle. When the slot is open, the air flows through the slot and over the airfoil. The slot is a boundary-layer control device and the air thus channeled energizes the boundary layer about the wing and retards the separation. The airfoil can then be flown at a higher angle of attack before stall occurs and thus get a higher...

Boundary-layer control.- Another method of increasing CL,max is by boundary-layer control. The idea is to either remove the low-energy segment of the boundary layer and let it be replaced by high-energy flow from above or by adding kinetic energy to the boundary layer directly. Both of these methods maintain a laminar flow for a longer distance over the airfoil, delay separation, and allow one to get a larger angle of attack before stall occurs, and thus a higher CL,max The slot was shown to be one means of passing high-energy flow over the top surface of a wing.


Flow separation from the top of the airfoil, i.e., stall, results from the loss of the kinetic energy in the boundary layer due to viscous shear and an adverse pressure gradient. A turbulent boundary layer is better able to delay flow separation than a laminar boundary layer because of the higher energy associated with the turbulence. For this reason it is better to have a turbulent boundary layer over the airfoil. Vortex generator are put on the top surface of a wing for the purpose of forcing the early transition of the boudary layer to turbulent.

Vortex generators are using a completely different method, the 'turbulence' they are creating is simply in the form of vortices to draw in energy to a portion of the airflow.

http://www.aerospaceweb.org/question/aerodynamics/q0228.shtml

The advantage of wing devices that create vortices is that a vortex adds energy to the airflow and increases its forward momentum. This momentum encourages the airflow to remain attached to the surface of the wing at higher angles of attack than it would otherwise. As a result, the wing is able to continue generating lift in conditions where it would have stalled. This behavior is particularly advantageous on high-performance military aircraft that need to be extremely maneuverable at high angles of attack in combat. The advantage for commercial airliners is increased safety since the plane is less likely to experience a wing stall during critical stages of flight like takeoff and landing.

The method by which these vortex devices work can be better understood by studying the above diagram of vortex generators on a wing. A vortex generator is much like a miniature wing perpendicular to the main wing. These generators are mounted at an angle of attack to the airflow over the wing so that each creates a vortex off the exposed tip, much like a trailing vortex created by a wing. The above example shows vortex generators aligned in opposite directions so that the vortices they create rotate opposite to each other. These vortices serve to increase the speed of the downstream airflow so that it is "entrained" to follow the sharp curvature of the deployed flap and remain attached to its surface. Otherwise, the airflow would likely separate from the flap causing a loss of lift.

http://www.aerospaceweb.org/question/aerodynamics/vortex/generator.jpg







Now hopefully you will be able to explain to us all exactly what are the mechanics involved in complete stall/spin avoidance once a slatted wing has been taken beyond it's maximum angle of attack?

[Hood]

Now hopefully you will be able to explain to us all exactly what are the mechanics involved in complete stall/spin avoidance once a slatted wing has been taken beyond it's maximum angle of attack?

I haven't read Crump literally.

I've read it as:

"Slats are an anti-spin device in that they extend to prevent the wing stalling, thus giving a pilot a chance to avoid a spin when non-operation of the slats would cause a stall and a possible spin. They also slow down the stall so there is a greater chance that the stall does not result in a spin."

Like ABS. It's a device to stop you skidding. It doesn't mean it'll stop you skidding in every situation though.

Who was the Finnish 109 pilot who said they don't know what happened in a stall/spin because they never stalled/spun?

And isn't this getting away from the original topic, which is do they have any effect in this game?

Hood

[taildraggernut]

Slats are or should I say were in the 1930's/40's primarily a device to improve low speed handling qualities and cannot be anti-spin, the only true form of anti-spin is propper handling of the aircraft, slats simply make the behaviour at stall more benign but their effectiveness has a cut-off point beyond which there is nothing to provide these protections, in high speed manouvering the chances of exceeding those limits are much higher.

I believe the relevance of these extended discussions to the original subject is to do with what some people are expecting from the effect of slats, the original question I believe is almost impossible to answer without being able to disable the slats, and that is subject to whether they are actually coded as separate devices as opposed to the FM being modelled with simple wings that reflect performance with slats.

[Crumpp]

Slats are an anti-spin device. What is so hard to understand about it?

If you have ever flown an aircraft with slats, you can immediately notice the difference in slow flight and stall behaviors.

Here is the slats in my old airplane:

http://www.youtube.com/watch?v=-vbqgfjyW2Q

[taildraggernut]

Slats are NOT an anti-spin device...what is so hard to understand about it?

I have flown aircraft with slats....have you?

you can immediately notice the difference in slow flight and stall behaviors.

Right, now ask someone to make a video of the same aircraft doing high speed stalls taking the aircraft beyond the limiting angle of attack and we can compare the results.

[Crumpp]

Now hopefully you will be able to explain to us all exactly what are the mechanics involved in complete stall/spin avoidance once a slatted wing has been taken beyond it's maximum angle of attack?

Now your trying to morph the discussion into something else.

You keep confusing "anti-spin" device with a spin resistant airplane.

Spin resistant airplanes employ anti-spin devices such as wing cuffs, LE slats, and slots to build spin resistance.

What you are missing is the ability to put it all together. If we were talking about the entire wing being able to stall at once, then the airplane will enter a spin.

It takes a lot of work to do that in a Bf-109 by design.

First of all, only the outboard portion of the wing receives the benefit of the slats in the Bf-109.

In any airplane, the most desirable stall progression is for the wing root to stall first and the tips to stall last.

This leaves the wingtip unstalled and the ailerons effective.

The next feature of the slats is the automatic deployment. Air pressure operates the slats and they will deploy to exactly the position the wing requires for a given condition. That is why in a skid, they will asymmetrically deploy. For some reason, gamers tend to think "asymmetrical" deployment of the slats is a bad thing, it is not unless there is a malfunction of the slats. Instead, the slats deploy to exactly what the wings need automatically and unless the pilot looks out and is somehow psychologically disturbed by seeing the slats out at different amounts, the airplane skids normally without noticeable effect.

The last feature in the Bf-109 is the elevator control is set up so that with the wing root stalled, the pilot cannot continue to raise the nose. The Socata Rallye is designed that way as are many aircraft.

The designer uses control design to keep the pilot safe by limiting the moment the elevator can produce about the CG. This way, the wing tips remain effective throughout the stall. Cessna does this in a C-172 as well. Again, it is a common feature in a properly designed aircraft.
Now, Mtt did have to demonstrate spin entry and normal recovery in the Bf-109. They did this by adversely loading the aircraft to its rearward CG limit and modifying the slats to be pilot controlled. In other words, the airplane was at its rear most CG limit and the pilot could lock the slats so they did not deploy.

[Crumpp]

I have flown aircraft with slats....have you?


:confused:

That is my airplane and I am at controls in the film.

:rolleyes:

[taildraggernut]

:confused:

That is my airplane and I am at controls in the film.

:rolleyes:

if you say so, hardly evidence though is it, a medium level turn pumping the elevator to make slats deploy.

Now your trying to morph the discussion into something else.

You keep confusing "anti-spin" device with a spin resistant airplane.

I'm pretty sure I'm not the confused one in this discussion.....anyway...carry on.

Spin resistant airplanes employ anti-spin devices such as wing cuffs, LE slats, and slots to build spin resistance.

Can I stop you here again....sorry but anti-spin would mean spin proof, resistance implies it's not proof, you know like waterproof vs water resistant, none of those devices can be considered a proof against spinning.

What you are missing is the ability to put it all together. If we were talking about the entire wing being able to stall at once, then the airplane will enter a spin.

It takes a lot of work to do that in a Bf-109 by design.

............


The last feature in the Bf-109 is the elevator control is set up so that with the wing root stalled, the pilot cannot continue to raise the nose. The Socata Rallye is designed that way as are many aircraft.

The designer uses control design to keep the pilot safe by limiting the moment the elevator can produce about the CG. This way, the wing tips remain effective throughout the stall. Cessna does this in a C-172 as well. Again, it is a common feature in a properly designed aircraft.
Now, Mtt did have to demonstrate spin entry and normal recovery in the Bf-109. They did this by adversely loading the aircraft to its rearward CG limit and modifying the slats to be pilot controlled. In other words, the airplane was at its rear most CG limit and the pilot could lock the slats so they did not deploy.

and here finally (in bold) is the first bit of credible understanding you show, but subsequently you have exposed the real protection in this case to come from blanking the elevator, you do realise you have just excluded the slats completely from the equation, given that you could design an aircraft without slats that puts the elevator into the turbulent flow and it would have exactly the same pitch limiting effects, the side effect of that is you seriously limit the manouverability......is this starting to make sense or what?

wait a minute...MTT had to lock the slats but still had to put the CoG back too? why bother with the CoG? sounds to me like there was some crazy black magic going on with that aircraft and spin resistance had nothing to do with slats.....more and more NZTyphoons recently deleted comedy poster is making sense.

[Glider]

I think you are just trolling.

Honestly, slats are an anti spin device.

So what do you think an airplane equipped with an anti-spin device would require good flying to prevent a spin?

Or do you think the training wheels would work to keep the bicycle upright so it does not tip over and fall?

:rolleyes:

The logical result of your position is that aircraft with slats cannot spin as they are anti spin devices. Are you really sure that is what you are saying?

As a CFI you cannot seriously say that is a fact. The slats are a device that delay the stall, but pushed too far will stall. It doesn't stop a spin.

The Glider I flew that cannot be spun is a K21, it doesn't have slats, but it certainly could be stalled. If anyone is interested we used K13's for spin training.

[raaaid]

from my paragliding lessons i learnt an stall is not an spin but falling like a rock due to lose of dynamic sustentation by going to slow

in the past someone would say that with stalls off the game is more realistic(il246) which is an interesting point

[*Buzzsaw*]

Salute

For whatever reason, this is a pattern which we see again and again on these boards.

With the same protagonist on one side.

I believe Crrump has some valid points, however the insistence on an 'all or nothing' argument is not useful.

For the record, I understand the following. Feel free to correct me.

1) The low wing area, hence high wing loading on the 109 was an attempt by the designer to reduce weight and drag to increase overall speed and climb. This fit with the most important goal listed by the RLM, ie. an interceptor which was light enough to climb to altitude quickly, and fast enough to catch the modern stressed skin monoplane bombers which were beginning to arrive in the early '30's. Turn capability was very much of secondary importance. At the time of the competition, newer bombers were faster than the existing generation of biplane fighters which were common at the time. A secondary preferred requirement of the competition was a fighter which could be easily transported by rail. The removable wings on the 109 were a design feature intended to satisfy this requirement. At the same time, these removable wings created another issue, that being the requirement to attach the undercarriage to the fuselage, with the result being the off camber wheels, with their inherent instability in landing. This instability would be exacerbated in high speed landings.

2) As a result of the small wing area the aircraft, if equipped with standard slat-less wings, and without the modern flaps which were an innovative part of the 109, would have had a very high stall speed. The stall speed for a 109 without slats and flaps can be estimated as roughly the speed at which the slats on the historical aircraft open without the flaps down. In the case of the 109E3, the RAE test showed with flaps up, the slats opening at 120.5 mph, 25 mph higher speed than the 95.5 mph actual stall speed. With flaps down, slats opened at 100.5, 18.5 mph faster than the 88.5 mph stall speed with flaps down. A landing at 120.5 mph would by the standards of 1934, be unacceptably high. Especially with the wheel instability issue. Messerschmidt obviously understood the issues of high speed stall brought with his high wingloading, hence the installation of the slats and modern design flaps, with their improvements to low speed stall performance.

http://www.kurfurst.org/Tactical_trials/109E_UKtrials/Morgan_files/image011.jpg

The primary goal of the slats and the flaps was to reduce stall speed to a manageable low speed, and thus allow safe controllable landings on the off camber undercarriage.

A secondary benefit was the improved low speed maneuverability, and lowered stall speed the slats gave with landing flaps up. This was not the primary goal of the devices, it was welcome additional benefit.

To suggest the primary design goal of the slats was a 'spinless' aircraft is stretching the point considerably, and is not supported by the historical documentation.

At the same time, there is no doubt the slats did give much more benign stall characteristics to the 109 than many other aircraft. Under the control of a pilot who reacted appropriately to a stall, there was very little chance of a spin occurring. Under the control of a pilot who ignored the requirements for stall recovery, the aircraft was undoubtably capable of entering a spin. Spinless?? I don't think so. Easy to recover from a stall? Yes.

Finally, this entire thread has gone so far off track in order to satisfy the viewpoints of posters that it is missing the original point.

Does the game 109 replicate the characteristics of the historical aircraft?

No, it clearly doesn't. Among other mismodelled characteristics, the tendency of the 109 to easily enter, and be difficult to recover from, spins, is clearly wrong.

[NZtyphoon]

First is an abridged lecture given by Frederick Handley Page describing the operation of what are, in fact, called automatic slots - the slats are simply the moving airfoil sections.

http://i91.photobucket.com/albums/k304/Major_Sharpe/1928-0471-page-001.jpg

http://i91.photobucket.com/albums/k304/Major_Sharpe/1928-0472-page-001.jpg

and, from 1939:

http://i91.photobucket.com/albums/k304/Major_Sharpe/1939-H-Pslats-page-001-1.jpg
http://i91.photobucket.com/albums/k304/Major_Sharpe/1939-1942-page-001-1.jpg

Operative words "the slot could be made to open at a pre-determined angle of incidence....make the wing stable at a large angles of incidence and so ensuring that, although the aircraft would stall, it would not "drop a wing" and go into a spin."

Therefore, automatic slots are not fully effective at all AOAs at low speeds, let alone combat speeds - which, BTW, have not been mentioned - until the wing has reached a certain, pre-set angle of incidence. What was the pre-determined angle of incidence for the 109? And at what speeds did the slots open?

Effectiveness v basic airfoil:

http://i91.photobucket.com/albums/k304/Major_Sharpe/1933-0454-page-001a.jpg

[*Buzzsaw*]

First is an abridged lecture given by Frederick Handley Page describing the operation of what are, in fact, called automatic slots - the slats are simply the moving airfoil sections.

http://i91.photobucket.com/albums/k304/Major_Sharpe/1928-0471-page-001.jpg

http://i91.photobucket.com/albums/k304/Major_Sharpe/1928-0472-page-001.jpg

and, from 1939:

http://i91.photobucket.com/albums/k304/Major_Sharpe/1939-H-Pslats-page-001-1.jpg
http://i91.photobucket.com/albums/k304/Major_Sharpe/1939-1942-page-001-1.jpg

Operative words "the slot could be made to open at a pre-determined angle of incidence....make the wing stable at a large angles of incidence and so ensuring that, although the aircraft would stall, it would not "drop a wing" and go into a spin."

Therefore, automatic slots are not fully effective at all AOAs at low speeds, let alone combat speeds - which, BTW, have not been mentioned - until the wing has reached a certain, pre-set angle of incidence. What was the pre-determined angle of incidence for the 109? And at what speeds did the slots open?

Effectiveness v basic airfoil:

http://i91.photobucket.com/albums/k304/Major_Sharpe/1933-0454-page-001a.jpg

Most of the questions you are asking have been answered by the chart in the post above yours.

The chart you have provided showing effectiveness vs basic aerofoil is quite dated, and I am not sure it can be taken as effective.

NACA did a later, more comprehensive study of wing lift devices, including leading edge slats, I have a copy somewhere in my files, and there should be a link at the NACA site.

[NZtyphoon]

The chart you have provided showing effectiveness vs basic aerofoil is quite dated, and I am not sure it can be taken as effective.

The intention is to show some of the literature that was around at the time the H-P slot was invented. The table dates back to 1933 so, of course it predates the NACA data, but it was the type of material that would have been available at around the time that the Bf 108 and 109 were under development.

What I should have asked is at what combat speeds were slots effective? The data shows they opened at speeds ranging between 90-120.5 mph, but I doubt that a 109 in combat slowed to those speeds.

[robtek]

Afaik the deployment of the slats is dependent on the aoa, not the speed, so the slats might very well deploy in a tight turn at combat speed.

[taildraggernut]

Afaik the deployment of the slats is dependent on the aoa, not the speed, so the slats might very well deploy in a tight turn at combat speed.

Yes robtek is correct here, slats operate as a function of AoA and that remains a fixed quantity but there is means of calculating what speeds slats would open under certain loads.

[TomcatViP]

At any time Lift(L) equate Weight (mg)

Hence during a turn at X nbr of g the total lift of the plane is L=Xmg

Let's assume the simple flows theo of thin wing with no camber (flat wing) where CL=2Pi()Alpha where CL is the coef of Lift (L/0.5roV²) with V the speed of the air and ro the volumic mass of the air

Then Alpha=Xmg/(2Pi()*0.5roV²) and V(alpha)== SQRT(2Xmg/Pi()roAlpha)

hence for a given alpha at (let's say) 1.5 stall speed and 1g, the speed at witch slats will deploy is augmented as the square of the G ratio.

hence at 4G the speed is the double. AT 8g, teh speed is three time more.

Etc.. etc..

Regarding the 109:

-Slats are deployed in front of the ailerons in order to keep ctrl at stall conditions. No wing drop (and full airflow around the pouter portion of teh wing), no asymmetric stall . Hence no spin. This is why Crumpp refer it as an anti-spin device. So Crumpp was right (again...)

-The 109 undercarriage was not build that way to facilitate it's shipping via train (at least not only - but this is the first time I think that I have to read it). It was made to make assembly easier with the wing being plugged onto the fuselage. Remind that Bf (and not Mtt at the time ;) ) did not have the production facilities that would be needed for such a big order by the RLM. Many parts were subcontracted (heinkel etc...) and had to be moved from one facility to another. Having the fuselage "crated" by its own undercarriage as soon as possible facilitate the production and made the wing stronger for a given weight (and Mr Messer was addicted to weight reduction as any good eng shld be!).

- Providing early 1930's document is a bit risky to prove a given argument in aero term. As I hve alrdy said many time there was a revolution in 1935. And this flow slowly ard the globe from Germany then USA and all obver the globe after 1945.

[TomcatViP]

Humm forgot the wing surface above. As it is a cte in the relation V=f(alpha) there is no impact on the overall result.

And it seems I was way too short in my explanation abt the revolution in aero theo in 35. For one time NZ, don't bounce me too hard on tht one :rolleyes:

[Robo.]

-Slats are deployed in front of the ailerons in order to keep ctrl at stall conditions. No wing drop (and full airflow around the pouter portion of teh wing), no asymmetric stall . Hence no spin. This is why Crumpp refer it as an anti-spin device. So Crumpp was right (again...)

Wurster slowed down, pushing back the throttle to idle. As the Bf 109V2 slowed, the automatic leading-edge slats deployed and the warning horn sounded in the cockpit. The controls gently shuddered. The plane was now on the edge of a stall. With both the rudder and ailerons ineffective, the control stick going forward towards the instrument panel, he pushed the nose about ten degrees below the horizon. The left wing dropped and the aeroplane went into a spin. (...)

[TomcatViP]

Wurster slowed down, pushing back the throttle to idle. As the Bf 109V2 slowed, the automatic leading-edge slats deployed and the warning horn sounded in the cockpit. The controls gently shuddered. The plane was now on the edge of a stall. With both the rudder and ailerons ineffective, the control stick going forward towards the instrument panel, he pushed the nose about ten degrees below the horizon. The left wing dropped and the aeroplane went into a spin. (...)

V2!

[Robo.]

V2!

Same wing, same slats.

[Crumpp]

Bf-109V2

Excellent story....

Might want to do some background research on the design.

;-)

[Crumpp]

Same wing, same slats

Nope....

[Robo.]

Nope....

I am not saying 'identical', I am aware of the small differences of earlier and even later models but the slats are slats - they do have same function and effect, have they not? Were the early 109s V-2 including not 'spin-resistant' even when they had the (same) slats? :o

Comparsion of the V-2 and E-3 wings:

https://dl.dropbox.com/u/10668862/misc/109w.jpg

[Glider]

Excellent story....

Might want to do some background research on the design.

;-)

Crumpp
What do you tell your students about leading edge slots? Do you tell them:-

a) That they are devices that delay the stall or
b) That they are anti spin devices

Just wondering

[fruitbat]

I am not saying 'identical', I am aware of the small differences of earlier and even later models but the slats are slats - they do have same function and effect, have they not? Were the early 109s V-2 including not 'spin-resistant' even when they had the (same) slats? :o

Comparsion of the V-2 and E-3 wings:

https://dl.dropbox.com/u/10668862/misc/109w.jpg

Its funny isn't it, when they're arguing about the wings the V2 is different beyond all measure to the E3, but when they were talking about the top speeds, they were identical.

:rolleyes:

[taildraggernut]

Regarding the 109:

-Slats are deployed in front of the ailerons in order to keep ctrl at stall conditions. No wing drop (and full airflow around the pouter portion of teh wing), no asymmetric stall . Hence no spin. This is why Crumpp refer it as an anti-spin device. So Crumpp was right (again...)


Then why is washout not automatically considered an anti-spin device? it has exactly the same function, to prevent the outer portions of the wing from stalling and maintain aileron effectiveness during the stall and prevent assymetrical stall, if you do consider washout an anti-spin device then what makes it inferior to slats?

so why is it that 2 aircraft with 2 solutions to the same problem (Spit/109) apparently have totally different behaviours? is it really because of the elevator design on the 109 which prevented the use of pitch at stalling angles? or perhaps the design was too stable (see RAE report) which meant there was not enough elevator authority?
either way it seems you get 2 choices here, either the 109 was able to turn well (and possibly suffer a spin if overdone) or you have limited elevator authority which impedes manouverability.

[Crumpp]

Then why is washout not automatically considered an anti-spin device?

Washout does not energize the boundary layer....

[taildraggernut]

Washout does not energize the boundary layer....

neither do slats once they have gone beyond maximum angle of attack and stalled........

[Glider]

Washout does not energize the boundary layer....

Still Wondering

Crumpp
What do you tell your students about leading edge slots? Do you tell them:-

a) That they are devices that delay the stall or
b) That they are anti spin devices

Just wondering

[TomcatViP]

neither do slats once they have gone beyond maximum angle of attack and stalled........

The section of the wing close to the wing roots have alrdy stalled at that time (pls refer to the diag that has been alrdy posted on another similar topic). Hence the stall has alrdy occured before the slotted portion of the wing has stalled!!!

It's all abt having such device.

Washout is good but produce a lot of drag. Accetable for a GA aircraft but not good for a fighter! It's one of the raison why the Spitty was so slow!

[Crumpp]

neither do slats once they have gone beyond maximum angle of attack and stalled........


Right, they don't fly to the moon either despite being an anti-spin device.

What that has to do with anything, I don't know. Maybe it is significant in your mind?

What they do is energize the boundary layer by increasing the high energy turbulent portion so that stall is delayed significantly compared to plain airfoil.

Twisting on the otherhand, simply moves the angle of incidence a few degrees.

Go back a few pages and look over the definition of "spin resistant airplane".

Maybe the light bulb will come on for you and maybe not?

[*Buzzsaw*]

A-The 109 undercarriage was not build that way to facilitate it's shipping via train (at least not only - but this is the first time I think that I have to read it). It was made to make assembly easier with the wing being plugged onto the fuselage. Remind that Bf (and not Mtt at the time ;) ) did not have the production facilities that would be needed for such a big order by the RLM. Many parts were subcontracted (heinkel etc...) and had to be moved from one facility to another. Having the fuselage "crated" by its own undercarriage as soon as possible facilitate the production and made the wing stronger for a given weight (and Mr Messer was addicted to weight reduction as any good eng shld be!).

I have seen several sources which say the requirement for train transport was listed by RLM in the competition. Yes, Bayerische Flugzeugwerke was compelled to outsource many of its manufacture, but that did not require a design which had the undercarriage mounted as it was.

there was a revolution in 1935. And this flow slowly ard the globe from Germany then USA and all obver the globe after 1945.

Suggesting an aero revolution occurred only in Germany, and spread from there is not accurate. In fact, modern designs were being created in many other countries at the same time as the 109, some of which could be called further advanced, some less.

And further, many of the design elements of the 109 were taken from many other aircraft, i;ncluding those from outside Germany. To suggest these elements originated only in Germany again is inaccurate.

Aircraft design in the early '30's, as it is today, was a process of osmosis, with ideas and innovations rapidly circulating and moving from one location to another.

[*Buzzsaw*]

Washout is good but produce a lot of drag. Accetable for a GA aircraft but not good for a fighter! It's one of the raison why the Spitty was so slow!

The drag profile for the Spitfire showed the majority of the drag was a function of its radiator placement, not the washout.

And are you suggesting slats don't produce drag? Any device this size extended into the airstream below the wing is obviously going to produce a very large amount of drag.

Even when the slats are not extended there was drag.

And the 109 wing's tendency to early compressibility was partially a function of the slats being present.

If you haven't seen it, then time to look at the following analysis, by an engineer who was on the Messerschmidt design staff:

http://www.wwiiaircraftperformance.org/me109/Hoerner-Me_109.pdf

[taildraggernut]

Right, they don't fly to the moon either despite being an anti-spin device.

What that has to do with anything, I don't know. Maybe it is significant in your mind?

What they do is energize the boundary layer by increasing the high energy turbulent portion so that stall is delayed significantly compared to plain airfoil.

Twisting on the otherhand, simply moves the angle of incidence a few degrees.

Go back a few pages and look over the definition of "spin resistant airplane".

Maybe the light bulb will come on for you and maybe not?

when it comes to defining resistant I think you provide the perfect example.

Heres a really nice and simple way to illustrate this for you...you have pitched up in your 109....inboard section of the wing begins to stall and the lovely slats have deployed keeping you nice and safe....you keep pulling and your angle of attack is still increasing (even for the magic outboard section of the wing).....now you have pitched so much that you have stalled the outboard section of the wing because you have gone beyond the maximum angle of attack the slats allow.......please explain from this point what magic force is in place to prevent a spin.

Now if you are sticking with the 109 elevator being unable to provide enough force to pitch beyond that point then you have:

1. eliminated the slats from actually being the main protection.
2. just highlighted exactly why the 109 was inferior in turn performance.

I see that not even NACA managed to educate you on the real mechanics behind boundary layers.....go back a few pages and you will see how they completely contradict your theories.

now what washout does is because of the physical twist in the wing putting the tips at lower incidence, the outboard sections of the wing remain unstalled when the inboards are stalled because the outboard sections are at a lower angle of attack.....which means the boundary layer is still adhereing to outboard section ofthe wing (because they are NOT stalled), airflow is still flowing over the ailerons making them effective...pretty much all the same conditions that are applying to the 109.....now if only there was some way of preventing pitching beyond critical angle of attack my Spit would be unspinnable.......no stall = no spin remember.

Trust me...my lightbulb is on AND I'm home too.

[TomcatViP]

The drag profile for the Spitfire showed the majority of the drag was a function of its radiator placement, not the washout.

And are you suggesting slats don't produce drag? Any device this size extended into the airstream below the wing is obviously going to produce a very large amount of drag.

Even when the slats are not extended there was drag.

And the 109 wing's tendency to early compressibility was partially a function of the slats being present.

If you haven't seen it, then time to look at the following analysis, by an engineer who was on the Messerschmidt design staff:

http://www.wwiiaircraftperformance.org/me109/Hoerner-Me_109.pdf

C'mon a lot of modern fighter use slat and are supersonic. I don't see any link.

More over when you hve 1000hp in front of your airplane you don't care that much abt low speed drag (but to weight).
Washout are draggy during cruise (range) and when you attend your max perf range.

Ok enough of this especially after your argument abt going into the stall after your plane is shaking during a fight (but no mention here from you abt stick travel and af Cg huh).

[Al Schlageter]

C'mon a lot of modern fighter use slat and are supersonic. I don't see any link.

Don't you mean drooping leading edges.

[Crumpp]

Heres a really nice and simple way to illustrate this for you...you have pitched up in your 109....inboard section of the wing begins to stall and the lovely slats have deployed keeping you nice and safe....you keep pulling and your angle of attack is still increasing (even for the magic outboard section of the wing).....now you have pitched so much that you have stalled the outboard section of the wing

Let me fix that for you as it the highlighted portion is the source of your confusion on this issue.

Heres a really nice and simple way to illustrate this for you...you have pitched up in your 109....inboard section of the wing IS STALLED and the lovely slats have deployed keeping you nice and safe....


Why don't you schedule some flying lessons and explain to the instructor how the elevator can increase angle of attack AFTER the wing is stalled.

[ACE-OF-ACES]

Still Wondering

Crumpp
What do you tell your students about leading edge slots? Do you tell them:-

a) That they are devices that delay the stall or
b) That they are anti spin devices

Just wondering
As are the rest of us..

But I suspect Crump will avoid answering this question because any atemp in doing so will only highlight how silly his position is on the matter.

[taildraggernut]

Let me fix that for you as it the highlighted portion is the source of your confusion on this issue.

Why don't you schedule some flying lessons and explain to the instructor how the elevator can increase angle of attack AFTER the wing is stalled.

Really? that's the best you've got? instead of answering the question you just keep playing the 'why don't you go take flying lessons because I don't need to because the movie TOP GUN was all about me'?

Heres a nice link to some material us actual flying instructors use..

Standard Stall Recovery (SSR) from a fully stalled condition is then taught. Recovery
action should be initiated at the first full stall sign. Noting the entry height will again
enable the height lost during recovery to be demonstrated illustrating the increased
height loss in the event of a full stall. This emphasises the benefit of early recognition
and recovery at the incipient stage.
Recovery without power can then follow. This clarifies that to recover from the stall the
angle of attack must be reduced using the elevator, which remains effective in the stall.

That bit again..

angle of attack must be reduced using the elevator, which remains effective in the stall.

taken from GAPAN (Guild of Air Pilots and Air Navigators)..

www.gapan.org/file/666/teaching-stalling.pdf

Home website..

https://www.gapan.org/

I should remind you that slats deploy before the main wing has actually stalled which makes my original text quite correct thanks.

While were at it perhaps you could educate us all on exactly what phenomenon takes place that renders elevators inoperative when the wing is stalled? I'm pretty sure if there is airflow over the elevator then it has something to create a pitch force with

Heres my ORIGINAL question without ammendment as it's the one that makes sense and highlighted in BOLD is the part I'd like to know more about.

Heres a really nice and simple way to illustrate this for you...you have pitched up in your 109....inboard section of the wing begins to stall and the lovely slats have deployed keeping you nice and safe....you keep pulling and your angle of attack is still increasing (even for the magic outboard section of the wing).....now you have pitched so much that you have stalled the outboard section of the wing because you have gone beyond the maximum angle of attack the slats allow.......please explain from this point what magic force is in place to prevent a spin.

please, no more cheap insults or suggestions I need to educate myself, that stuff gets old real quick, just answer my question.

Thanks in advance.

[Glider]

Why don't you schedule some flying lessons and explain to the instructor how the elevator can increase angle of attack AFTER the wing is stalled.

If I ask the flying instructor the following what do you think the reply will be:-

What do leading edge slots do, do they:-

a) Delay the stall or
b) Are they anti spin devices

Just wondering if my flying instructor give the same reply, that you who has told us is a CFI would give.

My money is on (A) what do you think?

[*Buzzsaw*]

C'mon a lot of modern fighter use slat and are supersonic. I don't see any link.

Modern slats may be intended to achieve improvements in lift at low speeds in the same way as the 109's slats, but they are not all the same design as the 109's. Gaps are almost imperceptible in comparison to the 109's when not deployed, when deployed, they move forward almost seamlessly, there is nothing in the way of the large open gaps displayed by the 109's slats when deployed. Modern leading edge flaps are a completely different system. These modern leading edge flaps are also computer controlled, with a degree of sophistication in their deployment which makes the 109's slats appear crude at best.

Slats of the 109 era do confer some benefits, but they also impose penalties.

[Crumpp]

Glider says:

If I ask the flying instructor the following what do you think the reply will be:-

What do leading edge slots do, do they:-

a) Delay the stall or
b) Are they anti spin devices

Just wondering if my flying instructor give the same reply, that you who has told us is a CFI would give.

My money is on (A) what do you think?
Today 05:49 PM



To deliver spark to an engines combustion chamber, we use a "spark plug"! Does it plug up the spark? NO, it is just the name of the device used to provide an ignition source.

When we design a spin resistant airplane, we use anti-spin devices to build that spin resistance.

Because folks do not understand the technical terminology, which I been nice enough to explain which is unfortunately lost in the zeal to prove me wrong by a small select portion, the community ends up with all these pointy-tin foil hat theories that have nothing to do with the spin resistant design of the Bf-109.

[Crumpp]

Modern slats may be intended to achieve improvements in lift at low speeds in the same way as the 109's slats, but they are not all the same design as the 109's. Gaps are almost imperceptible in comparison to the 109's when not deployed, when deployed, they move forward almost seamlessly, there is nothing in the way of the large open gaps displayed by the 109's slats when deployed. Modern leading edge flaps are a completely different system. These modern leading edge flaps are also computer controlled, with a degree of sophistication in their deployment which makes the 109's slats appear crude at best.

Slats of the 109 era do confer some benefits, but they also impose penalties.


:confused:

You must be trolling in this reply.

LE flaps are completely different in the aerodynamics from slots or automatic slats.

LE flaps change the camber of the wing and slots/automatic slats energize the boundary layer.

Do you know what a camber change means and how it looks on the polar? A camber changes shifts the entire polar to the left. This has the effect of producing the same coefficient of lift at a lower angle of attack. TE flaps are also camber changers and this is the primary reason we use them on landing. It allows the nose to be lowered so the pilot can see the runway without sacrificing coefficient of lift. Depending on the design, the flap can also raise the maximum coefficient of lift but this too will shift to the left on the polar.

While they are both high lift devices, you are comparing apples and oranges so your post makes no sense at all.

[taildraggernut]

To deliver spark to an engines combustion chamber, we use a "spark plug"! Does it plug up the spark? NO, it is just the name of the device used to provide an ignition source.

When we design a spin resistant airplane, we use anti-spin devices to build that spin resistance.

Because folks do not understand the technical terminology, which I been nice enough to explain which is unfortunately lost in the zeal to prove me wrong by a small select portion, the community ends up with all these pointy-tin foil hat theories that have nothing to do with the spin resistant design of the Bf-109.

Let's call them fish blankets instead, that should avoid any confusion :rolleyes: we are after all all talking about the same device, but just out of interest are you really saying that anti-spin is somewhat of a mislabeling for their actual function?.....or in essence admitting your own pointy tin foil hat zeal to claim the 109 as unspinnable is flawed?

[*Buzzsaw*]

:confused:

You must be trolling in this reply.

LE flaps are completely different in the aerodynamics from slots or automatic slats.

LE flaps change the camber of the wing and slots/automatic slats energize the boundary layer.

Do you know what a camber change means and how it looks on the polar? A camber changes shifts the entire polar to the left. This has the effect of producing the same coefficient of lift at a lower angle of attack. TE flaps are also camber changers and this is the primary reason we use them on landing. It allows the nose to be lowered so the pilot can see the runway without sacrificing coefficient of lift. Depending on the design, the flap can also raise the maximum coefficient of lift but this too will shift to the left on the polar.

While they are both high lift devices, you are comparing apples and oranges so your post makes no sense at all.

Salute Crrump

You clearly haven't read the post which I was responding to.

I do not say the 109 era slats were equivalent to modern era LE flaps, that claim was put forward by Tomcat. In fact I was pointing out the big differences between these devices.

On the issue of 109's entering spins: It's clear your insistence, against all the evidence presented, that the 109's slats made the aircraft "spin proof", is simply not factual. Do they lessen the chance of a spin? Yes, I doubt anyone here would disagree.

However, this does not seem to be enough for you.

We are now in the usual counterproductive and meaningless back and forth which always seems to occur when you enter a thread.

Whether or not other posters agree partially with your arguments seems to make no difference, you seem incapable of accepting the central concept of healthy debate, that being differing viewpoints allow an arrival at a conclusion which may not agree with either side's starting position.

Without any apparent willingness on your part to consider other viewpoints, there is point to further discussion.

[Crumpp]

That bit again..


Taildragger can you explain what reducing the angle of attack to prevent a stall has to do with your claim of raising the nose on the BF-109 with the elevator to completely stall the energized boundary layer of the tips while the rest of the wing is stalled?

I don't see the connection.

[Crumpp]

Let's call them fish blankets instead, that should avoid any confusion

It is not my confusion, Taildragger.

Like I said, it is not the first time that terminology has been explained in this thread.

[Crumpp]

I do not say the 109 era slats were equivalent to modern era LE flaps, that claim was put forward by Tomcat. In fact I was pointing out the big differences.


He is right, many modern fighters do use automatic slats. What is the issue??

[Crumpp]

Buzzsasw says:

It's clear your insistence, against all the evidence presented, that the 109's slats made the aircraft "spin proof", is simply not factual.

Look Buzzsaw, the act of spin proofing an airplane by the application of anti-spin devices builds a spin resistant design. Are you confused by the terminology??

Crumpp says:

The Bf-109 exhibits the same normal behavior for LE Slats. It is difficult at best to get it to spin under normal operating conditions

http://forum.1cpublishing.eu/showpost.php?p=485702&postcount=67

That was page 6 and you never answered my question on why you leaped in spouting the same exact thing I said!!

We are now in the usual counterproductive and meaningless back and forth which always seems to occur when you enter a thread.


I asked you in your first post Buzzsaw to clarify what you think I exaggerated which is your claim and to point out exactly your point of contention.

I have asked you several times. Do that and we will clear it up.

There won't be any conflict just be honest and let's get the facts out.

It is pretty obvious most posters in this thread do not know the terms and confused them.

[taildraggernut]

Taildragger can you explain what reducing the angle of attack to prevent a stall has to do with your claim of raising the nose on the BF-109 with the elevator to completely stall the energized boundary layer of the tips while the rest of the wing is stalled?

I don't see the connection.

Do you actually read the posts people respond to you with? It is apparent you have great difficulty grasping the context of many of them, so I will need to explain my perfectly clear and highlighted in bold quote was saying the elevators remain effective in the stall, did you get that? The elevators remain effective in the stall......now if you have effective elevators you have the ability to pitch beyond critical angle of attack, now are going to stick with the theory that the 109 had some form of pitch inhibition?

[Crumpp]

I should remind you that slats deploy before the main wing has actually stalled which makes my original text quite correct thanks.




Ok taildragger,

Do you understand that the basic effect of the slats is to add energy to the boundary layer and delay seperation?

On the lift polar, the slats have the effect of extending the lift polar increasing both maximum co-efficient of lift tied to that, available angle of attack. This is a completely different effect from increasing camber, btw.

The wing stalls at a higher angle of attack with the slats deployed.

The plain airfoil cannot reach that same angle of attack and is stalled while the tips continue to fly. When the plain airfoil, which makes up the majority of the Bf-109's wing is stalled, the pilot does not have enough control to raise the nose and stall the tips which do gain the benefit of the slats.

Study the diagram below and explain to me how the plain airfoil can continue to fly and reach the slated portion CLmax??

[taildraggernut]

Crumpp says:

The Bf-109 exhibits the same normal behavior for LE Slats. It is difficult at best to get it to spin under normal operating conditions


Under normal operating conditions

Now is pulling hard turns in combat 'normal operating conditions'?

[Crumpp]

so I will need to explain my perfectly clear and highlighted in bold quote was saying the elevators remain effective in the stall, did you get that?

OK....:confused:

Come on and let's do some stalls.

You try to keep the nose up with elevator!!!

:-P

You understand the aerodynamic center in a normal stable airplane is behind the Center of Gravity. When our wing produces less lift, the reduction in aerodynamic force on the aerodynamic center causes the nose to drop. It is not hard to size the elevator appropriately. In fact, the forward CG limit is defined by our inability to raise the nose at landing velocity (not Vref, flare).

[taildraggernut]

Ok taildragger,


Study the diagram below and explain to me how the plain airfoil can continue to fly and reach the slated portion CLmax??

No, you explain to me what the phenomenon is that prevents the still effective elevator from allowing you to pitch beyond the slatted portion of the wings maximum angle of attack.

[Crumpp]

Now is pulling hard turns in combat 'normal operating conditions'?


:confused:

For a fighter, yes!!

Read the RAE report, guy!

When the slots were fully open the aircraft could be turned quite steadily until very near the stall. If the stick was then pulled back a little more the aircraft suddenly shuddered, and either tended to come out of the turn or dropped its wing further, oscillating meanwhile in pitch and roll and rapidly losing height ; the aircraft immediately unstalled if the stick was eased forward. Even in a very tight turn the stall was quite gentle, with no tendency for the aircraft to suddenly flick over on to its back and spin.

[Crumpp]

No, you explain to me what the phenomenon is that prevents the still effective elevator from allowing you to pitch beyond the slatted portion of the wings maximum angle of attack.


I have explained three times already. It just does not sink in!

Crumpps says:

The plain airfoil cannot reach that same angle of attack and is stalled while the tips continue to fly. When the plain airfoil, which makes up the majority of the Bf-109's wing is stalled, the pilot does not have enough control to raise the nose and stall the tips which do gain the benefit of the slats.

[taildraggernut]

I have explained three times already. It just does not sink in!

You haven't explained why there is no authority for a start, now can you explain to us the phenomenon that allows a 109 to maintain a tight turn in combat despite apparently it's elevator being rendered ineffective as soon as the inboard section of the wing is stalled?

[taildraggernut]

OK....:confused:

Come on and let's do some stalls.

You try to keep the nose up with elevator!!!

:-P

So you are basically disagreeing with GAPAN?

[Crumpp]

So you are basically disagreeing with GAPAN?


No, you are!!

:-)

GAPAN says:
angle of attack must be reduced using the elevator, which remains effective in the stall

The elevator can certainly reduce the angle of attack. That is pushing down, taildraggernut NOT pulling the nose up.

Once the angle of attack is reduced, Pitch + Power = Performance and our speed increases which allows us to use the elevator to RAISE the nose once we have some speed.

What that has to do with your claim of raising the nose with the elevator at the stall, I cannot imagine.

[taildraggernut]

No, you are!!

:-)

The elevator can certainly reduce the angle of attack. That is pushing down, taildraggernut NOT pulling the nose up.

Once the angle of attack is reduced, Pitch + Power = Performance and our speed increases which allows us to use the elevator to RAISE the nose once we have some speed.

What that has to do with your claim of raising the nose with the elevator at the stall, I cannot imagine.


Wow you just don't get it, if the elevator is EFFECTIVE then you can control pitch both ways, what you just don't appear to grasp is the actual reason an aircrafts nose drops once the wing is completely stalled, that is simply because once stalled there is no pivot for elevator forces to act upon, all the time there is even the slightest portion of the wing still flying then the elevator has effect, only once the wing is FULLY stalled does the elevator run out of authority, once a wing is FULLY stalled inboard outboard and slats what is the protection against spinning?

[Crumpp]

Taildraggernut, if the elevator is so effective in a stall, why do power on stalls sometimes result in a nose up attitude descent??

Take a wild guess!

[Glider]

To deliver spark to an engines combustion chamber, we use a "spark plug"! Does it plug up the spark? NO, it is just the name of the device used to provide an ignition source.

When we design a spin resistant airplane, we use anti-spin devices to build that spin resistance.

Because folks do not understand the technical terminology, which I been nice enough to explain which is unfortunately lost in the zeal to prove me wrong by a small select portion, the community ends up with all these pointy-tin foil hat theories that have nothing to do with the spin resistant design of the Bf-109.

As highlighted by my example of the K21 glider, which you can easily check, it is possible to have an aircraft that cannot spin but can stall.

There is of course a world of difference between a spin and a stall. The leading edge slats delay the stall and give the pilot greater control resulting in an aircraft that is more difficult to spin.

The leading edge slats DO NOT STOP THE AIRCRAFT FROM SPINNING.

When teaching the stall I used to fully stall the glider then encourage the student to do what they liked with the controls for a few seconds and nothing would happen. Soon gravity would take over the nose would drop and authority is regained.

The period where the controls have no authority is very brief. One of the most dangerous events in a glider is a cable break on a winch launch at a low altitude say 100ft. The forces on the glider tend to 'throw' the nose up and without immediate action, its possible to be almost vertical with no momentum. As a result a serious quite probably fatal accident is basically certain. Students are taught that as soon as the cable breaks to immediately push the stick forward to its max before releasing what is left of the cable from the glider.
I mention this as it shows the controls are effective for all but a few seconds while the wing is fully stalled. However swift action when there is any airflow over the wings normally stops this happening. Even if the wing does fully stall and the conrols lose their effectiveness, then the momentum gained in the immediate actions prior to losing authority ensure a safe recovery.

In normal parlance an Anti Spin device is one that makes the recovery from a spin easier such as an anti spin strake, or a recovery parachute. They don't stop the aircraft spinning, they help with recovery.

Something that helps the aircraft maintain control such as a leading edge slat help delay the stall. again the two are not the same.

Which brings us back to the question which you refuse to reply to in simple terms.

Do you tell your students that the leading edge slats:-

a) That they delay the stall or
b) That they are anti spin devices.

Delaying a stall is not an anti spin device unless it helps the recovery from a spin.

Which brings me to a second question. Why does someone who says that they are a CFI need to be told something as basic as this?

PS don't try to impress by including a copy of a licence. I can understand not wanting your licence no or name to be broadcast, but why delete the expiry date when its only recently been issued?

[taildraggernut]

Taildraggernut, if the elevator is so effective in a stall, why do power on stalls sometimes result in a nose up attitude descent??

Take a wild guess!

Well one of the most OBVIOUS reasons is because you have POWER ON you are creating PROPWASH which acts on the ELEVATOR making it even more EFFECTIVE, now can you tell me why even in a POWER OFF stall some aircraft can 'mush' down in a NOSE UP DESCENT?

I'll save you the bother as I don't think you actually could answer it without consulting google.

when you have made a smooth and progressive decceleration down to the aircrafts 'minimum' stall speed in level flight you will find you are using 'maximum' deflection of 'up elevator' to maintain attitude, because your airspeed is so low and you have used up all elevator travel you run out of pitch authority but the aircraft has found equlibrium with the EFFECTIVE elevator at max deflection holding the aircraft at it's maximum angle while the minimum airspeed is still sufficient to maintain the elevators EFFECTIVENESS to hold the attitude, the nett result is you hold the aircraft in a stall with a constant pitch moment about the lateral axis thanks only to an elevator which is still EFFECTIVE, now here is the really salient part, it's thanks to things like washout, slats, slots etc etc that ensure the outboard sections of the wing stalls last that prevent the aircraft from making a complete departure and entering a spin, even a Spitfire should be able to carry out that excercise due to it's washout maintaing that lateral stability.

Heres our dear old friends the NACA to explain it all to you.

Spitfire MkV handling trials........I wonder if these have been shown before? :rolleyes:

https://docs.google.com/viewer?a=v&q=cache:qja0r_5X7o4J:www.wwiiaircraftperformance.o rg/NACA-Spitfire-V-Stalling.pdf+&hl=en&gl=uk&pid=bl&srcid=ADGEESj0Mm0kkYnWZzOj0I5s6LsgrzZiQNWCLrwdE4iH iIAF4LIeb5SJaPLTcMVD5smPXi4-yYYeu67gl6pDQAVovjlC6YtSSjo5nyV09C4R2eZ0f-DZE0or8tmAJ7c-aM1wAMbZGPv0&sig=AHIEtbQfZqSCZSXM4BRyhUeuiqgiZzKi2g

please forgive typos in my quote as I am cutting and pasting text from a PDF image.

Stalling characteristics in the gliding condition of
flight In the gliding condition with the gun ports covered,
the airplane showed no tendency to roll off. Figure
8 shows a stall in which the controls were held approximately
in the positions required at the first sign of the
stc.ll. At speeds of about l0 miles per hour above the
minimum speed, the tufts at the trailing edge of the left
wing root wore observed to reverse and buffeting was :felt
in the elevator and rudder controls, This buffeting
caused a fairly violent and unmistakable shaking of the
airplane. In figure 8 and the following time histories,
the buffeting is indicated on the figure by an oscillation
of the normal acceleration record. Actually all the instrument
records showed vibrations, but it was thought
unnecessary to indicate thls fact on the time histories.
The approximate amplitude of the variation In normal acceleration
is shown by the plotted curve, but no attempt
has been ms.de to reproduce the frequency of the oscillation
that was recorded.
At approximately 6 miles per hour above the minimum.
speed, the tufts fluctuated above the entire left side of
the center section and some right aileron motion was needed
to maintain trim. A mild pitching and yawing oscillation
developed, but no tendency to roll was observed. In
no case did the flow ahead of the ailerons separate from
the wing surface..
The shaking of the airplane caused some movement of
the controls, in spite of the efforts of the pilot to hold
them fixed. The uncontrolled stalls may be distinguished:
from the controlled stalls by the fact that a large amount of up elevator was applied during the controlled stalls
Figure 9 shows a gliding stall with :the gun ports
covered in which the stick was moved far back after minimum
speed was reached. Use of the ailerons finally resulted in the development of a rolling oscillation and the
violent buffeting continued throughout the stall. As in
the previous stall s the only portions of the wing from
which the flow separated were the left side of the center
section and the extreme tips. Lateral and longitudinal
control sufficient to prevent any violent motions were
still available beyond the stall,

Again..

the only portions of the wing from
which the flow separated were the left side of the center
section and the extreme tips. Lateral and longitudinal
control sufficient to prevent any violent motions were
still available beyond the stall

I should really come back to some qualities of the 109 here from this quote from the RAE report..

When the slots were fully open the aircraft could be turned quite steadily until very near the stall. If the stick was then pulled back a little more the aircraft suddenly shuddered, and either tended to come out of the turn or dropped its wing further, oscillating meanwhile in pitch and roll and rapidly losing height ; the aircraft immediately unstalled if the stick was eased forward. Even in a very tight turn the stall was quite gentle, with no tendency for the aircraft to suddenly flick over on to its back and spin.

The part in bold is describing a stall with the incipient stages of a spin, so in this case the evidence shows that slats have absolutely failed in prevention of the condition, the BIG factor here is that the slats DO make facility for an almost instantaneous recovery almost of an automatic nature.

[Crumpp]

PROPWASH which acts on the ELEVATOR making it even more EFFECTIVE

Yes the propwash gives just enough elevator force to balance the AC keeping the nose up, however as an airplane control, it is NOT effective.

It is one of the cautions pilots should be aware of in a power on stall and accidents have occurred as pilots did not realize they were stalled, experiencing a loss of control until impact with the ground.

But there is even a more critical consideration related to use of power during stall events and this relates to flight conditions where the stall is entered with the power on—when the power is on when the stall is entered, the airflow over the stabilator or elevator will create an artificial nose-up attitude and thereby conceal the final stall symptom, which—of course—is the nose drop. In a power-on stall, the nose may not drop! It will simply hang up while in fact the aircraft is clearly stalled and is losing altitude and suffering from control loss associated with normal stall.

http://www.langleyflyingschool.com/Pages/Stall.html

Why would a designer allow a pilot to take an aircraft someplace it cannot fly anyway??

why delete the expiry date when its only recently been issued?

The information is blanketed so my personal details do not become privy to the internet.

There is no such as thing as "not recently issued" CFI license, Glider. The certification is only good for two years in the US and is re-issued at that time.

Notice it has a separate certificate number and is only good when accompanied by my Commercial certificate. You have to carry both and cannot fly with the CFI certificate alone.

The rest of your stuff is just a repeat of the same question I have answered so I have to conclude you are only trolling at this point. Obviously, you cannot accept the answer I have given you twice already. That is your problem and not mine.

As they say, you can lead a horse to water but you cannot make them drink.

http://img854.imageshack.us/img854/1277/spinresistance4.jpg (http://imageshack.us/photo/my-images/854/spinresistance4.jpg/)

http://img259.imageshack.us/img259/1583/spinresistance3.jpg (http://imageshack.us/photo/my-images/259/spinresistance3.jpg/)

http://imageshack.us/a/img856/5310/spinresistance.th.jpg (http://imageshack.us/photo/my-images/856/spinresistance.jpg/)

http://imageshack.us/a/img846/4238/spinresistance2.th.jpg (http://imageshack.us/photo/my-images/846/spinresistance2.jpg/)

[Crumpp]

Taildraggernut says:
should really come back to some qualities of the 109 here from this quote from the RAE report..



LOL, you very conveniently emphasize only the facts that fit your world without considering the final conclusion of the RAE.


Taildraggernut says:

The part in bold is describing a stall with the incipient stages of a spin,

Yes it does describe the conditions a spin should result in!!

Thank you for recognizing that!!
However your conclusion is not correct.

Taildraggernut says:
in this case the evidence shows that slats have absolutely failed in prevention of the condition

As evidenced by the RAE report:

RAE report says:

When the slots were fully open the aircraft could be turned quite steadily until very near the stall. If the stick was then pulled back a little more the aircraft suddenly shuddered, and either tended to come out of the turn or dropped its wing further, oscillating meanwhile in pitch and roll and rapidly losing height ; the aircraft immediately unstalled if the stick was eased forward. Even in a very tight turn the stall was quite gentle, with no tendency for the aircraft to suddenly flick over on to its back and spin.

Which is the normal effect of Handley Page automatic slats....

[taildraggernut]

Yes the propwash gives just enough elevator force to balance the AC keeping the nose up, however as an airplane control, it is NOT effective.

No the propwash allows you to make excessive pitch input due to increased effectiveness of the elevator and preventing the natural tendency of the aircraft to drop it's nose and recovering, this is why power on stalls give a greater chance of wing drop because you are able to hold the aircraft attitude beyond critical angle of attack.....it also answers this question of yours...

Why would a designer allow a pilot to take an aircraft someplace it cannot fly anyway?

because in this case if a designer didn't wan't to give you the ability to go beyond the flight regime he wouldn't have put an engine in and for that matter he might not have given you facility for 'any' control of the aircraft as it also gives you the chance to screw up, so why did the designer even bother with wings?

It is one of the cautions pilots should be aware of in a power on stall and accidents have occurred as pilots did not realize they were stalled, experiencing a loss of control until impact with the ground.

it's amazing you can say this yet clearly understand none of why it is so.

http://www.langleyflyingschool.com/Pages/Stall.html

From your own source......whoever Langley flying schools are.

Describing a POWER OFF stall.

The most important lesson from this sequence of stall exercises is that the aircraft will stall at any speed and in any attitude—in all cases, a stall occurs when the critical angle of attack—usually 18°--is exceeded. The job of the pilot during the recovery is therefore quite simple: smoothly and steadily decrease the angle of attack with controlled, smooth, and steady, forward motion of the control column. Never snap or jerk the control column forward as this simply confuses the aircraft and excites your Instructor. Don't be a jerk! Always be slow, purposeful and smooth during your inputs to pitch the nose forward to decrease the angle of attack. Equally important, never give up excess pitch to a stall--the pitching forward or pushing forward of the control column should only progress to the point that the stall symptoms recede and disappear. This is important because we want to be effective in recovering from a stall in close proximity to the ground.

Now if as you suggest that during a power off stall the elevator has become completely ineffective how exactly is the pilot expected to use such purposeful and smooth recovery inputs? shouldn't it be the case the elevator input is now redundant according to your theory? you can only purposefully operate an effective control, if it is not effective then you may as well be moving a toilet plunger attached to the floor.

LOL, you very conveniently emphasize only the facts that fit your world without considering the final conclusion of the RAE.

No I simply emphasised a FACT (thanks for recognising that) any convenience is coincidental.

Yes it does describe the conditions a spin should result in!!

Thank you for recognizing that!!
However your conclusion is not correct.

How can it be?

When the slots were fully open the aircraft could be turned quite steadily until very near the stall. If the stick was then pulled back a little more the aircraft suddenly shuddered, and either tended to come out of the turn or dropped its wing further, oscillating meanwhile in pitch and roll and rapidly losing height ; the aircraft immediately unstalled if the stick was eased forward. Even in a very tight turn the stall was quite gentle, with no tendency for the aircraft to suddenly flick over on to its back and spin.

it describes clearly:

1. there is still elevator authority enough to take the aircraft beyond stall of the slatted portion of the wing.
2. the aircraft stalled despite having slats.......amazing.
3. a wing dropped......clearly the beginnings of the incipient stages of a spin.
4. slats failed completely to prevent entering into that.
5. the quote makes no suggestion of a continued pitch input to delay recovery, this leaves it open to speculation as to what would happen should the pilot not ease off on the stick.
6. given that the evidence has now proved there is enough elevator authority to take even the slated portion of the wing beyond critical angle of attack and maintain that condition...(or have you forgotten theres an engine giving you thrust which affects the elevator?) what is the phenomenon that prevent the 109's magic wings from behaving like any other plain wing once all of its slats usefullness has run out? are you really saying that a slatted wing can pitch infinitely without penalty? so a 109 can actually do a Pugachev's cobra?

[Crumpp]

the gun ports
covered

That is the key condition in the NACA report, btw.

Uncover the gun ports and the NACA found the same stall characteristics as noted in all the early mark Spitfires Operating Notes.

So, does the game model a Spitfire without weapons available or one that is fighting??

:grin:

[Crumpp]

Even in a very tight turn the stall was quite gentle, with no tendency for the aircraft to suddenly flick over on to its back and spin.

:rolleyes:

[Crumpp]

Now if as you suggest that during a power off stall the elevator has become completely ineffective how exactly is the pilot expected to use such purposeful and smooth recovery inputs?

Taildraggernut, why don't you squash all your theories with some experience? Get in an airplane and try to raise the nose at the stall to see what happens. Make sure you have plenty of altitude and an instructor with you. Don't want to see you get hurt.

Read the RAE report too. Look for the words "Stick back to the stops".

In otherwords, the stick was all the way back at the stall point in the Bf-109 by design.

That is normal for many properly designed aircraft.

[taildraggernut]

In otherwords, the stick was all the way back at the stall point in the Bf-109 by design.

Now think very very carefully what you have said here.......take your time, you may eventually understand that if you really had to deflect elevator fully to the stop in a high speed stall then you are probably flying an aircraft with elevator controls the size of trim tabs.....is it sinking in yet?

Taildraggernut, why don't you squash all your theories with some experience? Get in an airplane and try to raise the nose at the stall to see what happens. Make sure you have plenty of altitude and an instructor with you. Don't want to see you get hurt.

I really wouldn't be saying any of this stuff unless I had the experience, anyway this constant questioning of actual real life experiences is completely redundant, I don't know who you are or what you are boy/girl/slimy green tentacled monster or actually a real flying instructor.
all I can say for sure is the stuff you are pumping out on here is absolute garbage, i just can't figure out why someone would do that.

[Crumpp]

Taildraggernut,

It will be more useful for you to seperate pre-stall behaviors from stall behaviors. You keep confusing and blending the two. They are very different conditions of flight.

Taildraggernut says:
How can it be?


In the Bf-109, the main wing is stalled when the wing drops. The slats remain effective preventing spin entry and the aircraft experiences loss of elevator control to raise the nose further. That loss of elevator control prevents the pilot from increasing angle of attack beyond the stall point of the slatted portion of the airfoil.

When the slots were fully open the aircraft could be turned quite steadily until very near the stall. If the stick was then pulled back a little more the aircraft suddenly shuddered, and either tended to come out of the turn or dropped its wing further, oscillating meanwhile in pitch and roll and rapidly losing height ; the aircraft immediately unstalled if the stick was eased forward. Even in a very tight turn the stall was quite gentle, with no tendency for the aircraft to suddenly flick over on to its back and spin.

The RAE is not discussing pre-stall behavior, they are talking about the accelerated STALL of the aircraft:

Even in a very tight turn the stall was quite gentle, with no tendency for the aircraft to suddenly flick over on to its back and spin.

[taildraggernut]

No, the wing drops when one of the outboard sections of the wing stalls, this can only happen if the slot had run out of puff and stalled itself.

now about that loss of elevator control, what causes it?

[Robo.]

So, does the game model a Spitfire without weapons available or one that is fighting??

:grin:

When you take off in this game, your Spitfire's gun ports are indeed covered.

Now when you know the wing and slats of V2 were the same, would you care to comment on the spin test report I quoted a couple of pages back?

I agree the stall characteristics of the 109 in game are incorrect but I believe you're equally wrong with you claims about 'non-spinnable design' and 'devices'.

[robtek]

You can even get a C152 to spin, but you have to work for it, same with the 109, it seems, you can get it to spin, if you work at it, but it is very difficult to get the spin without forcing the plane to spin.
That is how i read it.

[taildraggernut]

You can even get a C152 to spin, but you have to work for it, same with the 109, it seems, you can get it to spin, if you work at it, but it is very difficult to get the spin without forcing the plane to spin.
That is how i read it.

Not quite, what it really means is the 109's behaviour in the stall is relatively forgiving and gives ample opportunity to recover before things get too far out of shape, the fact remains that slats simply delay onset of a stall and not prevent it completely, if you keep pulling back on the stick after the slats have become ineffective then you increase your chances of entering a spin, the severity of which is subjet to debate but likely to be quite easy to deal with, the key point is once you have been forced into recovery technique during a combat turn you have effectively left the engagement and you are vulnerable.

[robtek]

Not quite, what it really means is the 109's behaviour in the stall is relatively forgiving and gives ample opportunity to recover before things get too far out of shape, the fact remains that slats simply delay onset of a stall and not prevent it completely, if you keep pulling back on the stick after the slats have become ineffective then you increase your chances of entering a spin, the severity of which is subjet to debate but likely to be quite easy to deal with, the key point is once you have been forced into recovery technique during a combat turn you have effectively left the engagement and you are vulnerable.

If you reduce it to that, the key point is that the 109 is controlable all the time, even in a high speed stall, and its adversaries aren't, which is a great achievement by itself and should be represented in game.

[taildraggernut]

If you reduce it to that, the key point is that the 109 is controlable all the time, even in a high speed stall, and its adversaries aren't, which is a great achievement by itself and should be represented in game.

I'm not sure why you get that impression of it's adversaries, the NACA report on the MkV (which was the worst Spit in terms of stability) was actually quite good, the 109 is not in control all the time, if an aircraft is stalled it has technically lost control and the reports show the 109 could stall with an uncomanded wing drop, an uncomanded motion is by definition not in control, what should be represented in the game is something close to reality and that reality is that both 109's and Spits had very desireable stall handling qualities with both aircraft being pretty benign and in the Spitfires case having particularily good stall warning, I might add that if you were to believe Crumpp then the 109 also loses elevator control.

STALLING CHARACTERISTICS IN MANEUVERS


The stall warning posessed by the Spitfire was especially
beneficial in allowing the Pilot to reach maximum
lift coefficient in accelerated maneuvers.Because of the
neutral static stability of this airplane, the pilot obtained
no indication of the lift coefficient from the motion
of the control stick, nevertheless, he was able to
pull rapidly to maximum lift coefficient in a turn without
danger of inadvertent stalling.Figure 17 shows a time history of a 180 ° turn in
which the stall was reached. The stall in accelerated maneuvers
was very similar to that in the gliding condition.
with gun ports closed, the pilot was able to pull the stick far back without losing control or interrupting the
turn. The airplane tended to pitch down when stalled and
to recover by itself if the stick were not pulled back.
It would be possible for a pilot pursuing an enemy in a
turn to bring his sights on him momentarily by pitching
beyond the stall without fear of rolling instability.

with gun ports open, a right roll occurred if more
than about 10°up elevator were applied. This reaction
caused the airplane to roll out of a left run and into a
right turn.

Time histories of these maneuvers are shown
on figures 18 and 19. In spite of the lateral instability
that occurred in turns with gun ports open, the pilot
was able to approach maximum lift coefficient closely because
of the desirable stall warning.

The maximum lift
coefficient reached in turns from level flight with flaps
up was 1.22. The airplane could be flown beyond the stall
at even lower lift coefficients.

This value of maximum lift coefficient is closer to
that reached from stalls in straight flight with power
off than the value renched with power on because the slipstream
effects in high-speed turns are relatively small,
The lower value of the maximum lift coefficient offsets, to
some extent, the benefit gained by the Spitfire from its
low wing loading in making turns of small radius. Good
stall warning characteristics appear to be essentiai on an airplane with neutral static stability. In airplanes
tested previousiy, which had neutral static stability and
poor stall warning, inadvertent stalling in rapid maneuvers
was practically unavoidable, The stalling characteristics
of the Spitfire are therefore its redeeming feature.
It should be desirable, however, to obtain these characteristics
without sacrificing a high value of the maximum
lift coefficient.

CONCLUSIONS


The Supernarine Spitfire airplane possessed stalling
characteristics essentially in compliance with the requirements
for satisfactory stalling characteristics given
in reference 1 These characteristics may be summarized
as follows:

1. Warning of the complete stall was provided by the
occurrence of buffeting that set in at speeds several miles
per hour above the minimum speed and by the rearward movement
that could be made with the stick after the start of
the stall flow breakdown without causing violent motions
of the airplane.

2. Stall recovery could be made by application of
down elevator, although the recovery from a roll was somewhat
slower than has been measured on some previously
tested airiolanes.

3. The airplane exhibited no dangerous ground-looping
tendencies in landing. Tail-first landings could be readily
made without the occurrence of either lateral or directional
instability due to stalling.

The airplane posessed some unusual characteristics
in stalls that are not required in reference 1. The motion
beyond the stall was not violent and an unusual
amount of lateral control was available in many flight
conditions, even when full up elevator was applied. The
good stalling characteristics allowed the airplane to be
pulled rapidly to maximum lift coefficient in accelerated
maneuvers in spite of its neutral static longitudinal
stability.

I am struggling to find an aspect in that report saying the Spitfire should spin wildly out of control

[TomcatViP]

Modern slats may be intended to achieve improvements in lift at low speeds in the same way as the 109's slats, but they are not all the same design as the 109's. Gaps are almost imperceptible in comparison to the 109's when not deployed, when deployed, they move forward almost seamlessly, there is nothing in the way of the large open gaps displayed by the 109's slats when deployed. Modern leading edge flaps are a completely different system. These modern leading edge flaps are also computer controlled, with a degree of sophistication in their deployment which makes the 109's slats appear crude at best.

Slats of the 109 era do confer some benefits, but they also impose penalties.


I guess you was typing to fast and that charcters outrun your mind.

Hve a look to an F4E wing (or an A4). ;)

[robtek]

As usual the answer is only refering with evidence that is supporting the posters opinion and hair-splitting.
1. Did the 109 recover from a high speedstall with only minimal control input? The RAE report says so. Hardly a uncontrolled flight situation then, i'd say.
2. Did the early Spitfire depart from controlled flight in a high speed stall with a flip over and a following spin? Afaik all sides so far have admitted that.

There is no dispute that the controlled stall in the Spitfire was not hard to manage, but then, that was not asked for.

[taildraggernut]

As usual the answer is only refering with evidence that is supporting the posters opinion and hair-splitting.
1. Did the 109 recover from a high speedstall with only minimal control input? The RAE report says so. Hardly a uncontrolled flight situation then, i'd say.
2. Did the early Spitfire depart from controlled flight in a high speed stall with a flip over and a following spin? Afaik all sides so far have admitted that.

There is no dispute that the controlled stall in the Spitfire was not hard to manage, but then, that was not asked for.


Please, can I respectfully ask that you don't descend into this mad poo flinging fest that arises every time someone simply has a different oppinion and shows evidence to back up why they have that oppinion.

I merely reminded of the good qualities of the Spitfire handling after you had basically claimed otherwise..

If you reduce it to that, the key point is that the 109 is controlable all the time, even in a high speed stall, and its adversaries aren't, which is a great achievement by itself and should be represented in game.

1. Did the 109 recover from a high speedstall with only minimal control input? The RAE report says so. Hardly a uncontrolled flight situation then, i'd say.

Both the 109 and Spitfire had this quality.

2. Did the early Spitfire depart from controlled flight in a high speed stall with a flip over and a following spin? Afaik all sides so far have admitted that.

I don't admit to this, as far as I'm concrned the MkV was the worst Spitfire for longitudinal stability, earlier Spits by default will have had better qualities.

[ACE-OF-ACES]

I am still waiting on Crump's to tell us what he tells his so called students..

As in what does he tell them the purpose of leading edge slats are..

1) The purpose of leading edge slats is to reduce the chance of a stall
2) The purpose of leading edge slats is to reduce the chance of a spin

I think most agree the purpose of leading edge slats is to reduce the chance of a stall

Where as it appears that Crump is saying the purpose of leading edge slats is to reduce the chance of a spin

I think it would be interesting, and telling, to have Crump explain this line of reasoning..

Especially in light of the fact that there are many accounts of how leading edge slats CAUSED spins!!

Where, for what ever reason, the leading edge slats did not deploy evenly and thus induces (CAUSE) the plane to spin..

Not to mention the accounts of the leading edge slats POPPING out suddenly such that they 'changed' the aerodynamics such that the pilot had to quickly adjust his controls.. In essence startling the pilot such that he may have over compensated and CAUSE the plane to stall or even spin

In summary

It appears this is another cause of Crump cherry picking Luftwaffe attribute..

Where here only talks about the PROS of a certain attribute and totally ignores the CONS of a certain attribute

[TomcatViP]

AoA with such a name you shld know that it is both. And then with logics in mind it's the 2nd arguments tht is the most valid

In the absurd an anti spin decice IS a device reducing the chance of a spin to occur

You know, flight manuals are full of such simplification. A pilot is not a always a Phd holder in physics. It can eitherbe a carpenter, a greedy politicians or a nightclub hotess!

[ACE-OF-ACES]

AoA with such a name you shld know that it is both. And then with logics in mind it's the 2nd arguments tht is the most valid

In the absurd an anti spin decice IS a device reducing the chance of a spin to occur

You know, flight manuals are full of such simplification. A pilot is not a always a Phd holder in physics. It can eitherbe a carpenter, a greedy politicians or a nightclub hotess!
So using your logic..

The purpose of the breaks in my car are NOT to stop my car..

The purpose of the breaks in my car are to prevent me from getting speeding tickets..

Hmmm..

Sorry but no sale!

Ill stick with the intended purpose of the breaks in my car and not the multitude of what if's purposes the breaks in my car can be associated with to try and make a point..

Nice try though! You and Crump get a gold star for effort!

[robtek]

Sorry AoA, but with such arguments you are soo far out, that you will find it hard to see the objective, imo, of course.

And Taildraggernut, you are promoting the theory that the Spitfire didn't flip over and started a spin if pulled too hard in a high speed turn?? Really???
Afaik this was used by experienced pilots as a last ditch maneuvre to escape from a 109 on their tail.

[taildraggernut]

Sorry AoA, but with such arguments you are soo far out, that you will find it hard to see the objective, imo, of course.

And Taildraggernut, you are promoting the theory that the Spitfire didn't flip over and started a spin if pulled too hard in a high speed turn?? Really???
Afaik this was used by experienced pilots as a last ditch maneuvre to escape from a 109 on their tail.

Are you suggesting that Spitfire pilots had to exploit a lateral instability as opposed to deliberately entering the spin by actually making pro-spin inputs? really?

putting an aircraft into a spin is a technique available to any pilot in any aircraft as a deliberate manouver.

[ACE-OF-ACES]

Sorry AoA, but with such arguments you are soo far out, that you will find it hard to see the objective, imo, of course.
Don't be sorry

In that I fully expected you and yours standard off topic reply in an attempt to take the focus off what I said..

Not to mention how you and yours totally ignored the points I brought up about the historic accounts of the Bf109 slats causing more spin issues than they solved..

[robtek]

Don't be sorry

In that I fully expected you and yours standard off topic reply in an attempt to take the focus off what I said..

Not to mention how you and yours totally ignored the points I brought up about the historic accounts of the Bf109 slats causing more spin issues than they solved..

Now there you have to bring some proof that the assymetric action of the flaps, which was intended, was causing spins.

And the points you've brought are as usual black and white with no room for intermediate.

[Al Schlageter]

Now there you have to bring some proof that the assymetric action of the flaps, which was intended, was causing spins.

And the points you've brought are as usual black and white with no room for intermediate.

Isn't this thread about SLATS?

[*Buzzsaw*]

If you reduce it to that, the key point is that the 109 is controlable all the time, even in a high speed stall, and its adversaries aren't, which is a great achievement by itself and should be represented in game.

This is a fundamental misunderstanding which comes up again and again in the course of discussions re. the 109's 'controllability'.

An aircraft in a stall is out of control by the very definition of the word 'stall'.

It is no longer in flight. It has ceased to be anything but a falling object. Maybe the 109 will fall in a predictable and logical fashion, but it is still falling.

A 109 in a stall is out of control. No if's, and's or but's.

Can a 109 be recovered fairly quickly?

Yes, but a recovery requires the standard stall recovery procedure, ie. centered or slightly forward controls, allowing the aircraft to gain speed and lift, and gentle application of controls only after the normal conditions for flight have been re-acquired.

A stall in a 109 like any other aircraft is going to result in loss of control and height. Perhaps the stall can be recovered fairly quickly, but recovery is still a requirement. While the aircraft is out of control, it cannot be flown in any normal sense. Any attempt to 'fly' a stalled aircraft is going to increase the severity of the stall, and prolong the time the aircraft will remain in a stall. Want to put a 109 in a spin? Continue to try to 'fly it' after it has entered a stall.

To quote again the RAE report on LOW speed turn stalls:

When the slots were fully open the aircraft could be turned quite steadily until very near the stall. If the stick was then pulled back a little more the aircraft suddenly shuddered, and either tended to come out of the turn or dropped its wing further, oscillating meanwhile in pitch and roll and rapidly losing height ; the aircraft immediately unstalled if the stick was eased forward. Even in a very tight turn the stall was quite gentle, with no tendency for the aircraft to suddenly flick over on to its back and spin.


Note the requirement for the stick to be eased forward (brought forward GENTLY) to allow the aircraft to regain speed and lift. Standard stall recovery. Any attempt to use the controls to do other than stall recovery would result in a prolonged stall.

[*Buzzsaw*]

As usual the answer is only refering with evidence that is supporting the posters opinion and hair-splitting.
1. Did the 109 recover from a high speedstall with only minimal control input? The RAE report says so. Hardly a uncontrolled flight situation then, i'd say.
2. Did the early Spitfire depart from controlled flight in a high speed stall with a flip over and a following spin? Afaik all sides so far have admitted that.

There is no dispute that the controlled stall in the Spitfire was not hard to manage, but then, that was not asked for.

As has been mentioned several times on this board, the Spitfire's stall was very easy to read and anticipate. Even rookie pilots were capable of learning this, and even in a high speed situation:



From FIRST LIGHT, by Geoffrey Wellum

"I start to black out. Must be pulling 6 G's. Lean forward, raise my feet on to the rudder pedal extensions; God, they're heavy.
The Spit judders, a high speed stall. You can hold a Spitfire on this judder if you're good. Hold on, Geoff! Hold onto this turn. Fly her like hell.

I reckon I'm just a little above, just a fraction, and therefore gaining.

The German pilot is trying to tighten his turn still more to keep up with me and I'm sure I see the 109 flick. I can see the shape of his head quite clearly and even the dark shape of his oxygen mask. Yet again, I imagine that the 109 gives a distinct flick, on the point of a high speed stall. He has to ease his turn a fraction. The Spitfire gains slowly.

I can quote quite a number of other examples.

The Spitfire's 'judder' or shudder or buffet happened before the stall, and it was quite possible to ride this edge for maximum turn rate.

Only those who were ham-handed or completely inexperienced would not know how to use this indicator.

Yes, if pushed beyond this, the Spitfire would flick over on its back and spin, but given the fact its stall speed was lower than the 109's, and it turn circumference was smaller, there was no need to for a pilot to take it that far.

Notice also in this description the 109 'flick' referred to. This is mentioned in many combat accounts, and tells us clearly that in an accelerated stall condition, there was the potential for a wing drop on the 109 if the stall indications are ignored and controls continue to be over-applied.

[Crumpp]

Taildraggernut says:

I am struggling to find an aspect in that report saying the Spitfire should spin wildly out of control


From the Spitfire Mk II Operating Handbook. The same warning appears in all early mark Spitfires:

http://img835.imageshack.us/img835/3166/spinningoperatinghandbo.jpg (http://imageshack.us/photo/my-images/835/spinningoperatinghandbo.jpg/)

Roll instability near the stall as noted the NACA agrees with the Operating Note warnings:

http://img405.imageshack.us/img405/3886/spitstallwarning.jpg (http://imageshack.us/photo/my-images/405/spitstallwarning.jpg/)

That help?

[*Buzzsaw*]

Thanks for providing that documentation to bolster my comments.


Roll instability near the stall as noted the NACA agrees with the Operating Note warnings:

http://img405.imageshack.us/img405/3886/spitstallwarning.jpg (http://imageshack.us/photo/my-images/405/spitstallwarning.jpg/)


"The Spitfire possessed GOOD stall warning in the form of buffeting....
...the stick could be moved well back before lateral instability occurred"

"...rolling instability was noted AFTER an unmistakeable warning in the form of buffeting occurred."

Of course the Spitfire's capability of entering a spin off a high speed stall has nothing to do with the 109's slats.

However, I guess this thread has established two things which are incorrectly modelled in the game:

1) The 109's tendency to enter spins easily and the tendency for recovery from spins to be difficult.

2) The lack of modelling of the Spitfire's pre-stall buffeting.

The game Spitfire will clearly enter a spin out of a high speed stall through the path of a flick onto its back.

[Crumpp]

The lack of modelling of the Spitfire's pre-stall buffeting.


I agree.

The pre-stall buffeting of the Spitfire and its effects should be modeled.

it was quite possible to ride this edge for maximum turn rate.


Yes, except maximum turn rate occurs in smooth airflow not buffeting. The buffet is often used to find this point and then backing off to smooth air.

If you turn in the buffet, your rate will decrease and your radius increase.

The more high energy the buffet, the greater the effect.

[NZtyphoon]

I agree.

The pre-stall buffeting of the Spitfire and its effects should be modeled.



Yes, except maximum turn rate occurs in smooth airflow not buffeting. The buffet is often used to find this point and then backing off to smooth air.

If you turn in the buffet, your rate will decrease and your radius increase.

The more high energy the buffet, the greater the effect.

Of course Crumpp fails to point out the pre-conditions noted in the NASA report, steeply banked turns with open gun ports; nor does the report state that the instability was actually dangerous, and it does not explain how all of this affected the Spitfire in combat or as a combat aircraft. Nor does Crumpp explain that the Spitfire's stall behaviour was more often praised than slated by NACA, in this and in another report on the Spitfire's stalling characteristics.

And, of course, this is not about the Spitfire anyway - Crumpp has obsessively chased this subject already in other threads - but as to modelling this pre-stall buffet, perhaps, crumpp could develop a program which will allow all gamers to feel this buffeting, either through their joysticks, or the seat of their pants?

[Glider]

I agree.

The pre-stall buffeting of the Spitfire and its effects should be modeled.



Yes, except maximum turn rate occurs in smooth airflow not buffeting. The buffet is often used to find this point and then backing off to smooth air.

If you turn in the buffet, your rate will decrease and your radius increase.

The more high energy the buffet, the greater the effect.

For once a posting that I totally agree with.

As to how to replicate the buffet in the game, I suggested once that in the ideal world everyone would have a feedback controller which would vibrate. However we have to recognise that this will not be the case so I suggested a visual cue where the cockpit view would vibrate.

Now back to the question yet to be replied to

Crumpp
Do you tell your students that leading edge slats :-
a) are a device that delays the stall or
b) Is an anti spin device.

Do you agree that the correct solution is (a)?

[taildraggernut]

From the Spitfire Mk II Operating Handbook. The same warning appears in all early mark Spitfires:

http://img835.imageshack.us/img835/3166/spinningoperatinghandbo.jpg (http://imageshack.us/photo/my-images/835/spinningoperatinghandbo.jpg/)

Roll instability near the stall as noted the NACA agrees with the Operating Note warnings:

http://img405.imageshack.us/img405/3886/spitstallwarning.jpg (http://imageshack.us/photo/my-images/405/spitstallwarning.jpg/)

That help?

Yeah, so only 'AFTER' the Spitfire has actually fired it's guns does it begin to suffer any form of lateral instability, just got to make sure the first burst counts then.
Like NZtyphoon says, Crumpp completely ignores the 95% of positive report on the Spitfire but emphasises the negative 5%, NACA summaried their report saying the Spits stalling characteristics were it's redeeming feature.

[VO101_MMaister]

You are amazing guys... How the hell did you end up on the spit`s high speed stall characteristic in a thread about the leading edge slats of the 109?????

There are no spinproof airplanes, there ones which are hard to put in a spin. The wing is stalled when the airflow become turbulent over the whole upper wing area and so it looses its lifting effect. The slats ensure a laminar flow over the outer wing around the ailerons at low speed so you have some more control before the wing stall. No magic here. It can postpone the stall but it won`t eliminate it.

The spin is when only one of the wing is stalled due to the assyimetrical flow. The slats could open independently, so they could prevent a spin by opening only on the wing which was just about the stall. But again it was only postponing the spin in this case and gave you more control.

On the other hand the slats could make a fuss, when only one of them opened due to some mechanical failure, and it resulted an assymetrical lift and so an unpredicted spin at low speed. Also they raised the drag when they were open, what meant quicker de-accceleration.

I have never flown an aircraft with slats, so no practical experience here, but as I understand Crumpp did, and he gave a quite good description about the acting of such an airplane.

I also feel that the 109 in the game is a bit sensitive, but hey, I can`t tell if it is right or not. Can you? I have never flown one, and I have never read a review of the current flight modell by a real life 109 jockey. Have you? There are quantitive specs what can be measured and checked in numbers and graphs. And then there are the sensations. It is quite hard to translate a pilot`s story into an accurate flight model. In these stories you can only get what that particular guy felt in that particular situation, and then how he can recall it after maybe 60-70 years. Well it is not bomb proof for sure. Now translate it into a computer game for guys who are flying in an office chair, and they pull as hard as they want without feeling the punishment of the real G-forces or the physical exhausting of an aerial battle. So we can have a depute on it for 1000 years and we never gonna agree.

[Crumpp]

As to how to replicate the buffet in the game

Start another thread, it is pretty easy to simulate correctly the effect.

Crumpp completely ignores the 95% of positive report on the Spitfire but emphasises the negative 5%

Nothing to do with any emotional attachment one way or the other to the Spitfire. I like the airplane.

With certain posters on these boards though there is no reason to repeat the strengths of the design as that is all they emphasize.

Therefore anybody who seeks the historical balance is stuck in the position of repeating what has has already been pointed out AND adding in the overlooked qualities OR just stating the overlooked qualities that achieved that balance!

[Crumpp]

You are amazing guys... How the hell did you end up on the spit`s high speed stall characteristic in a thread about the leading edge slats of the 109?????

There are no spinproof airplanes, there ones which are hard to put in a spin. The wing is stalled when the airflow become turbulent over the whole upper wing area and so it looses its lifting effect. The slats ensure a laminar flow over the outer wing around the ailerons at low speed so you have some more control before the wing stall. No magic here. It can postpone the stall but it won`t eliminate it.

The spin is when only one of the wing is stalled due to the assyimetrical flow. The slats could open independently, so they could prevent a spin by opening only on the wing which was just about the stall. But again it was only postponing the spin in this case and gave you more control.

On the other hand the slats could make a fuss, when only one of them opened due to some mechanical failure, and it resulted an assymetrical lift and so an unpredicted spin at low speed. Also they raised the drag when they were open, what meant quicker de-accceleration.

I have never flown an aircraft with slats, so no practical experience here, but as I understand Crumpp did, and he gave a quite good description about the acting of such an airplane.

I also feel that the 109 in the game is a bit sensitive, but hey, I can`t tell if it is right or not. Can you? I have never flown one, and I have never read a review of the current flight modell by a real life 109 jockey. Have you? There are quantitive specs what can be measured and checked in numbers and graphs. And then there are the sensations. It is quite hard to translate a pilot`s story into an accurate flight model. In these stories you can only get what that particular guy felt in that particular situation, and then how he can recall it after maybe 60-70 years. Well it is not bomb proof for sure. Now translate it into a computer game for guys who are flying in an office chair, and they pull as hard as they want without feeling the punishment of the real G-forces or the physical exhausting of an aerial battle. So we can have a depute on it for 1000 years and we never gonna agree.

Good post. Your right, the thread is getting off track and needs to get back on.

The behaviors of the Bf-109 are fairly well documented and we have some measured data. There is enough there to construct a reasonable facimile. Unfortunately the RAE did not have a standard or the measuring equipment developed by the NACA until later.

Also other reports and the Operating Notes give some really good clues about the stability and control of the Bf-109. For example, the Bf-109 (in a trimmed condition) was limited by design to about 5G's. This keeps the pilot safe and allows maximum attainable manuverability with gusting. You can see this in the turn performance evaluation by the RLM/Mtt of the Bf-109E.

5600/140 = 40 lbs MINIMUM control force required on the elevator at 1G and we require a stick force per G greater than 8lbs/g.

I would think CloD FM is sophisticated enough to use sections. If that is the case, simulating the slats effect on stall behaviors should be a matter of doing exactly what the designers did.

Adjust the coefficient of moment of the elevator accordingly with the outboard wing sections and stalled main portion wing sections.

At the forward CG point where our elevator requires the most moment, the airplane should not spin. As the CG moves rearward, the ability to enter a spin is increased until at its most rearward position a spin entry is possible with deliberate effort.

Reading the synopsis of the Mtt spin trials the Bf-109 at rearward CG reminds me of a C-172 spin qualities at the Cessna forward CG. You must enter a power on stall and give a vigorous rudder input to the direction you want to spin. The break is crisp as the rudder feel is noticeably sloppy near the break but solid until that vicinity. The airplanes settles into more of a corkscrewing dive than a developed spin. The PARE can be pretty sloppy in a 172, letting go of the controls will effect recovery many times. Reducing power and stepping on the high wing results in immediate recovery. You can just about ignore the A and E in PARE in a C172 as long as they are not extreme.

[ACE-OF-ACES]

Now there you have to bring some proof that the assymetric action of the flaps, which was intended, was causing spins.
First you 'flip' and said 'with such arguments I am soo far out'.. Now you 'flop' and want me to provide proof of such arguments that are too far out?

Why bother, Ill just give you a few more min to 'flip' back and poo poo it again.

And the points you've brought are as usual black and white with no room for intermediate.
Agreed..

But I can not take all the credit for these points.. I was simply pointing out what pilots who have flown the 109 had to say about the uneven slat activation.

[Crumpp]

Stalling the 109
Me 109 E:
"The airplane was equipped with a 60 foot trailing static head and a swiveling pitot head. Although, as may be imagined, operation of a trailing static from a single-seater with a rather cramped cockpit is a difficult job, the pilot brought back the following results:
Lowering the ailerons and flaps thus increases CL max of 0.5. This is roughly the value which would be expected from the installation. Behaviour at the stall. The airplane was put through the full official tests. The results may be summarized by saying that the stalling behaviour, flaps up and down, is excellent. Both rudder and ailerons are effective right down to the stall, which is very gentle, the wing only falling about 10 degrees and the nose falling with it. There is no tendency to spin. With flaps up the ailerons snatch while the slats are opening, and there is a buffeting on the ailerons as the stall is approached.. Withs flaps down there is no aileron snatch as the slats open, and no pre-stall aileron buffeting. There is no warning of the stall, flaps down. From the safety viewpoint this is the sold adverse stalling feature; it is largely off-set by the innocuous behaviour at the stall and by the very high degree of fore and aft stability on the approach glide.
It is important to bear in mind that minimum radii of turn are obtained by going as near to the stall as possible. In this respect the Bf.109E scores by its excellent control near the stall and innocuous behaviour at the stall, giving the pilot confidence to get the last ounce out of his airplanes turning performance."- RAF Royal Aircraft Establishment (RAE) Farnborough handling trials,Bf.109E Wn: 1304. M.B. Morgan and R. Smelt of the RAE, 1944.

Me 109 E-4:
"I was amazed at how docile the aircraft was and how difficult it was to depart, particularly from manoeuvre - in a level turn there was lots of warning from a wide buffet margin and the aircraft would not depart unless it was out of balance. Once departted the aircraft was recovered easily by centralizing the controls."
- Charlie Brown, RAF Flying Instructor, test flight of restored Me 109 E-4 WN 3579. Source: Warbirds Journal issue 50.

Me 109 G:
"- How the Messerschmitt reacted to hard pull? Did she stall?
There is the general opinion that you could not make her stall by pulling but she could 'slip'."
- Kyösti Karhila, Finnish fighter ace. 32 victories. Source: Interview by Finnish Virtual Pilots Association.



Me 109 E:
"I was particularly interested in the operation of the slats, the action of which gave rise to aileron snatching in any high-G manoeuvres such as loops or tigh turns so I did a series of stalls to check their functioning more accurately. The stall with the aircraft clean, with half fuel load and the engine throttled right back occurred at 105 MPH (168 km/h). This was preceded by elevator buffet and opening the slats about 20 mph (30 km/h) above the stall, these being accompanied by the unpleasant aileron snatching as the slats opened unevenly. The stall itself was fairly gentle with the nose dropping and the port wing simultaneously dropping about 10 degrees."
- Eric Brown
- The author writes about an "unpleasant" event. Nothing catastrophic! Surely all of the planes of that time had features, that were unpleasant, just as well as many planes today have. Curtiss Hawk 75 was surely unpleasant to fly with the rear fuselage fuel tank filled, as flying acrobatics could get you killed. P-51 was at least unpleasant with fuselage tanks filled.

Me 109 E:
"The Bf 109s also had leading edge slats. When the 109 was flown, advertently or inadvertently, too slow, the slats shot forward out of the wing, sometimes with a loud bang which could be heard above the noise of the engine. Many times the slats coming out frightenened young pilots when they flew the Bf 109 for the first time in combat. One often flew near the stalling speed in combat, not only when flying straight and level but especially when turning and climbing. Sometimes the slats would suddenly fly out with a bang as if one had been hit, especially when one had throttled back to bank steeply. Indeed many fresh young pilots thought they were pulling very tight turns even when the slats were still closed against the wing. For us, the more experienced pilots, real manoeuvring only started when the slats were out. For this reason it is possible to find pilots from that period (1940) who will tell you that the Spitfire turned better than the Bf 109. That is not true. I myself had many dogfights with Spitfires and I could always out-turn them.
One had to enter the turn correctly, then open up the engine. It was a matter of feel. When one noticed the speed becoming critical - the aircraft vibrated - one had to ease up a bit, then pull back again, so that in plan the best turn would have looked like an egg or a horizontal ellipse rather than a circle. In this way one could out-turn the Spitfire - and I shot down six of them doing it. This advantage to the Bf 109 soon changed when improved Spitfires were delivered."
- Erwin Leykauf, German fighter pilot, 33 victories. Source: Messerschmitt Bf109 ja Saksan Sotatalous by Hannu Valtonen; Hurricane & Messerschmitt, Chaz Bowyer and Armand Van Ishoven.

Me 109 E:
"And there I discovered the first thing you have to consider in a 109. The 109 had slots. The slot had a purpose to increase the lift during takeoff and landing. In the air automatically it's pressed to the main wing. And if you turn very roughly you got a chance, it's just by power, the wing, the forewing, comes out a little bit, and you snap. This happened to me. I released the stick immediately and it was ok then. "
- Major Gunther Rall in April 1943. German fighter ace, NATO general, Commander of the German Air Force. 275 victories. Source: Lecture by general Rall.

Me 109 E/F/G: - The plane had these wing slats and you mentioned they pop open uneven?
"Two meter slots on fore wings. The reason was to increase the lift during low speed take off and landing. To reduce the length of runway you need. In the air, if you make rough turns, just by gravity, the outer slot might get out. You can correct it immediately by release of stick, you know? Only little bit, psssssssht, its in, then its gone. You have to know that. And if you know it, you prevent it."
- Major Gunther Rall. German fighter ace, NATO general, Commander of the German Air Force. 275 victories. Source: Lecture by general Rall.

Me 109 G:
"- How often did the slats in the leading edge of the wing slam open without warning?
They were exteneded always suddenly but not unexpectedly. They did not operate in high speed but in low speed. One could make them go out and in by moving the stick back and forth. When turning one slat functioned ahead of the other one, but that did not affect the steering. In a battle situation one could pull a little more if the slats had come out. They had a positive effect of the slow speed handling characteristics of the Messerschmitt.
- Could the pilot control the leading edge slats?
No. The slats were extended when the speed decreased enough, you could feel when they were extended. "
- Kyösti Karhila, Finnish fighter ace. 32 victories. Source: Interview by Finnish Virtual Pilots Association.

Me 109 G:
"- In a battle, which was the case: did the pilot endure more than the Messerschmitt could do or vice versa?
The fact is that when you pulled hard enough the wing leading edge slats slammed open. After that the pilot could not tighten the turn. The plane would have stalled. I don't know, I never tried to find out what the plane would do after that. I never heard anybody else saying that he would have banked so hard that the slats came out. I did that a few times, for example once over the Isthmus I tried to turn after an enemy, banking so hard that both slats came out, but I had to give up.
- How did the slats behave in such a situation, did they go in and out ?
It depended on speed, if you pulled more,they came out, then back in
The slats came out completely, never half-way?
I never came to watch them so intensely. You just knew they had come out, you could see them and feel that the lift increased pretty much.
- So the plane warned that now you are on the edge.
Yes, you knew the plane is about to spin."
- Antti Tani, Finnish fighter ace. 21,5 victories. Source: Interview by Finnish Virtual Pilots Association.

Me 109 F/G:
"- Did pilots like the slats on the wings of the 109?
Yes, pilots did like them, since it allowed them better positions in dogfights along with using the flaps. These slats would also deploy slightly when the a/c was reaching stall at higher altitudes showing the pilot how close they were to stalling.....this was also useful when you were drunk "
- Franz Stigler, German fighter ace. 28 victories. Interview of Franz Stigler.

Me 109 G:
"As CL max is reached the leading edge slats deploy - together if the ball is in the middle, slightly asymmetrically if you have any slip on. The aircraft delights in being pulled into hard manuevering turns at these slower speeds. As the slats pop out you feel a slight "notching" on the stick and you can pull more until the whole airframe is buffeting quite hard. A little more and you will drop a wing, but you have to be crass to do it unintentionally."
- Mark Hanna of the Old Flying Machine Company flying the OFMC Messerschmitt Bf 109 G (Spanish version).

Me 109 G:
"There was nothing special in landing the plane. It was heavy but the wing slats opened up when speed slowed down and helped flying in slow speed."
-Kullervo Joutseno, Finnish fighter pilot. Source: Hannu Valtonen, "Me 109 ja Saksan sotatalous" (Messerschmitt Bf 109 and the German war economy), ISBN 951-95688-7-5.

Me 109 G:
"It was beneficial to keep the throttle a little open when landing. This made the landings softer and almost all three-point landings were successful with this technique. During landings the leading edge slats were fully open. But there was no troubles in landing even with throttle at idle."
-Mikko Lallukka, Finnish fighter pilot. Source: Hannu Valtonen, "Me 109 ja Saksan sotatalous" (Messerschmitt Bf 109 and the German war economy), ISBN 951-95688-7-5.Source: Hannu Valtonen, "Messerschmitt Bf 109 and the German war economy"

Me 109 G:
"We didn't have time for acrobatics but we weren't forbidden from doing them, though. Snap roll was fast and easy, and the engine didn't cough as in older planes. Immelman turn was splendid when you tightened the stick a bit on the top. The automatic wing slats did their trick and you didn't need ailerons at all for straightening the plane."
-Otso Leskinen, Finnish fighter pilot. Source: Hannu Valtonen, "Me 109 ja Saksan sotatalous" (Messerschmitt Bf 109 and the German war economy), ISBN 951-95688-7-5.

"Unexperienced pilots hesitated to turn tight, bacause the plane shook violently when the slats deployed. I realised, though, that because of the slats the plane's stalling characteristics were much better than in comparable Allied planes that I got to fly. Even though you may doubt it, I knew it [Bf109] could manouver better in turnfight than LaGG, Yak or even Spitfire."
- Walter Wolfrum, German fighter ace. 137 victories.



http://www.virtualpilots.fi/feature/articles/109myths/

[taildraggernut]

Nothing to do with any emotional attachment one way or the other to the Spitfire. I like the airplane.

Nobody mentioned emotional attachments.

With certain posters on these boards though there is no reason to repeat the strengths of the design as that is all they emphasize.

They tend only to repeat the positive aspects after certain posters go out of their way to emphasise the minor negative aspects.

[taildraggernut]

At the forward CG point where our elevator requires the most moment, the airplane should not spin. As the CG moves rearward, the ability to enter a spin is increased until at its most rearward position a spin entry is possible with deliberate effort.

So basically you aknowlege the RAE evaluation that the aircraft was 'too stable' for a fighter, if you are having to use up elevator effect simply to counter the CoG then you have afairly impeded manouverability.

[Crumpp]

If you have never flown a slat equipped aircraft, it is a different experience despite the slats being totally unnoticeable for the vast majority of their operation.

Once you have, the idiosyncrasies of the slats becomes part of the airplane and the tactile clues are comforting acknowledgements that everything is working as it should.

Once you explore the low speed performance of a slat equipped aircraft you will miss them on airplanes that lack such a device.

[II/JG53 Rolf]

One of the most amusing threads I have ever read... You can learn so many details about slats and its function while there is an agreement that in-game Bf-109 E doesn't have realistic stall and spin characteristics... Well done chaps.:)

[ACE-OF-ACES]

http://www.virtualpilots.fi/feature/articles/109myths/
LOL

Leave it to Crumpp to cut-n-paste quotes from a website with the title 109 myths as PROOF that uneven slat activation could NOT cause spins.. Yup no chance of bias at that website! NOT! One glance at that site and anyone can see that site goes way out of it's way to interpret what was said about uneven slat activation in the best possible light for the 109

With that said, instead of 'words' from a biased Internet website, how about 'words' from actual Bf109 pilots in a book by David Isby called The Decisive Duel: Spitfire vs 109? Will this meet your standards of proof robtek?

Less experienced pilots could put a Bf 109 into a stall and spin when the slats deployed on one wing and not the other in a tight turn. When slats deployed unevenly in tight turns, they would disrupt the airflow, causing the ailerons to ‘snatch’ enough to shake a Bf 109, spoiling the pilot’s aim

Now it is decision time.. As in who are you going to belive?

1) A biased website quote posted by Crumpp.
2) A quote of an actual WWII Bf109 pilot.

The choice is clear, but I am sure that some folks like Crumpp, Tomcat, and robtek will find creative ways to disregard what this actual WWII Bf109 pilot had to say about the slats causing spins..

[Crumpp]

RAE evaluation that the aircraft was 'too stable'


It is a fact the RAE pilot felt that way. It is also a fact the RAE had no defined stability and control standards outside of pilot opinion. They did not have the measurements and definitions of the NACA or the RLM.

It is also a fact if you apply those definitions and standards, the Bf-109 was designed to be thrown around the sky at maximum performance the physics and physiological limits of the real world allowed.

Gust factor is a very real limit to airplanes. Flying around the other day, I had to stay below Vno just cruising because the sky was so bumpy.

If you pull a 6G maneuver and hit a gust acceleration, you have damaged the airplane. Not only that, 6G's sucks!! It is very uncomfortable and exhausting! IIRC, the USAF did a study and a fighter pilots ability to accurately track a target for a gun solution is degraded ~85% of normal after a few seconds exposure to just 4.5G's.

What Mtt did was apply a stability and control standard to ensure the pilot could quickly and precisely maneuver the guns onto target in order to make the most accurate shot possible. They tried to ensure the airplane achieved maximum performance to get where it needed to be in a condition to destroy other airplanes.

The designed a stable shooting platform and built an airplane around it.

[Crumpp]

Crumpp to cut-n-paste quotes from a website with the title 109 myths as PROOF that uneven slat activation could NOT cause spins..

Why don't you get some experience in an automatic slat equipped aircraft and come back to tell us how it works.

You don't seem to count my experience so share yours!!

[Crumpp]

Bf 109 into a stall and spin when the slats deployed on one wing and not the other

Airframes break apart in flight, Flaps break, engines breakdown, spark plugs foul, fabric balloons, and slats malfunction...

http://img338.imageshack.us/img338/3954/spunandwingsfail.jpg (http://imageshack.us/photo/my-images/338/spunandwingsfail.jpg/)


All things mechanical can fail especially if not properly maintained or abused.

What does that have to do with me or the physics of how slats operate?

[ACE-OF-ACES]

Why don't you get some experience in an automatic slat equipped aircraft and come back to tell us how it works.
Why? When I have something better, as in an actual WWII Bf109 quote, i.e.

Less experienced pilots could put a Bf 109 into a stall and spin when the slats deployed on one wing and not the other in a tight turn. When slats deployed unevenly in tight turns, they would disrupt the airflow, causing the ailerons to ‘snatch’ enough to shake a Bf 109, spoiling the pilot’s aim

You don't seem to count my experience so share yours!!
Don't take it personally!

I just think the experience of an actual WWII Bf109 pilot trumps Crumpp's modern civilian aircraft pilot experience when talking about how a Bf109 acts..

Guess I am just silly like that! ;)

[ACE-OF-ACES]

Flaps break, engines breakdown, spark plugs foul, fabric balloons, and slats malfunction...

All things mechanical can fail especially if not properly maintained or abused.

What does that have to do with me or the physics of how slats operate?
Not sure Crumpp..

But it sounds like your saying you know better than Oberleutnant Erwin Leykauf wrt how slats worked on a Bf109 in flight..

If so,

well..

I guess you can 'feel' that way..

Just know that I an others are probally going to stick with Oberleutnant Erwin Leykauf experance on this mater over yours

[II/JG53 Rolf]

AOA - Sir, you have just done the same thing. While he posted numerous pilot records about slats, you choose one from a single book as a proof... :) Is the book reliable in all aspects? Does the author really understand aerodynamics? Now I don't have the book in my place, so I can't check it, but it seems to me that this is one I've actually read and there were several mistakes caused by authors misunderstanding of how things work and were designed.

It sort of reminds me a book by Stephen Bungay who was trying to mathematically prove that the 8 machine guns of a spit/hurry were more effective than 2 cannons of Bf-109 E...

Now to your quote - "...Less experienced pilots could put a Bf 109 into a stall and spin when the slats deployed on one wing and not the other in a tight turn..." Sir, Less experienced pilots is the key here. It means they ignored the warning the slats had given them and continued pulling on the stick :-) ... It was mistake of a pilot not a plane... and less experienced pilots avoided near stall conditions at all... and it and it has been reported many times...

World would be a better place if we listened to each other instead of shouting...

And THE QUESTION about slats has both answers actually ;) - they do both in logical sequence... :-)

[taildraggernut]

purely in the interest of balance.

Stalling the 109
Me 109 E:
"The airplane was equipped with a 60 foot trailing static head and a swiveling pitot head. Although, as may be imagined, operation of a trailing static from a single-seater with a rather cramped cockpit is a difficult job, the pilot brought back the following results:
Lowering the ailerons and flaps thus increases CL max of 0.5. This is roughly the value which would be expected from the installation. Behaviour at the stall. The airplane was put through the full official tests. The results may be summarized by saying that the stalling behaviour, flaps up and down, is excellent. Both rudder and ailerons are effective right down to the stall, which is very gentle, the wing only falling about 10 degrees and the nose falling with it. There is no tendency to spin. With flaps up the ailerons snatch while the slats are opening, and there is a buffeting on the ailerons as the stall is approached.. Withs flaps down there is no aileron snatch as the slats open, and no pre-stall aileron buffeting. There is no warning of the stall, flaps down. From the safety viewpoint this is the sold adverse stalling feature; it is largely off-set by the innocuous behaviour at the stall and by the very high degree of fore and aft stability on the approach glide.
It is important to bear in mind that minimum radii of turn are obtained by going as near to the stall as possible. In this respect the Bf.109E scores by its excellent control near the stall and innocuous behaviour at the stall, giving the pilot confidence to get the last ounce out of his airplanes turning performance."- RAF Royal Aircraft Establishment (RAE) Farnborough handling trials,Bf.109E Wn: 1304. M.B. Morgan and R. Smelt of the RAE, 1944.

Nice report, but apparently the RAE knew nothing and didn't have nice spangly testing equipment.....see quote below.

The behaviors of the Bf-109 are fairly well documented and we have some measured data. There is enough there to construct a reasonable facimile. Unfortunately the RAE did not have a standard or the measuring equipment developed by the NACA until later.

Me 109 E-4:
"I was amazed at how docile the aircraft was and how difficult it was to depart, particularly from manoeuvre - in a level turn there was lots of warning from a wide buffet margin and the aircraft would not depart unless it was out of balance. Once departted the aircraft was recovered easily by centralizing the controls."
- Charlie Brown, RAF Flying Instructor, test flight of restored Me 109 E-4 WN 3579. Source: Warbirds Journal issue 50.

Here is where someone has basically confirmed the aircraft will spin, of course this is a contemporary report on a restored aircraft which is not loaded the same as a wartime machine.

Me 109 G:
"- How the Messerschmitt reacted to hard pull? Did she stall?
There is the general opinion that you could not make her stall by pulling but she could 'slip'."
- Kyösti Karhila, Finnish fighter ace. 32 victories. Source: Interview by Finnish Virtual Pilots Association.

Note the oppinion was 'general' and not explicit.

Quote:
Me 109 E:
"I was particularly interested in the operation of the slats, the action of which gave rise to aileron snatching in any high-G manoeuvres such as loops or tigh turns so I did a series of stalls to check their functioning more accurately. The stall with the aircraft clean, with half fuel load and the engine throttled right back occurred at 105 MPH (168 km/h). This was preceded by elevator buffet and opening the slats about 20 mph (30 km/h) above the stall, these being accompanied by the unpleasant aileron snatching as the slats opened unevenly. The stall itself was fairly gentle with the nose dropping and the port wing simultaneously dropping about 10 degrees."
- Eric Brown
- The author writes about an "unpleasant" event. Nothing catastrophic! Surely all of the planes of that time had features, that were unpleasant, just as well as many planes today have. Curtiss Hawk 75 was surely unpleasant to fly with the rear fuselage fuel tank filled, as flying acrobatics could get you killed. P-51 was at least unpleasant with fuselage tanks filled.

I'm sure all Mr Brown meant was 'unpleasant' and there is nothing more to be read into it.

Me 109 E:
"The Bf 109s also had leading edge slats. When the 109 was flown, advertently or inadvertently, too slow, the slats shot forward out of the wing, sometimes with a loud bang which could be heard above the noise of the engine. Many times the slats coming out frightenened young pilots when they flew the Bf 109 for the first time in combat. One often flew near the stalling speed in combat, not only when flying straight and level but especially when turning and climbing. Sometimes the slats would suddenly fly out with a bang as if one had been hit, especially when one had throttled back to bank steeply. Indeed many fresh young pilots thought they were pulling very tight turns even when the slats were still closed against the wing. For us, the more experienced pilots, real manoeuvring only started when the slats were out. For this reason it is possible to find pilots from that period (1940) who will tell you that the Spitfire turned better than the Bf 109. That is not true. I myself had many dogfights with Spitfires and I could always out-turn them. One had to enter the turn correctly, then open up the engine. It was a matter of feel. When one noticed the speed becoming critical - the aircraft vibrated - one had to ease up a bit, then pull back again, so that in plan the best turn would have looked like an egg or a horizontal ellipse rather than a circle. In this way one could out-turn the Spitfire - and I shot down six of them doing it. This advantage to the Bf 109 soon changed when improved Spitfires were delivered."
- Erwin Leykauf, German fighter pilot, 33 victories. Source: Messerschmitt Bf109 ja Saksan Sotatalous by Hannu Valtonen; Hurricane & Messerschmitt, Chaz Bowyer and Armand Van Ishoven.

Another pilot report, subject to all the ego and fading memory issues, there is no clear evidence that the 6 Spitfires shot down were not being flown by fresh young pilots of the RAF.

Me 109 E:
"And there I discovered the first thing you have to consider in a 109. The 109 had slots. The slot had a purpose to increase the lift during takeoff and landing. In the air automatically it's pressed to the main wing. And if you turn very roughly you got a chance, it's just by power, the wing, the forewing, comes out a little bit, and you snap. This happened to me. I released the stick immediately and it was ok then. "
- Major Gunther Rall in April 1943. German fighter ace, NATO general, Commander of the German Air Force. 275 victories. Source: Lecture by general Rall.

Heres a point showing the true function of the slats.

Me 109 E/F/G: - The plane had these wing slats and you mentioned they pop open uneven?
"Two meter slots on fore wings. The reason was to increase the lift during low speed take off and landing. To reduce the length of runway you need. In the air, if you make rough turns, just by gravity, the outer slot might get out. You can correct it immediately by release of stick, you know? Only little bit, psssssssht, its in, then its gone. You have to know that. And if you know it, you prevent it."
- Major Gunther Rall. German fighter ace, NATO general, Commander of the German Air Force. 275 victories. Source: Lecture by general Rall.

Same guy same reasoning, slats were for low speed handling.

Me 109 G:
"- How often did the slats in the leading edge of the wing slam open without warning?
They were exteneded always suddenly but not unexpectedly. They did not operate in high speed but in low speed. One could make them go out and in by moving the stick back and forth. When turning one slat functioned ahead of the other one, but that did not affect the steering. In a battle situation one could pull a little more if the slats had come out. They had a positive effect of the slow speed handling characteristics of the Messerschmitt.- Could the pilot control the leading edge slats?
No. The slats were extended when the speed decreased enough, you could feel when they were extended. "
- Kyösti Karhila, Finnish fighter ace. 32 victories. Source: Interview by Finnish Virtual Pilots Association.

Slightly confusing, the slats didn't open at high speed?, but another confirmation of the true function of slats.

Me 109 G:
"- In a battle, which was the case: did the pilot endure more than the Messerschmitt could do or vice versa?
The fact is that when you pulled hard enough the wing leading edge slats slammed open. After that the pilot could not tighten the turn. The plane would have stalled. I don't know, I never tried to find out what the plane would do after that. I never heard anybody else saying that he would have banked so hard that the slats came out. I did that a few times, for example once over the Isthmus I tried to turn after an enemy, banking so hard that both slats came out, but I had to give up.
- How did the slats behave in such a situation, did they go in and out ?
It depended on speed, if you pulled more,they came out, then back in
The slats came out completely, never half-way?
I never came to watch them so intensely. You just knew they had come out, you could see them and feel that the lift increased pretty much.
- So the plane warned that now you are on the edge.
Yes, you knew the plane is about to spin."- Antti Tani, Finnish fighter ace. 21,5 victories. Source: Interview by Finnish Virtual Pilots Association.

Interesting, after the slats were open you didn't wan't to pull more or the aircraft would stall, a pilot showing a healthy reluctance to go beyond the envelope, and finishing by saying the aircraft would spin.


Me 109 F/G:
"- Did pilots like the slats on the wings of the 109?
Yes, pilots did like them, since it allowed them better positions in dogfights along with using the flaps. These slats would also deploy slightly when the a/c was reaching stall at higher altitudes showing the pilot how close they were to stalling.....this was also useful when you were drunk "
- Franz Stigler, German fighter ace. 28 victories. Interview of Franz Stigler.

I just liked the drunk part.

Me 109 G:
"As CL max is reached the leading edge slats deploy - together if the ball is in the middle, slightly asymmetrically if you have any slip on. The aircraft delights in being pulled into hard manuevering turns at these slower speeds. As the slats pop out you feel a slight "notching" on the stick and you can pull more until the whole airframe is buffeting quite hard. A little more and you will drop a wing, but you have to be crass to do it unintentionally."
- Mark Hanna of the Old Flying Machine Company flying the OFMC Messerschmitt Bf 109 G (Spanish version).

Mark Hanna was killed in a Buchon in a low speed low altitude departure...

Me 109 G:
"There was nothing special in landing the plane. It was heavy but the wing slats opened up when speed slowed down and helped flying in slow speed."
-Kullervo Joutseno, Finnish fighter pilot. Source: Hannu Valtonen, "Me 109 ja Saksan sotatalous" (Messerschmitt Bf 109 and the German war economy), ISBN 951-95688-7-5.

Again the true purpose of slats

Me 109 G:
"It was beneficial to keep the throttle a little open when landing. This made the landings softer and almost all three-point landings were successful with this technique. During landings the leading edge slats were fully open. But there was no troubles in landing even with throttle at idle."
-Mikko Lallukka, Finnish fighter pilot. Source: Hannu Valtonen, "Me 109 ja Saksan sotatalous" (Messerschmitt Bf 109 and the German war economy), ISBN 951-95688-7-5.Source: Hannu Valtonen, "Messerschmitt Bf 109 and the German war economy"

it's all about the low speed handling qualities for approach and landing.

Me 109 G:
"We didn't have time for acrobatics but we weren't forbidden from doing them, though. Snap roll was fast and easy, and the engine didn't cough as in older planes. Immelman turn was splendid when you tightened the stick a bit on the top. The automatic wing slats did their trick and you didn't need ailerons at all for straightening the plane."
-Otso Leskinen, Finnish fighter pilot. Source: Hannu Valtonen, "Me 109 ja Saksan sotatalous" (Messerschmitt Bf 109 and the German war economy), ISBN 951-95688-7-5.


Snap roll is a spin entered at high speed.


"Unexperienced pilots hesitated to turn tight, bacause the plane shook violently when the slats deployed. I realised, though, that because of the slats the plane's stalling characteristics were much better than in comparable Allied planes that I got to fly. Even though you may doubt it, I knew it [Bf109] could manouver better in turnfight than LaGG, Yak or even Spitfire."
- Walter Wolfrum, German fighter ace. 137 victories.

Depends on who is flying them I guess.

[raaaid]

stall is not equal to spin

you know what stall is?

think youre flying level but actually going so slow you are aactually falling as a rock

at some point the game modelled this

[taildraggernut]

If you have never flown a slat equipped aircraft, it is a different experience despite the slats being totally unnoticeable for the vast majority of their operation.

Once you have, the idiosyncrasies of the slats becomes part of the airplane and the tactile clues are comforting acknowledgements that everything is working as it should.

Once you explore the low speed performance of a slat equipped aircraft you will miss them on airplanes that lack such a device.

I don't miss aircraft with slats at all, I am quite capable of handling aircraft without them, of course if you feel your own competence is questionable then there is nothing wrong with 'training wheels'

[ACE-OF-ACES]

AOA - Sir, you have just done the same thing. While he posted numerous pilot records about slats, you choose one from a single book as a proof... :)
Ah.. I see where you are confused

Note what I posted was a quote of an actual WWII Bf109 pilot.. Not my 'take' or 'interpretation' of what the actual WWII Bf109 pilot said.

Which is very different from the website Crumpp provided where the webiste provides you their 'take' and/or 'interpretation' of what the WWII pilots actually were trying to say or meant to say.. I guess some folks need others to do their thinking for them?

Hope that helps!

Now allow me to point out to those reading this post how Rolf and Crump totally ignored the actually WWII Bf109 pilot's quote I provided that said uneven slat activation can cause spins and tried to make this about me!

Nice try guys!

Gold star for effort!

But no sale! ;)

[Crumpp]

Mark Hanna was killed in a Buchon in a low speed low altitude departure...


Different airplane but yes, the nose up attitude at the stall and descent can be very dangerous if the pilot is not on his toes.

Your stalled and the danger is you don't realize in time.

[taildraggernut]

Different airplane but yes, the nose up attitude at the stall and descent can be very dangerous if the pilot is not on his toes.

Your stalled and the danger is you don't realize in time.

everything behind the firewall is a 109....including the slats.

[taildraggernut]

It is a fact the RAE pilot felt that way. It is also a fact the RAE had no defined stability and control standards outside of pilot opinion. They did not have the measurements and definitions of the NACA or the RLM.

It is also a fact if you apply those definitions and standards, the Bf-109 was designed to be thrown around the sky at maximum performance the physics and physiological limits of the real world allowed.

Gust factor is a very real limit to airplanes. Flying around the other day, I had to stay below Vno just cruising because the sky was so bumpy.

If you pull a 6G maneuver and hit a gust acceleration, you have damaged the airplane. Not only that, 6G's sucks!! It is very uncomfortable and exhausting! IIRC, the USAF did a study and a fighter pilots ability to accurately track a target for a gun solution is degraded ~85% of normal after a few seconds exposure to just 4.5G's.

What Mtt did was apply a stability and control standard to ensure the pilot could quickly and precisely maneuver the guns onto target in order to make the most accurate shot possible. They tried to ensure the airplane achieved maximum performance to get where it needed to be in a condition to destroy other airplanes.

The designed a stable shooting platform and built an airplane around it.

Actually I remember a thread that proved your theories the RAE had no established stability and control standards completely false.

The 109 was designed to be flown at high speed towards a target to throw bullets at it and then GTFO in a hurry too, a small wing with such a high loading was not designed to be thrown around and that is why they put slats on them, to improve it's low speed handling.

why does 6g suck? I personally like aerobatics and have been to 7g, of course you tend to avoid manouvering in conditions you 'know' likely to be gusty.

[II/JG53 Rolf]

AOA - Sir, with all respect, could you explain how could uneven deployment of slats cause the above effect? I mean it, sir. No irony. Say, we have a Bf-109 E4 in a tight right horizontal turn trying to gain enough lead to kill a spit. It's on the edge of stall. Does it mean that the slat on the right thing wouldn't deploy entirely but, say, lower part more than the upper part. There was construction a diagram shown here, where it shouldn't be possible so it must have been malfunction - and sir, all planes were not the same (e.g. max speeds show average number, actual outputs of the plane could be +/- 5-10%, up to 20% in case of Russian planes). Or does it work differently (I could be missing something.)

And your point about me ignoring something in your post wasn't valid I am afraid, as I tried to explain that the cause could have been the actual experience of the pilot. There was mentioned before that there could be mechanical problems with slats because of dust, so they didn't deploy evenly or at all. However, I would say that this is simple malfunction, not a construction thing.

[ACE-OF-ACES]

AOA - Sir, with all respect, could you explain how could uneven deployment of slats cause the above effect? I mean it, sir.
No need for me to explain it..

In that based on Erwin Leykauf quote, an actual WWII Bf109 pilot we know that it happened, i.e.

Less experienced pilots could put a Bf 109 into a stall and spin when the slats deployed on one wing and not the other in a tight turn. When slats deployed unevenly in tight turns, they would disrupt the airflow, causing the ailerons to ‘snatch’ enough to shake a Bf 109, spoiling the pilot’s aim

Agreed?

Or are you saying you know better than Erwin Leykauf? Or that Erwin Leykauf was lying when he said that?

Eitherway you seem a little confused..

Allow me to bring you up to speed!

Back on page 19 robtek ask for PROOF, i.e.

Now there you have to bring some proof that the assymetric action of the flaps, which was intended, was causing spins.

To which I did not bother providing in that I knew robtek would just poo poo anything I did provide

After that Crumpp felt the need to chime in with his cut-n-paste Bf109 myths site 'take on' what actual WWII pilots said as proof that uneven slat activation can NOT cause a spin because the Bf109 myth site, FOR SOME REASON left that part of Erwin Leykauf quote out of thier section called "Wing leading edge slats - good or bad?".

My guess is that it was just to black and white for them to 'spin' (pun intended) what Erwin Leykauf said into something positive..

So the Bf109 myth site conventally left that part of the quote out of their section devoted to uneven slat activation issue.

Talk about poster boys for 109 bias! ;)

After seeing that weak attempt by Crumpp to present the biased Bf109 myth site reinterpretation of WWII pilot quotes as proof I decided to post Erwin Leykauf quote here as PROOF of what I was saying

Hope that helps!

[II/JG53 Rolf]

AOA - Sir, how could this happen? If the slat opened on the lower wing, it would increase lift there thus preventing stall for a few moments. What the pilot said was that less experienced pilot went into the stall/spin (stall first spin later) when this happened. On previous pages there was a description of RL pilot doing the same with only one difference - he was very experienced and recovered without a problem. The point is - you have a pilot with say 150 hours in the heat of the fight to the death who is turning hard to avoid being shot at or to gain a shot on an enemy - he could have missed those warnings. So the pilot told the truth, but as in many examples from that era it is only part of it. In the same manner you are ignoring his quotes telling the opposite. If we just step back a bit - to sum it up:
1) Slats were designed to open unevenly because the aerodynamic effects were uneven on both wings, especially in high AOA.
2) Slats helped at stall speeds at low speeds, discussion is held about high speed with not much evidence for either case in this thread.
3) Slats could have malfunctions as any other part of a plane - not all planes and pilots have the best ground crew. The slat then could open partially which could cause inexperienced pilot to stall/spin.
4) Recovery from the spin of slats equipped 109 was considered easy.
5) This whole thread was started because of stall and spin characteristics of bf-109 in CLOD game ;) .

[Crumpp]

Actually I remember a thread that proved your theories the RAE had no established stability and control standards completely false.


Really?

Wow, you should tell the engineering departments of every major university because they are teaching the wrong information.

Maybe you should tell one of the pioneers of stability and control engineering. A British engineer who strived during the war and after to get the RAE on a defined standard after his experience working with the NACA. What is even more funny is the fact stick force per G, which Gates developed, was adopted by the NACA as part of the 1942 standard!

The United States NACA adopted a British engineers ideas and made them standard long before the British RAE listened to their own guy! That was the basis of his invitation to come to the United States and observe the stability and control developments at the NACA.

Here is the first page of the proposed standards for longitudinal stability, in fact.

I think World War II in Europe ended in May 1945. Pretty sure September 1947 is after the conflict was over....

http://img607.imageshack.us/img607/8906/britishlackofastandard.jpg (http://imageshack.us/photo/my-images/607/britishlackofastandard.jpg/)

[ACE-OF-ACES]

AOA - Sir, how could this happen?
Does not mater how..

In that based on Erwin Leykauf quote, an actual WWII Bf109 pilot we know that it happened, i.e.

Less experienced pilots could put a Bf 109 into a stall and spin when the slats deployed on one wing and not the other in a tight turn. When slats deployed unevenly in tight turns, they would disrupt the airflow, causing the ailerons to ‘snatch’ enough to shake a Bf 109, spoiling the pilot’s aim

Agreed?

Either way you seem a little confused..

Allow me to bring you up to speed!

This all started with me saying the following..


Especially in light of the fact that there are many accounts of how leading edge slats CAUSED spins!!

Where, for what ever reason, the leading edge slats did not deploy evenly and thus induces (CAUSE) the plane to spin..

Not to mention the accounts of the leading edge slats POPPING out suddenly such that they 'changed' the aerodynamics such that the pilot had to quickly adjust his controls.. In essence startling the pilot such that he may have over compensated and CAUSE the plane to stall or even spin

To which robtek responded asking for proof of the accounts, i.e.

Now there you have to bring some proof that the assymetric action of the flaps, which was intended, was causing spins.

Initially I didn't bother digging up the historic accounts because I knew robtek would just poo poo anything I did provide..

But after that Crumpp felt the need to chime in with his cut-n-paste Bf109 myths site 'take on' what actual WWII pilots said as proof that uneven slat activation can NOT cause a spin because the Bf109 myth site, for some reason they conventually left that part of Erwin Leykauf quote out of their section called "Wing leading edge slats - good or bad?".

My guess is that it was just to black and white for them to 'spin' (pun intended) what Erwin Leykauf said into something positive..

But I digress..

After seeing that weak attempt by Crumpp to present the Bf109 myth site reinterpretation of what WWII pilot said as PROOF

I decided to post Erwin Leykauf quote here as PROOF of what I was saying..

IMHO there is no debating this issue

Unless your willing to say Erwin Leykauf was mistaken and you know better than he on how the Bf109 flys, or your willing to say Erwin Leykauf was lying?

So in summary

1) I pointed out uneven activation of the slats can cause spins..
2) rotek ask for proof of uneven activation of the slats can cause spins.. (aka bring it)
3) I provided proof of uneven activation of the slats can cause spins.. (aka brung it)

Hope that helps!

[Crumpp]

everything behind the firewall is a 109....including the slats.


Exactly!

You have an airframe designed for one engine that is now having to work with another one.

This is why STC's are required and you just cannot swap motors in certified design airplanes.

The merlin prop swung at a lower rpm, weight is different, and the thrustline was higher. At least it turned in the same direction.

You do understand airframe are built to counteract the effects of spiral slipstream and torque?

That is why engine mounts/firewalls are angled and verticle stabilizers angled.

Mounting an engine with different properties results in different handling qualities.

Why are we even discussing this and what does it have to do with effect of the slats?

Is it just your justification for using an example which has nothing to do with the original topic?

[Crumpp]

II/JG53 Rolf,

My suggestion would be just to ignore AoA, ie, TAGERT.

[ACE-OF-ACES]

II/JG53 Rolf,

My suggestion would be just to ignore AoA, ie, TAGERT.
Yes, just like the Bf109 myth site you provided as proof ignored Erwin Leykauf quote! ;)

[Crumpp]

to sum it up:
1) Slats were designed to open unevenly because the aerodynamic effects were uneven on both wings, especially in high AOA.
2) Slats helped at stall speeds at low speeds, discussion is held about high speed with not much evidence for either case in this thread.
3) Slats could have malfunctions as any other part of a plane - not all planes and pilots have the best ground crew. The slat then could open partially which could cause inexperienced pilot to stall/spin.
4) Recovery from the spin of slats equipped 109 was considered easy.
5) This whole thread was started because of stall and spin characteristics of bf-109 in CLOD game

Good summary.

I would add:

2) Slats helped at stall speeds at low speeds and ensured gentle stall behaviors, discussion is held about high speed with not much evidence for either case in this thread.

4) Entry into a spin was difficult and Recovery from the spin of slats equipped 109 was considered easy.

[taildraggernut]

Really?

Wow, you should tell the engineering departments of every major university because they are teaching the wrong information.

Maybe you should tell one of the pioneers of stability and control engineering. A British engineer who strived during the war and after to get the RAE on a defined standard after his experience working with the NACA. What is even more funny is the fact stick force per G, which Gates developed, was adopted by the NACA as part of the 1942 standard!

The United States NACA adopted a British engineers ideas and made them standard long before the British RAE listened to their own guy! That was the basis of his invitation to come to the United States and observe the stability and control developments at the NACA.

Here is the first page of the proposed standards for longitudinal stability, in fact.

I think World War II in Europe ended in May 1945. Pretty sure September 1947 is after the conflict was over....

http://img607.imageshack.us/img607/8906/britishlackofastandard.jpg (http://imageshack.us/photo/my-images/607/britishlackofastandard.jpg/)

Theres standards and then theres standardisation, you can have standards without standardisation, it simply means there was not a universally applied standard, I asure you the British aircraft industry was not a free-for all where they let the tea ladies get in on the act because it 'looked pretty', there were people who were very aware of what stability and control was within the RAE.
I am not arguing a point about whether a universal standard was adopted, I'm arguing against your bizarre claims the British had 'no' standards and therefore the RAE reports on the 109 may as well have been performed by monkeys.....until of course you want to 'cherry pick' anything positive.

[taildraggernut]

Exactly!

You have an airframe designed for one engine that is now having to work with another one.

This is why STC's are required and you just cannot swap motors in certified design airplanes.

The merlin prop swung at a lower rpm, weight is different, and the thrustline was higher. At least it turned in the same direction.

You do understand airframe are built to counteract the effects of spiral slipstream and torque?

That is why engine mounts/firewalls are angled and verticle stabilizers angled.

Mounting an engine with different properties results in different handling qualities.

Why are we even discussing this and what does it have to do with effect of the slats?

Is it just your justification for using an example which has nothing to do with the original topic?

The point is the aircraft had slats, the same ones on the 109, the same ones you claim could not result in a spin, the same airframe from Mark Hannas quote you were more than happy to include to reflect the 109's behaviour, you do this all the time, completely contradict yourself.

are you really saying that the Spanish simply 'nailed' a merlin into the aircraft and thought 'to hell with the consequences'?

and how much did the basic 109 airframe design change through development when they used RR kestrel engines and Jumo's?

[raaaid]

for what ive understood slats are an all or nothing thing

but in the game the get just half way deployed sometimes

[TomcatViP]

You are amazing guys... How the hell did you end up on the spit`s high speed stall characteristic in a thread about the leading edge slats of the 109?????

There are no spinproof airplanes, there ones which are hard to put in a spin. The wing is stalled when the airflow become turbulent over the whole upper wing area and so it looses its lifting effect. The slats ensure a laminar flow over the outer wing around the ailerons at low speed so you have some more control before the wing stall. No magic here. It can postpone the stall but it won`t eliminate it.

The spin is when only one of the wing is stalled due to the asymmetrical flow. The slats could open independently, so they could prevent a spin by opening only on the wing which was just about the stall. But again it was only postponing the spin in this case and gave you more control.

On the other hand the slats could make a fuss, when only one of them opened due to some mechanical failure, and it resulted an asymmetrical lift and so an unpredicted spin at low speed. Also they raised the drag when they were open, what meant quicker de-accceleration.

I have never flown an aircraft with slats, so no practical experience here, but as I understand Crumpp did, and he gave a quite good description about the acting of such an airplane.

[...]


Thx for reminding this.

Spin is not only the result of the stall of one wing. The drag diff. is also important (stall = high drag). If only one Slat is deployed then this a factor aggravating the likelihoods of a spin.

But regarding the deceleration, remind that at low speed 1000hp is by far enough to offset the drag penality such as in the case of a WWII fighter. So far that the size of the slats were reduced in span on the F to put them out of the propeller stream.

[NZtyphoon]

II/JG53 Rolf,

My suggestion would be just to ignore AoA, ie, TAGERT.


I am not arguing a point about whether a universal standard was adopted, I'm arguing against your bizarre claims the British had 'no' standards and therefore the RAE reports on the 109 may as well have been performed by monkeys.....until of course you want to 'cherry pick' anything positive.

Everybody, My suggestion would be just to ignore Crumpp, ie, GENE. :rolleyes::rolleyes:

Long story short, there will be no further improvements to the flight qualities of any of the aircraft in CLOD, whether it be the Bf 109, or the Spitfire unless there are people who are willing and able to modify the product to represent the flight qualities desired by the players. My guess is no matter what improvements are made there will still be those who will not be satisfied until every tiny nuance of all aircraft is replicated to the nth degree.

[fruitbat]

Everybody, My suggestion would be just to ignore Crumpp, ie, GENE. :rolleyes::rolleyes:

i did, a while back....

[Gabelschwanz Teufel]

i did, a while back....

It only works if everybody does it or the ones that don't will stop quoting him.

[Crumpp]

are you really saying that the Spanish simply 'nailed' a merlin into the aircraft and thought 'to hell with the consequences'?


There is nothing they can do about the airframe changes without a complete redesign of the aircraft.

Why do you think they called the Avia S-199 the "Mule"?

The Ha-112 was a different airplane.

The higher thrust line, weight differences, and difference in rpm results in different dynamic pressure ranges in the spiral slipstream than the airframe was designed. It will have different flying qualities.

I guess you hate me for pointing out that fact!!

Try flying a piston engine porter and a turbine porter if you don't think engine makes a difference in flying qualities.

:eek:

[Crumpp]

The slats ensure a laminar flow

Turbulent flow....not laminar!!

;)

[*Buzzsaw*]

All of this may be somewhat academic, as the game engine has been dropped.

See announcement on main forum.

New forum for BATTLE OF STALINGRAD is here:

http://forum.il2sturmovik.net/index.php?

[Crumpp]

Theres standards and then theres standardisation, you can have standards without standardisation, it simply means there was not a universally applied standard, I asure you the British aircraft industry was not a free-for all where they let the tea ladies get in on the act because it 'looked pretty', there were people who were very aware of what stability and control was within the RAE.
I am not arguing a point about whether a universal standard was adopted, I'm arguing against your bizarre claims the British had 'no' standards and therefore the RAE reports on the 109 may as well have been performed by monkeys.....until of course you want to 'cherry pick' anything positive.


The RAE left things up to the opinion of the pilot as the definative source on the stability and control.

That is why you had such a variation in stability and control in British designs.

Here I will quote Lyons in his report:

It is recommended that Q be adopted for designers' use, that its limits of validity be checked by careful tests on one aeroplane, and that more force measurements in pull out from dives be made on a number of aeroplanes in order that numerical standards may be attached to Q. Reference is made to American standards....

A compact formula Im a criterion of manoeuvrability Q the stick force per g is proposed as a basis of design.

If Q is adopted as a criterion, numerical standards should be attached to it. More measurements are needed of stick force in pulling out of dives, particularly on bombers, before these can be fixed.

[taildraggernut]

There is nothing they can do about the airframe changes without a complete redesign of the aircraft.

Why do you think they called the Avia S-199 the "Mule"?

The Ha-112 was a different airplane.

The higher thrust line, weight differences, and difference in rpm results in different dynamic pressure ranges in the spiral slipstream than the airframe was designed. It will have different flying qualities.

I guess you hate me for pointing out that fact!!

Try flying a piston engine porter and a turbine porter if you don't think engine makes a difference in flying qualities.

:eek:

Do I hate you for pointing out the HE-112 was a different aircraft therefore irrelevant?.......no, it's one of the few things you've said that's true, I don' even hate you for bringing up the Pilatus porter which is also irrelevant. I Do have less than complimentary feelings for your hypocrisy at having quoted Mark Hanna describing the Bouchon's positive handling as an example of the 109 and then immediately contradicting yourself by saying it's not comparable.

[Skoshi Tiger]

Do you think the Leading edge slats will be moddled any better in BOS?

[NZtyphoon]

The RAE left things up to the opinion of the pilot as the definative source on the stability and control.

That is why you had such a variation in stability and control in British designs.

Here I will quote Lyons in his report:

Just to quote one moderator who got tired of a subject being regurgitated time and again: http://forum.1cpublishing.eu/showpost.php?p=453200&postcount=934

If Crump wants to provide Game test data or observed and documented characteristics and furnish the developers with the supporting valid realworld data (NACA or other I dont care). He can do it in private directly to Ilya, this thread has had more than enough time and data thrown at it to "prove" his theory if its correct. This thread is just causing more and more heated arguments and personal attacks and has failed to be objective. And yes I have read most of it because Ive had to moderate it continuously.

Personally I dont see the point of wasting this much energy on a single characteristic of a single aircraft at the expense of all other aspects and all other aircraft. In doing so it would unbalance the game and overall flight model of the aircraft in question. I would also have to question whether Crump holds an objective view of this flight characteristic and flight data given the single bloody-mindedness of the argument.

The developers have their criteria and approach to modelling flight characteristics and should not be pushed to change a FM based on one persons argument against the community. While I am impressed by the amount of research and data and the extreme effort to prove the spit was unstable, where was the game testing data to back up that infact the FM is incorrect? Nada, zero, zilch... so I have to conclude this is just a massive one-man-band trolling of the community.

Dead right, and it applies here as well - this is meant to be about improving 109 control characteristics in CLOD - which evidently won't be happening soon, as pointed out by Buzzsaw.

If Crumpp wants to exhaustively pursue his dead-end obsessions about whether or not the British had standards, or the Spitfire's control characteristics or his clear belief that he alone has all the answers about everything to do with aerodynamics and aeronautics, he can start his own site and troll that instead.

http://forum.1cpublishing.eu/showpost.php?p=23990&postcount=1

10. Off topic discussion - in full or in part. Purposeful and/ or continuous off topic discussion.

[JG52Uther]

You do all know CoD is dead don't you? All this is pretty pointless in the context of CoD, which is what this forum is about.Nothing will change, or be fixed. Its over.
I'm sure the new forum will be thrilled when you take all your knowledge there to share with everybody.I don't think there is an FM forum there yet, but its early days for the new project.
http://forum.il2sturmovik.net/

[ACE-OF-ACES]

It only works if everybody does it or the ones that don't will stop quoting him.
I smell a trend! ;)

[KG26_Alpha]

Yea its called flogging a dead horse.

These threads always end up the same, locked with the same few people doing the same whining and personally insulting each other regardless what the topic is.

:rolleyes: