A newbies impression of the 109 and spit

[gimpy117]

Honestly, I'm not really impressed with the me, only because the spit seems to be a clown wagon. I don't know if im over turning the me-109, but to me it seems even the spit Ia can toy with 2 aircraft (did it against a Bf-110 and Me-109) and still came out on top. It just turns so darn well without stalling, which just seems suspect to me. I know it had "the better turn rate", but the spit seems really easy to make fly it's best rather than the me 109.
I just don't get it...to me it just seems like an aircraft with the proper difficulty of a fighter is pitted against a Cessna 172 that can make good speed and has .308 guns. I really don't know if this is realistic or not...but it just seems dubious to me. I think both planes would be more evenly matched if the spit wasn't so brain dead easy to fly, and it actually took effort to pull high AoA turns in the spit like it seems to in the 109. It just seems like night and day. The Me-109 you have to think about turn rates, and not bleeding energy to stay in the air...and the spit is more like "whats energy again I've got pretty wings and a Merlin remember!"

[Robo.]

Do you mean Spitfire Mk.II or Mk.I?

[robtek]

He wrote about the spit 1a.

[Robo.]

He wrote about the spit 1a.

It just said 'Spit' at the time I was reading it, sorry.

Anyway, the 2 German pilots were not very good then.

[Osprey]

They must've been idiots.

Try it post patch and have more than one flight.

[gimpy117]

I'm speaking about the Spit Ia or really all the spits. I think it's too easy to fly in general. Not really too fast, but just too easy in general to skillfully maneuver. I suppose I wasn't clear as to what i was talking of

lets put it this way:

In ROF the Camel has also been characterized as having a very light and touchy elevator, this makes the camel the most agile plane in the game...but also tricky to fly...yet rewarding. Currently with my limited experience with the spit it seems to not have touchy elevators, but just effective everything controls.

I dunno, I was reading reports from German pilots saying: (paraphrasing) "was on par with the ME-109 or inferior, unless flown by an exceptional pilot". Now, I just jumped in the thing and played around in the mud, with garbage tactics when i knew i should be dead...and won...flying circles around these guys...and I'm no master pilot as far as i know.

[Robo.]

I dunno, I was reading reports from German pilots saying: (paraphrasing) "was on par with the ME-109 or inferior, unless flown by an exceptional pilot".

I would say that this is very much the case in the sim. It certainly is inferior to the 109.

Now, I just jumped in the thing and played around in the mud, with garbage tactics when i knew i should be dead...and won...flying circles around these guys...and I'm no master pilot as far as i know.

I suggest you try her a bit more against competent pilots, that might give you better picture.

[335th_GRAthos]

I think you are already self-consious enough Gimpy with the title of your post "A newbies...."

Just out of curiocity, you are flying with Complex Engine Management ON and all additional difficulty options engaged and, you are testing the Spit 1a against online pilots (not AI), right?

A well flown Bf109 rules over a Spit 1a, unless the Bf109 run out of ammo...

~S~

[Kurfürst]

I'm speaking about the Spit Ia or really all the spits. I think it's too easy to fly in general. Not really too fast, but just too easy in general to skillfully maneuver. I suppose I wasn't clear as to what i was talking of

lets put it this way:

In ROF the Camel has also been characterized as having a very light and touchy elevator, this makes the camel the most agile plane in the game...but also tricky to fly...yet rewarding. Currently with my limited experience with the spit it seems to not have touchy elevators, but just effective everything controls.

I dunno, I was reading reports from German pilots saying: (paraphrasing) "was on par with the ME-109 or inferior, unless flown by an exceptional pilot". Now, I just jumped in the thing and played around in the mud, with garbage tactics when i knew i should be dead...and won...flying circles around these guys...and I'm no master pilot as far as i know.

Indeed this is the most annoying thing about the whole Spit model, which was very much like the famous Camel in this regard. The elevator touchiness is not modeled (nor was in old Il-2). Every manual, report, pilot commenting on the issue noted that the Spitfire elevator was exceedingly light, and sensitive and required very delicate control. Stick force / g was in the order of 4 lbs / G, so you could easily pull 12-13 Gs with one hand, which would certainly black you out in short order, stall or even break the aircraft.

In Il-2 COD, pulling the sick full back not even stalled the Spit II for example...

The handling is fishy for all aircraft I would say, its very hard to stall them and outright impossible to break them (and I tried really hard flying in the most dangerous fashion possible: full nose up trim AND full stick-on-stomach at the end of the dive at around 350-400 mph IAS, which would be certain to break any fighter in the game two, but you simply can't...). I guess its just more profilic in the case of the Spit, which had ultra sensitive pitch control compared to all others.

[ATAG_Snapper]

Hi gimpy117!

Hope you can join us sometime on the ATAG server -- be sure to have Teamspeak installed!

Snapper

[gimpy117]

Indeed this is the most annoying thing about the whole Spit model, which was very much like the famous Camel in this regard. The elevator touchiness is not modeled (nor was in old Il-2). Every manual, report, pilot commenting on the issue noted that the Spitfire elevator was exceedingly light, and sensitive and required very delicate control. Stick force / g was in the order of 4 lbs / G, so you could easily pull 12-13 Gs with one hand, which would certainly black you out in short order, stall or even break the aircraft.

In Il-2 COD, pulling the sick full back not even stalled the Spit II for example...

The handling is fishy for all aircraft I would say, its very hard to stall them and outright impossible to break them (and I tried really hard flying in the most dangerous fashion possible: full nose up trim AND full stick-on-stomach at the end of the dive at around 350-400 mph IAS, which would be certain to break any fighter in the game two, but you simply can't...). I guess its just more profilic in the case of the Spit, which had ultra sensitive pitch control compared to all others.

I agree with that. It's just a little to easy to fly. I'm sure a well flown Me-109 can win a battle...but the fact is...IMO the skill and practice required to fly the Me-109 is not even remotely mirrored by the Spitfire. Making the spit rightfully touchy would solve this. It was always difficult in RoF because the camel was so touchy and took discretionary control inputs to fly at it's best, just yanking the stick back all the way to turn resulted in a stall.

Also, I do fly on the Atag server. and against other planes



I suggest you try her a bit more against competent pilots, that might give you better picture.

yes, but just the fact I could put myself in a terrible position, the 1st time in the a/c and still come out on top, while flying the plane to a much higher level at 2:1 odds kinda says something...or at least in my opinion.

[ATAG_Doc]

Hi gimpy117!

Hope you can join us sometime on the ATAG server -- be sure to have Teamspeak installed!

Snapper

What he said.

[~Deacon]

Also, I do fly on the Atag server. and against other planes

You currently stand at 29 "entries" on ATAG server, with 11 kills + 12 deaths.

I fly the Spit 1a a lot...a whole lot, I fly only on ATAG. Come fly the Spit 1a a bit more on ATAG as I am sure that your impression will change when you go against Mr. X, notafinger, Little D, vit unit, Recoilfx, etc. I could go on with names but it would be pointless.

As you said, you're new and inexperienced, go up vs. an Experten and they will OWN you in the Spit 1a. The only card you hold in the Spit 1a is turning...that's it. It's slow, can't climb to save itself, can't dive, can't do anything but turn.

It really sucks when you've got your throttle & pitch wide open and watch the 109's just climb away and not a damn thing you can do about it. Put your tail between your legs, dive, and start to turn because you're going to die as soon as they hammerhead your ass...

Given that, I have 3 words...YOU GOT LUCKY.

Be quite careful what you post and what kind of flame war you look to start. :evil:

[AKA_Tenn]

Be quite careful what you post and what kind of flame war you look to start. :evil:

lol yea he was flaming on the atag server last night about how the 109 can't turn with it haha

[gimpy117]

lol yea he was flaming on the atag server last night about how the 109 can't turn with it haha

lol i was more actively complaining ;) lol I tend to do that when I have reservations about FM's, but if it came across as flaming...I sincerely Apologize. Wasn't attacking the people, just the way the planes fly. I don't have beef with anybody as far as I know...

[Robo.]

lol i was more actively complaining ;) lol I tend to do that when I have reservations about FM's, but if it came across as flaming...I sincerely Apologize. Wasn't attacking the people, just the way the planes fly. I don't have beef with anybody as far as I know...

Nobody is interested to read that kind of stuff in the chatline. We all know what the issues with the FMs are. ;)

[gimpy117]

Nobody is interested to read that kind of stuff in the chatline. We all know what the issues with the FMs are. ;)

yeah i know lol I was on a little bit of a rant. Remember 8 hours between the bottle and throttle ;)

[justme262]

I have seen a former spitfire pilot interview on youtube in which he says

" anyone could fly a spitfire, but you had to be an expert to fly a 109"

This is roughly how it is in COD.

Sound like you were just lucky and flew against some pilots who didn't know how to use the advantages of the 109.

[Osprey]

Indeed the Spitfire had few vices, this is well documented from BoB pilots. Kurfurst refers to the elevator as if there is a problem, but he is referring to the report that Jeff Quill gave after one of the early test flights, so Supermarine made some adjustments and then it was fine.

Don't reply Kurfurst, I am not interested in your biased, one-sided view on the Spitfire vs 109.

[Sandstone]

I guess its just more profilic in the case of the Spit, which had ultra sensitive pitch control compared to all others.

I think it was sensitive and like many aircraft of this era had poorly harmonised controls, but it can't realistically be described as "ultra sensitive", otherwise the literature would be full of accounts of Spits getting bent in PIOs on landing. It's also possible to over-estimate the impact of poorly-harmonised controls. In my limited experience of flying, you quickly adjust to the control forces needed for different aircraft and it ceases to be a problem, unless they are so high as to be tiring.

[41Sqn_Stormcrow]

I agree that spit pilots learnt with exercise to handle the difference between elevator and roll sensitivity which was noticed by several pilots. I do not know if it caused much trouble for pilots as I do not have much flying experience with badly harmonized controls though. I imagine that it does require a bit of learning.

The stall behaviour seems a bit odd in any plane right now imho. And the 109 does turn like a brick while I think it was more agile even though not as agile as the spit turn radius and to a certain extend turn rate wise.

[Catseye]

yeah i know lol I was on a little bit of a rant. Remember 8 hours between the bottle and throttle ;)

Hi Gimpy117,
I saw this question to you earlier but don't recall seeing a reply.

"Are you flying with Complex Engine Management turned on?"

S!

[gimpy117]

Hi Gimpy117,
I saw this question to you earlier but don't recall seeing a reply.

"Are you flying with Complex Engine Management turned on?"

S!

as far as i know yes

[Catseye]

as far as i know yes

I gather then that you haven't gone into the settings area to set your preferences up?

Boxes need to be checked etc.

Suggest you pop in there and see if you have your settings set to advanced.

Makes a very big difference.

Cheers,

[Crumpp]

refers to the elevator as if there is a problem,

Wow...

There is no problem unless you are a stability and control engineer, have some knowledge about airplanes, or dead because of the longitudinal instability.

[Robo.]

Wow...

There is no problem unless you are a stability and control engineer, have some knowledge about airplanes, or dead because of the longitudinal instability.

Wow

There is no problem, unless you play different sim than everybody else.

[gimpy117]

I agree that spit pilots learnt with exercise to handle the difference between elevator and roll sensitivity which was noticed by several pilots. I do not know if it caused much trouble for pilots as I do not have much flying experience with badly harmonized controls though. I imagine that it does require a bit of learning.

The stall behaviour seems a bit odd in any plane right now imho. And the 109 does turn like a brick while I think it was more agile even though not as agile as the spit turn radius and to a certain extend turn rate wise.

I've has sim experience in ROF flying with the camel, you need a feather touch on the elevator and can over turn the camel with ease. It's also a trick to fly level, as to not overshoot your controls and nose up or down wildly.

I do kinda agree with the Me-109 turn. It should of course, not be able to hold with the spit in a sustained turn...but it seems right now to not nearly to be able to stay with the spit even with an energy advantage. I got bounced by an ME-109 today (he ran me down from my 6 so he was moving faster) who somehow missed with his cannons. I immediately broke left and held a tight turn with ease, Looped around and found him in a now lower energy state after attempting to follow me. I pumped some rounds into him and killed his pilot pretty quickly. It just makes me wonder how I held so much energy from that hard turn, where as the ME-109 seemed to bleed a crazy amount, and be a sitting duck for me to come around and fill him with lead. The Spit should turn better yes, But my question is...does it bleed energy as fast and is this historic? Maybe we could do a test and make a hard turn and see how long it takes to stall, or alternatively how high we can get in altitude after the turn. this would have a comparison of energy retained after a vigorous turn possibly. We wouldn't be comparing turn radius, just energy retained after a min turn radius turn.

[Robo.]

gimpy you seem to be lucky meeting inexperienced 109 pilots. Or was that an AI?

In my book it's not the plane that holds energy, it's the pilot. If you did your evasive turn to the left clean enough and he tried to follow you and turn with you instead of climbing (and not missing the burst in the first place) and yo yo into your turn (no matter how tight, 109 rolls fast enough) outmanoevering you effectively. If the 109 was me, I'd probably turn with you for a while, especially so after scoring some hits and if you'd be gaining angles on me I would still be able to extend safely, horizontally or vertically. And I am not quite as good as 109 specialists.

Same goes for the Spitfire - if your turn is sloppy, you'd lose lots of E, drop wing or stall alltogether.

The above is based on my experience online as RAF or LW pilot, yrmv of course.

[Glider]

I love this constant reference to longitudinal instability, from a plane that everyone who flew it be they allied or German found very easy to fly and land.

Don't you think its being over egged

[Kurfürst]

I love this constant reference to longitudinal instability, from a plane that everyone who flew it be they allied or German found very easy to fly and land.


... and longitudally unstable:

The German view:

The rolling ability of the enemy fighters at high speeds is worse than that of the Bf 109. Quick changes of the trajectory along the vertical axis cause especially with the Spitfire load changes around the cranial axis, coming from high longitudinal thrust momemtum, and significantly disturb the aiming.

In summary, it can be said that all three enemy planes types are inferior to the German planes regarding the flying qualities. Especially the Spitfire has bad rudder and elevator stability on the target approach. In addition the wing-mounted weapons have the known shooting-technique disadvantages.

http://kurfurst.org/Tactical_trials/109E_vergleich110SpitHurCurtiss/109E_vergleichsflg_Aug1940.html

The British view:

[Catseye]

It just makes me wonder how I held so much energy from that hard turn, where as the ME-109 seemed to bleed a crazy amount, and be a sitting duck for me to come around and fill him with lead. The Spit should turn better yes, But my question is...does it bleed energy as fast and is this historic?

Gimpy117,
Not having your realism settings set accordingly can initiate unrealistic performance as you describe.

Here is a pic of the realism settings FYI - check your Engine settings and Atomosphere and Handling.

S!

[Kurfürst]

The real 109E could do sustained turns in 18.92 secs at 1.3ata at SL, we have the 1.35ata version so probably it can be marginally better than that.. anyway, I did a quick test and got about that much, so I don't there's something wrong there.

I don't know how fast Hurris and Spits turn though. They should be better, but by how much? If they would do a sustained turn in 11-12 secs I'd say something is definietely stinking (that's a biplane only zone), but 15-16 secs would sound about right.

[BlackbusheFlyer]

Sorry Kurfurst but you are wrong about the spit elevators, they were sensitive yes but can in no way way be classed as ultra sensitive. I am a real world aerobatic pilot generally flying a Pitts special, and have flown many aerobatic types. The elevator on these aircraft IS sensitive, much much more so than the Spit. The Spitfire that went into service was and always has, been described as having well balanced controls (a twitch elevator would not accord this distinction!).

It is a well known fact that the British aircraft types were much more forgiving than the German equivalents, a factor in itself in the supremacy of the Spitfire over the ME109 during the Battle of Britain. You had 'green' pilots on both sides, but the Spitfire was markedly easier to fly for those pilots allowing inexperienced pilots to get more out of the machine than was typical of the Germans.

[Crumpp]

Sorry Kurfurst but you are wrong about the spit elevators, they were sensitive yes but can in no way way be classed as ultra sensitive. I am a real world aerobatic pilot generally flying a Pitts special, and have flown many aerobatic types. The elevator on these aircraft IS sensitive, much much more so than the Spit. The Spitfire that went into service was and always has, been described as having well balanced controls (a twitch elevator would not accord this distinction!).

It is a well known fact that the British aircraft types were much more forgiving than the German equivalents, a factor in itself in the supremacy of the Spitfire over the ME109 during the Battle of Britain. You had 'green' pilots on both sides, but the Spitfire was markedly easier to fly for those pilots allowing inexperienced pilots to get more out of the machine than was typical of the Germans.


Longitudinal Instability and the Pitts elevator are not comparible. There is a huge difference between the minimal stability exhibited by a Pitts and a dangerous instability exhibited by the Spitfire.

The Bf-109 is much more forgiving than any straight wing high aspect ratio design without LE slats. Think of the slats just like training wheels. An elliptical wing on the other hand exhibits very harsh stall characteristics because of its shape.

[bongodriver]

dangerous instability exhibited by the Spitfire.



OMG...you really do believe this crap!


An elliptical wing on the other hand exhibits very harsh stall characteristics because of its shape.


Yet the spitfire is well documented as having benign characteristics.......

[NZtyphoon]

Longitudinal Instability and the Pitts elevator are not comparible. There is a huge difference between the minimal stability exhibited by a Pitts and a dangerous instability exhibited by the Spitfire.

Yeah Right, the Spitfire was so dangerous that pilots dreaded flying the machine and it was roundly condemned by the A&AEE, the RAE and by Supermarine test pilots, and has since been banned by the FAA and other aviation authorities worldwide. :grin::grin::grin:

No doubt Kurfurst will bring up the Spitfire V crashes described in Shacklady and Morgan...pp 160-161 (I think)

Or he'll post the attached paper and claim that this proves how dangerous and unstable the Spitfire was because so many of them broke up in flight.

So, to save all our time from his predictable arguments here's what Supermarine Chief Test pilot Jeffrey Quill had to say about the "dangerously unstable" Spitfire (Spitfire:A Test Pilot's Story. John Murray, 1983):

"In a high-performance fighter, lack of stability can be exceedingly dangerous in the course of manoeuvring at high speeds...Therefore, in aeroplanes such as the Spitfire, which were entirely manually controlled, any inherent instability was unacceptable and potentially dangerous....

There were other factors which affected the aerodynamics of the stability of the Spitfire. For example the aerodynamic characteristics of the elevator itself (as opposed to the fixed tailplane) also had a major influence on stability and at Supermarine we exploited this and increased the stability margins as we moved from one mark of Spitfire to another. (229-230)

In general configuration the Mk I and Mk II production aeroplanes were almost identical to the prototype and so there was no problem with their stability. (231-232)

The Mk III Spitfire did not go into production, but the success of the bobweight experiment in curing its instability...opened up the possibility of its use for later marks of Spitfire....which was just as well as we had to...respond to a nasty situation which developed in 1942.

The Mk V aircraft was...in full service with Fighter Command and,...a fair amount of additional operational equipment had gradually crept into the aircraft, most of it stowed within the fuselage. The aftmost acceptable position for the aircraft's centre of gravity had been fixed in the normal course of flight testing by the firm and by the A & AEE....Any rearward movement of the centre of gravity in service, for whatever reason, would begin to destabilise the aircraft. Therefore, for each sub-variant of the Mk V detailed instructions for the correct loading of the aircraft were issued to squadrons....However the importance of these loading instructions was not generally appreciated in squadrons and in the daily round of operational activity they tended to be disregarded." (pages 232-233 -Quill goes on to describe 65 Sqn's Spitfire Vbs which were found to be dangerously unstable)

There was thus a real chance that, as of that moment, in almost every squadron in the Command Spitfires were flying in a dangerous state of instability....Up to that time there had been a distressing and increasing incidence of total structural failure of Spitfires in the air, which was causing great concern in the MAP and especially at Supermarine. (pages234-235)

....our aerodynamicists at Hursley Park thought that an even more effective answer could be obtained by enlarging the horn balance of the standard elevator and this we did in stages. The effect was astonishing.

At last a way had been found to improve the basic stability of the aeroplane, thus giving more flexibility in centre of gravity movement, without our having resource to any enlargement of the fixed tail surfaces....The enlarged horn balance of the elevator produced a slightly unpleasant 'feel' of the aeroplane at low speeds...This effect was trivial by comparison with the gains in stability margins." (p 237)

Once the bobweights had been introduced and, in later marks, the modified mass balances on the elevators...it was statistically established that, as soon as the longitudinal stability of the Spitfire was thus brought under control, the problem of the unexplained breakings-up of aircraft in mid-air,...'softly and suddenly vanished away'. (page 238 )


Note the comments that stability margins increased over the course of Spitfire production; with the introduction of the Griffon engined Spitfires, and especially the five bladed propellers of the 65 series the size of the tail surfaces were increased to help cope with the bigger blade area and extended nose - there were some marginal instability problems, but not enough to make the aircraft dangerous. There were problems with the early Spitfire F. Mk 21's control characteristics, but these were ironed out with further developments in the elevator balance weights and configuration. The Mk Vs breaking up in flight were badly loaded with extra equipment in squadron service, with their cg pushed too far back, thus they were dangerously unstable, but this was not an inherent problem with the airframe.

No doubt Crumpp will try to claim that with his vast aviation experience he knows better than Jeffrey Quill and there'll be other smokescreens by another Spitfirephobe who has posted here but the fact is that All claims about the Spitfire being inherently dangerously unstable are quite false and not worth bothering with.

[NZtyphoon]

And here's what Alex Henshaw, Chief Test Pilot at Castle Bromwich, says about the flight characteristics: Spitfire demo flights (http://www.theaviationindex.com/publication/volume-23-issue-09-1995/article/spitfire-test-pilots-defence):

"...The Spitfire would then continue with a series of loops and half-rolls to gain height over the airfield to between 4,000 and 5,000ft. Depending on the precise position of the aircraft in relation to the airfield, the usual procedure was to dive to 450-470 mph in front of the flight shed and then pull out and complete an upward roll to the left, one to the right and a half-roll left. This manoeuvre might be repeated or continued with a vertical dive with aileron turns...Considering how often this was demonstrated with all marks of Spitfires I am surprised that it should ever be suspected that wings might suffer structural failure in such a situation when excessive aileron loads were used in high-speed dives.

From the Mk I Spitfire up until the Mk 21 the Vne was set by the Supermarine technical department at 470 mph IAS at a height assumed to be between 5,000 and 10,000 feet....At no time did the Supermarine test pilots reduce the Vne from 470 mph to 450 mph....If ever any doubts existed within our own test pilots as to the structural risks of diving the Spitfire they were dispelled when reports were received from combat units to the effect that some of their pilots complained of excessive engine revs when diving under extreme conditions....The basic pitch setting of the de Havilland propeller was set to give 3,000 rpm at 9lb boost on take-off, and would remain in the constant speed range up to full power and not exceed 3,000 rpm up to its Vne of 470 mph...it was decided to investigate the problem to its limits.
A standard Mk V without calibrated instruments or modifications was taken up to 37,000 ft. A maximum speed run at full power with engine revs at 3,000 was carried out for 2 minutes before peeling off with a half-roll to dive down to near ground level. Up to the Vne of 470 mph the propeller constant speeded with engine revs at 3,000, and then as the speed increased the propeller came up against its basic pitch setting stop and engine revs climbed rapidly. The ASI indicated what might be assumed to be some degree of accuracy within the normal range, but as the speed progressed beyond the these limits the needle climbed so far into the region beyond the 450 mark that it was obvious that no further notice should be taken of it. We were not certain that the machine had in fact reached its terminal velocity point...it was decide to carry out another dive with greater concentration on the rev counter....This final dive proved two factors. With the single-stage blower Merlin, the Spitfire could not be dived faster, and at 3,700-3,800 rpm in those conditions the basic pitch setting should be readjusted." (Aeroplane Monthly September 1995, 55-56)

Yep the Spitfire was so dangerously unstable that Henshaw flew it like a maniac and crashed and died several times.

[NZtyphoon]

Sorry Kurfurst but you are wrong about the spit elevators, they were sensitive yes but can in no way way be classed as ultra sensitive. I am a real world aerobatic pilot generally flying a Pitts special, and have flown many aerobatic types. The elevator on these aircraft IS sensitive, much much more so than the Spit. The Spitfire that went into service was and always has, been described as having well balanced controls (a twitch elevator would not accord this distinction!).

Henshaw: "Compared with the Compar Swift, de Havilland T.K.4 or the Mew Gull the elevator controls on the Spitfire were quite heavy. To the young pilot trained on Tiger Moths or Magisters, however, the Spitfire elevators would indeed feel light, so that time and experience would be needed to get used to the feel." (AM September 1995 p. 55)

Quill on the prototype:
"The A&AEE pilots remarked also that the elevator was too light and too powerful and they recommended reducing the gear ratio between the elevator and the control column. I suspected at the time, and later with more experience and understanding of the problem I became quite convinced that they were wrong in blaming the elevator for being too light. This was much too simplistic a conclusion. The aeroplane was on the borderline of instability and making a heavier elevator, or even a smaller one, would have been no solution." cf his comments about further development increasing the stability margins. (Spitfire:ATPS p. 231)

[41Sqn_Stormcrow]

An elliptical wing on the other hand exhibits very harsh stall characteristics because of its shape.

As this phrase, as it stands here, is to my knowledge right, it does not apply to the spitfire. The spit had cranked wings with a reduced angle of attack at the outer parts of the wing (where the ailerons were). This meant that if, for a given speed, the angle of attack became too high on the inner section of the wing to generate lift it was still small enough on the outer sections. Hence while the wing stalled first on the inner section it stalled later on the outside section.

This was a security measure installed by supermarine because they were aware of the problem of the elliptical wing that you just mentioned.

When you read raf pilot accounts they repeatedly mention that they got buffeting shudder on the brick of a stall warning them about an imminent stall. This situation occured when the inner section stalled but not the outer section where the ailerons were, allowing the spit to be still controllable around the roll axis.

Of course cranking the wing also meant to deteriorate the aerodynamical properties of the elliptical wing so that it was less optimal aerodynamic wise. The induced drag was hence bigger than with an uncranked wing. As the advantage of the elliptical wing was later found to be minimal with respect to a trapezoid wing it was abandonned in aviation as the disadvantages in terms of production outweighted its minimal benefits. That's why I definitely think that the elliptical form in itself had nothing to do with the great performance. What supermarine however probably managed to pull off was to design a wing with a large surface which however created more drag but allowed for high lift which was still light weight and in particular very thin.

[Kurfürst]

Sorry Kurfurst but you are wrong about the spit elevators, they were sensitive yes but can in no way way be classed as ultra sensitive. I am a real world aerobatic pilot generally flying a Pitts special, and have flown many aerobatic types. The elevator on these aircraft IS sensitive, much much more so than the Spit. The Spitfire that went into service was and always has, been described as having well balanced controls (a twitch elevator would not accord this distinction!).

I would have respectfully disagree with you assessment, particularly about control harmony. It was a weak part of Spitfire control, as the elevator indeed touchy, while. One Spitfire pilot described the phenomenon as 'touching the elevator with a light fingertip, while arm-wrestling the ailerons'. I would suggest you to study the Spitfire II pilot notes on control aspects, basically they all about instability in pitch and poor control harmony, here: http://forum.1cpublishing.eu/showpost.php?p=409817&postcount=4

It particularly challenging thing to do when flying near the stall, NACA for example found that the stall boundary on the controls was very small, just 3/4 inch of stick movement having been found between the first sign of stall and actual stall. This was offset party of course by ample stall warnings and otherwise good stall characteristics, but it took an experienced pilot to fly the aircraft to its limits.

[QUOTE]It is a well known fact that the British aircraft types were much more forgiving than the German equivalents, a factor in itself in the supremacy of the Spitfire over the ME109 during the Battle of Britain. You had 'green' pilots on both sides, but the Spitfire was markedly easier to fly for those pilots allowing inexperienced pilots to get more out of the machine than was typical of the Germans.

Again, an urban myth. British reports from the time readily admit the opposite. See:
http://kurfurst.org/Tactical_trials/109E_UKtrials/Morgan.html



5. Fighting Qualities of the Me. 109. – 5.1. Dog-fights with Spitfire and Hurricane.

Mock fights were staged between the Me. 109 and a Spitfire, both flown by pilots of the R.A.E. In addition a number of fighter pilots, all of whom had recent experience of operational flying, visited the R.A.E. with their Spitfires and Hurricanes in order to practice combat with the Me.109 ; during these fights the Me.109 was flown by an R.A.E. pilot who had completed the handling tests described earlier in this report, and was thus thoroughly familiar with the aircraft and could be expected to get the best out of it. A brief account of the information provided by these fights has already been publishedlO. The following notes summarise the results obtained.

The arrangements were for the aircraft to take off singly and meet at about 6,000 ft. The Me.109 then went ahead and commenced to turn as tightly as possible to see if it would out-turn our own aircraft. After doing three or four tight turns in both directions the Me.109 was put into a dive, followed by a steep climb. The aircraft then changed position and repeated the above programme, after which the pilots engaged in a short general fight.

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. 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.

The good control near the stall during these turns at full throttle contrasts with the results obtained from the ADM. 293 tests (section 4.42)) for when gliding the aircraft becomes unsteady at 10 m.p.h. above the stall. Slipstream thus appears to have a steadying influence on the behaviour of the Me.109 near the stall.

After these turns the Me.109 was put into a steep dive at full throttle with the airscrew pitch coarsened to keep the r.p.m. down. It was found that both the Hurricanes and the Spitfires could keep up with the Me.109 in the dive; the aircraft with constant speed airscrews could do this more readily than those with two-pitch airscrews. The ailerons and elevator of the Me.109 became so heavy in the dive that rapid manceuvring was impossible, while, as explained in section 4.22, banked turns could be done more readily to the right than to the left because of the absence of rudder bias.

The Me.109 was then pulled out of the dive and climbed at a very low airspeed at an unusually steep attitude. The aircraft was under perfect control during the climb, and could be turned with equal facility in either direction. Under these conditions it outclimbed our aircraft in most cases, since most of our pilots climbed at a higher airspeed and a flatter angle, keeping below the Me.109 and waiting for it to come out of the climb.

However, other pilots who chose to climb at very low airspeeds, mainly those with constant-speed airscrews, succeeded in keeping on the tail of the Me.109, although the Me.109 pilot thought they would have difficulty in keeping their sights on him steadily, as he was at a steeper attitude than their sights could " line ".

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. During the general fighting which folIowed the set programme, one other feature of advantage to the Me.109 emerged. If a negative g is put on the aircraft for a short time, the engine does not cut as it is of the direct injection type; whereas on the Spitfire or Hurricane the engine immediately splutters and stops when negative g is applied, because the carburettor quickly ceases to deliver petrol under these conditions. Hence the Me. 109 pilot found that a useful manceuvre when being chased was to push the stick forward suddenly and do a semi-bunt, if our fighters followed him their engines cut giving the Me.109 a chance to get away ; this was particularly useful against the Hurricane, as its top level speed is less than that of the Me. 109 so that once the Me. 109 had escaped in this way it could avoid combat. The Spitfire, on the other hand, soon caught the Me.109 after this manceuvre.

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.

The oversensitiveness of the Spitfire I elevator and its tendency to flick over fall entering a spin was also noted by earlier British trials (April 1940) involving a Curtiss Hawk and by German trials in the summer of 1940, and by NACA in 1941 on Spit VA (metal ailerons):

[41Sqn_Stormcrow]

I don't understand your point, Kur.

Yes, the Spit may have had a sensitive elevator. Yes, in case it went into a spin it may have done so in a violent manner.

But again, there is abundant indications by pilots that flew the spit that the airframe provided pilots with sufficient warning before this dangerous behaviour occured. This is, as I explained above, due to the fact that the spit had cranked wings with the inner sections of the wing stalling before the outer sections. The resulting buffeting provided a warning to the pilot.

Stalling on the inner section is in no way dangerous as long as it is approximately symmetrical. I've seen with my own eyes during an experimental flight on a piper that also had cranked wings that basically this plane needs only 1/3 of its wing unstalled to provide sufficient lift. It will have been similar for the spit.

Now what you do is to confuse inexperienced pilots with seasoned ones. Inexperienced pilots of course will have the natural reflex to avoid any situation that puts them at discomfort as they still lack the confidence that comes with routine. They were absorbed by too many things to do at the same time that they had simply no mental resources to make the intelectual reflexion about buffeting as a safety warning even though they might have been told so in theory. They heard that being taught to them but only retained that buffeting means that stall is imminent and therefore has to be avoided. BTW on the German side inexperienced pilots also usually avoided to fly in that way that opened the slats. My guess is for the same reason as their British counterparts. Just try to put yourself in their shoes or remember you after having won your driving license. My guess is that anybody who loves his life will be prudent when trying to familiarize with a new way of motion (driving, flying) or a new type. The procedure most will adopt is to slowly increase the envelop of one's action with growing confidence. Well, that's how I feel when I have a new car with which I am not familiar with. It takes me a while to become more bold with it. I am surely not starting to race like Schumacher on the German Autobahn with a newly bought car.

[NZtyphoon]

I don't understand your point, Kur.

Yes, the Spit may have had a sensitive elevator. Yes, in case it went into a spin it may have done so in a violent manner.

But again, there is abundant indications by pilots that flew the spit that the airframe provided pilots with sufficient warning before this dangerous behaviour occured. This is, as I explained above, due to the fact that the spit had cranked wings with the inner sections of the wing stalling before the outer sections. The resulting buffeting provided a warning to the pilot.

Stalling on the inner section is in no way dangerous as long as it is approximately symmetrical. I've seen with my own eyes during an experimental flight on a piper that also had cranked wings that basically this plane needs only 1/3 of its wing unstalled to provide sufficient lift. It will have been similar for the spit.


Stormcrow's comments are borne out by
NACA report Spitfire Va stalling Characteristics (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930092581_1993092581.pdf)

I also note the following conditions in the Wright Field report quoted by Kurfurst:
NACA report Measurements of the Flying Characteristics of the Spitfire Va (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930092582_1993092582.pdf)

(Tests, Results and Discussion, page 5) All of the flying qualities tests were made with the
center of gravity at a distance of 31.4 inches behind the
leading edge of the wing at the root. The mean aerodynamic
chord of 85 inches was computed to be 4.80 inches
back of the leading edge of the wing at the root. The
center of gravity was therefore at 31.4 percent of the
mean aerodynamic chord. Because no accurate drawings of
the Spitfire were available, the calculated location of
the mean aerodynamic chord may be somewhat in error.


The center-of-gravity location with full military
load is not known.

According to the cg diagram of an earlier Spitfire I (attached) the cg was a maximum of 7.6" aft of the datum point, which is 19.5" aft of the wing leading edge, a total of 27.1" aft of the wing leading edge, or 4.3" forward of NACA's calculated cg.

while here (http://www.spitfireperformance.com/x4922.html) the cg for a Spitfire Va tested at a loaded weight of 6,450 lbs by the A&AEE was 6.2" aft of the datum point, or 25.7" aft of the wing trailing edge, almost 6" forward of NACA's calculations, making their Va tail heavy, albeit their Spitfire weighed 6,184 lbs, which should not be enough of a difference to affect the cg that much.

How is it possible for a report to determine elevator characteristics when the cg of the test aircraft may not be set up properly? Nor do we know how the Spitfire in the RAE tests was set up.

[Kurfürst]

I don't understand your point, Kur.

Yes, the Spit may have had a sensitive elevator. Yes, in case it went into a spin it may have done so in a violent manner.

But again, there is abundant indications by pilots that flew the spit that the airframe provided pilots with sufficient warning before this dangerous behaviour occured. This is, as I explained above, due to the fact that the spit had cranked wings with the inner sections of the wing stalling before the outer sections. The resulting buffeting provided a warning to the pilot.

My point is basically the difference how the Spitfire and 109 behaved when getting near the stall. Both gave plenty of warnings, but the difference was as I see it is that once riding the stall, the Spitfire gave very little margin before you actually stalled, and once stalled it went medieval on you. The 109 otoh could be still pulled with confidence, with plenty of margin for pilot error, as the pitch control was not so sensitive at all, and stall itself was benign and recovery by easing back on the stick instant once it occured. In short I believe the stall and flying the aircraft to its limits was much easier on the 109 - which I as not such a good pilot admire the most when I fly it, and which is why I never liked to fly the 190, Spit or Yak 3. All the latter require much more finesse to fly.

That is said, the 109 due to its higher stalling speed had lower absolute limits when it came to manouvering, so it could not pull such a tight/fast turn, but this is not so important to me as I can reliably push the 109 to its limits all the time.

The 'handling' issue is complex.




Stalling on the inner section is in no way dangerous as long as it is approximately symmetrical. I've seen with my own eyes during an experimental flight on a piper that also had cranked wings that basically this plane needs only 1/3 of its wing unstalled to provide sufficient lift. It will have been similar for the spit.

Absolutely true, but IMHO there is some misunderstanding about the stalling of the wing roots. All fighters and aircraft are designed as such, its hardly unique to the Spitfire at all. They make planes to stall in the root first because the pilot needs to retain aileron control. On the Spit, Fw 190 etc., pretty much every plane w/o slats its achieved by using washing, or cranking the wings so that the outer section has lower AoA than the inner and would thus reach stalling incidence later. On slatted aircraft like the 109, Lavochkins etc. the same is achieved by leading edge slats - its no coincidence that these cover the wing area ahead of the ailerons!

Now what you do is to confuse inexperienced pilots with seasoned ones. Inexperienced pilots of course will have the natural reflex to avoid any situation that puts them at discomfort as they still lack the confidence that comes with routine. They were absorbed by too many things to do at the same time that they had simply no mental resources to make the intelectual reflexion about buffeting as a safety warning even though they might have been told so in theory. They heard that being taught to them but only retained that buffeting means that stall is imminent and therefore has to be avoided. BTW on the German side inexperienced pilots also usually avoided to fly in that way that opened the slats. My guess is for the same reason as their British counterparts. Just try to put yourself in their shoes or remember you after having won your driving license. My guess is that anybody who loves his life will be prudent when trying to familiarize with a new way of motion (driving, flying) or a new type. The procedure most will adopt is to slowly increase the envelop of one's action with growing confidence. Well, that's how I feel when I have a new car with which I am not familiar with. It takes me a while to become more bold with it. I am surely not starting to race like Schumacher on the German Autobahn with a newly bought car.

Absolutely agree, when I was doing my licence I had three cars to learn on (one of them being an absolutely horrid old Ford Escort, which I absolutely hated) and I always needed about 5 hours in the new ones to get familiar and instinctly 'feel' their behaviour. OTOH I am very familiar with my own car, which has superb and delightful response (which is why I am so reluctant to give it up) and can really get the maximum out of it now, and with growing experience, I need a lot less time to adjust to a new car.

Back to the planes, as a rookie I would be more confident to experiment and push things a bit more in a plane that tolerates my mistakes more. Straightforward handling and not having to bother with a million others things like engine controls helps a confused rookie a lot. The car example is pretty good actually, because while learning to drive the most difficult thing was to absorb all the things and information that were happening around me, giving me very little capacity to actually drive the car. With time and experience, much of that absorbing becomes a second nature, and automatic, instinctual.

ps. as for the Autobahn, its a dreadful experience at first if you are not got used to cars flashing by constantly at 200 + km/h..

[NZtyphoon]

My point is basically the difference how the Spitfire and 109 behaved when getting near the stall. Both gave plenty of warnings, but the difference was as I see it is that once riding the stall, the Spitfire gave very little margin before you actually stalled, and once stalled it went medieval on you.
NACA report Spitfire Va stalling Characteristics (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930092581_1993092581.pdf) with reference to the concluding remarks on page 9...
The airplane possessed 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.


From Spitfire Va Flight CharacteristicsCharacteristics of the elevator control in accelerated Flight: (pages 8 & 9)

The elevator control was found to be powerful enough to develop either the maximum lift coefficient or the allowable load factor at any speed....(page 8 )

The Spitfire airplane had the unusual quality that allowed it to be flown in a partly stalled condition in accelerated flight without becoming laterally unstable. Violent buffeting occurred, but the control stick could be pulled relatively far back after the initial stall flow breakdown without causing loss of control. With the gun ports open, lateral instability in the form of a right rolll occurred, but not until an up-elevator deflection of 10° had been reached and unmistakeable warning in the form of buffeting had occurred. This subject is discussed more fully in reference 2.

The excellent stall warning made it easy for the pilots to rapidly approach maximum lift coefficient in a turn so long as the speed was low enough to avoid undesirably large accelerations at maximum lift coefficient.
The excellent stall warning possessed by the Spitfire was obtained at the expense of a high maximum lift coefficient. The maximum lift coefficient in accelerated flight was 1.21, while the average lift coefficient throughout a stalled turn was usually about 1.01 (9)

The report goes on to state:
In turns at speeds high enough to prevent reaching maximum lift coefficient because of the excessive accelerations involved, the small static longitudinal stability of the Spitfire caused undue sensitivity of the normal acceleration to small movements of the stick. As shown by the time histories of high-speed turns (figs. 15 to 18 ), it was necessary for the pilot to pull back the stick and then ease it forward almost to its original position in order to enter a turn rapidly without overshooting the desired normal acceleration. Although this procedure appears to come naturally to a skillful pilot, flight records from other airplanes show that a turn may be entered rapidly and the desired normal acceleration may be held constant by a single rearward motion of the stick provided the static stability of an airplane is sufficiently large. By careful flying, the pilot was able to make smooth turns at high speed, as shown by figures 17 and 18. Ordinarily, however, small movements of the stick caused appreciable variations in the normal acceleration, as shown in figures 15 and 20.


This hardly speaks about a deadly stall and it certainly doesn't mean the Spitfire was inherently dangerously unstable as claimed by Crumpp. It would be interesting to know whether this Spitfire, as tested, might have been marginally unstable, because, as noted, the cg position was not accurately known. It would also be interesting to know how the elevator control was affected by the extended mass balances described by Jeffrey Quill.

Getting back to flight qualities in CloD, how would it be possible to replicate these qualities?

[Crumpp]

As this phrase, as it stands here, is to my knowledge right, it does not apply to the spitfire.

Yes and that is why I specifically did not address the Spitfire. In the Spitfire, the benefit of having an elliptical wing efficiency was all but eliminated in compensating for the stall characteristics of an elliptical wing.

[Crumpp]

Stormcrow's comments are borne out by
NACA report Spitfire Va stalling Characteristics


It would help if you understood everything that report says instead of select phrases out of context. If you can't do that , it is practically impossible to hold a discussion.


If you read the report, it states the conditions the aircraft exhibited a very harsh stall. One of those conditions would be in a steep bank with gun ports open. Under those conditions, the aircraft would develop a roll instability and resulting spin.

The conditions matter in aerodynamics.

Yes the Spitfire gave very good stall warning. That large buffet zone comes at a price in diminishing turn performance.

Longitudinal Stability has nothing to do with stall characteristics except to determine how fast the pilot can move the wing through its useable angle of attack range.

The NACA rated the Spitfire as having unacceptable longitudinal stability and control in all conditions of flight. It is either neutral or unstable and this was corrected with bob weights in later marks.

That is not a bias, it is just a fact. None of these aircraft were perfect regarding stability and control. Some were worse than others and it is a fact the early mark Spitfires exhibited a dangerous longitudinal instability. It was an infant science when they were developed.

[6S.Manu]

The motion beyond the stall was not violent and an unusual
amount of lateral control was available in many flight conditions

The Spitfire airplane had the unusual quality that allowed it to be flown in a partly stalled condition in accelerated flight without becoming laterally unstable

You know that this matter can't be resolved right, do you?

not violent: there is no meter for the stall to be "violent/not violent".
unusual amount: is it possible to quantify the usual one? And usual compared to?
many flight conditions: which ones?
party stlled: again... no numbers.

If we want the real numbers we have to rent a spitfire, install on it all the modern testing stuff and run it.

I've never loved much the 109 while I've always hated the Oleg's Spitfire (but I love the real one since I was a kid): anyway I've never trusted the myth of the elliptical wings because of these planes fly against the physic laws compared to all the other ww2 planes.

[NZtyphoon]

It would help if you understood everything that report says instead of select phrases out of context. If you can't do that , it is practically impossible to hold a discussion.

Some were worse than others and it is a fact the early mark Spitfires exhibited a dangerous longitudinal instability. It was an infant science when they were developed.

Nonsense Crumpp - you are the one who is taking things out of context - note what the report said about the cg calculations cf the A&AEE report on the same aircraft type - the possibility was that the Spitfire flown by NACA was slightly tail heavy.

Not forgetting also what Quill had to say about the early Spitfires - "In general configuration the Mk I and Mk II production aeroplanes were almost identical to the prototype and so there was no problem with their stability. (231-232)" I'll take his word over yours any day.

As for having a "discussion" with you Crumpp - not interested because I know you'll turn it into a loooong, tedious thread, arguing over minute detail, while sticking to your opinion that the Spitfire was "dangerously unstable" no matter what. I don't care what you think because I know you're not interested in any one else's opinion, except when they agree with you.

[NZtyphoon]

You know that this matter can't be resolved right, do you?

not violent: there is no meter for the stall to be "violent/not violent".
unusual amount: is it possible to quantify the usual one? And usual compared to?
many flight conditions: which ones?
party stlled: again... no numbers.

If we want the real numbers we have to rent a spitfire, install on it all the modern testing stuff and run it.

I've never loved much the 109 while I've always hated the Oleg's Spitfire (but I love the real one since I was a kid): anyway I've never trusted the myth of the elliptical wings because of these planes fly against the physic laws compared to all the other ww2 planes.

The numbers and graphs start on page 25 of the NACA report on the Spitfire Va flight characteristics - which can be downloaded and viewed in its entirety, as can the NACA report on the Spitfire Va stall. Testing a real one would be interesting - Duxford anyone?

[Crumpp]

the possibility was that the Spitfire flown by NACA was slightly tail heavy.


Operating Notes Spitfire Mk IIa:

http://img571.imageshack.us/img571/5556/spinning1n.jpg (http://imageshack.us/photo/my-images/571/spinning1n.jpg/)

Operating Notes warning on the Longitudinal Instability:

http://img35.imageshack.us/img35/3848/elevatorload.jpg (http://imageshack.us/photo/my-images/35/elevatorload.jpg/)


NACA on the stall:

http://img521.imageshack.us/img521/5849/gunportsopenstall.jpg (http://imageshack.us/photo/my-images/521/gunportsopenstall.jpg/)

NACA on the Longitudinal Instability:

http://img208.imageshack.us/img208/5619/spitfirestability.jpg (http://imageshack.us/photo/my-images/208/spitfirestability.jpg/)

While CG certainly does effect stall onset and characteristics, I am certain the NACA was capable of doing a weight and balance. A new weight and balance would have been a requirement once the aircraft was rigged for testing.

They were very aware of the effect of CG position on stall characteristics too.

Both the stall characteristics and the longitudinal instability are included in the General Operating Notes for the Marks that did not recieve bob weights.

[Kurfürst]

Nonsense Crumpp - you are the one who is taking things out of context - note what the report said about the cg calculations cf the A&AEE report on the same aircraft type - the possibility was that the Spitfire flown by NACA was slightly tail heavy.

Every report ever written on the Spitfire has apparently flawed because they were always have been made on a 'rogue' plane or a single example that proves nothing etc.

How boring.


Not forgetting also what Quill had to say about the early Spitfires - "In general configuration the Mk I and Mk II production aeroplanes were almost identical to the prototype and so there was no problem with their stability. (231-232)" I'll take his word over yours any day.

Except that everyone knows that Quill is khmm... the most outspoken priest of the Spitfire ever. If you ask Quill, the thing had no faults, and they were also immediately and complete fixed. Over and over again. Which is why he is liked to be quoted so much, as if his word was some kind of ultimate judgement which overwrites detailed reports. Quill may have an opinion, but these reports have the hard facts.

Personally I find Henshaw far, far more objective. At least he doesn't try to make it like how everything was made just perfect, despite some very obscene hiccups in the development (fabric ailerons being one of them)

As for having a "discussion" with you Crumpp - not interested because I know you'll turn it into a loooong, tedious thread, arguing over minute detail, while sticking to your opinion that the Spitfire was "dangerously unstable" no matter what. I don't care what you think because I know you're not interested in any one else's opinion, except when they agree with you.

That's pretty much the very best self-description I have ever read. I mean you keep playing the know-it-better smartass everytime, and then make it like as if the 'a loooong, tedious thread' its someone else fault, and then comes the usual yada-yada about your precious time and how you will put everyone on ignore.

Problem is, you've only registered here to carry over some feuds from other places, and you have made almost as many posts in 2 months as Crumpp or I did in 4 years. :D

Nope, arguing over minute details is exactly what you like to do. At least don't blame it on others. ;)

[Al Schlageter]

Quill is to the Spitfire as Barbi is to the Bf109.

[41Sqn_Stormcrow]

Actually I find this highlighted phrase (bold) more interesting in the quote of NZTyphoon:

Characteristics of the elevator control in accelerated Flight: (pages 8 & 9)

The elevator control was found to be powerful enough to develop either the maximum lift coefficient or the allowable load factor at any speed....(page 8 )

The Spitfire airplane had the unusual quality that allowed it to be flown in a partly stalled condition in accelerated flight without becoming laterally unstable. Violent buffeting occurred, but the control stick could be pulled relatively far back after the initial stall flow breakdown without causing loss of control. With the gun ports open, lateral instability in the form of a right rolll occurred, but not until an up-elevator deflection of 10° had been reached and unmistakeable warning in the form of buffeting had occurred. This subject is discussed more fully in reference 2.

The excellent stall warning made it easy for the pilots to rapidly approach maximum lift coefficient in a turn so long as the speed was low enough to avoid undesirably large accelerations at maximum lift coefficient.
The excellent stall warning possessed by the Spitfire was obtained at the expense of a high maximum lift coefficient. The maximum lift coefficient in accelerated flight was 1.21, while the average lift coefficient throughout a stalled turn was usually about 1.01 (9)

It says clearly that when riding the stall the margin was still big on pulling the stick.

I find the red phrase also interesting. Perhaps somebody with excellent understanding of flight mechanics can explain why large accelerations may be bad when flying at stall limit.

[Ze-Jamz]

Actually I find this highlighted phrase (bold) more interesting in the quote of NZTyphoon:



It says clearly that when riding the stall the margin was still big on pulling the stick.

I find the red phrase also interesting. Perhaps somebody with excellent understanding of flight mechanics can explain why large accelerations may be bad when flying at stall limit.

Hmm, Im no expert, far from it but wouldnt/doesnt the AoA change when power is applied (torque) hence changing the flow over the wings?

[41Sqn_Stormcrow]

Yes, to my understanding it would increase the speed (if longitudinal acceleration is considered) hence reduce AoA which hence should reduce stall.

With lateral acceleration increase (into the turn) the velocity vector should turn more but I do not understand how this could worsen the stall situation.

[bongodriver]

Hmm, Im no expert, far from it but wouldnt/doesnt the AoA change when power is applied (torque) hence changing the flow over the wings?

Sort of correct, mainly it's the AoA increase would put you over critical and you would get a departure, torque would just define which way you go into the resulting spin, the propwash wouldn't help much in this case.

[41Sqn_Stormcrow]

The excellent stall warning made it easy for the pilots to rapidly approach maximum lift coefficient in a turn so long as the speed was low enough to avoid undesirably large accelerations at maximum lift coefficient.

My guess is that they do not address thrust increase otherwise they would have written it I think.

Reading more closely the phrase I come to think that they perhaps wanted to say "as long as g level remained low during maximum lift pulls" meaning that the absolut lift was low while providing maximum lift for that given speed.

[Glider]

I admit to wondering what all the fuss is about. The vast majority of my flying experience has been in gliders so what I say comes with that caviet.

Any high speed stall is an exciting event even in a glider. By definition things happen quickly and often violently, so no suprise there.

Where the pilots notes warn about rough conditions causing the pilot to make control movements that can impact flight, its common sense and often happens. It could be that my experience is different here as what a powered plane calls turbulance is what we call potential lift and have more experience flying in those conditions. This warning would apply to any small aircraft, be it a Spitfire, 109, Piper Cub or glider.

Flying on the edge of a stall using the stall warning to stay close to the maximum performance is again a good thing, glider pilots often fly on the edge and in one case when I lost my instruments whle thermalling in a cloud with driving rain, had a good deal to do with my safe exit.
Edit - had my glider had automatic front edge slats like the 109, I may well have had to bail out, never thought of that before.


A violent spin if you push past the boundary is again nothing to worry about, it happens and you are trained not to go past the edge. I have seen international standard pilots make this mistake and spin out of a stack. You soon recognise the warning signs.

A couple of general observations,
a) the best fighters are by design borderline unstable.
b) Nearly all the reports I have seen from German pilots who flew captured Spifires said that they were easier to fly than the 109. This again supported by the Jugoslav airforce who had both Hurricanes and 109E's and used the Hurricane as a lead in to the 109 because of accidents. The RAF didn't use Hurricanes as a lead in to the Spitfire.

[Osprey]

Except that everyone knows that Quill is khmm... the most outspoken priest of the Spitfire ever. If you ask Quill, the thing had no faults

I find it a bit of a failure in job description that a test pilot would not report any faults because he thought it was perfect. Get real Kurfurst.

[fruitbat]

I just find it pure comedy gold that Kurfursts arrogance and general hatred of the Spit is such that he genuinely believes that he knows more about Spits that Quill did.

says everything you need to know.

[Crumpp]

A violent spin if you push past the boundary is again nothing to worry about,

Sure, in an aircraft with acceptable stability and control characteristics...

If you don't have that then the pilot can kill himself and turn the aircraft to aluminum confetti as the Spitfire Operating Notes tells you.

[Crumpp]

Quill

Keep in mind that pilots in the 1930's and 1940's were not the technical experts found in today's aviation world.

They were practical pilots who got there mostly on their courage. It was felt that it was beyond the pilots comprehension to delve too deeply into the science of flight.

Pilots were given a rudimentary knowledge of aerodynamics at best and strict left/right limits required to operate the aircraft.

[NZtyphoon]

Keep in mind that pilots in the 1930's and 1940's were not the technical experts found in today's aviation world.

They were practical pilots who got there mostly on their courage. It was felt that it was beyond the pilots comprehension to delve too deeply into the science of flight.

Pilots were given a rudimentary knowledge of aerodynamics at best and strict left/right limits required to operate the aircraft.

ie: Quill was a no nothing pilot who just operated the controls and hoped for the best - yeah right! Interesting how Barbi and Crumpp now attack one of the most highly regarded test plots of his generation because they don't like what he wrote about the Spitfire...way to go guys! :rolleyes:

[Kurfürst]

Well we just noted that Quills opinion is at odd with the very detailed testing findings of RAE, NACA and E'Stelle Rechlin. I am quite sure you are right that all these organisations experience objectiveness in testing aircraft and assessing their flying qualities pales in comparison with that of the manufacturer's own test pilot. ;)

[Glider]

Sure, in an aircraft with acceptable stability and control characteristics...

If you don't have that then the pilot can kill himself and turn the aircraft to aluminum confetti as the Spitfire Operating Notes tells you.

You push any aircraft past its limits and failure may happen. However it is a rare case. What I find intersting is that you don't take note of the comments from the German pilots who flew the Spitfire and said that it was easier to fly than the 109, or the Jugoslav pilots who flew the Hurricane and Me109. Why do you just ignore that?

Does anyone have the pilots notes for the 109, I am confident that if they are to the same scope then they will have their won warnings.

[Glider]

Keep in mind that pilots in the 1930's and 1940's were not the technical experts found in today's aviation world.

They were practical pilots who got there mostly on their courage. It was felt that it was beyond the pilots comprehension to delve too deeply into the science of flight.

Pilots were given a rudimentary knowledge of aerodynamics at best and strict left/right limits required to operate the aircraft.

Partly true, however the UK were the first to train test pilots in the 40's Germany and the USA didn't.

[Kurfürst]

What I find intersting is that you don't take note of the comments from the German pilots who flew the Spitfire and said that it was easier to fly than the 109, or the Jugoslav pilots who flew the Hurricane and Me109. Why do you just ignore that?

Because you haven't shown any...? I believe Moelders stated that the Spitfire and Hurricane are easier to land than the 109. He also added that they are otherwise miserable as fighter aircraft.

Does anyone have the pilots notes for the 109, I am confident that if they are to the same scope then they will have their won warnings.

Yes I have. It doesn't have any of the longitudal stability references as the Spitfire pilot's notes, however. There are a few similarities - both manuals warn the pilot against the dangers of using the ailerons too hard in dives, as there is a danger of structural failure (twisting forces).

[Osprey]

Because you haven't shown any...? I believe Moelders stated that the Spitfire and Hurricane are easier to land than the 109. He also added that they are otherwise miserable as fighter aircraft.



Molders:
"It was very interesting to carry out the flight trials at Rechlin with the Spitfire and the Hurricane. Both types are very simple to fly compared to our aircraft, and childishly easy to take-off and land

The Spitfire is one class better. It handles well, is light on the controls, faultless in the turn and has a performance approaching that of the Bf 109......"

And he only had an 87 octane 2 stage prop aeroplane to test which is why he goes on to criticise it a little. I guess he changed his mind after the Battle of Britain lol

[Kurfürst]

Molders:
"It was very interesting to carry out the flight trials at Rechlin with the Spitfire and the Hurricane. Both types are very simple to fly compared to our aircraft, and childishly easy to take-off and land

The Spitfire is one class better. It handles well, is light on the controls, faultless in the turn and has a performance approaching that of the Bf 109......"

Full quote instead of the usual selective quoting:

"It was very interesting to carry out the flight trials at Rechlin with the Spitfire and the Hurricane. Both types are very simple to fly compared to our aircraft, and childishly easy to take-off and land. The Hurricane is good-natured and turns well, but its performance is decidedly inferior to that of the Me 109. It has strong stick forces and is "lazy" on the ailerons.

The Spitfire is one class better. It handles well, is light on the controls, faultless in the turn and has a performance approaching that of the Bf 109. As a fighting aircraft, however, it is miserable. A sudden push forward on the stick will cause the Motor to cut; and because the propeller has only two pitch settings (take-off and cruise), in a rapidly changing air combat situation the motor is either overspeeding or else is not being used to the full."

So he though the Spitfire is not quite the same performance as the 109, and otherwise it's 'miserable'. I guess that concludes the story. ;)

And he only had an 87 octane 2 stage prop aeroplane to test which is why he goes on to criticise it a little. I guess he changed his mind after the Battle of Britain lol

Source please to 87 octane fuel only. Why would the Germans test an aircraft on 87 octane fuel, when supposedly all Spitfires were running on 100 octane, and would be captured in such state..? Hmm?

[Osprey]

Full quote instead of the usual selective quoting:



Yeah I did that one purpose because you already had, thus exposing your hypocracy. The model he had did not use 12lbs nor CSP - that is why it approaches the performance rather than exceeds it. An emergency bunt and run is a defensive move in a dogfight, very useful but not as a killing tactic.


Source please to 87 octane fuel only. Why would the Germans test an aircraft on 87 octane fuel, when supposedly all Spitfires were running on 100 octane, and would be captured in such state..? Hmm?

Now why would exactly would they fuel it with 100 octane then Kurfurst? I though you said the RAF weren't using it. Prove to me that they put 100 in it - that's your claim not mine.

Sensible people can use deduction and logic anyway. The very fact that it is a 2 stage Spitfire means that it has a Merlin II and was in operation during the Battle of France, and that a Merlin II required conversion to accept 100 octane fuel and make use of 12lbs of boost in the first place. Then there is the fact that Molders doesn't mention use of the ABC which he would have had to use in order to get over 6.25lbs anyway.

So, either the LW decided to fuel an aircraft with a fuel that would destroy the engine or the RAF had all their fighters converted by the Fall of France but then decided to stop using it and convert them back again when the BoB started. Yeah, right.........just stop being so silly would you.

[NZtyphoon]

I note here (http://kurfurst.org/Tactical_trials/109E_vergleich110SpitHurCurtiss/109E_vergleichsflg_Aug1940.html) that one of the sources listed is;
1 - Quoted from Page 61 - Osprey's Aircraft of the Aces - 'Spitfire Mk.I/II Aces' by Dr. Alfred Price.
ISBN 84-8372-207-0

Sic - it is on page 90, so not even that is right. Dr Price goes on to state Interestingly the Luftwaffe test centre at Rechlin also carried out comparative fighting trials between Bf 109s and a captured Bf 109....The two sets of trials showed that the 'home team' possessed the superior fighter type. Given the naivety with which the trials were conducted any other finding would probably have been regarded as 'politically incorrect'....the Mark I and Mark II Spitfires were roughly equal to the Bf 109 in capability. In the fleeting air combats that were the norm, tactical initiative counted for more than the relatively small performance differences that existed between the opposing fighter types.

[NZtyphoon]

My guess is that they do not address thrust increase otherwise they would have written it I think.

Reading more closely the phrase I come to think that they perhaps wanted to say "as long as g level remained low during maximum lift pulls" meaning that the absolut lift was low while providing maximum lift for that given speed.

The report includes a series of graphs recording the information (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930092582_1993092582.pdf); incidentally

Reference 1. REQUIREMENTS FOR SATISFACTORY FLYING QUALITIES
OF AIRPLANES can be found here (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930092506_1993092506.pdf)

[Crumpp]

Quill was a no nothing pilot who just operated the controls and hoped for the best

That is not what I said. Pilots in the 1930's and 1940's were given only very elementary training in aerodynamics. It was considered unnecessary and demanded too much mathematical knowledge. That is straight out of the RAF Flying Manual.

They are not the experts in aerodynamics that we see today in the cockpit.

Glider,

The Spitfire Mk I had unacceptable longitudinal instability. The RAE knew it and corrected it in later marks.

It is a fact.

3/4 inch stick movement to run the usable Angle of Attack range at weak or neutral stability with light stick forces is going to make for a squirrely airplane.

;)

Read the report, the stick force gradient on the longitudinal axis was considered too light by most of the pilots.

By careful flying, maximum performance turns could be made.

The yaw wise stability experiences a pitch up with large deflections that coupled with the longitudinal instability caused the plane to experience rapid accelerations. That means it is very difficult for the pilot to precisely control the elevator. That asymetrical loading is what can cause the airframe to break apart in spin recovery.

[Crumpp]

Guys,

The Spitfire was a great airplane and a very effective fighter. There was no such thing as a Stability and Control Engineer when the Spitfire was designed.

It was a new science and almost all of the World War II era fighters have some sort of stability and control issue. It is just as important as the aerodynamics in their fighting abilities.

The Bf-109 had issues with the coupling effects of yaw-wise and the lateral axis at high speed.

The FW-190 and P-51 had longitudinal axis stick force reversals at low speeds.

Airplanes simply got faster and heavier so quickly that the engineering science did not keep up. It did matter so much when airplanes were slow and light.

[bongodriver]

The average military pilot might have had basic aerodynamics training but you can bet you ass test pilots had alot more.

[Crumpp]

Guys,

The Spitfire was a great airplane and a very effective fighter. There was no such thing as a Stability and Control Engineer when the Spitfire was designed.

It was a new science and almost all of the World War II era fighters have some sort of stability and control issue. It is just as important as the aerodynamics in their fighting abilities.

The Bf-109 had issues with the coupling effects of yaw-wise and the lateral axis at high speed.

The FW-190 and P-51 had longitudinal axis stick force reversals at low speeds.

Airplanes simply got faster and heavier so quickly that the engineering science did not keep up. It did matter so much when airplanes were slow and light.

[Glider]

Guys,

The Spitfire was a great airplane and a very effective fighter. There was no such thing as a Stability and Control Engineer when the Spitfire was designed.

It was a new science and almost all of the World War II era fighters have some sort of stability and control issue. It is just as important as the aerodynamics in their fighting abilities.

The Bf-109 had issues with the coupling effects of yaw-wise and the lateral axis at high speed.

The FW-190 and P-51 had longitudinal axis stick force reversals at low speeds.

Airplanes simply got faster and heavier so quickly that the engineering science did not keep up. It did matter so much when airplanes were slow and light.

This I totally agree with, problems were not unique to the Spitfire.

[Crumpp]

This I totally agree with, problems were not unique to the Spitfire.

The Spitfire has unique stability and control characteristics.

The most outstanding issue is the Longitudinal Stability and Control of the early marks.

This was corrected in later variants.

The average military pilot might have had basic aerodynamics training but you can bet you ass test pilots had alot more.

Not really Bongo. They were the guys that had the balls to climb into an uproven machine.

Hans Sander related a story of performing a max G pullout from a dive in the early testing of the FW-190. The aircraft was well into the transonic realm of flight and upon recovery exhibited water vapor condensation behind the normal shock.

It turned the wings completely white for a second. He had no idea at the time what happenend and effect scared the pants off him at first. He thought something was wrong with the aircraft. He paused, ensured he had control of the aircraft and all engine indications were in the green. He was prepared to bail out if necessary.

You can see the same effect in this video:

http://www.youtube.com/watch?v=DQDJGlewGIU&feature=related

[bongodriver]

Nice video, what was it and what are wings? I don't know what this aerodynamite is you speak of.....I'm only a pilot.

[Crumpp]

Nice video, what was it and what are wings? I don't know what this aerodynamite is you speak of.....I'm only a pilot.


In context, the pilots of the 1930's and early 40's had never experienced such a thing.

[Kurfürst]

Yeah I did that one purpose because you already had, thus exposing your hypocracy.

You selectively quoted on purpose to expose my hyporcracy.

Brilliant. :D


Now why would exactly would they fuel it with 100 octane then Kurfurst? I though you said the RAF weren't using it.

Nope I've said that only select squadrons have used it.


Prove to me that they put 100 in it - that's your claim not mine.


And he only had an 87 octane 2 stage prop aeroplane to test which is why he goes on to criticise it a little.

No comment.

Sensible people can use deduction and logic anyway. ...

Osprey pulls out a shotgun with a big grin...

... The very fact that it is a 2 stage Spitfire means that it has a Merlin II and was in operation during the Battle of France, and that a Merlin II required conversion to accept 100 octane fuel and make use of 12lbs of boost in the first place. Then there is the fact that Molders doesn't mention use of the ABC which he would have had to use in order to get over 6.25lbs anyway.

... then shoots himself in the leg, twice, and finally falls into a punji. The crowd is absolutely blasted by the show.

[Crumpp]

And he only had an 87 octane 2 stage prop aeroplane to test which is why he goes on to criticise it a little.

Wasn't the claim 100 Octane was used in the Battle of France made in that thread?

:rolleyes:

[Al Schlageter]

Wasn't the claim 100 Octane was used in the Battle of France made in that thread?

:rolleyes:

Hurricanes in France did.

[Kurfürst]

Wasn't the claim 100 Octane was used in the Battle of France made in that thread?

:rolleyes:

I think you confuse it with the one about 'poor Jerries reliedin the BoB entirely on British 100 octane stock captured in France'-thread. ;)

And this one is the 'yet they could not figure out how to put these captured stuff in Spitfires which were all supposed to run on the stuff by this time'-thread. :D

[Glider]

The Spitfire has unique stability and control characteristics.

The most outstanding issue is the Longitudinal Stability and Control of the early marks.

This was corrected in later variants.

But everyone said that it was easy to fly, were all the pilots stupid of every nation. Or could it be that the training and the pilots notes did what they should do, warn and enable the pilots to get used to it.

All aircraft have their own unique feature, old and new. To pretend that only the Spitfire had its own problems is foolish pilots notes are not the be all and end all. Most planes have a warning that intentional spins should be avoided but they get spun. The notes are a warning, no more no less

[Kurfürst]

Define easy to fly.

[Crumpp]

Most planes have a warning that intentional spins should be avoided but they get spun.

This is just not true. Spinning an aircraft that is not approved is just plain stupid. The only people that do it are those who do not understand the aerodynamics.

There is a good reason it is not approved to spin. Reason's like it does not recover for example.

Even aerobatic aircraft that must pass spin testing can enter unrecoverable conditions.

"Mayday mayday mayday Pitts 260DB in an unrecoverable flat spin at 3,500 feet."

The airplane crashed in the Everglades, coming to rest partially inverted and nearly vertical in several feet of water. The canopy, which had been jettisoned in flight, was several hundred feet away. The bodies of the pilots were closer by the wreckage; both had bailed out, but there had not been time for their parachutes to open.


Why did this aerobatic aircraft enter an unrecoverable condition in a spin?

Only one aft limit for the CG is specified, but it assumes the maximum acrobatic weight; excessive weight exaggerates the effect of an aft CG position on spin recovery.

The pilot failed to adhere to the Operating Limits as listed in the Pilots Manual. He violated the airworthiness of the design. The aft CG flattened the spin until the dirt barrier stopped it.

http://www.flyingmag.com/safety/accident-investigations/unrecoverable-spins

Easy to fly doing what? A few circuits of the field, cross country cruise, rolls or loop or two? Sure it was easy to fly.

Easy to fly is very subjective. Longitudinal stability and control measurements and characteristics are not subjective. They are quantifiable characteristics with definitive limits.

[von Brühl]

You're arguing with non-engineers...

[CaptainDoggles]

You're arguing with non-engineers...

Evidently.

[winny]

I thought I'd provide Molders full quote.

"it was very interesting to carry out the flight trials at Rechlin with the Spitfire and Hurricane. Both types are very simple to fly compared to our aircraft, and childishly easy to take off and land. The Hurricane is good natured and turns well, but it's performance is decidedly inferior to that of the Me 109. It has strong stick forces and is 'lazy' on the ailerons.
The Spitfire is one class better. It handles well, is light on the controls, faultless in the turn and has a performance approaching that of the Me 109. As a fighting aircraft it is miserable. A sudden push of the stick will cause the engine to cut, and because the propeller has only 2 pitch settings ( take off and cruise ), in a rapidly changing air combat situation the engine is either over-speeding or else not being used to the full."

It's a pretty fair assessment of the 2 pitch Spit.

And a few lines from the actual trials at Rechlin.

Before turning fights with the Me 109E, it must be noted that in every case, that all three ( Spitfire, Hurricane, Curtiss ) foreign planes have significantly smaller turning circles and turning times. An attack on the opponent as well as a disengagement can only be accomplished on the basis of existing superiority in performance.

What is interesting about the A&AEE trials is that the Spitfire used was using 100 octane and CSP. In May 1940. Which goes some way to explaing the difference between the British and German trials results.

I'm happy to concede that there was an issue with the 109 used. It was the same aircraft that was trailed against the Hurricane in France and if you compare the 2 trials there's a definite decline in the 109's performance between the 2 trials. There was a forced landing made between the 2 dates (about 2 months apart) which probably contributed to this.

I don't think either the Rechlin or A&AEE trails can be considered as 100% accurate. They are what they are! Tests of aircraft on both sides that were not particularly good examples of their types.

[Crumpp]

You're arguing with non-engineers...


:grin:

It is funny that Morgan and Shacklady quote several pilots who disliked the Spitfire's elevator after the longitudinal instability was fixed by the addition of bob-weights.

They felt it ruined the feel and made the elevator sluggish.

I laughed when I read it.

I bet it did make it feel sluggish if you are used too 3/4 inch stick travel for the available Angle of Attack at 5 lbs per G in neutral or just statically stable!!

:shock:

[NZtyphoon]

You're arguing with non-engineers...

Nope, the problem here is that someone who claims to know something about aviation can also make a blanket claim that the Spitfire was an inherently dangerous aircraft, based on two reports which say nothing of the sort.

What they do say is that it did not reach certain NACA standards which had been introduced in 1941 Reference 1. REQUIREMENTS FOR SATISFACTORY FLYING QUALITIES OF AIRPLANES can be found here (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930092506_1993092506.pdf)

It would help if you understood everything that report says instead of select phrases out of context. If you can't do that , it is practically impossible to hold a discussion.


If you read the report, it states the conditions the aircraft exhibited a very harsh stall. One of those conditions would be in a steep bank with gun ports open. Under those conditions, the aircraft would develop a roll instability and resulting spin.

The conditions matter in aerodynamics.

Yes the Spitfire gave very good stall warning. That large buffet zone comes at a price in diminishing turn performance.

Longitudinal Stability has nothing to do with stall characteristics except to determine how fast the pilot can move the wing through its useable angle of attack range.

The NACA rated the Spitfire as having unacceptable longitudinal stability and control in all conditions of flight. It is either neutral or unstable and this was corrected with bob weights in later marks.

That is not a bias, it is just a fact. None of these aircraft were perfect regarding stability and control. Some were worse than others and it is a fact the early mark Spitfires exhibited a dangerous longitudinal instability. It was an infant science when they were developed.

Nowhere in any of these reports does it state the Spitfire was dangerous. Strangely enough I actually agree with Kurfurst that it did have a sensitive elevator in certain conditions, but, whatever longitudinal instability it did have was controllable, and most pilots learned to handle it, including wet-behind-the-ears trainees transitioning from the Harvard, which could bite if pushed the wrong way.

All fighters are supposed to have a certain amount of controllable instability, otherwise they would not be able to manoeuvre effectively. Remember the BE2? This was an aircraft which was designed to be stable about all axes and it failed miserably as a fighter, and it was all too easy to shoot down because of that built in stability, although it made a great observation platform which was its original purpose. On the opposite pole there was the Camel which was dangerous to its pilots, although still effective when handled properly.

[CaptainDoggles]

Guys, aircraft stability is not something that's subject to interpretation. Either an aircraft is stable about a particular axis or it is not.

Even NACA (http://books.google.ca/books?id=wpYDYLuOix4C&pg=PA42&lpg=PA42&dq=spitfire+longitudinal+stability&source=bl&ots=fO3NR_DkPc&sig=mvafGBPm68J9eyw-3_W4j5uFUfg&hl=en&sa=X&ei=CR-pT-G9DqOd6AGfhJywBA&ved=0CGEQ6AEwAg#v=onepage&q=spitfire%20longitudinal%20stability&f=false) agrees that the Spitfire V did not have positive longitudinal stability.

...yet neither of these famous aircraft had the specified levels of the most basic stability of them all, static longitudinal stability...

"Stability" is a quantifiable property, not a subjective classification. An aircraft that is not statically stable can still have good flying qualities. To say that the Spitfire was not statically stable is not to say that all the pilots praising the Spit's handling qualities were wrong.

You guys are getting so caught up in your quest to prove Crumpp wrong that you're losing sight of the facts.

[bongodriver]

Even NACA (http://books.google.ca/books?id=wpYDYLuOix4C&pg=PA42&lpg=PA42&dq=spitfire+longitudinal+stability&source=bl&ots=fO3NR_DkPc&sig=mvafGBPm68J9eyw-3_W4j5uFUfg&hl=en&sa=X&ei=CR-pT-G9DqOd6AGfhJywBA&ved=0CGEQ6AEwAg#v=onepage&q=spitfire%20longitudinal%20stability&f=false) agrees that the Spitfire V did not have positive longitudinal stability.



Maybe so but this isn't any indication of the 'dangerous instability' crumpp is pushing.
all it means is the spitfire was agile....a desireable quality in a fighter non?

[CaptainDoggles]

Maybe so but this isn't any indication of the 'dangerous instability' crumpp is pushing.
all it means is the spitfire was agile....a desireable quality in a fighter non?

No, not "maybe so".

The Spit V had zero stability, this is fact.

[bongodriver]

No, not "maybe so".

The Spit V had zero stability, this is fact.

So how were mere humans able to fly them? total instability is the realms of 5th generation fighter jets that need computers to fly them.

Sorry but you guys are blowing it out your asses if you claim the spitfire had 'no' stability.

[JtD]

Neutral static longitudinal stability doesn't mean no stability at all.

[CaptainDoggles]

So how were mere humans able to fly them? total instability is the realms of 5th generation fighter jets that need computers to fly them.

Sorry but you guys are blowing it out your asses if you claim the spitfire had 'no' stability.

I think maybe you should go learn about aircraft stability before you tell me I'm "blowing it out my ass" because you are incorrect.

There are three classifications of static stability: positive, negative, and neutral (or zero).

Don't be so hostile.

[bongodriver]

I think maybe you should go learn about aircraft stability before you tell me I'm "blowing it out my ass" because you are incorrect.

There are three classifications of stability: positive, negative, and neutral (or zero).

Don't be so hostile.

actually theres static and dynaminc, I don't need to learn anything from people claiming the spitfire was 'unstable', and believe me static (or neutral) stability is by no means unstable.

Sorry if I sound hostile, no intention but I understand.

[CaptainDoggles]

actually theres static and dynaminc

Edited my post, as I was typing too fast. There are three conditions of static or dynamic stability: Positive, Negative, and Neutral. The spitfire had neutral (when i was in school we used the term "zero") static longitudinal stability. An aircraft can only be said to be statically stable if it has positive stability.

I don't need to learn anything from people claiming the spitfire was 'unstable', and believe me static (or neutral) stability is by no means unstable. It's not my fault if you're misusing the accepted terminology. I've provided a reference from the National Advisory Committee for Aeronautics that supports my case.

Go look up a reference that proves me wrong, showing the spitfire had positive static stability.

[bongodriver]

Go look up a reference that proves me wrong, showing the spitfire had positive static stability.



I don't claim the spitfire had dynamic stability, I say it is neutral, which simply means it does not try to return to it's original condition, as opposed to dynamic instability where the aircraft would increase it's amplitude of error, enough proof against dynamic instability is the fact the aircraft was not notorious for PIO (pilot induced oscilation) incidents, neutral stability is a desireable quality for an aircraft built purpousely to be agile/manouverable......seems Mitchel designed it just right.

I attached a scan from Kermodes 'Mechanics of flight' and have highlighted in red the 3 conditions, perhaps there are differences in our understanding but I feel it explains where I'm coming from.

[CaptainDoggles]

Kermode's terminology is a bit dated, I think. What's the publication date?

Most textbooks and the industry people I know prefer the following breakdown:


Dynamic Stability:

Positive
Negative
Neutral

Static Stability:

Positive
Negative
Neutral

[bongodriver]

Kermode's terminology is a bit dated, I think. What's the publication date?

Most textbooks and the industry people I know prefer the following breakdown:


Dynamic Stability:

Positive
Negative
Neutral

Static Stability:

Positive
Negative
Neutral



can you scan or point me to a source for this, seems a bit odd th have these distinctions......what's the difference between neutral dynamic stability and neutral static stability?

[CaptainDoggles]

I'll see if I can provide you a scan later today, but in the interim have a look at the Centennial of Flight website which is run by NASA, so I'd say it's a reasonably authoritative source.

http://www.centennialofflight.gov/essay/Theories_of_Flight/Stability/TH26.htm

Edit: You can also have a look at this textbook, an earlier edition of which I used in school. Stengel's Flight Dynamics (http://www.princeton.edu/~stengel/FlightDynamics.html)

[bongodriver]

Yeah I see the 'static' stability as what nasa like to call 'stick-fixed' stability, to be honest not an issue that causes difficulty in flight, it simply means the aircraft maintains attitude when displaced or simply put its light in pitch due to no resistance, hardly a bad quality in an aircraft you are trying to point around the sky to put a gunsight on target, if it were coupled with vicious characteristics in a stall it might cause problems, but again the Spit was known to be docile.

for an aircraft to be considered stable or unstable it really comes down to the dynamic stability, if the Spitfire was dynamically unstable as I believe the Spit bashers are claiming then it would have been impossible to fly in any form of manouvering due to the increasing amplitude of displacement and the subsequent pilot induced oscilations to correct it, by all accounts there was never an issue with this and further more it's practically inconceivable that a typical monoplane format aircraft of that era with a concentration of weight in it's nose to be dynamically unstable.

[bongodriver]

Kermode may be 'dated' by todays standards but given we are talking 1930/40's aircraft then it covers everything applicable for the time, the new deffinitions of stability you give really have come about since the advent of aircraft capable of all these different states.

[JtD]

Stick fixed is just one version of static stability, you're keeping the elevator angle constant over a speed range and check how the aircraft responds. In case of the Spitfire, no trim change occurred, so the plane would keep the same AoA over the entire speed range at the same elevator deflection. That's neutral stability.

The other version NACA was looking at is stick force stability, if you want to call it that, where you are keeping the stick force constant through the speed range and check how the aircraft responds. In case of the Spitfire, stick force increased with the speed, which in turn leads to smaller elevator deflections which means some sort of positive stability.

The Spitfire was dynamically stable.

All for longitudinal stability.

[CaptainDoggles]

Kermode may be 'dated' by todays standards but given we are talking 1930/40's aircraft then it covers everything applicable for the time, the new deffinitions of stability you give really have come about since the advent of aircraft capable of all these different states.The laws of physics haven't changed since the war. Stability isn't something that an aircraft is "capable of".

if the Spitfire was dynamically unstable as I believe the Spit bashers are claimingI don't think anyone here is claiming the spit was dynamically unstable, nor would I say anyone here is a "Spit basher".

It's not "bashing" the spitfire to say it was not statically stable. Facts are facts. If you're going to get emotionally invested in this discussion then I'd rather not engage with you.

[bongodriver]

I don't think anyone here is claiming the spit was dynamically unstable, nor would I say anyone here is a "Spit basher".

Well a 'spit basher' would say that, no point admitting to it if you hope to keep under the bias radar and hide the emotional investment in it's counterpart, ok glad we cleared the dynamic stability issue though as thats the only real stability issue which would cause significant problems.

It's not "bashing" the spitfire to say it was not statically stable. Facts are facts. If you're going to get emotionally invested in this discussion then I'd rather not engage with you.

it is 'spit bashing' if that characteristic is being used as an example of a stability problem, I don't mind if you don't wish to engage with me, please don't be under the impression I need it.

The laws of physics haven't changed since the war. Stability isn't something that an aircraft is "capable of".

understanding of physics has however, stability is an inherrent capability of an aircraft, you must realise that a Cof G shift can cause a change in stability.

[CaptainDoggles]

Well a 'spit basher' would say that, no point admitting to it if you hope to keep under the bias radar and hide the emotional investment in it's counterpart, ok glad we cleared the dynamic stability issue though as thats the only real stability issue which would cause significant problems. Is it your favorite aircraft or something? I've stated nothing but facts and you're calling me biased.

it is 'spit bashing' if that characteristic is being used as an example of a stability problem, I don't mind if you don't wish to engage with me, please don't be under the impression I need it.I never said it was a problem. I just said the spitfire is not statically stable.

understanding of physics has however, stability is an inherrent capability of an aircraft, you must realise that a Cof G shift can cause a change in stability.CG shift has nothing to do with the topic at hand.

[bongodriver]

Is it your favorite aircraft or something? I've stated nothing but facts and you're calling me biased.

I don't aim the claim at you per se, but the general feeling on these topics are mainly led by bias, my favourite aircraft.....late mark perhaps....but not a fan of early spits, couldn't say a particular favourite but I am a secret lover of the cessna 150/152 believe it or not..bloody fantastic little aircraft.

I never said it was a problem. I just said the spitfire is not statically stable.

then why was it brought up in the first place?

CG shift has nothing to do with the topic at hand.

No, but it was a response to your claim stability is not a capability of an aircraft, if it can be changed then it is a variable, which if used to advantage is a capability, now try denying that some aircraft can shift C of G to their benefit.

[CaptainDoggles]

then why was it brought up in the first place?Because people throw terms like "stable" around without really knowing what it means, and think that because an RAF pilot said the Spitfire was "easy to fly" that it must therefore mean the Spitfire was a very stable aircraft.

No, but it was a response to your claim stability is not a capability of an aircraftNever mind. Linguistic difference. I was just pointing out that you don't say "The P-51 is capable of static stability." You say "The P-51 is statically stable." An aircraft is designed to be stable under a particular set of conditions. If you change the conditions then the aircraft might not be stable under those conditions, but you aren't changing the aircraft.

if it can be changed then it is a variable, which if used to advantage is a capability, now try denying that some aircraft can shift C of G to their benefit.Why on earth would I deny that and why is it relevant to the Spitfire?

[bongodriver]

Because people throw terms like "stable" around without really knowing what it means, and think that because an RAF pilot said the Spitfire was "easy to fly" that it must therefore mean the Spitfire was a very stable aircraft.?

Nonsense, people interpret it for exactly what it means, the spitfire was easy to fly, nobody mentioned stability until someone wanted to deride the spitfire.

Never mind. Linguistic difference. I was just pointing out that you don't say "The P-51 is capable of static stability." You say "The P-51 is statically stable." An aircraft is designed to be stable under a particular set of conditions. If you change the conditions then the aircraft might not be stable under those conditions, but you aren't changing the aircraft.

Where did I say anything about the spitfire being 'capable of stability'? I will say it again it was a response to your 'black and white' statement 'Stability isn't something that an aircraft is "capable of".'

Why on earth would I deny that and why is it relevant to the Spitfire?

Where did I claim it was?

[CaptainDoggles]

Nonsense, people interpret it for exactly what it means, the spitfire was easy to fly, nobody mentioned stability until someone wanted to deride the spitfire.This is my point. Aircraft stability and aircraft flying qualities are two different things. The spitfire had good flying qualities but was not statically stable.

Where did I say anything about the spitfire being 'capable of stability'? I will say it again it was a response to your 'black and white' statement 'Stability isn't something that an aircraft is "capable of".' Like I said. Never mind. It would take too much energy to explain.

Where did I claim it was?You brought it up.

[bongodriver]

This is my point. Aircraft stability and aircraft flying qualities are two different things. The spitfire had good flying qualities but was not statically stable..

the sentence should end at 'easy to fly'....static stability is just not something to consider in this case, if something is easy to fly then it has no appreciable stabiltiy issues.

Like I said. Never mind. It would take too much energy to explain..

You brought it up

You brought it up .

I'm not too lazy to explain so I'll do it again, response to your odd statement.

[CaptainDoggles]

http://i181.photobucket.com/albums/x7/dementia_dreams/GIF%20archive/BarneyNPHsuicide.gif

[Al Schlageter]

'Stability isn't something that an aircraft is "capable of".'

However do free flight models fly then?

http://smallflyingarts.com/category/model-showcase/

[bongodriver]

However do free flight models fly then?

http://smallflyingarts.com/category/model-showcase/


Amazing isn't it, doggles claims he was setting the record straight for all the 'ignorants' that don't understand stability but forgot it was Kurfurst that raised the stability issue in the first place.

[CaptainDoggles]

I don't care who raised the issue. Not every f***ing thing on these forums has to be about taking sides. Just because I have a 109 in my sig doesn't mean I am biased toward a guy who runs a 109 website. I don't care who raised the issue.
Facts are facts.

However do free flight models fly then?It was a linguistics thing. Never mind.

[bongodriver]

oooooohhhh! who's tired

[CaptainDoggles]

oooooohhhh! who's tired

I thought Danger Dogz pilots were supposed to be mature?

[bongodriver]

I thought Danger Dogz pilots were supposed to be mature?

Umm....yes.....of course we are, it's a strict policy to not have a sense of humour and we all come from the planet Vulcan.

[41Sqn_Stormcrow]

Is it necessary that all discussions on the fm turn into a verbal slap fest instead of an exchange of ideas and thoughts on a topic?

And please do not come again with "it's X who started it" or "Y is so biaised" or "Z just claims things without proof". Even if X started it if you returned the favour you're not better. And as far as I can judge all or nearly all participating in this slap fest are strongly lobbying their favorite aircraft and have made claims without proof.

For someone with an interest in genuine flight mechanics, the FM and its comparison with RL this is really boring.

*end of rant*

[winny]

On the subject of stability.

The only real questions this whole debate brings up are..

1. Is this instability modlled in CloD?
2. Does any of this effect MkI / Mk II Spitfires (I'm asking because there's been mention speifically of inertia weights on MkV's)
3. Do other aircraft have similar, technical 'issues' and are they included, or is all this deeper than the sim goes?

Whe I fly sims I don't really know the 'maths' behind it all.. I either fly or fall out of the sky. Is this just a carry over from the other thread wrapped up as a problem or is it a problem?

[Glider]

This is just not true. Spinning an aircraft that is not approved is just plain stupid. The only people that do it are those who do not understand the aerodynamics.

There is a good reason it is not approved to spin. Reason's like it does not recover for example.



I am sorry but that is plain wrong. If you look at almost any aircraft in the RAF at almost any time you will see that it says intentional spinning is banned. That includes the Spitfire, however it doesn't stop the fact that spinning is undertaken.
Pilots had to be trained to get out of a spin in a combat aircraft, and therefore you have to be in a spin to learn how the aircraft behaves. In reality it means that it should be done under supervision not as a matter of course until experience has been gained

Corkscrewing as an evasion technique is far more violent than a spin but all RAF bombers including Halifax and Lancasters undertook such a method.

This is one area I can speak of with some experience. When I started learning to spin some of this was undertaken in a Hunter T8. If you look at the pilots notes for the Hunter you will find, yes you guessed it, intentional spinning is banned.

Re the comment someone made about arguing with non engineers, I served in the RN as an airframes and engines artificer in the early 70's if that is of interest.

Just an observation, but the RAF never needed to develop a two seat Spit or Hurricane and trained many thousands of pilots to fly them. But the Luftwaffe needed to develop two seat 109's with the inevitable distruption on the design and production teams, presumably because they needed to.

[Crumpp]

Nobody is "attacking the Spitfire". That statement is ridicules and paranoid, deserving of a pointy tin foil hat.

The Longitudinal stability and control of the Spitfire is well documented.

YES, it can kill the pilot and that is why it is "unacceptable". It did kill pilots.

Is the Spitfire a dangerous aircraft that is not airworthy? NONSENSE, of course it is an airworthy aircraft and one the great fighter designs of WWII.

The limitations of that airworthiness are published in the Pilot's Operating Notes.

The arguments over stability and control do not make anybody look intelligent when they don't know what it means. I don't say that to be a jerk, know-it-all, or

I will try to explain the issue with the Spitfire so that it makes more sense.

All aircraft motion is oscillary. There are two categories of oscillations, long period and short. Short period oscillation represents a wide variation in Angle of Attack. Short period oscillation must be dampened in static stability and disappear without pilot input for the aircraft to be airworthy. Long Period oscillation is considered to have a constant Angle of Attack. It really does not but the variation is minor.

The Spitfire's stability issue was with long period oscillation in the longitudinal axis. These are generally not a big deal and the pilot controls them.

Static, Dynamic, stick fixed, and stick free are all different things.

First let's discuss some general stability terms:

Static Stability - The initial tendency of the aircraft movement when displaced. It is the first thing the airplane will do. If it initially moves opposite of the displacement, it has positive static stability. If it moves farther in the direction of displacement, it has negative static stability. If it does not move farther away or attempt to return from its equilibrium position, it has neutral static stability.

Dynamic Stability is the movement of the aircraft with respect to time. If it is disturbed from it equilibrium point and the maximum displacement decreases with time, it has positive Dynamic stability. If it increases with time, it has negative Dynamic stability. If it remains constant with time, the aircraft has neutral dynamic stability.

An aircraft must have positive static stability. The dynamic stability can be positive to be acceptable. The dynamic stability cannot be negative as oscillations over time are divergent or neutral as . That can cause the pilot to lose control or if coupled with accelerations on other axis can destroy the aircraft.

That coupling with yaw-wise pitch up acceleration is what can cause the Spitfire to break apart in the spin.

Control terms:

Stick fixed and stick free are two of the most abused terms in aviation when discussing stability and control. They are control terms and NOT references to stability.

Stick fixed is simply the pilot is in the cockpit, the controls are fixed so that they do not move, and the mechanical reversible linkage has mass as well as friction.

Stick free is the controls are free to move and the mechanical linkage has no mass or friction.


Now to the Spitfire early marks....the bold statements are explanations for the NACA language in the Conclusions found in "Measurements of the Flying Qualities of a Supermarine Spitfire Mk VA Airplane."

1. The short period longitudinal oscillation was satisfactorily dampened in all conditions of flight. The aircraft is positively statically stable and airworthy

2. In all flight conditions the stick fixed longitudinal stability is either neutral or unstable, and therefore failed to meet acceptable standards. The longitudinal dynamic stability is either neutral or negative. This means over time, the long period oscillations on the longitudinal axis stay the same or grow larger. It is unacceptable and is the stability issue. It is a dynamic stability issue. The requirement for a stable stick force gradient was met in all conditions of flight except for the condition with flaps down, power on. This describes how the stick forces change as we move away from the trim speed. The Spitfire's stick forces remained on a stable gradient except when the flaps were down and power on. In this condition, the stick forces would change noticeably as we moved farther from trim speed.

3. The stick force gradient in maneuvers was 5.0 pounds per G. The requirement for a force gradient of less than 6lbs per G was therefore satisfied. Some pilots in the NACA felt it was too light but that is opinion. Measurements reveal it is within standards.

4. The stick motion required to stall in maneuvers was 3/4 inch. This value is much less than the 4 inch stick travel recommended for satisfactory flying qualities. The Spitfire's elevator required a "two finger" touch. 3/4 of an inch travel to run the gamut of your useable Angle of Attack is not much at all. This is why we see the Operating Notes advising the pilot to brace his elbows on the cockpit sides to steady his hand when maneuvering. Combined with light stick forces, neutral or negative dynamic stability would make the Spitfire squirrely in any kind of chop or gust conditions. The control characteristics aggravate the stability characteristics. Only having 3/4 of an inch stick travel to work with means the pilot will have trouble in any unexpected or violent maneuver being precise. It makes the aircraft more vulnerable to such things as Pilot Induced Oscillations.

http://en.wikipedia.org/wiki/Pilot-induced_oscillation

The rest of the conclusions are normal with the exception of trim characteristics. Here the longitudinal characteristics shine and the aircraft required little trim input from changes in power or configuration.

Ok, so when is all this unacceptable and badness mean in practical terms?

Three common conditions the Longitudinal stability is dangerous are:

1. Steep turns with the gun ports open...
Stall is violent in the condition and without immediate application of the correct control input will result in a spin. We have already covered why spins can destroy the airframe in the Spitfire.

2. High speed maneuvering - Recovery from a dive or hard maneuvering above Va. Any airplane will break and even destroy itself at full control deflections above Va. It is easier to inadvertently make a full elevator control deflection in the Spitfire above Va.

3. Spins...already covered..see Operating Notes and why deliberate spins are prohibited. The Spitfire recovers from a spin very quickly relative to many WWII aircraft if accidently spun. IIRC, it loses about 2000 feet between input and recovery so after pull out you only need the recommended 4000 to 6000 feet altitude. Many WWII aircraft lost anywhere from 4000 to 6000 feet just in recovery resulting in spins being prohibited below 10,000 feet.

[Crumpp]

Don't confuse accidentally spinning with intentional spinning.

Corkscrewing is not spinning.

Re the comment someone made about arguing with non engineers, I served in the RN as an airframes and engines artificer in the early 70's if that is of interest.


He is not refering to "engineers" who would be called "Repairman" or "Airframe and Powerplant" qualified. He is referring to the ones all the Historians, Political Science Majors, and Lawyers started out as but could not do the math.

[Glider]

Don't confuse accidentally spinning with intentional spinning.

Corkscrewing is not spinning.

Crumpp I was the one in the aircraft and can promise you that they were intentional spins. You don't train in an accidental spin.

I don't understand why you find difficult to grasp that pilots have to be trained to get out of a spin in a plane they fly in combat. To do that training you need to go into a spin and be default its an intentional spin.
You need this training in case you find yourself in an unintentional or accidental spin.

PS I know a corkscrew isn't a spin and I know its more violent than a spin.

In Gliders it isn't uncommon to spin if you want to lose height quickly, as they are very slippery and you can easily exceed the VNE in a dive.

[winny]

All very interesting.. But, what has a MkV Spitfire got to do with MkI/II?

And more importantly what has any of this got to do with CloD?
(I'm not being sarcastic here)

Is this level of detail contained in CloD? If we're dealing with stick forces?
Last time I checked Spitfires didn't come equipped with a Microsoft standard keyboard. I checked, it's not in the pilots notes...

Edit: I can if you wish find you some examples where BoB pilot's exceeded recommended limits etc.. Including intentional spins, proper ones. They did this mainly because someone was trying to kill them at the time.

[Crumpp]

All very interesting.. But, what has a MkV Spitfire got to do with MkI/II?


Until it was addressed with bob-weights, it existed in all early mark Spitfires.

Read the Operating Notes....

[Crumpp]

Crumpp I was the one in the aircraft and can promise you that they were intentional spins. You don't train in an accidental spin.


I would have to call you on this and ask for proof the aircaft were placarded. I have done plenty of spin training and it is always performed in an aircraft approved for spining.

[Glider]

I would have to call you on this and ask for proof the aircaft were placarded. I have done plenty of spin training and it is always performed in an aircraft approved for spining.

Check the pilots notes.

[winny]

Until it was addressed with bob-weights, it existed in all early mark Spitfires.

Read the Operating Notes....

Ok, what has it got to do with CloD?

[Crumpp]

I don't understand why you find difficult to grasp that pilots have to be trained to get out of a spin in a plane they fly in combat.

Glider,

They were trained but they did not spin Spitfires intentionally. The RAF Training Manual clearly states you will not intentionally spin an aircraft that is placarded against spinning.

The FAA, in following convention estabilished by British law says:

Spin training must be accomplished in an aircraft that is approved for spins. Before practicing intentional spins, the AFM or POH should be consulted for the proper entry and recovery techniques.

The pilot of an airplane placarded against intentional spins should assume that the airplane may become uncontrollable in a spin.

http://nobleairventures.com/StallandSpinAwareness.pdf

[Gabelschwanz Teufel]

Jesus wept...:roll:

[winny]

Glider,

They were trained but they did not spin Spitfires intentionally. The RAF Training Manual clearly states you will not intentionally spin an aircraft that is placarded against spinning.

The FAA, in following convention estabilished by British law says:





http://nobleairventures.com/StallandSpinAwareness.pdf

Weren't the FAA set up in 1958?

[Crumpp]

Weren't the FAA set up in 1958?


You guys would have a better understanding of what you are reading in these documents and manuals if you learned a little about Aviation Law and Legislation. It would really help you to understand how to fit them into context. Testing standards and certification of airframes, engines, fuels, pilots manuals are all part of the airworthiness of the design. They were all done on the same principles with very little variation by the convention signers.

The FAA was created by merging the two aviation authorities in the United States under one roof. Before the FAA, aircraft were administered by both the Department of Commerce and the Department of Transportation.

It relocated everyone under one roof like the Air Ministry but the rules established by convention still applied and remained in place!

The FAA is based on British Aviation Law. The same law the Air Ministry still followed in 1940.

At the Paris Peace Conference in 1919 the Aeronautical Commission (a legal subcommittee) drafted the first set of international aviation laws, The International Air Navigation Convention. The laws were patterned after British aviation laws and dealt with both concrete and abstract principles.

The United Kingdom pioneered Aviation Law and was a major player in helping to establish an international standard for all convention signers.

Great Britain, in 1909, was the first nation to address the possibility of government control of aviation manufacturing and aviation transportation. British laws became a reality when the first successful cross-channel flight in 1909 jeopardized Britain’s national security. That year, under British encouragement, the first International Conference in Paris was held. During the conference a host of aviation problems, from the sovereignty of airspace to the spread of contagious diseases, were debated. While no laws were enacted, it was apparent that aviation law was soon to become a reality.

Then in 1917 Great Britain formed the Civil Aerial Transportation Committee to organize growing civil and commercial air traffic trade. The Committee suggested that the government regulate all forms of British aviation, both nationally and internationally. The creation of the committee was an important gesture; it signaled Britain’s intent to transform its military strength from naval to air power, and instigate European aviation reform. The European community of nations was not far behind the British, for it was realized that aviation had become a force to be reckoned with in the final phase of World War I.

Even though the United States was a world power, its government had no impact on the code drafted by Aviation Mission; apparently the United States did not desire to be involved in any law-making other than its own.

http://specialcollections.wichita.edu/collections/ms/92-18/92-18-A.HTML

[Glider]

There we have our ongoing difference between the practical and experience vs theory.

Logic - how can you train someone to spin a combat aircraft without putting it in an intentional spin, plus experience - someone who has actually done it.
vs
Theory - the paper says you cannot do it therefore you didn't do it

Logic - if the fuel is installed at a station and we have pilots combat reports that says they used the fuel therefore a) the fuel was in use in those stations and squadrons and b) the aircraft had to be modified to use it
vs
Theory - I haven't got the right paperwork therefore it didn't happen

I havn't been able to find a T8 Pilots notes but the T7 was basically the same aircraft and the F6 was also exactly the same apart from the cockpit so I would expect them to have the same notes re spinning if that helps

[Kurfürst]

Just an observation, but the RAF never needed to develop a two seat Spit or Hurricane and trained many thousands of pilots to fly them.

That's just plain silly. Everybody needed two seat trainers, but it wasn't widely practiced in WW2, the need it was just began to be realized.

BTW: Supermarine Spitfire T9:

http://www.key.aero/central/images/news/2084.jpg

[Glider]

I will reword my previous posting:-

Just an observation, but during WW2 the RAF never needed to develop a two seat Spit or Hurricane and trained many thousands of pilots to fly them. But the Luftwaffe needed to develop two seat 109's with the inevitable distruption on the design and production teams, presumably because they needed to.

--------------------------------------------------------------------------------

[Kurfürst]

Still plain silly. You want to make the lack of a proper two seat trainer variant a good thing...

[bongodriver]

I've got to step in to defend Crumpp on something......partially, let's be fair, you can't just nonsense everything someone says just because you are arguing with them.

spin training absolutely is done on aircraft 'cleared' for spinning, if an aircraft is not cleared for spinning it has been deemed so beause of some form of complexity in its recovery behaviour 'OR' it never went through spin trials for certification, as for the issue of spinning a hunter I hold my hands up and say 'I just can't comment', my belief is that the aircraft cannot be willfuly spun if it is placarded not to because those placards form a legal base that would be crazy to ignore, imagine the investigators sifting through a wreckage of a spin accident and finding the placard, insurers will just walk away and lawyers will be rubbing their hands together.

RAF pilots would have received spin training in the Tiger Moth, because spin recovery 'technique' is universal and it is a skill that can be applied to all aircraft.

But I am quite frankly amazed crumpp claims the Spitfire would 'break up' in a spin, if he really knows anything about this subject he would know a spin is 'not' a high stress manouvre, if an aircraft is going to break up in a spin it would break up in normal flight too, more than likely the Spitfire was found to have an undesireably long recovery time due to it's small rudder and/or it's neutral static stability, there really aren't many aircraft that can't actually be spun and recovered but they all have different behaviour, the clearance to spin would be granted on the basis of wether an 'average' pilot using standard recovery techniques can recover in a specified amount of time/altitude, if an aircraft can't do this it's just easier to not clear it than bring in a specialised spin training course for the aircraft.

some of my aerobatic experience is on the Military variant of the Slingsby T-67 Firefly both 160hp and 260hp(USAF T-3) variant, this aircraft was banned from spinning by the USAF and ultimately withdrawn from service after the loss of some aircraft and sadly some students and instructors too, the USAF said it was 'dangerous' and didn't recover........but I'm still alive despite having spun it countless times, the issue with the firefly is the spin recovery 'must' be done by the book but it is still just the standard technique and it will recover very predictably, get it wrong or be complacent and you beter hope you remembered the parachute if you didn't start with enough altitude, it is still cleared for spinning by the british military and civil aviation authority.

[Glider]

Still plain silly. You want to make the lack of a proper two seat trainer variant a good thing...

Just an observation, there were no ww2 spitfire two seat trainers and thousands of pilots were trained to fly them, and the Luftwaffe did have two seat 109's and 190's for a reason.

Personally I have often wondered why the RAF didn't have trainer versions. The jump from a Harvard to a Spit/Typhoon/whatever is a serious leap and a two seat version for at least the first say three - five flights makes sense, just to make sure they remember all the drills and can handle the extra speed.

[NZtyphoon]

I will reword my previous posting:-

Just an observation, but during WW2 the RAF never needed to develop a two seat Spit or Hurricane and trained many thousands of pilots to fly them. But the Luftwaffe needed to develop two seat 109's with the inevitable distruption on the design and production teams, presumably because they needed to.

--------------------------------------------------------------------------------
Going way o/t here...

I'd think the main reason that the British didn't develop trainer versions of the Spitfire and Hurricane was because they had powerful advanced trainers such as the Harvard and Miles Master (http://www.flightglobal.com/pdfarchive/view/1939/1939-1- - 0265.html), which replicated most of the flight characteristics of fighters, albeit they didn't have the same high speed capabilities. One pilot who describes transitioning from the Harvard to a Spitfire in 1940 was Geoffrey Wellum; he didn't seem to have a huge amount of difficulty. The Harvard could bite pilots who got careless, but I don't know much about the Master, although it looked likely to be a good intro to the Hurricane. Interesting that it was equipped with a Rotol C/S prop. (Maybe another aircraft type for the developers???)

The Germans used aircraft such as the Ar 96. There really wasn't much call for a two-seat 109 until later in the war, otherwise the Jagdfliegervorschulen, the basic fighter training units, used various version of the 109 and captured D.520s etc; the pilots then transitioned to Ergänzungsgruppe which were similar to OTUs but attached to Jagdgeschwader

[Crumpp]

That is not what I said. Pilots in the 1930's and 1940's were given only very elementary training in aerodynamics. It was considered unnecessary and demanded too much mathematical knowledge. That is straight out of the RAF Flying Manual.

They are not the experts in aerodynamics that we see today in the cockpit.

Glider,

The Spitfire Mk I had unacceptable longitudinal instability. The RAE knew it and corrected it in later marks.

It is a fact.

3/4 inch stick movement to run the usable Angle of Attack range at weak or neutral stability with light stick forces is going to make for a squirrely airplane.

;)

Read the report, the stick force gradient on the longitudinal axis was considered too light by most of the pilots.

By careful flying, maximum performance turns could be made.

The yaw wise stability experiences a pitch up with large deflections that coupled with the longitudinal instability caused the plane to experience rapid accelerations. That means it is very difficult for the pilot to precisely control the elevator. That asymetrical loading is what can cause the airframe to break apart in spin recovery.


That asymetrical loading is what can cause the airframe to break apart in spin recovery.

Completely different condition of flight from in a spin.

Bongodriver says:
But I am quite frankly amazed crumpp claims the Spitfire would 'break up' in a spin,


As for the T-67, it depends on the type. Some are certified to spin and some are not. There is no blanket prohibition in either country.

Either way, the United States and Great Britain follow convention. It is impossible for an aircraft to be disapproved of something in the United States and approved of it by another convention signer without violating the convention.

Read the Type Certificate issued by the United Kingdon Civil Aviation Authority. It quotes FAR/JAR and CFR's. That stands for Federal Aviation Regulation/Joint Aviation Regulation and Combined Federal Regulations.

In otherwords, all convention signers are on the same standard for airworthiness. In aviation, what is British Law, is United States Law as well as everyone else who signed the convention. We all do things basically the same. It has been that way since 1919.

http://www.caa.co.uk/docs/1419/srg_acp_ba17-08.pdf

[Crumpp]

The jump from a Harvard to a Spit/Typhoon/whatever is a serious leap

Not really. The Harvard is a beast to fly and if you master it, the Fighters are "easy to fly" by very subjective comparison. The Harvard's mission is prepare pilots to fly these fighters. It does that very well and will bite a student hard if he does not follow the basic rules. That is the airplanes purpose in life, to teach pilots to become pilots and not break those rules. It is not to be gentle and docile so that a pilot thinks he can get away with something. A good trainer should bite but not kill you. It is hard to make the next lesson if you are dead.

The Spitfire is "easy to fly" compared to the Harvard/Texan.

The T-6 Texan is over 70 years old and is still a legend in the aviation world. It is referred to as the Pilot Maker because of all of the pilots it taught during WWII and continues to teach today the fine art of flying big engine tail wheel airplanes. The Texan is considered the basic trainer for those who want to transition into a Mustang or other high performance warbirds. However, with over 8,500 hours in the Mustang, Lee Lauderback will be the first to say jokingly, “the P-51 Mustang is a great trainer for the T-6 Texan!” The Mustang is easier to handle in several areas of operation, especially ground handling and crosswind situations. The Texan has been and still is a demanding teacher, not willing to compromise on basic rules and will slap you hard with the proverbial ruler if you break them.

http://www.stallion51.com/news-press-releases.php?i=9

The airplane is harder to fly than a P-51. I’ve flown both now, and I never would have never thought that was true. Understand, it’s nothing a competent pilot can’t handle, but the aircraft is the consummate trainer; she demands constant attention to be flown well – just like the T-38 did.


http://www.warbirdalley.com/articles/T6-sf.htm

[Al Schlageter]

How does the civilian aviation relate military aviation?

[fruitbat]

How does the civilian aviation relate military aviation?

and in wartime as well.

anyone who's had any contact with the military will know for sure that peace time rules and war time rules are not the same. Safety levels are somewhat different.

:rolleyes:

[Crumpp]

and in wartime as well.


The only exemption from the convention is the navigation rules for state aircraft in wartime.

In short, it says you don't have to file a flight plan or notify customs if you are at war with a convention signing nation to overfly their airspace with state aircraft.

:grin:

I don't think airplanes were an issue the last time the United States and England went to war.

[fruitbat]

I don't think airplanes were an issue the last time the United States and England went to war.

lost me on that one, but i am willing to concede that point.:-)

[Crumpp]

Safety levels are somewhat different.


The rules for airworthiness remain the same.

[fruitbat]

The rules for airworthiness remain the same.

i don't disagree that the rules are the same.

i just don't believe they are adhered to in the same way.

[Crumpp]

IIRC, the War of 1812 was the last time England and the United States declared war on each other, Fruitbat.

Airplanes were not an issue in that war.

[fruitbat]

IIRC, the War of 1812 was the last time England and the United States declared war on each other, Fruitbat.

Airplanes were not an issue in that war.

i'm aware of that, i just don't understand what relevance that has to do with the price of fish.

[bongodriver]

That asymetrical loading is what can cause the airframe to break apart in spin recovery.

Completely different condition of flight from in a spin.



recovery....reshmovery and where the hell did that quote come from anyway, Spitfires did not break up in spin recovery but some did break up recovering from dives because granted the Spit was built a little delicately for it's sensitivity in pitch.

what exactly was your link to the CAA supposed to show me?

[Crumpp]

i just don't believe they are adhered to in the same way.


Of course they were adhered too. Dead is dead. It does not matter if the enemy kills you or the airplane.

Not only that, if you suddenly had everyone in your force going out breaking airplanes, what are you going to fight the enemy with while all your airplanes are getting fixed? Idiots making airplane noises on the ground because they think they know more than the designers?

You guys read a few anecdotes from a very small group who gambled and won. You don't get the wartime feedback from the 85% who lost because they are not around to tell you, "Hey, that did not work like I thought it would."


Those rules and operating limits define the airworthiness of the aircraft. Within those limits, you are flying an airplane, outside of them you are no longer in an airplane but a trainwreck headed for disaster.

[bongodriver]

I like fish....

[Crumpp]

where the hell did that quote come from anyway


Quite a few pages back when I first mentioned it.

what exactly was your link to the CAA supposed to show me?

All convention signers are on the same rules for airworthiness, then and now.

[bongodriver]

Quite a few pages back when I first mentioned it.



and the origin of that original statement?


All convention signers are on the same rules for airworthiness, then and now.


No...it seems to just show some FAR's for certification in the US, much like American light aircraft certificates show UK/European requirements likewise, really not an indication of similarity but more of differences in standards.

[Crumpp]

Spitfires did not break up in spin recovery but some did break up recovering from dives

And what are doing in spin recovery?

Asymmetrical loading....

With a significant yaw-wise pitch up.....in the Spitfire

An airplane with a neutral or negative dynamically stable airplane with 3/4 inch stick travel at 5 lbs per G.....

SPINS. Since a stabilized spin is not essentially different from a stall in any element other than rotation, the same load factor considerations apply as those which apply to stall recovery. Since spin recoveries usually are effected with the nose much lower than is common in stall recoveries, higher airspeeds and consequently higher load factors are to be expected. The load factor in a proper spin recovery will usually be found to be about 2.5 G's.

http://avstop.com/ac/flighttrainghandbook/loadfactorsandflightmaneuvers.html

Asymmetrical loading is the mechanism. It significantly degrades the airframe load factor limits when you start adding multiple axis accelerations. You are approaching the airframe limits on normal recovery. Stomp the rudder too much or add in some gusting and you can break the airplane.

Read the pilot notes as it will tell you how to operate the aircraft so that is stays within its airworthy limitations.

[VO101_Tom]

Just an observation, but the RAF never needed to develop a two seat Spit or Hurricane and trained many thousands of pilots to fly them. But the Luftwaffe needed to develop two seat 109's with the inevitable distruption on the design and production teams, presumably because they needed to.

Hi. Only about ~100 aircraft were modified to G-12 standards (it was conversion only, G-2, G-3, G-4, G-6 types). I think these aircrafts used more for combat training, not for the basic exercises, circuits. For example, the RHAF did not use the G-12 type (Hungary also produced 109 G-6, G-8, G-14 types). If this was really necessary, then they would have converted.

[VO101_Tom]

You guys read a few anecdotes from a very small group who gambled and won. You don't get the wartime feedback from the 85% who lost because they are not around to tell you, "Hey, that did not work like I thought it would."

Yep, this is why i hate the war stories as technical or performance "evidence". Interesting stories, but nothing more :) Best example is the maneuverability. Both sides said they're all turned better than the other side. Ok, but what were the circumstances of the situation? That is very little read, and one of the most important thing in the pre-battle situation. :rolleyes:

[bongodriver]

And what are doing in spin recovery?



Not pulling out of a Vne dive thats for sure, if you think spitfires all broke up in post spin dives then every one of them would have crashed.

absolutely nothing you have written here applies specifically to the Spit, you cling on to the obscure certification entry about 'no intentional spins' which if you know anything you will accept it can be down to factors I described earlier.

A load factor of 2.5 G's......wow massive, the Spit airframe could stand 10 G's, serously find a official source for claims spitfires 'broke up' post spin.

[Crumpp]

No...it seems to just show some FAR's for certification in the US, much like American light aircraft certificates show UK/European requirements


It is a fact all convention signers follow the same rules, principles, and procedure for aircraft airworthiness.

That is why we all use the same regulations and quote them.

Here is a quick highlight of the worlds aviation conventions. The only thing state and military aircraft are exempt from is the navigation rules.

They still must abide by the convention airworthiness standards.

October 1919 , Paris : Convention Relating to the regulation of Air navigation

Sovereignity over Airspace.

Standard for airworthiness

Certificates of competency for crews

Definition of aircraft


http://www.fabioaddeo.com/2011/02/26/relevant-international-aviation-conventions-and-agreements/

[Crumpp]

A load factor of 2.5 G's......wow massive, the Spit airframe could stand 10 G's

10G's asymmetrically? You think?

[bongodriver]

10G's asymmetrically? You think?

Yup

[bongodriver]

I can't be bothered to wait for you to browse wiki or scour the internet for other obscure stuff....

You don't really seem to even know what asymetrical g load is, remember that thread about roll rate at high speed? well......diving a spit to 400 mph and applying max stick roll force.....thats aymetrical loading my friend.....I don't seem to recall wings peeling off in those tests, if it could take those asymetrical loads then there is no way in hell it will break up in spin recovery no matter how sensitve the elevator is or how staticaly neutral it is.

[Crumpp]

Yup

Well you are dead wrong bongodriver.

First of all the 10G's is to the failure point. It is 10G's on a single axis and assumes a perfect airframe. That 10 G's represents a 100% chance the airframe will be permanently deformed and we run a good chance of having the airplane turn to confetti. This is why the POH warns the airframe will certainly fail if this limit is much exceeded.

Our we run the risk of damage threshold is lower than that at 6G's.

That too, is 6G's on one axis with a perfect airframe.

Just like your car suspension wears, so does an airframe. It is not the spars or major structures that fail first, it is the ribs, skin, and supporting structures. An airframe flexes in flight, even at 1G. Gusting, accelerations, and turbulence all add wear to the airframe and lower those limits. It is just like your cars suspension wears from driving all the bumps it has to absorb.

Asymmetrical loading significantly reduces the airframe limitations. The average is about 20%. So our 6G damage limit is now 4G's with an asymmetrical loading.

Our normal spin recovery AVERAGES about 2.5G's so on AVERAGE we could spin a Spitfire safely as long as the pilot correctly and precisely applied the control inputs.

But wait, he has a very hard time being precise with control inputs especially when he is subjected to the same accelerations. Oh yeah, when he steps on the rudder, it also produces even more acceleration on the longitudinal axis adding to his difficulty.

He has 1.5G's to play with before he can damage the airframe. The airframe is now weaker and will fail at a lower point.

Now let's add in the vertical load from gusting...Oh crap we are at the threshold in light turbulence!! The POH also warns of this! Coincidence?

You botch the recovery, damage the airframe, and it re-enters the spin, as the POH once again warns the pilot about. Why can you re-enter a spin so quickly and must build up your speed? In any airplane if you don't have enough speed you can re-enter the spin. In the Spitfire is especially important. The pilot needs that speed to have better precision on the controls. He only has 3/4 of an inch of stick travel to use up all of this angle of attack at 5lbs per G. The heavier he can make that stick, the more precise he can be in controlling the acelerations. If he re-enters the spin with a damaged airframe his chances are even less of coming home.

Now do you see why spins are prohibited in the Spitfire? The average time you spin the airplane, it will come out "just fine". The margins between "just fine" and disaster are tighter than you think.

If the pilot could precisely control the accelerations and did not have the yaw-wise pitch up, it would be a much safer aircraft to spin.

[Crumpp]

diving a spit to 400 mph and applying max stick roll force

What is a max stick force roll at that speed? :grin: Don't confuse stick forces and control surface deflection.

You realize that 400 mph is well over Va so full control deflection will exceed the airframe limits on just one axis......

Think about what you are saying in this claim.

[robtek]

I think the point is, that in a spit, during a stall-recovery, it is extraordinarily easy to exceed the stick movement necessary to overload the airframe.

Much more easy as in the comparable planes, which needed more stick-travel and force.

[Crumpp]

Yep, this is why i hate the war stories as technical or performance "evidence". Interesting stories, but nothing more Best example is the maneuverability. Both sides said they're all turned better than the other side. Ok, but what were the circumstances of the situation? That is very little read, and one of the most important thing in the pre-battle situation.

Exactly. Conditions mean everything and without them, it is useless to draw general conclusions.

I think the point is, that in a spit, during a stall-recovery, it is extraordinarily easy to exceed the stick movement necessary to overload the airframe.

Much more easy as in the comparable planes, which needed more stick-travel and force.

Right, the majority of the warnings in the Spitfire Operating Notes are in relation to the unacceptable longitudinal dynamic stability.

How would this effect your game?

It compresses the turn performance differences especially for large angle of bank turns. The Spitfire is harder to control precisely in that condition and the stall is extremely rough and will result in a spin.

It is like that punk skateboarder kid. He can do some really cool tricks but when he makes a mistake, it is a whooper.

The Bf-109 on the otherhand has those LE slats on a flat top polar. It is like a a racing bicycle with training wheels.

Read the stall behaviors:

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

It has yaw-wise stability issues but stall behavior is typical for an aircraft equipped with LE slats. It simply stops flying and begins to descend. No violent behaviors and no tendency to spin at all. LE slats are a typical anti-spin device if you want to spin-proof an airplane. They really are like training wheels.

Both airplanes have excellent stall warning with adequet control and can be flown in a partially stalled condition. The Bf-109's stall is a non-event and the Spitfires is a the begining of wild ride.

It is no wonder you read anecdotes of Bf-109 pilots who swore the airplane would outturn the Spitfire.

[JtD]

In case some folks can't be bothered to read the NACA tests, I'll post a part to put the "unacceptable longitudinal dynamic stability" into proper perspective.
STALLING CHARACTERISTICS IN MANOEUVRES

The stall warning possessed by the Spitfire was especially beneficial in allowing the Pilot to reach maximum lift coefficients 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....
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. ... 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.

CONCLUSIONS

The Supermarine Spitfire airplane possessed stalling chareteristics essentially in compliance with the requirements for satisfactory stalling characteristics given in reference 1. These characteristics may be summarised as follows:
1. Warning of the comlete 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 airplanes.
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 possessed 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.Eventually, the longitudinal stability was not unacceptable. The Spitfire was accepted into service with about 20+ military air forces, was built in 20000 examples, and is still being flown today. Unacceptable longitudinal stability would mean acceptance into 0 air forces, and a production of a handful of examples, and none would be cleared for flying today.
However, it is true that the Spitfire did not meet all the requirements set by NACA in "Requirements for Satisfactory Flying Qualities of Airplanes". Other planes that failed to meet all the requirements were for instance the P-39 or the XP-51.

[fruitbat]

Interesting stuff JtD.

you sure thats the same NACA report, lol.

[VO101_Tom]

Eventually, the longitudinal stability was not unacceptable. The Spitfire was accepted into service with about 20+ military air forces, was built in 20000 examples, and is still being flown today. Unacceptable longitudinal stability would mean acceptance into 0 air forces, and a production of a handful of examples, and none would be cleared for flying today...

This instability was fixed in the Spit V.
Several Spit pilots complained that the Spit V felt sluggish. Of course the flight characteristics was not worse, just more stick movement and force was needed. iirc Crumpp showed a couple of documents about this.

[lane]

In case some folks can't be bothered to read the NACA tests, I'll post a part to put the "unacceptable longitudinal dynamic stability" into proper perspective.

STALLING CHARACTERISTICS IN MANOEUVRES

The stall warning possessed by the Spitfire was especially beneficial in allowing the Pilot to reach maximum lift coefficients 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....
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. ... 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.

CONCLUSIONS

The Supermarine Spitfire airplane possessed stalling chareteristics essentially in compliance with the requirements for satisfactory stalling characteristics given in reference 1. These characteristics may be summarised as follows:
1. Warning of the comlete 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 airplanes.
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 possessed 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.

Eventually, the longitudinal stability was not unacceptable. The Spitfire was accepted into service with about 20+ military air forces, was built in 20000 examples, and is still being flown today. Unacceptable longitudinal stability would mean acceptance into 0 air forces, and a production of a handful of examples, and none would be cleared for flying today.
However, it is true that the Spitfire did not meet all the requirements set by NACA in "Requirements for Satisfactory Flying Qualities of Airplanes". Other planes that failed to meet all the requirements were for instance the P-39 or the XP-51.

Hi JtD,

Thanks for the perspective. You might find the following RAE comments of the NACA test to be of interest, in case you havn't already seen them.

http://www.spitfireperformance.com/rae1106_Page_1.jpg

http://www.spitfireperformance.com/rae1106_Page_2.jpg

[NZtyphoon]

recovery....reshmovery and where the hell did that quote come from anyway, Spitfires did not break up in spin recovery but some did break up recovering from dives because granted the Spit was built a little delicately for it's sensitivity in pitch.

According to Alex Henshaw about 25 Spitfires were known to have broken up in flight; the majority of those were Spitfire Vs which had been badly loaded at a squadron level pushing their cg too far back, and breaking up during dive recovery. As Jeffrey Quill explained, this helped lead to the addition of bob weights in the tail, then the larger mass balances on the elevators. Some of these are documented in Morgan and Shacklady.

Apart from that I'd like to see Crumpp provide some documentary evidence that Spitfires regularly broke up in flight during spin recovery.


OT slightly; NACA's report on the P-47D (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090022749_2009022139.pdf) which had some problems of its own; one of the few fighters to meet NACA standards was the P-51H (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050028754_2005019354.pdf).

[41Sqn_Stormcrow]

Putting weights to the tail for what purpose?

[NZtyphoon]

Putting weights to the tail for what purpose?

Better to say inertia weights (or bob weights) were added to the control circuits of the elevators - I'm not sure if later Spitfires with the bigger elevator mass balances continued to use them.

[NZtyphoon]

The Bf-109's stall is a non-event and the Spitfires is a the begining of wild ride.


That's not what the NACA report says:

"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. "

[winny]

Putting weights to the tail for what purpose?

The weight was built into the elevator circuit, in simple terms it was used to counteract the effect of light elevators and high g forces. The weight was effected by the g forces so if there was a high load the elevators needed more force to move them.

It was fitted to spitfires to solve the problem of spitfires breaking up when pulling out of a high speed dive, which was a known, and big problem at the time.

Because the elevators were so light pilots were pulling out of the dives and over stressing the airframe. There were loads of examples of this happening.

So basically the more g that was pulled the harder the elevators became to move. As far as I know it had nothing to do with any instability.

[41Sqn_Stormcrow]

Thanks, winny. That is now pretty clear to me. Wouldn't have made sense to put weights to the tail in order to improve stability. It would just worsen it.

[winny]

Thanks, winny. That is now pretty clear to me. Wouldn't have made sense to put weights to the tail in order to improve stability. It would just worsen it.

Yeah, it was only a small weight, 3.5 or 6.5 lb, depending on which wing was fitted, the lighter was for browning wing heavier for cannon wing, added to the actual control cables. It was about 3 quarters of the way down the fuselage.

[IvanK]

"The stall warning possessed by the Spitfire was especially beneficial in allowing the Pilot to reach maximum lift coefficients 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...."

A nice feature in a fighter !

[Al Schlageter]

If the Spitfire was such a terrible a/c, at least according to Eugene, why did the USAAF accept them for service?

[Crumpp]

You might find the following RAE comments of the NACA test to be of interest, in case you havn't already seen them.


You might find the following information useful....

Gilruth's developed the concept of stick force per G, control movement measurement, and pretty much wrote the standards of measurement for stability and control as used by the NACA.

Only two nations in the world had stability and control standards during World War II, the United States and Germany.

The NACA's measurement and classification system developed by Gilruth was not published until 1941 and was classified. It was not released to Allied Nations until 1943.

Even Gates, a very prominent RAE researcher who pioneered stability and control standards for the RAE was not privy to them during his 1942 "dash around America" tour of the United States research facilities. Gates was the one who defined Aerodynamic Center, stability margin, and maneuver points during his lifetime. He had a passion for stability and control and published some 130 papers before his death. Before him, the neutral point was termed the metacentric ratio.

Unfortunately, nobody at the RAE paid much attention to Gates and it was not until post war that the United Kingdom adopted any defined standards of what is acceptable and what is not in terms of stability and control. When they did, it was a mirror of Gilruths work at the NACA.

So, by what standard is the RAE refuting the NACA? The answer is really none. The RAE had no defined standards of stability and control except subjective opinion.

[NZtyphoon]

You might find the following information useful....

Gilruth's developed the concept of stick force per G, control movement measurement, and pretty much wrote the standards of measurement for stability and control as used by the NACA.

Only two nations in the world had stability and control standards during World War II, the United States and Germany.

The NACA's measurement and classification system developed by Gilruth was not published until 1941 and was classified. It was not released to Allied Nations until 1943.

Even Gates, a very prominent RAE researcher who pioneered stability and control standards for the RAE was not privy to them during his 1942 "dash around America" tour of the United States research facilities. Gates was the one who defined Aerodynamic Center, stability margin, and maneuver points during his lifetime. He had a passion for stability and control and published some 130 papers before his death. Before him, the neutral point was termed the metacentric ratio.

Unfortunately, nobody at the RAE paid much attention to Gates and it was not until post war that the United Kingdom adopted any defined standards of what is acceptable and what is not in terms of stability and control. When they did, it was a mirror of Gilruths work at the NACA.

So, by what standard is the RAE refuting the NACA? The answer is really none. The RAE had no defined standards of stability and control except subjective opinion.

Still doesn't prove the Spitfire was a dangerous aircraft to fly; apart from that I'd like to see Crumpp provide some documentary evidence that Spitfires regularly broke up in flight during spin recovery.

[Crumpp]

Stick fixed is just one version of static stability, you're keeping the elevator angle constant over a speed range and check how the aircraft responds. In case of the Spitfire, no trim change occurred, so the plane would keep the same AoA over the entire speed range at the same elevator deflection. That's neutral stability.

First of all, stick fixed is not a version of static stability. Stick fixed is a control term and just means you are using the maneuver point that the pilot, controls, and the mechanical linkage has friction and mass. Static stability is the aircrafts initial reaction to displacement.

It has absolutely nothing to do with keeping the elevator constant. It is about the oscillations.

The other version NACA was looking at is stick force stability, if you want to call it that, where you are keeping the stick force constant through the speed range and check how the aircraft responds. In case of the Spitfire, stick force increased with the speed, which in turn leads to smaller elevator deflections which means some sort of positive stability.

They are looking for a stable gradiant. They are not keeping the force constant, they are looking for a slope as it moves away from trim speed. They are looking for a smooth increase in stick forces. The stick forces will change as they are based on velocity.

The Spitfire was dynamically stable.

The longitudinal dynamic stability (Long Period Oscillations) was neutral or negative as recorded by the NACA.
All for longitudinal stability.

;)

[JtD]

I didn't say any of the parts in bold, which you claim to be quoting from me.

[Crumpp]

I'd like to see Crumpp provide some documentary evidence that Spitfires regularly broke up in flight during spin recovery

First of all, let's get what I said correct. Feel free to point out where I make any reference to "regularly". That is your own pointy tin foil hat theory.

I said it could happen to the Spitfire. The Operating Notes clearly warn the pilot of the hazardous longitudinal stability characteristics.


http://img546.imageshack.us/img546/8175/spinairframedamage.jpg (http://imageshack.us/photo/my-images/546/spinairframedamage.jpg/)

http://img209.imageshack.us/img209/9334/spinairframedamage2.jpg (http://imageshack.us/photo/my-images/209/spinairframedamage2.jpg/)

[Crumpp]

I didn't say any of the parts in bold, which you claim to be quoting from me.


Right, I did the bold.

[WTE_Galway]

Quote from page 46 of a book by Morgan & Shacklady taken from this discussion:

http://forum.keypublishing.com/showthread.php?t=75816


The Air Ministry was not completely satisfied with the spin recovery of the Spitfire, and at a meeting on 17 January 1938, chaired by Air Cdr. Verney, Supermarine persuaded those in attendance that no modifications be made to production aircraft apart from the addition of an anti-spin parachute. For the Air Ministry Verney said that based upon model tests at Farnborough production aircraft could not be passed for spinning even with a tail parachute. Supermarine then pointed out that Jeffrey Quill had made sixteen successful spins of eight turns in the prototype. After more discussion the DTD agreed to accept the Supermarine proposal and that the first 20 production models should be fitted with the tail parachute and undergo further spinning trials. He, DTD, would be satisfied with recovery at 15,000 ft. When the first production Mk 1 Spitfire, K9787, was completed at the beginning of May 1938 an anti-spin parachute was duly fitted and the aircraft made its first flight from Eastleigh, piloted by Quill, on 14th of the same month .

[Crumpp]

In case some folks can't be bothered to read the NACA tests, I'll post a part to put the "unacceptable longitudinal dynamic stability" into proper perspective.
Eventually, the longitudinal stability was not unacceptable. The Spitfire was accepted into service with about 20+ military air forces, was built in 20000 examples, and is still being flown today. Unacceptable longitudinal stability would mean acceptance into 0 air forces, and a production of a handful of examples, and none would be cleared for flying today.
However, it is true that the Spitfire did not meet all the requirements set by NACA in "Requirements for Satisfactory Flying Qualities of Airplanes". Other planes that failed to meet all the requirements were for instance the P-39 or the XP-51.

The DC-3 also had longitudinal stability and control issues. The fact both the Spitfire and DC-3 had long careers is not an excuse to dismiss flying quality requirements. It is perfectly reasonable to assume that both of these fine airplanes would have been even better had they been more longitudinally stable under all flight conditions. Nobody has ever run definitive, statistically valid experiments on the value of good flying qualities in terms of accident reduction or military success. Common sense prevails and the entire world has since adopted stability and control standards to reduce accidents and increase air to air combat effectiveness.

http://img99.imageshack.us/img99/5849/gunportsopenstall.jpg (http://imageshack.us/photo/my-images/99/gunportsopenstall.jpg/)

[JtD]

Right, I did the bold.In that case, maybe you can next time avoid putting your words in my mouth by using proper formatting.

On the contents you added, I won't disagree with what you've said regarding the stick fixed and stick free stability testing, as it is absolutely right. You should, however, keep in mind that I try to explain things in a way that the concept can be understood by anyone interested, not just those with a suitable education or years of experience in the field. In my opinion, it is easier to understand "no trim change with constant elevator when speed changes" than to understand a description of an initial reaction to displacement.

However, I disagree withThe longitudinal dynamic stability (Long Period Oscillations) was neutral or negative as recorded by the NACA., because NACA says:
regarding dynamic stability:only the short-period oscillation is dealt with hereand regarding neutral or negative stability which they recorded:
static longitudinal stability.
To sum it up, NACA did not record long period oscillations for the Spitfire and the assessment of neutral or negative stability was made for static longitudinal stability.

[JtD]

Static stability is the aircrafts initial reaction to displacement.Your words. It is my understanding that this is exactly what NACA assessed and what they found to be neutral or unstable, only that they used a different method for testing.
NACA didn't have a problem with (short period) oscillations over time, the Spitfire would dampen any (short period) oscillations within a cycle or two.
NACA did have a problem with the fact that a bit of extra elevator at any speed, if not reduced, would change the AoA for good, meaning the plane would not come back to a more level attitude even when speed was reduced.

Looking at the easy to understand diagrams CaptainDoggles (http://forum.1cpublishing.eu/showthread.php?p=422030#post422030) linked, neutral static stability (http://www.centennialofflight.gov/essay/Theories_of_Flight/Stability/TH26G1.htm) appears to be exactly the problem NACA had with the Spitfire.

I see you deleted your last post, but it might still help if I leave this one up to make sure we all use the same terminology.

[Crumpp]

To sum it up, NACA did not record long period oscillations for the Spitfire and the assessment of neutral or negative stability was made for static longitudinal stability.

They are talking about static stability. Wow, shows you how much things have changed and how new stability and control was as a science during WWII.

Static instability is horrible in an airplane. Seriously...the FAA and ICAO would send you back to the drawing board if you were seeking certification.

http://www.law.cornell.edu/cfr/text/14/23.173

The longitudinal dynamic stability (Long Period Oscillations) was neutral or negative as recorded by the NACA.

Poor choice of words on my part. Long period Oscillation has specific meaning and it should read:

The longitudinal dynamic stability (Oscillations over time) was neutral or negative as recorded by the NACA.

[Crumpp]

Looking at the easy to understand diagrams CaptainDoggles linked, neutral static stability is exactly the problem NACA had with the Spitfire

Good diagrams and I have some others that will make it clearer for you all.

That diagram would make you think the elevator is held constant but it is not.

Keep in mind when that report was written there were not any standards of the day. It is not like testing processes or airworthiness. It was a very new science that was not covered in convention. In the 1980's there was even a "counter-revolution" in stability and control engineering.

[Kurfürst]

The weight was built into the elevator circuit, in simple terms it was used to counteract the effect of light elevators and high g forces. The weight was effected by the g forces so if there was a high load the elevators needed more force to move them.

It was fitted to spitfires to solve the problem of spitfires breaking up when pulling out of a high speed dive, which was a known, and big problem at the time.

Because the elevators were so light pilots were pulling out of the dives and over stressing the airframe. There were loads of examples of this happening.

So basically the more g that was pulled the harder the elevators became to move. As far as I know it had nothing to do with any instability.

As I understand and from RAE papers the installations of bob weights to the elevator and longitudal instability were related. To my best understanding - and do correct me if I am wrong - instability means that if you pull the controls (in whatever direction), the aircraft will not only change its roll/pitch/yaw to the extent of control movement, but also keep increasing it on its own, as if there were some kind of inertia/acceleration going on. This was noted on Spitfire Vs by the British.

By adding the bob weights and making the controls progressively harder to move for greater deflections, it made this increased acceleration problem more difficult to encounter.. It did not cure the instability itself, which was an inherent aerodynamic feature of the design, but made it harder for the pilot to make it happen.

[Kurfürst]

Quote from page 46 of a book by Morgan & Shacklady taken from this discussion:

http://forum.keypublishing.com/showthread.php?t=75816


The Air Ministry was not completely satisfied with the spin recovery of the Spitfire, and at a meeting on 17 January 1938, chaired by Air Cdr. Verney, Supermarine persuaded those in attendance that no modifications be made to production aircraft apart from the addition of an anti-spin parachute. For the Air Ministry Verney said that based upon model tests at Farnborough production aircraft could not be passed for spinning even with a tail parachute. Supermarine then pointed out that Jeffrey Quill had made sixteen successful spins of eight turns in the prototype. After more discussion the DTD agreed to accept the Supermarine proposal and that the first 20 production models should be fitted with the tail parachute and undergo further spinning trials. He, DTD, would be satisfied with recovery at 15,000 ft. When the first production Mk 1 Spitfire, K9787, was completed at the beginning of May 1938 an anti-spin parachute was duly fitted and the aircraft made its first flight from Eastleigh, piloted by Quill, on 14th of the same month .

Its interesting to note that the Bf 109 won the fighter tender against its Heinkel rival due to the excellent spinning and stability characteristics much desired by the Imperial Air Ministry. Green notes, that the Commission ultimately ruled in favour of the Bf 109 because of the Messerschmitt test pilot's demonstration of the 109's capabilities during a series of spins, dives, flick rolls and tight turns, throughout which the pilot was in complete control of the aircraft.

[bolox]

while not strictly related to the spit/109 debate, the fitting of elevator bob weights wasn't unique

http://p51h.home.comcast.net/~p51h/sig/TO/01-60-90.pdf

[Crumpp]

while not strictly related to the spit/109 debate, the fitting of elevator bob weights wasn't unique


Stability and Control issues were not unique in WWII era aircraft. The science was very young and there were no standards in place. Most if not all of them had some sort of issue.

It is the area WWII fighters show the most variation in performance and is just as important to their fighting abilities as the aerodynamics.

Germany was the only combatant to have standards when the war started. The United States had standards by the time it entered the war as well. Everyone else did not adopt any defined standards until after the war.

[NZtyphoon]

Putting the Pilot's Notes in context:
Also issued along with the Pilot's Notes were Pilot's Notes General A.P. 2095 which explain the limitations in the Pilot's Notes, and the reasons for them: (2nd ed, 1943):
Part I Note A Flying Limitations
1. Introductory.
(i.) The Pilot's Notes for each type of aircraft lay down certain flying limitations. They state, broadly speaking, the demands which it is safe to make of the airframe. Non-observance of the flying limitations may lead to increased maintenance work, or, in extreme cases, to structural failure in flight.

(ii.) In the fixing of these limitations there is of course a margin or factor of safety allowed. This factor for airframes varies according to the degree of confidence with which their strength and likely stresses can be predicted, but is commonly around 2. This means, for instance, that a wing which is intended to withstand 4g should not break until 8g is imposed, but there is increasing risk of strain and failure as g rises above 4.

(iii.) The flying limitations also involve questions of safe handling from the aspect of controllability.

(iv.) In combat and emergencies pilots must take risks with their aircraft, balancing one risk against another; limitations must be strictly observed in so far as there is no sufficient reason to exceed them.

First, the Pilot's Notes were deliberately conservative to ensure that most pilots flew well within the limitations of the airframe thus avoiding too many overstressed, high maintenance aircraft on operational service.

However, the RAF acknowledged that in combat it was up to the pilot to choose what risks needed to be taken; whatever legal status the pilot's notes had in peacetime that legality could be overruled under combat conditions because if pilots were expected to fly by the rules all the time they were easy meat. One reason so many pilots were shot during their first combat was because they hadn't yet learned how to fly their aircraft at or beyond the limits set down in the pilot's notes.

4. Manœuvres not Permitted
(i.) Intended spinning of operational aircraft is permitted only in the case of certain approved single-engine fighters within the limitations stated in the Pilot's Notes. (Normal Methods will usually effect recovery - A.P. 129 Ch. III)

(iv.) The reasons underlying these prohibitions are partly considerations of aircraft strength and partly of control. Aircraft are designed to fulfill their operational role and not to perform manœvres of no operational value...

Why spin when you don't have to?

RAF Pilot's Notes for operational single-engine fighters which permit spinning:
Spitfire VII and VIII, IX & XVI, XIV & XIX: Spinning permitted but with a height limit of 10,000 feet.
Typhoon: permitted, without bombs or drop tanks
Tempest V: not permitted until proper tests had been carried out
Mustang III: only when rear fuel tank was empty
Corsair: Spinning not permitted

[winny]

As I understand and from RAE papers the installations of bob weights to the elevator and longitudal instability were related. To my best understanding - and do correct me if I am wrong - instability means that if you pull the controls (in whatever direction), the aircraft will not only change its roll/pitch/yaw to the extent of control movement, but also keep increasing it on its own, as if there were some kind of inertia/acceleration going on. This was noted on Spitfire Vs by the British.

By adding the bob weights and making the controls progressively harder to move for greater deflections, it made this increased acceleration problem more difficult to encounter.. It did not cure the instability itself, which was an inherent aerodynamic feature of the design, but made it harder for the pilot to make it happen.

The simple answer is I don't know how the longitudal instability manifested it's self. As I understand it the BoB weight was specifically fitted because people were breaking spits when coming out of dives. As you say the bob weight didn't resolve the instability because it was an aerodynamic issue. So how could the pilot "make it happen"? Wasn't it happening all the time? I think it was Tim Viggors who recalled writing off a Mk1 spitfire simply by pulling out of a dive, the airframe was so badly bent it was un repairable. He was lucky, the usual result was you said goodbye to your wings.

Can you explain to me how fitting a bob weight would correct an aerodynamic problem? I've never claimed to be an aerodynamics expert and tbh it doesn't really interest me. Despite this, I'm learning quite a bit from this thread.
The reason I ask is that in Morgan and Shacklady there are numerous mentions to the inertia weight, and none of them mention instability, they all however mention pulling out of high speed dives and that it was too easy to break the A/C because of the elevators being so light.

I thought the instability was more of a twitchy thing, as mentioned in the Rechlin trials? Specifically the "suffers from quick changes of trajectory along the vertical axis, coming from high longitudinal thrust momentum, and significantly disturb aiming" bit and the reference to "bad elevator and rudder stability on the target approach". So was the impact of the inertia weight a double edged sword? Ie it resolved the dive problem and softened the elevator problem?

[Crumpp]

Can you explain to me how fitting a bob weight would correct an aerodynamic problem?

The fitting of bob-weights does not fix the stability issue. It compensates for the stability by increasing control.

It artificially increases the stick force gradiant. This makes the rise in stick forces as we get farther away from our trim point steeper.

In short, it makes the stick heavier so that it takes more effort to move it that 3/4 of an inch.

"suffers from quick changes of trajectory along the vertical axis, coming from high longitudinal thrust momentum, and significantly disturb aiming"

Right, it is a twitchy airplane under certain conditions and steep turns was one of them.

So was the impact of the inertia weight a double edged sword?

Yes it was a double edge sword especially for veteran pilots who grew accustom to a two finger airplane.

[Crumpp]

First, the Pilot's Notes were deliberately conservative to ensure that most pilots flew well within the limitations of the airframe

Nonsense, as they mention the engineering margins are just too tight in aviation. The Operating Limitations are that margin.

they were easy meat.

They were not "easy meat" by observing the operating limitations. Where do you get this stuff?

The RAF says the exact same thing I told you multiple times...the engineering margins are just too tight in order to even achieve flight. The Operating Limitations are that margin.

Read this a couple of times very carefully to allow it to sink in:

wing which is intended to withstand 4g should not break until 8g is imposed, but there is increasing risk of strain and failure as g rises above 4.

Now, imagine you don't have a reset button and when you skin your knee, it really does hurt.

RAF acknowledged that in combat it was up to the pilot to choose what risks needed to be taken;

Yes, by BALANCING that risk.

That means choose your death.....

1. You will die due to enemy action.

2. You might die if you violate the limits. If you do violate the airworthiness of the aircraft, about 85% of the time it will be a factor in your death in an airplane.

It means just that, balance your risk. It does NOT say contact with the enemy is license to violate the airworthiness of the aircraft. Those limitations are based on physical laws that define the airworthy limitations of the design and just like the RAF tells you, a chance exist's you are going to die if you violate them. You want the ability to throw that airworthiness out the window in order in to have some magical performance in your game shape. It does not work that way in reality. The anecdotes from those who survive having to make such a choice of their death are filled with bent airframes and damaged engines for a reason. Just as the RAF warns their pilots. The did it and got lucky.

In combat and emergencies pilots must take risks with their aircraft, balancing one risk against another; limitations must be strictly observed in so far as there is no sufficient reason to exceed them.

As for spinning, the RAF clearly warns of the danger of violating manuever limitations in an aircraft and why:

The reasons underlying these prohibitions are partly considerations of aircraft strength and partly of control.

[JtD]

If you still have 1946 installed, you could compare the flying qualities of the Spitfire V against the Spitfire IX. Both are very agile, the V being more unstable, more difficult to fly to the limit and easier to break.

[Kurfürst]

The simple answer is I don't know how the longitudal instability manifested it's self. As I understand it the BoB weight was specifically fitted because people were breaking spits when coming out of dives. As you say the bob weight didn't resolve the instability because it was an aerodynamic issue. So how could the pilot "make it happen"? Wasn't it happening all the time? I think it was Tim Viggors who recalled writing off a Mk1 spitfire simply by pulling out of a dive, the airframe was so badly bent it was un repairable. He was lucky, the usual result was you said goodbye to your wings.

Can you explain to me how fitting a bob weight would correct an aerodynamic problem? I've never claimed to be an aerodynamics expert and tbh it doesn't really interest me. Despite this, I'm learning quite a bit from this thread.

As I understand as weight gained by the time of the Spitfire V's appearance, the airplane tended began to overreact itself in pitch. In short the amount of pitch to stick movement / physical effort on the stick was not linear, and the aiplane 'tightened up' the turn on its own. It wasn't the oscillations ripping apart the plane in the dive, but the fact that pilot could rapidly exceed the safe g-limit of the aircraft due to this. He pulled a bit on the elevator, he pulled 3 g; a bit more which felt natural to be 4 g and he pulled 6 g in fact, and the aircraft accelerated in the turn, increasing the force and he soon found himself either spinning or breaking up the airframe. That's just how a longitudally unstable aircraft reacts, especially as the loadings in the airframe - guns, radios, armor etc. increase - the CoG shift s backwards, making the plane even more unstable. The bob weights progressively increased stick forces, so he was less likely to do that.

At least that's my layman's understanding of it.


The reason I ask is that in Morgan and Shacklady there are numerous mentions to the inertia weight, and none of them mention instability, they all however mention pulling out of high speed dives and that it was too easy to break the A/C because of the elevators being so light.

Yes that's pretty much why I raised this thread. When I fly different aircraft, I want to feel they react different. I want a Spitfire, a Hurricane, a 109 whatever all handle different, good and bad, I want to learn how to fly them, that's what a sim is all about, right?

Right now they all seem to respond all the same, as if there was a generic handling code which kills the whole point.

I thought the instability was more of a twitchy thing, as mentioned in the Rechlin trials? Specifically the "suffers from quick changes of trajectory along the vertical axis, coming from high longitudinal thrust momentum, and significantly disturb aiming" bit and the reference to "bad elevator and rudder stability on the target approach". So was the impact of the inertia weight a double edged sword? Ie it resolved the dive problem and softened the elevator problem?

Instability/stability characteristics as I understand are about how much the plane moves more (or less) around its axis than its supposed to. Move the stick in one direction, and a positively stable plane stops movement after a while and sets in a stable new course (good for a bomber), a neutral one keeps turning the same, and an unstable one starts turning faster and faster. The latter is good for manouverability, since you can initiate a turn very fast (no delay), but not so great if you want to fly accurate (for aiming), or hold a steady turn and fly near the stall.

As a sidenote, its funny to read German and British test reports on the other guy's plane's control characteristics. In short the Brits write the 109 is too stable, the Jerries write the Spits are too unstable. Go figure, it simply means they had a very different understanding what control characteristics are good for a fighter.

Now stick forces are a different thing, the 109 in pitch required rather high stick forces (20 lbs/G), which is good from the POV it prevents you from whacking the aircraft in dive recovery by pulling to many Gs, at lower speeds the amount of physical effort naturally feels just about right for a given movement, but it is more tiresome for your arms and can even limit you in maximum G (which is kinda the point). In comparison the Spit had very light stick forces in pitch, around 4 lbs /G, which made manouvering a physically easy thing and which you could do without your muscles become tired, but at the same time it presented a danger that if you pulled the stick too far backwards in dive recovery (nothing like high physical resistence there to prevent you) you could easily break the aircraft in two or stall in turns for pulling too much G.

Now in Cod and also in Il2, one of the most annoying thing is that the Spits light elevators are not being modelled. No matter how I tried, I could not break the airframe, even with the stick in maximum deflection. At 4 lbs/G you should be able to do that easily in a dive, by pulling around 13 g. At lower speeds, at this point you are probably stalled and spinning out of control, since no aircraft can pull that much without stalling unless the speed being very very high (stall speed iirc goes up with the square?).

[Kurfürst]

Funny how our dear Jeff first demands the evidence he has seen a great many times himself (the Spitfire pilot's notes), then when is shown that again he changes the subject and begins to say that the Spitfire's (or any other plane's) operational limitations are not really limitations at all, and they should be adhered only at the pilot's will.

Yeah right, the RAF was busy printing out manuals for aircraft and define their flying limitations simply because they had nothing better to do. :D

[winny]

Funny how our dear Jeff first demands the evidence he has seen a great many times himself (the Spitfire pilot's notes), then when is shown that again he changes the subject and begins to say that the Spitfire's (or any other plane's) operational limitations are not really limitations at all, and they should be adhered only at the pilot's will.

Yeah right, the RAF was busy printing out manuals for aircraft and define their flying limitations simply because they had nothing better to do. :D

I think this is slightly unfair. Pilot's who flew 'by the book' generally didn't last very long, on both sides. There are too many stories of people breaking 'planes out of desperation, panic or fear. Lot's of Spitfire and 109 pilot's took thier machines to the limit, and beyond. In fact nearly all the top guys did it.

Pilot's are given notes so that they understand the limits and dangers. There were no referees or people from the ministry flying around enforcing the law...

To simply dismiss this in such a trivial way "limitations are not really limitations at all, and they should be adhered only at the pilot's will." seems petty.

At the end of the day individuals made individual choices. If you returned from a mission with a bent airframe nobody grounded you for it, they just said 'oh he's bent the airframe' and ordered a new one.

@:Crumpp.
All this FAA stuff is a smokescreen. You find me a rule and I'll find you someone who broke it.. What has the FAA got to say about intentionally ramming another aircraft? Or shootng down another aircraft, or bailing out at 500 ft, inverted? Aor what you do when your left foot has just been blown off at the ankle?

[Crumpp]

Pilot's who flew 'by the book' generally didn't last very long, on both sides

That is not correct. Please present some facts to back it up.

It might work for your car but not airplanes. As the RAF tells its pilots, the margin in aviation are very small and the limits represent the point you are risking damage. The limits are just that, limits. They are not bound by feeling, opinion, or heroic fantasy, only physics.

You find me a rule and I'll find you someone who broke it..

Lot of idiots in the world, of course. In aviation you will find people who think they know better and the rules do not apply to them.

You can break man's laws and get away with it but not the laws of physics.

Notice the RAF does not say the wing will not break even at the upper limit of 4G. Why? Because it can break even at the approved limit because that limit assumes a perfect airframe. The Operating Notes define the limits the aircraft is airworthy.

intended[/B] to withstand 4g should not break until 8g is imposed, but there is increasing risk of strain and failure as g rises above 4. ]

[Kurfürst]

I think this is slightly unfair. Pilot's who flew 'by the book' generally didn't last very long, on both sides. There are too many stories of people breaking 'planes out of desperation, panic or fear. Lot's of Spitfire and 109 pilot's took thier machines to the limit, and beyond. In fact nearly all the top guys did it.

Absolutely, however some of the limitation were not soft ones. Say the manual may say spinning is not permitted below a said altitude, and it may well be on the safe side. However it wasn't there without a reason. The rules could only be bent to a certain degree, and after that line was left behind, there was no coming back, and no telling of stories.

Pilot's are given notes so that they understand the limits and dangers. There were no referees or people from the ministry flying around enforcing the law...

Mother Nature took care about enforcing it though..

To simply dismiss this in such a trivial way "limitations are not really limitations at all, and they should be adhered only at the pilot's will." seems petty.

It's not petty, it's realistic. If a plane can only take 12 gs before breaking up, it will at 12.1 g. If its humanly impossible to get it out from spin without having 5-10 000 feet of altitude, you will die in it.

What I find petty is that when some guy damands the same papers he has seen about 2 years ago already (back then the excuse was that it's a 'forgery'), he knows very well about it, then when he is presented with it, he changes to subject and tries argues that it really isn't to be taken so seriously.

The Pilot's notes describe the behaviour of an aircraft accurately. They cannot be just dismissed with that 'oh, its not set in stone'.

At the end of the day individuals made individual choices. If you returned from a mission with a bent airframe nobody grounded you for it, they just said 'oh he's bent the airframe' and ordered a new one.

Sure not, though I've heard some times the damages were deducted, if it was for careless flying. Combat of course is a different matter, anything goes. As Crumpp said, you take a ris k and choose between certain death and likely death, as cruel as it is.

The question is alway: Which one is which? Is flying within the limits or pressing your luck is more beneficial to your survival in combat? Sometimes its the former sometimes its the latter, and the unlucky ones do not tell stories.

Physics just keep working all the same, those rules cannot be bent.

[41Sqn_Stormcrow]

Just to throw in:

If it was for rules these two men would never have survived:

http://209.157.64.200/focus/f-news/1071076/posts

http://www.dailymail.co.uk/news/article-435377/The-man-fell-12-000-ft---survived.html

BTW there are some similar stories.

Sometimes, for whatever reason, rules can be bent.

[Kurfürst]

Impressive... these guys should try lottery! :)

[winny]

Absolutely, however some of the limitation were not soft ones. Say the manual may say spinning is not permitted below a said altitude, and it may well be on the safe side. However it wasn't there without a reason. The rules could only be bent to a certain degree, and after that line was left behind, there was no coming back, and no telling of stories.



Mother Nature took care about enforcing it though..



It's not petty, it's realistic. If a plane can only take 12 gs before breaking up, it will at 12.1 g. If its humanly impossible to get it out from spin without having 5-10 000 feet of altitude, you will die in it.

What I find petty is that when some guy damands the same papers he has seen about 2 years ago already (back then the excuse was that it's a 'forgery'), he knows very well about it, then when he is presented with it, he changes to subject and tries argues that it really isn't to be taken so seriously.

The Pilot's notes describe the behaviour of an aircraft accurately. They cannot be just dismissed with that 'oh, its not set in stone'.



Sure not, though I've heard some times the damages were deducted, if it was for careless flying. Combat of course is a different matter, anything goes. As Crumpp said, you take a ris k and choose between certain death and likely death, as cruel as it is.

The question is alway: Which one is which? Is flying within the limits or pressing your luck is more beneficial to your survival in combat? Sometimes its the former sometimes its the latter, and the unlucky ones do not tell stories.

Physics just keep working all the same, those rules cannot be bent.

I'm not arguing the physics. At all. I'm also definitely talking combat.
I'm highlighting the fact that context is important too.

History is important, i've read of at least 2 RAF pilot's intentionally spinning as a way to lose altitude whilst being shot at, and I think at least 1 LW guy. I'd have to check thru piles of books...

I'm sure that plenty of pilot's were killed by their own machines failing well within the limits, after all these were hand built. I'm equally sure some went through the limits and survived. It's being made out in this thread that because the pilot's notes say that xyz will get you killed, you get killed every time. I'm merely pointing out that this is actually xyz will probably get you killed.

I maintain that pilots notes alone are not proof of anything other than recommendations. There are too many variables to simply rely on a set of instructions.

[Kurfürst]

Basically, I agree with you. I don't think the positions that far away from each other either, its just difficult to form thoughts accurately in text on a discussion board. No, nothing is automatic, happening all the time as a certain results if you do something wrong, though the probability is high enough to warrant a warning in the pilot's little book.

OTOH I believe Pilot's instructions report a plane's characteristics faithfully. I guess we can agree on this. ;)

[41Sqn_Stormcrow]

I'm not arguing the physics. At all. I'm also definitely talking combat.
I'm highlighting the fact that context is important too.

History is important, i've read of at least 2 RAF pilot's intentionally spinning as a way to lose altitude whilst being shot at, and I think at least 1 LW guy. I'd have to check thru piles of books...

I'm sure that plenty of pilot's were killed by their own machines failing well within the limits, after all these were hand built. I'm equally sure some went through the limits and survived. It's being made out in this thread that because the pilot's notes say that xyz will get you killed, you get killed every time. I'm merely pointing out that this is actually xyz will probably get you killed.

I maintain that pilots notes alone are not proof of anything other than recommendations. There are too many variables to simply rely on a set of instructions.

BTW what commonly passes unnoticed: it's the fact that to break up the overload has to be applied for a certain minimum time.

This is a subject that is up to now not well understood by scientists and some research is done on this aspect. But basically if something usually breaks up at Xg it may not so if the time of exposure is very very small.

You will certainly believe like me that 30g is something human bones do not withstand, don't you.

Now you know that acceleration is delta(v)/delta(t) with v being the instantaneous velocity and t time.

Now when I jump from a chair my velocity will be not zero, let's say it is about 2 m/s right before I touch the ground. Now when touching the ground the velocity is reduced to zero, so delta(v) = 2 m/s. This happens basically instantly that's why delta(t)<<1. Which will make the acceleration incredibly high. Delta(t) just needs to be smaller than a millisecond to have a decceleration of 200g. Of course my reflects will absorb the shock but even if I'd just fell to the floor or jumped with stiff legs I would not break them. As much as I can break a plastic spoon easily with my two hands without much effort while it won't break if I threw it with force to the ground.

I for my part as an engineer and scientist am much thrilled and fascinated by this kind of intriguing phenomenon.

Of course this whole thing highly depends on the material as from daily experience I would say that elastic materials can take this ultra short loads much more easily than brittle material.

I guess that the lower the overload the longer the exposure times. So it is not unthinkable that if the overload was only for a little time the plane still might have survived it even if the book told that this never was going to happen.

Also remember that the limits for which the planes were designed were theoretical values based on experimental data on material properties obtained through probe measuring and some hand formula and sort of thump rules. These values also contained a certain margin that was dimension by some regulatory rules based on more thump rules.

No finite element methods back then.

Obviously a pilot would not or only in dispair engage in a manoeuver that he would be certain to break his plane with. Nevertheless his plane might not have broken up against all odds, if he was really lucky.

[winny]

Basically, I agree with you. I don't think the positions that far away from each other either, its just difficult to form thoughts accurately in text on a discussion board. No, nothing is automatic, happening all the time as a certain results if you do something wrong, though the probability is high enough to warrant a warning in the pilot's little book.

OTOH I believe Pilot's instructions report a plane's characteristics faithfully. I guess we can agree on this. ;)

To be fair to you, you haven't been the main culprit withe the regulations thing.

I feel that there is a strange attitude to using combat reports and pilot's recollections as evidence.
They are the only primary source available on the subject of how these aircraft performed, doing what they were designed, tested and regulated to do. Fly in combat. To ignore them is missing the whole picture. Numbers and physics are equally important. To ignore them is also missing the whole picture.

I read a LW account by one of the top pilots. He said he managed to turn inside a spitfire by flying and managing to maintain such a position that only the slats on one wing were deployed he shot it down, by the same token I've read Brian Lane's account of a 5 minute dogfight with a 109 where he rode they very edge of the stall, behind a 109 who's slats were deployed and who was suffering aileron snatching. He got behind after 2 full 360's, the 109 rolled out and dived away. I believe them both.

[Crumpp]

That is exactly it. Impressive and far from normal.

Also remember that the limits for which the planes were designed were theoretical values based on experimental data on material properties obtained through probe measuring and some hand formula and sort of thump rules. These values also contained a certain margin that was dimension by some regulatory rules based on more thump rules.

No finite element methods back then.


They are not theoretical values for structures. They could teach us a thing or two about subsonic aerodyanmics and piston engine aircraft design. The area's they lacked in were transonic realm, supersonic realm, and stability/control engineering.

Aircraft structure load limits are tested to destruction and are measured data.

Do you know how they tested the structural strength of a wing?

Simple, they suspended it and loaded it up with sandbags until it breaks. Now there are some things you have to do to make it applicable to air loads but that is the basic concept.

Today we use hydraulics.....

http://www.youtube.com/watch?v=Ai2HmvAXcU0

[Crumpp]

I maintain that pilots notes alone are not proof of anything other than recommendations

That is not true at all. They are the defined limits of the airworthiness of the design.

[NZtyphoon]

Flight situation not noted in Pilot's Notes:
http://http://www.youtube.com/watch?v=XABHcQjCun4

[Crumpp]

NzTyphoon,

Good humerous story. Does not have anything to do with Operating Notes, though.

[Crumpp]

Obviously a pilot would not or only in dispair engage in a manoeuver that he would be certain to break his plane with. Nevertheless his plane might not have broken up against all odds, if he was really lucky.


Absolutely. Failure points are a range and outliers exist. You can be a lottery winner on either end of that range.

I am sure every poor soul who has looped his aircraft into the ground was hoping to be a lottery winner in the last moments of their life.

[MiG-3U]

Ok. lets have a look to the first Spitfire Mk. II manual:

14. This aeroplane is stable, and rock-steady in flight athigh speed. The controls are not ideal, because it will be found that the aileron control become exceedingly heavy at high speed, while the elevator remains comparatively light and sensitive. Individual aeroplanes vary slightly, but in most cases care is needed in the use of the elevator control at high speed, to avoid sudden increases of load factor, or "g". During a tight turn or loop in bumpy conditions, movements of the pilot's body due to bumps are liable to cause movements of the controls and so large and sudden fluctuations in "g". It is then advisable to press the elbow into the side to steady it.
...
(iii) Stability in pitch.- This aeroplane, though just stable in a dive, tends to be a little unstable in pitch (or foreand-
aft) during turns; as the turn is tightened up so the elevator control tends to become lighter, or, at least, fails to increase in weight to a desirable extent. Therefore, care must be used with this control, especially in rapid manoeuvres. When flying in bumpy conditions at high cruising speed, the pilot's body is bumped severely on the seat, and this is very uncomfortable, even for a short time.

Then to the later Mk II manual revision (downloaded from Zeno's):

10. (i) Stability and control - This aeroplane is stable. With metal covered ailerons the lateral control is much lighter than with the earlier fabric covered ailerons and pilots accustomed to the latter must be careful not to overstress the the wings. Similar care is necessary in the use of the elevators which are light and sensitive.

And then aerodynamically similar Spitfire V manual:

10. GENERAL FLYING (i) Stability: The aircraft is stable about all axes.

Aerodynamics wise there is no difference between these and still early version claims the Mk.II little unstable in pitch during turns just like NACA found out in their tests of the Spitfire VA. However, later revisions of the manuals claim these planes stable. So, what's the difference?

Let's have look to the early Spitfire C.G. (center of gravity) diagram:

http://www.spitfireperformance.com/k-9788-cg-diagram.jpg

Note the CG horizontal position 7.6 inches behind the datum line.

Then the later C.G. diagram for the Spitfire I (this was used for another project but CG related parts are unchanged), it's the same for the II and V:

http://target4today.co.uk/_posted_images_/Mar302011/CoG_Iab.jpg

Note that without elevator inertia device the CG aft limit is 7.5 inches with the Rotol propeller. The earlier CG position, 7.6 inches, was too far aft without inertia device and the Spitfire VA, tested by NACA, apparently had the same problem (their measurements are not based on datum point but if measured from drawing, the CG during test was certainly close the aft limit if not behind it with the Rotol prop).

The claimed unstability in longitudinal axis was caused by CG being too far aft. Proof of this can be found also from Spitfire XVI manual:

41. General flying
(i) Stability
(a) At light load (no fuel in the rear fuselage tanks, no drop tank) stability around all axes is satisfactory and the aircraft is easy and pleasant to fly.
(b) When the rear fuselage tanks are full there is a very marked reduction in longitudinal stability, the aircraft tightens in turns at all altitudes and, in this condition, is restricted to straight flying, and only gentle manoeuvres; accurate trimming Is not possible and instrument flying should be avoided whenever possible.


PS: The later CG diagram for the Spitfire I also explains well the function of the elevator inertia device. The function and the reasons were the same in the P-51.

Over and out :)

[Crumpp]

Let's have look to the early Spitfire C.G. (center of gravity) diagram:


That is not a Spitfire Mk I load plan and is not applicable at all. The NACA was well aware of the CG limits and capable of performing a proper weight and balance.

Read the Pilots Operating Notes as you posted:

14. This aeroplane is stable, and rock-steady in flight athigh speed. The controls are not ideal, because it will be found that the aileron control become exceedingly heavy at high speed, while the elevator remains comparatively light and sensitive. Individual aeroplanes vary slightly, but in most cases care is needed in the use of the elevator control at high speed, to avoid sudden increases of load factor, or "g". During a tight turn or loop in bumpy conditions, movements of the pilot's body due to bumps are liable to cause movements of the controls and so large and sudden fluctuations in "g". It is then advisable to press the elbow into the side to steady it.
...
(iii) Stability in pitch.- This aeroplane, though just stable in a dive, tends to be a little unstable in pitch (or foreand-aft) during turns; as the turn is tightened up so the elevator control tends to become lighter, or, at least, fails to increase in weight to a desirable extent. Therefore, care must be used with this control, especially in rapid manoeuvres. When flying in bumpy conditions at high cruising speed, the pilot's body is bumped severely on the seat, and this is very uncomfortable, even for a short time.


Aerodynamics wise there is no difference between these and still early version claims the Mk.II little unstable in pitch during turns just like NACA found out in their tests of the Spitfire VA. However, later revisions of the manuals claim these planes stable. So, what's the difference?


Bob-weights......

[NZtyphoon]

Ok. lets have a look to the first Spitfire Mk. II manual:

14. This aeroplane is stable, and rock-steady in flight athigh speed. The controls are not ideal, because it will be found that the aileron control become exceedingly heavy at high speed, while the elevator remains comparatively light and sensitive. Individual aeroplanes vary slightly, but in most cases care is needed in the use of the elevator control at high speed, to avoid sudden increases of load factor, or "g". During a tight turn or loop in bumpy conditions, movements of the pilot's body due to bumps are liable to cause movements of the controls and so large and sudden fluctuations in "g". It is then advisable to press the elbow into the side to steady it.
...
(iii) Stability in pitch.- This aeroplane, though just stable in a dive, tends to be a little unstable in pitch (or foreand-
aft) during turns; as the turn is tightened up so the elevator control tends to become lighter, or, at least, fails to increase in weight to a desirable extent. Therefore, care must be used with this control, especially in rapid manoeuvres. When flying in bumpy conditions at high cruising speed, the pilot's body is bumped severely on the seat, and this is very uncomfortable, even for a short time.

Then to the later Mk II manual revision (downloaded from Zeno's):

10. (i) Stability and control - This aeroplane is stable. With metal covered ailerons the lateral control is much lighter than with the earlier fabric covered ailerons and pilots accustomed to the latter must be careful not to overstress the the wings. Similar care is necessary in the use of the elevators which are light and sensitive.

And then aerodynamically similar Spitfire V manual:

10. GENERAL FLYING (i) Stability: The aircraft is stable about all axes.

Aerodynamics wise there is no difference between these and still early version claims the Mk.II little unstable in pitch during turns just like NACA found out in their tests of the Spitfire VA. However, later revisions of the manuals claim these planes stable. So, what's the difference?

Let's have look to the early Spitfire C.G. (center of gravity) diagram:

http://www.spitfireperformance.com/k-9788-cg-diagram.jpg

Note the CG horizontal position 7.6 inches behind the datum line.

Then the later C.G. diagram for the Spitfire I (this was used for another project but CG related parts are unchanged), it's the same for the II and V:

http://target4today.co.uk/_posted_images_/Mar302011/CoG_Iab.jpg

Note that without elevator inertia device the CG aft limit is 7.5 inches with the Rotol propeller. The earlier CG position, 7.6 inches, was too far aft without inertia device and the Spitfire VA, tested by NACA, apparently had the same problem (their measurements are not based on datum point but if measured from drawing, the CG during test was certainly close the aft limit if not behind it with the Rotol prop).

The claimed unstability in longitudinal axis was caused by CG being too far aft. Proof of this can be found also from Spitfire XVI manual:

41. General flying
(i) Stability
(a) At light load (no fuel in the rear fuselage tanks, no drop tank) stability around all axes is satisfactory and the aircraft is easy and pleasant to fly.
(b) When the rear fuselage tanks are full there is a very marked reduction in longitudinal stability, the aircraft tightens in turns at all altitudes and, in this condition, is restricted to straight flying, and only gentle manoeuvres; accurate trimming Is not possible and instrument flying should be avoided whenever possible.


PS: The later CG diagram for the Spitfire I also explains well the function of the elevator inertia device. The function and the reasons were the same in the P-51.

Over and out :)
Thanks MiG - I explained all this in an earlier posting (http://forum.1cpublishing.eu/showthread.php?t=31252&page=5) but, as per usual Crumpp and co avoided/ignored/pretended it was irrelevant, with nonsense statements like: That is not a Spitfire Mk I load plan and is not applicable at all. and continues to pretend that he knows best about everything...as he has done for years, here and on other forums. *Yawn*

[Kurfürst]

Selective quoting. My favorite sin!

[Crumpp]

NZtyphoon

Reading is fundamental.

[Crumpp]

I noticed that is MIG's first post....

;)

[NZtyphoon]

That is not a Spitfire Mk I load plan and is not applicable at all. The NACA was well aware of the CG limits and capable of performing a proper weight and balance.

http://www.spitfireperformance.com/k-9788-cg-diagram.jpg

Yeah right, it says "C.G Diagram" in nice big letters at the bottom so people who can read understand it has nothing to do with the centre of gravity of Spitfire Mk Is.

NACA report Measurements of the Flying Characteristics of the Spitfire Va (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930092582_1993092582.pdf): As per usual Crumpp has fudged what the report actually says:

(Tests, Results and Discussion, page 5) All of the flying qualities tests were made with the center of gravity at a distance of 31.4 inches behind the leading edge of the wing at the root. The mean aerodynamic chord of 85 inches was computed to be 4.80 inches back of the leading edge of the wing at the root. The center of gravity was therefore at 31.4 percent of the mean aerodynamic chord. Because no accurate drawings of the Spitfire were available, the calculated location of the mean aerodynamic chord may be somewhat in error.

The center-of-gravity location with full military load is not known.

Crumpp has chosen to completely ignore that NACA's own report states that their calculations might have been in error, nor did NACA know what the cg was with full military load. " The NACA was well aware of the CG limits and capable of performing a proper weight and balance." completely wrong.

Reading is fundamental. ;) :rolleyes:

[Kurfürst]

More selective quoting and speculation. :)

[MiG-3U]

Quoting from the tests of the Spitfire I K.9789:

http://www.spitfireperformance.com/k9787-fuel.html

2. Handling and Flying Qualities.

The aeroplane has been flown at the following loadings and positions of gravity:-

Load for Weight (lb.) C.G. Position (inches aft of datum)
Typical service load ---5819---7.7
Extended aft.---5819---8.6
Forward limit---5338---5.8
...
(v) Stability - The aircraft is laterally stable at all speeds except in the immediate vicinity of the stall when it is unstable. The aircraft is directionally stable engine 'OFF' and 'ON' at all speeds, but on the climb this is difficult to assess owing to insufficient rudder bias. Longitudinally, the aircraft is stable with centre of gravity forward, but is unstable with centre of gravity normal and aft with engine 'OFF' and 'ON'. Longitudinal stability records are attached.

Later limits for the Spitfire 1A & 1B without and with the elevator inertia device (bob weigh):

http://target4today.co.uk/_posted_images_/Mar302011/CoG_Iab.jpg

3 With original standard elevator
Elevator inertia device---NIL---3.5 lb.---6.5 lb.
with De Havilland propellers--- 7.9 in.---8.2 in.---8.6 in.
with Rotol propellers---7.5 in.---7.8 in.---8.2 in.

With the Rotol propeller (as was in the Spitfire II and NACA tested Spitfire VA), the typical service load CG of the K.9787 was beyond the later limits without the inertia device (7.7 in. vs. 7.5 in limit). The extended aft CG of the K.9787, 8.6 in. aft the datum point, was clearly beyond the later limit, 8.2 in. even with the heavier 6.5 lb. weigh in the inertia device (with Rotol propeller).

RAE on the NACA stability testing posted by lane:

http://forum.1cpublishing.eu/showpost.php?p=422810&postcount=175

2.2. Stability and control at medium and low speeds. This was covered admirably, with the exception of static longitudinal stability. Trim at two C.G. positions were not done, so that the neutral points remained undetermined.

NACA did not test stability at different CG positions and, as NZtyphoon noted, they had no documentation about the correct CG limits nor accurate drawings.

Over and out :)

[robtek]

All this writing, or better copy 'n pasting, doesn't change the fact that the stick forces and stick travel for the elevator control in the early marks of the spitfire were too low and that has been changed in the later marks with the "BoB-weights".

If the low forces in connection with the small travel weren't regarded as dangerous, no change would have been necessary!

[bongodriver]

If the low forces in connection with the small travel weren't regarded as dangerous, no change would have been necessary!


not true, it was merely improved, not changed because it was dangerous, was everything that changed with the 109 do so because it was dangerous? I keep hearing how fantastic the leading edge slats were and then they were removed.........

[robtek]

not true, it was merely improved, not changed because it was dangerous, was everything that changed with the 109 do so because it was dangerous? I keep hearing how fantastic the leading edge slats were and then they were removed.........

Now that will be really, really hard to proof, All Bf109 / Me109 had and still have the slats!

And the rest of your opinion is grasping for straws, imo.

[bongodriver]

And the rest of your opinion is grasping for straws, imo.


IMO all the theories on the spitfire so far are the same.

[NZtyphoon]

All this writing, or better copy 'n pasting, doesn't change the fact that the stick forces and stick travel for the elevator control in the early marks of the spitfire were too low and that has been changed in the later marks with the "BoB-weights".

If the low forces in connection with the small travel weren't regarded as dangerous, no change would have been necessary!

The reason bob-weights were adopted was because several Spitfire Vs had been destroyed through poor loading at squadron level; this has been explained by Supermarine's Chief Test pilot Jeffrey Quill, although some Spitfirephobes consider him to be so totally biased he's incapable of telling the truth :rolleyes: Of course we have to believe these "experts' such as Crumpp or Barbi, and not Quill, who was the chief propagandist of the Spitfire: :grin:

In general configuration the Mk I and Mk II production aeroplanes were almost identical to the prototype and so there was no problem with their stability. (231-232)

The Mk III Spitfire did not go into production, but the success of the bobweight experiment in curing its instability...opened up the possibility of its use for later marks of Spitfire....which was just as well as we had to...respond to a nasty situation which developed in 1942.

The Mk V aircraft was...in full service with Fighter Command and,...a fair amount of additional operational equipment had gradually crept into the aircraft, most of it stowed within the fuselage. The aftmost acceptable position for the aircraft's centre of gravity had been fixed in the normal course of flight testing by the firm and by the A & AEE....Any rearward movement of the centre of gravity in service, for whatever reason, would begin to destabilise the aircraft. Therefore, for each sub-variant of the Mk V detailed instructions for the correct loading of the aircraft were issued to squadrons....However the importance of these loading instructions was not generally appreciated in squadrons and in the daily round of operational activity they tended to be disregarded....

There was thus a real chance that, as of that moment, in almost every squadron in the Command Spitfires were flying in a dangerous state of instability....Up to that time there had been a distressing and increasing incidence of total structural failure of Spitfires in the air, which was causing great concern in the MAP and especially at Supermarine. (pages234-235)

Once the bobweights had been introduced and, in later marks, the modified mass balances on the elevators...it was statistically established that, as soon as the longitudinal stability of the Spitfire was thus brought under control, the problem of the unexplained breakings-up of aircraft in mid-air,...'softly and suddenly vanished away'. (page 238 )

To say that they were adopted because of inherent design problems with the Spitfire Is and II is wrong; they were used on the Spitfire III because it had developed cg problems and adopted in Spitfire Vs because of poor loading and increased equipment.

[Al Schlageter]

not true, it was merely improved, not changed because it was dangerous, was everything that changed with the 109 do so because it was dangerous? I keep hearing how fantastic the leading edge slats were and then they were removed.........

Some pilots had the slats were wired shut, but that was the exception not the rule.

[robtek]

The reason bob-weights were adopted was because several Spitfire Vs had been destroyed through poor loading at squadron level; this has been explained by Supermarine's Chief Test pilot Jeffrey Quill, although some Spitfirephobes consider him to be so totally biased he's incapable of telling the truth :rolleyes: Of course we have to believe these "experts' such as Crumpp or Barbi, and not Quill, who was the chief propagandist of the Spitfire: :grin:



To say that they were adopted because of inherent design problems with the Spitfire Is and II is wrong; they were used on the Spitfire III because it had developed cg problems and adopted in Spitfire Vs because of poor loading and increased equipment.

Sorry NZTyphoon, but to say that the bobweights were introduced because of the "poor loading ad squadron level" sounds absolutely unconvincing to me.

The bobweights were used to reduce the ease of motion when actuating the elevators, reducing this way the possibility to inadvertently overstress the airframe, regardless of the flightsituation (spin, overspeed or else).

[NZtyphoon]

Sorry NZTyphoon, but to say that the bobweights were introduced because of the "poor loading ad squadron level" sounds absolutely unconvincing to me.

The bobweights were used to reduce the ease of motion when actuating the elevators, reducing this way the possibility to inadvertently overstress the airframe, regardless of the flightsituation (spin, overspeed or else).

It might sound unconvincing to you but its the truth - unless, like some others on this forum, you believe that you are more of an expert on the matter than Jeffrey Quill.

[MiG-3U]

Sorry NZTyphoon, but to say that the bobweights were introduced because of the "poor loading ad squadron level" sounds absolutely unconvincing to me.

The bobweights were used to reduce the ease of motion when actuating the elevators, reducing this way the possibility to inadvertently overstress the airframe, regardless of the flightsituation (spin, overspeed or else).

http://target4today.co.uk/_posted_images_/Mar302011/CoG_Iab.jpg

The inertia device (bob weighs in other words) was not needed if the CG was forward enough and the later marks, (VIII, IX...) did not have the device because the heavier engine moved the CG forward, 4-5 in. aft of datum point, except rare case of rear fuselage tank.

It can be said that the original CG limits were too aft with Rotol propeller and longitudal stability suffered, hence warnings in the early version of the Spitfire II manual. However, warnings were removed once the limits were revised.

Over and out :)

[JtD]

It is always possible to exceed safe margins through improper loading, but in case of the Spitfire, this margin was small by design; and if it is impossible to maintain safe limits in everyday service, it is a design problem. Saying it was just improper loading, or saying it was just faulty design for that matter, imho only is half the truth.

[bongodriver]

Some pilots had the slats were wired shut, but that was the exception not the rule.

Yes I just realised I meant disabled instead of 'removed', also it was an idea theorised by the americans on how the 109 might be improved after tests on captured aircraft.

[MiG-3U]

It is always possible to exceed safe margins through improper loading, but in case of the Spitfire, this margin was small by design; and if it is impossible to maintain safe limits in everyday service, it is a design problem. Saying it was just improper loading, or saying it was just faulty design for that matter, imho only is half the truth.

In some degree I agree, the same revised loading table also has limits for the modified elevators:

1. With modified horn balance elevator (Spitfire modification No. 789): - 9.0 in. aft of datum point.
2. With Westland convex elevator (Spitfire modification No. 743) - 8.2 in. aft of datum point.
Note: - 1. & 2.apply to all propellers no elevator inertia device should be fitted.

So there indeed was design changes to solve the problem but I won't call that as a design problem because the loading needs grew over the original specification.

Over and out :)

[NZtyphoon]

It is always possible to exceed safe margins through improper loading, but in case of the Spitfire, this margin was small by design; and if it is impossible to maintain safe limits in everyday service, it is a design problem. Saying it was just improper loading, or saying it was just faulty design for that matter, imho only is half the truth.

I think you're right about the narrow cg margin, not forgetting that when the Spitfire was designed in 1935-36 features like CS propellers, armour plate, armoured windscreen, IFF - even apparently small details such as extra ducting for gun heating equipment, shrouding for the gun bays etc - were three to four years into the future. Compare the equipment loaded into a pre-war Spitfire I with that loaded into a 1942 Mk V and the margin for error must have been relatively small.

Does anyone have any idea of how the Spitfire cg margins compare with (say) the P-51?

[robtek]

The reason bob-weights were adopted was because several Spitfire Vs had been destroyed through poor loading at squadron level; this has been explained by Supermarine's Chief Test pilot Jeffrey Quill, although some Spitfirephobes consider him to be so totally biased he's incapable of telling the truth :rolleyes: Of course we have to believe these "experts' such as Crumpp or Barbi, and not Quill, who was the chief propagandist of the Spitfire: :grin:



To say that they were adopted because of inherent design problems with the Spitfire Is and II is wrong; they were used on the Spitfire III because it had developed cg problems and adopted in Spitfire Vs because of poor loading and increased equipment.

The text you quoted, nztyphoon, says that the Spit1a b and the spit 2 had no stability problems and then continues with the cog problems of the spit 5.

There is nothing wrong with this text, but is it really applicable to this topic?

If the spit2 didn't had have stability problems, as you quoted, why were bobweights mounted?

[Crumpp]

Bob-weights have absolutely nothing to do with CG limits. The stabilty margin will shift with CG limits and the early mark Spitfire did have stable load conditions.

However all of that is completely irrelevant. CG shirts from consumption of consumables like oil and avgas. The NACA was well aware of all these characteristics and could do weight and balance.

The solution for the unacceptable and dangerous longitudinal instability of the Spitfire was bob-weights. These were added not because the NACA made a mistake in some half baked theory on weight and balance calculations. They were added by the RAE to correct a serious stability and control issue with the design.

http://img832.imageshack.us/img832/2489/bobweightsresults.jpg (http://imageshack.us/photo/my-images/832/bobweightsresults.jpg/)

[bongodriver]

The solution for the unacceptable and dangerous longitudinal instability of the Spitfire


Do you have a source showing thes unnacceptable and 'dangerous' in particular used to describe the Spitfire?

[Crumpp]

Do you have a source showing thes unnacceptable and 'dangerous' in particular used to describe the Spitfire?


NACA......

Operating Notes....

RAE.....

Air Ministry....

Take your pick.

[bongodriver]

So you say the Spitfires own operating notes say it is an unnaceptable and dangerous aircraft?.......verbatim?.......post some scans.

[IvanK]

"Dangerous" I don't believe appears in the NACA Spitfire document that is imo an embellishment. The term unacceptable also needs to be qualified ... it was unacceptable to the criteria NACA was using.

[Crumpp]

"Dangerous" I don't believe appears in the NACA Spitfire document that is imo an embellishment

No that is in the Operating Notes....

The term unacceptable also needs to be qualified ... it was unacceptable to the criteria NACA was using.

Yes, the only defined standards in the world at the time besides the German's. Post-war, the RAE adopted the exact same standards as the NACA.

So, we can say in 1940, the RAE had no standards, they just knew they had a dangerous airplane so they warn the pilot often.

In 1946, the early mark Spitfires would have been labeled as "unacceptable" by the RAE but since they had to have bob-weights, there was no need.

You won't find a Spitfire flying today without bob-weights.