Are you nuts???

Where in this thread have i ever talked about a 190 and its stall behaviour???

Even Spitfire pilots used this accelerated stall flick roll as a last resort escape maneuvre, i've read somewhere.

It is i. e. bad, when one is pursuing in a spit and it happens, changing the hunter to the prey in the worst case.

Btw, the 190 tactic was especially successful in a low level flight :D

Maybe you should define those long period oscillations and make sure that is what the OP is talking about.

Looking on the diagrams i see very short period oscillations.

It is still the target to make it as realistic as possible with proved data.

Wow! Tagert, this time you've excelled yourself. ;-)

Short period oscilations are measured in seconds.

Wiki I know but it explains it well enough.....

http://en.wikipedia.org/wiki/Aircraft_dynamic_modes

:rolleyes:

Long period Oscillation is not even considered in stability and control. It does not effect any airplane.

Once again, down the rabbit hole we go!!!

Not really, if an aircraft truly has a problem with short period oscilations then it's practically uncontrollable, and we know thats not true of the Spitfire, at worst the problem is 'slight'

Exactly. And it was the only unstable oscillation with the Spitfire.

This answer is a try to digress.

We are talking about that it is necessary to move the stick almost completely back to neutral after starting a turn, because of the longitudal slightly negative stability
of the Spitfire (early marks) the turn rate would increase otherwise without further input by the pilot.

We are talking about a very sensitive elevator control, paired with a very short stick travel for large reactions, completed by a relative insensitive aileron control.

We are talking about the former points making it a bit harder to ride the buffet, the excellent stall warning of the Spitfire, without entering the buffet and loosing the turn advantage.

Everything documented and proven.

All this together made the Spitfire to a thoroughbred which needed sensitive hands on the controls.

A plane for the virtuosos, not the ham-fisted.

No, documented and misrepresented.

The Spitfire was famed for being easy to fly 'IN COMBAT' by the very inexperienced pilots of the BoB....

you can embelish it all you want with the 'virtuoso' stuff, that ain't the way it was.

robtek, can you please prepare a list of planes documenting the elevator forces showing the range common to WW2 fighter aircraft and the spots of the various Marks of the Spitfire, depending on the CoG position, on that list? And please also mark the NACA recommendations, on that list.

It would certainly help you getting a perspective. Until you got it, don't waste your time replying to me.

Thereafter, we can talk about what happens say if the pilot does a pullout with a constant stick force in a 109. Will be interesting, too.

Eventually, you may realise that WW2 fighter aircraft in general were nothing for the ham-fisted.

And yet it was flown in combat, very successfully, by pilots with very low hours.

@ JTD

i'm not posting for your private tutoring.

@Sandstone

that is not mutually exclusive, i would believe that the more ham-fisted students would find themselves assigned to a Hurricane squadron or even BC.

You would believe wrong.

Sorry, i didn't know that you are that old to be participating on the selection process then.
But please enlighten us all with your first hand knowledge.

My uncle was training on Seafires when the war ended. Us boys grilled pretty good on the a/c and never once did he mention the elevator was a problem like some are trying to do.

Little jump start for that list, a certainly extreme example:
- F4U with CoG at .334 MAC, trim 1.7° up (neutral at 300 mph, 8500ft): 0in stick travel and 5lbs push force to maintain 5.5g in a steady turn.

Anyway, I got no time for this. Whoever may be interested in getting it right instead of having the last word and discrediting others can certainly dig up more data on his/her own.

If they were that ham fisted, they didn't survive the Harvard.

No.. are you?

Please re-read my post and note that I never said you did..

I simply noted how hypocritical some of the blue minded members in this forum can take one airplane trait, in this case the acc stall 'flick' and refer to it as a negative trait when talking about non-blue planes and refer to it as a positive when talking about blue planes..

That is to say I was not specifically talking to you, as much as I was talking about some of the the blue minded members of this forum.

In short, if the shoe fits, ware it, if not than don't.

Interesting..

So you agree that both the Spit and Fw190 had this trait..

And you also admitted how it can be a good trait when used to escape..

Yet in your previous post, when talking about the Spitfire you made no mention of the positive..

Only the negatives!

And it was not until I called you out on it that you agreed this trait can be a good thing.

Which speaks volumes about you IMHO..

For future reference

A more balanced approach, that mentions the pros and cons, would have brought a bit more credibility with it.

Bomber Command had the first choice of the pilots. Apart from 1940/2 when training would cream off the best to be trained as instructors.

interestingly Germany had a similar problem with Bomber Units having the first choice of pilots and almost a monopoly on staff officers

So you are saying that when a F4U at 300mph in level flight at 8500ft is banked it will make a 5.5 g turn without any pilot input except aileron for the banking
and 5 lbs forward pressure on the stick to keep the stick in neutral position?
If so, the plane is trimmed wrong for this turn.

To have a relation to the stick forces the planes should do a similar maneuvre , like a pull up, without airplane specific quirks, as the automatic 5.5g turn surely is one.

In the pull up the Spitfire with normal CoG and cruise speed needs three quarters of a inch stick travel with about 6lbs pull force to have a three g pull up.

I would be interested in the values of other planes in a similar set up.

I'm pretty sure the Spitfire values are pretty unique here.

It is always boring when the old red vs blue flag is waved again.

You should remember that it is not about this trait that we are talking, but how to get there!

Willingly or inadvertently?

Of course it was done, as a last resort, even as flick maneuvres were explicitly forbidden in the pilots notes.

Also there are enough Spitfire fans which will point out every positive aspect possible.

Even in a very specific thread where by now at least 50% of the posts are slightly or completely off topic.

Even some of mine, sorry for that.

Flicks were not forbidden in the MkII notes

Agreed 100%.. Which is why I was so surprised to see you waving the blue flag here in this spitfire thread.. In that your posts are typically balanced.. But here, clearly your bias was playing a part when you only made note of the negative aspects of this trait.

Agreed 100%.. I noticed that you (and others) were only talking about the 'inadvertently' case.. Which I suspect was done because it was the most negative aspect of the trait.. That is the reason I brought up the 'willingly' case to show how there is a positive aspect to this trait.. And to point out how the blue minded members typically only bring that aspect up when talking about the Fw-190.. Your post is a perfect example of this.. In that you knew in advance there was a positive aspect of this trait.. But you made no mention of it 'here' in this 'spitfire' topic.

Glad to see you agree with me

I don't know if I would go as far as to say last.. I suspect the order in which it was used depended a lot on the pilot and how comfortable he was with it and the situation at hand.

Got Link?

Oh don't get me wrong!

I realize there are blue and red biased members of this forum

Just up until now, I always considered you to be pretty balanced.. but now I see you have your moments of bias too!

Enh!

Topics are like a river.. They flow and bend and change direction.. No big whoop! Mater of fact I think one would be hard pressed to show any thread that has not had more than one or changing topics.. Except for the ones that get locked within the first page! ;)

So what is this thread all about ? The stated purpose by the OP is:

This thread is going to cover the definable and measure stability and control characteristics of the Spitfire. It is not going to cover opinion outside of stability and control engineers.

What this thread is not going to do:

1. Get into a debate about "easy to fly". It is not definable and has no bearing on the measured facts.

2. It is not going to discuss the sustained level turning ability of the aircraft. That is also measurable and definable. For Example, anyone who is capable of doing the math will see that the Spitfire outturns the Bf-109 is steady state constant altitude turns at low velocity.

It has now become the OP's intent to raise this as an issue for the Bugtracker

The issue is that a bugtracker item should be about some genuine bug. That assumes the author actually presents proof that the bug exists. Has he done that ? All I see is too and fro about Real World Spitfire stability. Not much about actual in game behaviour. The OP has stated that he doesn't even have the latest Beta version installed.

http://forum.1cpublishing.eu/showpos...4&postcount=12

Now we have yet another huge thread (53 pages as of today !) with opposing views that has supposedly become the ammunition to support a Bugtracker entry that the CLOD Spitfire FM is porked stability wise. 53 pages of discussion but not as far as I can see ANY actual attempt to determine if the existing game FM is actually porked stability wise. The OP opined a while ago that he found the Spitfire hard to trim accurately in pitch .... and which he also said that would make sense considering the stability characteristics of the real aircraft... which (if we accept the stability argument is correct) implies that the current FM stability wise (at the time of his comment) is reasonable.

So how about before raising a Bugtracker defect report the actual defect is demonstrated.

For the record lest we forget The OP has also made comments like :
".......and a dangerous instability exhibited by the Spitfire."
http://forum.1cpublishing.eu/showpos...4&postcount=34

Thank you Ivank for dropping the hammer!
/thread.

Absolute nonsense, both reports combined define the desirable stall behaviour as being both slow speed and high speed - the only one placing a false interpretation on the resulting explanations is your good self and Crumpp

http://i91.photobucket.com/albums/k3...-page-011a.jpg

http://i91.photobucket.com/albums/k3...-page-003a.jpg

http://i91.photobucket.com/albums/k3...-page-004a.jpg

Neither of the NACA reports make the completely unquantified and unsubstantiated claim made by Crumpp that the turn performance was curtailed:

http://i91.photobucket.com/albums/k3...pe/page15j.jpg

Oh so if I didn't happen to be participant of the Battle of Britain I have no reason to point out that your opinion is wrong (with all due respect)?

/On the other hand, some other people in this thread would say my precious memories are just anecdotes anyway and they would prefer some piece of paper with a graph drawn on it ;)/

robtek I understand what you're saying, but you are wrong that pilots were selected for Hurris or Spits on the criteria of ham-fistness. ;)

Ok, in the Mk II notes "AIR PUBLICATION 1565 B" is written:

The word forbidden is missing and at slow speed they are allowed.

Did you read the NACA report? Do you need me to highlight the part about long period oscillation is not considered????

Do you understand that none of the Operating Note warnings or NACA measurements include anything about long period oscillation.

The RAE measured stick free oscillation. The NACA measured stick fixed.

In otherwords, the early mark Spitfire was not a hands off aircraft. Left to its own devices, it would eventually destroy itself without pilot input in conditions it was divergent.

You're repeating what I said yet you try to make it sound as if you disagree with me. Why?

'NO' mark of spitfire was 'hands off', nor for that matter was 'any' aircraft of the time, have you really raised a thread with all the guff you posted at the beginning just to prove the aircraft would 'eventually' 'if' left 'unchecked' destroy itself? what do you think pilots do? they control the aircraft.

Please tell me this has all been just a bad joke, I ended up banned for doing nothing different to anyone else on this thread.

Gents time to all step away from the keyboard a bit and try and keep it from being personal. I dont want to have to lock the thread but I will if you cant all play nice! ;)

And im not singling anyone out, your all as bad as one another in different ways. :) Which often happens with us passionate lot but please have a bit of humility and humour in your discussions as if you were a couple mates having a good old disagreement over a beer at the pub! If you can discuss with that kind of banter and respect it will be more fun for everyone. REMEMBER NO ONE IS WRONG OR RIGHT im 99% of these discussions, it is discussion of opinion. Facts can be interpreted differently or differing accounts can be made for just about every claim or published article ever made on the spit, the 109 and most of the era's aircraft. Please remember you are not automatically right just because you found something on the "interweb". None of us are experts in testing and we are presenting and interpreting data without the proper training to do so.

So have I made it clear we are all here to learn and discuss and not make things personal, and also try not to take everything personally???
Sometimes its hard I know but please give it go gents. :)

My2 pennies.
I diidnt think any fighter was hans off at the time?
If i went to make a cuppa during flight i would most likely come back to a burning wreck no matter the plane i was flying.

We need structural damage modelling for all planes to stop unrealistic manouvers unger high g's. Is there bug tracker for this? Maybe a more sensitve elevator as this is well documented

Not going to comment on the rest as, to be frank, i dont understand it!

Crumpp
Can you name any aircraft, of any type, in any airforce, that was hands free during WW2, ie wouldn't eventually destroy itself without pilot input in conditions it was divergent?

V1 doodlebug

I don't know about 'hand off' but there were aircraft that couldn't even be flown 'feet off'. Must have been total crap planes ...

Even here there were a fair few failures.

All I am asking Crumpp to do is support/clarify a view.
a) If he believes that it was a common trait amongst WW2 aircraft that aircraft were not hands free then why single out the Spit for critisism.

or

b)If the Spit is an unusual example, then he should be able to nominate one that was hands free.

Pretty simple really.

Because I do disagree with you. You confuse apples and oranges between long period oscillations with stick free behaviors and the short period the NACA measured.

The RAE was not stupid. They measured the stick free behavior for a valid reason. You can quickly look at the those graphs to see the Spitfire has positive static and negative dynamic stability stick free. It shows the work load required of the pilot and the ability of the aircraft to maintain equilibrium. The Spitfire was neutral or divergent.

The NACA did not even consider long period oscillation. They only considered short period. Yes, it does matter. It matters so much, it was promptly corrected in the design.

Everything is "absolute nonsense" to you, yet you confuse so many things. My advice is to look at the exact conditions and take each statement one at time. It is a scientific report and the language is specific.

You might see that it all fits together and the NACA knew what they were doing. Otherwise, we are forced to concluded that you know more than they do regarding stability and control. I kind of doubt it, though.

Here is a few clues:

1. Guns ports open.....gun ports closed.....(drag picture)

2. Violent pre-stall buffet is not stall motions. It is the the "violent shudder" as noted in the Operating Notes as well as measured data from the NACA

Speak for yourself! :grin:

I worked very hard, investing both time and money for my education. Stability and control was covered and testable.

Most aircraft are not positive statically stable and negative dynamically stable stick free. It is an unacceptable characteristic.

It is a situation where the the aircraft moves toward the trim condition but increases the force on the axis of motion so that it overshoots the mark. The key is our force is increasing with each oscillation. This causes the motion over time to grow larger and the velocity along the axis of motion to increase. Eventually, the forces will overload the aircraft and it will destroy itself.

F6F, Hurricane Mk I and Mk II, F4F, Bf-109, FW-190, A6M, and the list goes on...

Glider,

Most aircraft are not positive statically stable and negative dynamically stable stick free. It is an unacceptable characteristic.

Really?.....are you sure?

Positive Static Stability—The initial tendency of the airplane to return to the original state of equilibrium after being disturbed.

Static Stability is measured by Short period oscilations.

This sounds like 'most' aircraft to me and is certainly what I have experienced, the Spitfire was neutraly staticaly stable which is what gave it the light controls.

Dynamic stability is shown by measuring the long period oscilation, in the Spitfires case it was 'slightly' longitudinaly unstable and this is is what contributed to the maneuverability of the spitfire.

i dont get the "stick free" comments here, why would you fly a plane without holding the stick?

and as someone posted before, can you (anybody) explain for my better understanding how what being discussed here is different than in game :confused: i.e what it should be doing compared to what it is doing now

A question for you all, can't find the answer myself, what was the first aircraft fitted with bob weights, and particuarly the first british plane?

Was it the Mk V Spit?

Thanks in advance.

You could also search for 'inertia weight'

You took that out of context. He's saying most aircraft do not have positive static but negative dynamic stability when stick free.

In that case you're disagreeing with NACA. Take it up with them.

No, JtD,
YOU are disagreeing with NACA, because YOU wrote that the long period oscillation is the only unstable oscillation for the Spitfire, where the NACA report ignored the long period oscillations as insignificant.

Maybe it helps if I sum it up:

A.&A.E.E. tested Spitfire K9788 (a Spitfire I) and it showed increasing long period oscillations, which means it is dynamically unstable.

NACA did not bother to investigate these, as "the well know long period oscillations have no correlation with the handling qualities of an airplane". NACA tested a Spitfire V. It evaluated short period oscillations, which all were damped satisfactory, and evaluated static stability, which was found to be neutral to positive flaps up, and negative flaps down.

Now I absolutely agree with NACA, in particular with the statement that the long period oscillations are irrelevant in terms of handling and in fact, dynamic instability was not atypical for fighter aircraft of the time. The Hurricane for instance, having gone through similar trials, proved to be far more dynamically unstable.

I've neglected the flaps down instability, which I consider irrelevant in air combat, because flaps down was no condition for combat.

As for the other qualities evaluated by NACA, be it good or bad, it sums up that there's nothing critical. Only characteristic, in that some points are rather weak, some excellent.

And all the hype about dangerously low elevator forces and changes to pilot notes - it was decided to add the part of the Mk II notes, which is repeatedly quoted here, after a total of 3 (three) Spitfire I's were lost due to mid air wing failures and investigation found that inexperienced pilots coming in fresh from training mostly in bi-planes needed an extra warning because they simple were not familiar with high speed pull outs and trimming in high speed dives.

The weakest point in terms of control were the fabric covered ailerons, whereas the overall control characteristics made the Spitfire an easy plane to fly, and an easy plane to fly to the limits. For a WW2 fighter aircraft.

Yet the RAE were stupid enough not to have any standards, according to Crumpp.

I would recommend you do the same Crumpp, instead of layering your interpretations on straight-forward comments.

Thank you JtD ;) This is pretty much how I read the facts in this thread.

The instability in the NACA report is, that a constant stick input, say one inch back with 6lbs pressure, led to a ever increasing g-load, and that was the malus for the Spitfire controls.

The ideal reaction would have been i. e. pull the stick 3 inches back with 15 lbs pressure and get a constant 5 g pull up.

No, there's nothing like that in the NACA reports. Neither in pull ups (figure 12), nor in turns (figure 21). The curves clearly show progressive elevator angle (stick travel) and progressive forces, even though the stick travel is small.

Yes it is what the NACA report says.

ONLY the abrupt pull ups are stick free.

Correct. The abrupt turns and all other conditions are stick fixed. The NACA did have to modify their force gauge to allow the pilot to adjust the force holding the stick fixed so as not to exceed the airframe limitations. He could move it to keep from damaging the airframe.

That is all explained in the report.

:rolleyes:

JtD, they flat out state the stick fixed longitudinal stability is unacceptable. That is the NACA, not me.

Why do you think bob-weights were added to the design to fix the longitudinal stability?

Because they just felt like changing something? Maybe they were bored and had nothing else to do?

Or maybe, just maybe, there was a real engineering issue with the longitudinal stability that required a real engineering solution? Nahhhh!!!

;)

http://img99.imageshack.us/img99/561...estability.jpg

NACA shows progressive stick travel and elevator force over lift coefficient and normal load. You are directly contradicting NACA. I'd appreciate if you could point out the chart or table you are basing your conclusion on.

Additionally - the Spitfire stability "failed to meet an accepted requirement". This does not make the stability unacceptable. It may seem to be the same for people unfamiliar with testing and test reports, but it is not. In this case the difference is evident from the fact that the Spitfire was accepted into service with 30+ air forces worldwide, among them the USAAF. This would not have happened had the stability been unacceptable.

Agreed 100%

+1

it's like adopting a standard where everything has to be purple and then testing something which is green and surprise surprise it fails the purple standard.

This was a test on a MkV, nothing in the test mentions a similarity with earlier models, and the MkV had a different weight and balance.
Was it the Americans that advised the addition of the bob weight?
I believe some RAF units asked for it to be removed so they could have the original flying qualities back, doesn't sound like the original ones were so bad in that case.

This whole thread has been about making a mountain out of a molehill.

In my reply to my question about any examples of any aircraft of any type in any airforce that was stable enought to meet your requirements and your reply

I take it that your reply is a very long way of saying no, you have no examples.

The words you have written are as far as I can ideological rubbish and would depend on the pilot being stupid enough to overcompensate with every oscillation. Nothing to do with examples which I take it you cannot supply.

Quill devotes an entire chapter to longitudinal stability (pages 229-241 Murray 1983) in his book "Spitfire a Test Pilot's Story" in which he goes into detail about the problems involving several Spitfire Vs which broke up in 1942; Quill describes the problem of Spitfire Vs breaking up; he then goes on to describe the solutions which were a): to ensure that when new equipment was added that the loading was kept within limits and b):the design of bobweights, which were added to the elevator circuit, as well as the modified elevators fitted to later Spitfire marks. After the bob-weights were fitted, and the loading sorted out, the problem disappeared.


Quill
"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 mormal 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 comcern 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 )

http://i91.photobucket.com/albums/k3...rpe/spits2.jpg

So the bob-or inertia weights were introduced in 1942 to help solve bad loading or overloading of Spitfire Vs at Squadron level - it had nothing to do with NACA's report.

I have to figure the slope anyway for the bugtracker. Might as well do it now.

Yellow:

Acceleration over time 3.5G-(-.5G) divided by 4.5s-3.5s = m
m = 4

Stick force over time: (19lbs - 0lbs) divided 5lbs/G all divide by 4.5s-3.5s = m
m = 3.8

The slopes should match and they are close enough. However, our stick force grows at a slower rate than our acceleration. This is the initial input of the pilot.
Now let's see the instability.

Green:
Stick force over time 15lbs-15lbs divided by 5lbs/G all divided by 6.8s-5.5s = m
m = 0
Of course m = 0, our stick is held fixed by the force measurement equipment
Acceleration over time 4.2G-3.2G divided by 6.8s-5.5s = m
m = .76

So, while our stick remains fixed, the aircraft continues to accelerate on its own. As the nature of instability, there is no correlation stick force input and acceleration.

Now, our pilot in this case only input force to reach 3.5G. In a stable airplane, we should see the aircraft dampen all subsequent accelerations which means the aircraft would not exceed 3.5G without control input.
In this case, the instability or divergent oscillation a 4.2G acceleration with stick fixed slightly below the stick force required to produce a 3.5G acceleration.

:confused:

Are we really gonna have this conversation??

:rolleyes:
I can't help it if you're confused: the-reason-inertia-weights-were-introduced-was-because-Spitfire Vs-were-being-badly-loaded-at-an-operational-level-in-1942. As more operational equipment was introduced some squadrons were ignoring the loading diagrams. It had nothing to do with the NACA report. :roll:

Why don't you read the Operating notes for any early mark Spitfire.

"longitudinal instability" is used often....

I am sure the Spitfire Mark V increase in weight and speed caused an unmistakeable as well as difficult to ignore increase in in-flight break ups.

:rolleyes:Nope, you are quoting well out of context: what caused some break-ups was poor loading by the squadrons, as was explained by Jeffrey Quill:

You can find similar spots in turn time histories for nearly all WW2 aircraft tested this way. Or, you can pick another spot on the very same curve and will find different figures or pick the curves 16-18 and get different results again. If it was a plane quality, there'd be the same behaviour in every test they've done, but it isn't.

NACA evaluates the the behaviour:

"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."

So, what they are saying again is that there are large reactions to small stick travel. Not that the plane was unstable. The stick force gradient and the elevator angle gradient were both found to be positive, as I've said already.

Yes, they definately say there are large aceleration changes for a small amount of elevator travel.

The other part is that they do say the airplane is unstable. Neutral or unstable......

At a neutral or unstable condition, the Spitfire is not able to hold a constant aceleration in a turn.

One can run the math on Cm and see that too.

At forward CG, the static stability is sufficiently large. At normal and aft CG the static margin is neutral or unstable.

But this applies to 'all' aircraft, it seems pretty odd to criticise the Spitfire for something that is universal, this is exactly the same problem the Mustang has with a full fuselage tank.

to determine how much of a problem this is for the Spitfire a decent weight and balance schedule is needed, from that it can be calculated how much fuel burn is required to put the CoG forward.

But is perfectly capable of doing so when flown by a pilot of even limited experience.

I always thought that the "breaking up in the air" of early Spits was mainly caused by design flaws on the tail section (like in the early Typhoons) which emerged in high speed dives.

No it does not.

It depends on the static margin. The static margin will move as the CG changes but most aircraft are designed to have positive stick fixed stability at the most rearward position.

In fact, that point defines the rear CG limit.

So then Mr Crumpp exactly what is wrong stability wise with the IL2 CLOD Spitfire MI I or II Ver 1.06.17582+Hot Fix

No I am not. You don't seem to understand the effect of weight and speed on airframe loads.

I have the entire report and will post it as part of the bugtracker.

Once again, you are going down the rabbit hole.

Thats what i want to know.

And this, gentlemen, is the 64,000 dollar question...

NACA says: "... the small static longitudinal stability of the Spitfire...". Not unstable...it's there in black and white, first sentence of the relevant paragraph. And, again, the stick force gradient and the elevator angle gradient were both found to be positive.

Yes, I'm curious to.

And how has it been tested?

Indeed.

Crumpp, you should answer this one.

The only one going down a rabbit hole is Crumpp, who doesn't seem to understand the cause and effect of bad cg loading on a basically sound design and now assumes that the Spitfire V was prone to break up because it had taken on extra weight and could fly faster.

And what report is Crumpp going to post?

Second question, how exactly can Crumpp's bugtracker replicate the longitudinal stability characteristics Crumpp thinks the CLOD Spitfire I & II should have, when there is no option for rough air conditions?

:rolleyes:

You keep quoting the summary as if it was the only and complete assessment, but it is not. The paragraph dealing with stability as such already gives a more detailed description, that being in general agreement with the summary, but more specific in that "The stability was essentially neutral in all flap-up, power-on conditions of flight except at low speeds, where some rearward motion of the stick occurred." And if we look for further detail on behaviour in accelerated flight, we find "the small static longitudinal stability of the Spitfire" I quoted. And this is proven by stick travel and stick force gradients, for anyone to see.

This doesn't change the fact that NACA found the plane neutral with power off and unstable with flaps down, but this is of no interested in power on accelerated flight.

If you want to sell instability to me, or anyone else who's got a good understanding of the matter, you'll need to explain how both of the above gradients can be positive in an unstable aircraft and how it was possible to fly the smooth stick fixed turns as shown in figures 17 and 18. Repeating the summary yet another time will not do the trick.

I think there's no point in submitting anything to the bugtracker before this has been clarified.

I think its worth remembering that Handling isn't a precise science. Many aircraft have been designed by trained designers well schooled in the theory and science. Yet all at one point or another have produced aircraft that handled poorly.
Any theory needs to be supported by comments from test pilots and others to support that view.

This is something that has often been requested but has yet to be shown apart from one attempt (posting 321 page 33) which backfired.

Ehhh, guys you should calm up.

There was a lot of planes designed in the mid 30's that had pitch instability.

I won't submit you to an aerodynamics exam but Britain, it's a fact, was lagging behind the leading countries in that field of knowledge that were Germany and USA. USA was among the leading country in part because Karman went to work at the NACA in 35/36 (read his book - it's a fascinating tale of time of the great pioneer).

Anyway this is why many british design were too rounded or to thin or somewhat bulky. Not individualy (there was many talented scientist and aerodynamist) but as an institution, they did not master the viscous conditions as much as the leading nations. What was the key to understand plainly aerodynamics.

France had the same amount of knowledge as UK at the time. This is why most of the French design were seen as low performers as the testing didn't meet the expectations of the design teams (hence lower strain on HP demands, higher thickness ratio, lower wing surfaces etc... - One good example of that is the Curtiss H-75 (P-36) from US that was designed before 1935).

Russian did realize that and after the outbreak of WWII a high priority was given again to fundamental research and testing (the TSAGI) up to the point that the late Russian design during the war were above performer (at least in their prototype form). By the way, a little note to the guy in this forum that put Britain at the forefront of aeronautics knowledge when a bit of search will tell you that all this started with Joukowsky, a Russian Mathematician (http://en.wikipedia.org/wiki/Joukowsky_transform)

Before you start repeating your tirade about how British were at the for front of the sciences of aerodynamics etc... Let me tell you this: The father of the Buccaner, leading engineer for years at Blackburnand then BAe (started his carreer at Gloster if I do remind well) explains all this in his book. It tell us the fascinating story of how the Brits test facility were relaying on inappropriate methods (at least not accurate) to simulate airflows in the 40's.

Oh, and by the way, he was also on the board of the British team that worked teh design of the SuperUberModern EF2000billions£. That tell you a lot about how much this design is ready to plink the 21'st century threats - Bah it's another story!

I don't have the name of course. But in regard to your disgusting way of smoking every thread, irrespective prose, and what can be called blatant lying I won't do a single search.

Easy to found : Buccaneer story published in the 80's - small format - no images just text- Cover red, white and blue of course !

I would like to know the name of the book if possible, the Bucaneer was one of the planes I was trained on and had a huge respect for it. Well ahead of its time and in many ways better than the Tornado that 'replaced' it, in my totally unbiased opinion.

As for the theory that the USA were so far ahead there are a few problems with that.

In 1938 the period when the Hurricane, Me109 and SPitfire were entering service the USA had the P35 and P36. Most wouuld consider the P36 to be the better machine but the P35 won the Contest for the USAAF.
The P43 entered service in 1940 when the RAF were getting the Spit II and the German Airforce were close to the 109F. The P40 was always behind the curve.

In bombers its a similar story. The Luftwaffe and RAF had Wellington, He111, Ju88, Do 17 Stuka, Hampden, even the Whitley. The USA had the B18, the Boston was on the way but not until 1940 which was too late and this had some issues. It wasn't all great, the Battle is an obvious example but the european countries had options.

I find it hard to see where this significant advantage the USA had in theory was being applied.

In transport aircaft the USA had a clear lead and naval aircraft.

The USA may have had theoretical advantages but its wrong to overstate it. Its also worth remembering that production of aircraft such as the Fw190 and Mosquito were close behind

Will do my best Glider but can't promise anything.

Edit : Here it is ! Sisi it include the Bucc full story ;) The book tittle was just made sexier with the added types for the neophytes ;)

Buy
http://www.amazon.co.uk/exec/obidos/...underandlightn

Review
http://www.flyingbooks.co.uk/acatalo...rofighter.html

According to Crumpp the Spitfire was dangerous:

http://forum.1cpublishing.eu/showpos...&postcount=245

"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."

(No they weren't, they were added by Supermarine to control a truly dangerous instability problem caused by poor loading at squadron level, but we can let Crumpp away with his poor grasp of history - he's only an engineer. :rolleyes:)

One solution to the "dangerous" instability exhibited by the Spitfire would be for the IL2 developers to add bob-weights - ASAP!

While no one can argue that the NACA was not at the forefront of aeronautics in the mid 1930's, the bashing of British aeronautics and the raising US dito as a beacon of enlightenment seems a bit simplistic given that the US fielded a TRANSPORT aircraft at this time that was actually longitudionaly UNSTABLE in some flight conditions: The Douglas DC-3 was with normal rated power and also under approach conditions statically UNSTABLE. See NACA TN 3088 (Can be downloaded from the NASA NTRS server) page 31 figure 5. Now compare that to figure 9 page 27 of NACA L-334: The Spitfire FIGHTER shows a NEUTRAL/SLIGHT POSITIVE stability and a better elevator force/speed curve than the UNSTABLE DC-3 TRANSPORT.

While both aircraft undoubtedly would have benefited by a larger margin of stability from a control perspective (logically larger for the DC-3 and smaller for the Spitfire) it is by far easier to overlook NEUTRAL stability in a FIGHTER rather than actual INSTABILITY in a TRANSPORT. Also note that the INSTABILITY inherent in the DC-3 did not stop it from becoming a legendary an popular aircraft held in high esteem by the pilots who actually FLEW them so I think one should be careful before making assertions that the NEUTRAL/SLIGHT POSITIVE stability exhibited by the Spitfire was a serious problem. Another thing to consider is that neutral stability in general means less drag and therefore higher performance and that the pilot can generally more easily transition between high and low speed conditions without retrimming or excessive control forces, both of which are valuable traits in a FIGHTER design.

Finally, I can only second the call to present what is actually wrong with the current Spitfire modeling in CoD: As the saying goes, if it ain't broke then don't fix it. While I readily admit to not having read through the entire 59 pages with a loupe the formulation of the actual problem and what needs to be fixed escapes me.

Thanks for that

:rolleyes:

http://img827.imageshack.us/img827/8...res17and18.jpg

Your good understanding? Is that with the long period oscillation's your claimed, the slopes of the curves, the difference between stick fixed, stick free, dynamic and static?? I am confused as to where your good understanding is demonstrated.

OK, I see the problem now: What Crumpp fails to understand is that while the actual stick movement is small, figures 17 and 18 show that the pilot uses between 10-20 lb of pull to HOLD the turn. If one looks at the force histogram its apparent that a relatively constant pull force is needed to keep the plane in the turn. So no increased pull force no increased load factor. Wherein lies the big problem? What would be troublesome would be if there was a need to apply a push force or substantial unloading in order not to tighten up the turn once it had been initiated. However, the histogram shows no such tendencies i.e. the behaviour looks quite benevolent.

Maybe this is also why we on the one hand have numerous accounts from pilots who actually flew the Spitfire and appreciated it and on the other have a private pilot armchair expert who is of a different opinion based on a myopic and selective interpretation of data.

:rolleyes:

Spitfire Mk I Operating Notes, July 1940:

http://img109.imageshack.us/img109/7976/page10jv.jpg

http://img26.imageshack.us/img26/2599/page12dh.jpg

http://img542.imageshack.us/img542/9202/page13o.jpg

http://img607.imageshack.us/img607/2471/page15j.jpg

http://img651.imageshack.us/img651/2456/page16lu.jpg

By all means continue Holtzauge.

Let's stick to what is definable and measureable, as this is my thread.

Yes, let's stick to that: To begin with follow your own advice: What you posted above is as has now been pointed out numerous times some general advice to the pilot on handling characteristics and hardly qualifies to your own strict limitations to what is definable and measurable so you can remove them from "your" thread.

Now what is pertinent and admissible according to your own definition above are figures 17 and 18 so please enlighten us with how these support your case as opposed to mine and JtD's interpretation above.

Why don't read the report about figures 17 and 18?

Here, I will post it once again....

http://img198.imageshack.us/img198/8...res17and18.jpg

Now, Holtzuage....

I would love to have this conversation with you. Should be a wonderful and refreshing change given your claims to be an engineer.

I wait with baited breath for your measured and definable evidence showing the early Mark Spitfire to have acceptable longitudinal stability by any modern definition. Feel free to use the RAE post war standards, NACA, R-1815A, SF119A, MIL-F-8785, FAR, JAR....

You pick!!

Looking forward to it. :grin:

Personally I am waiting for you to supply examples of any WW2 fighter that met modern standards

We know that the Spit didn't but we also know it wasn't a problem. We also know that the DC3 didn't meet the standards and can only assume that the people still flying these aircraft 70+ years after they were designed don't realise that they are so unstable.

We are still waiting for a load of information that you said you had that supported your case.

PS don't claim to have the training or qualifications that you claim to have but IIRC, MIL-F-8785 was mainly short period damping regarding roll, not the longitudinal stability of an aircraft

I have already answered your question. It is in the thread and it is specific to you about this same question.

I am not going to continue to post the information so that you can ignore it when convenient.

That must be when the negative comment was on the Prototype Spit and the second paper on the first production spit, confirmed that the problem was fixed.

Be fair, I did ask at the time if that was all you had and you didn't add anything to it.

So to sum up you have no examples (apart from the above) from any pilot or any test establishment of any nation to support the view that the Spitfire was difficult or uncomfortable or dangerous to fly.
Thank you for that

The DC-3 was unstable in cruise flight only at it's most rearward CG limit. That limit was moved forward.

You can of course prove that statement ?

I would post the NACA report but it is too big even zipped.

Yes, only at the rearward CG limit was the aircraft unstable and only below 120IAS. Above 160IAS, and trimmed out at the rearward CG limit, it was "almost neutral".

No, I gave you a list of examples. You did not bother to read them.

Actually I did and I have checked what you have said. Unfortunately what you have said and what so far I have checked don't tally. For example the Me109 certainly doesn't fit your criteria, without a rudder trim then eventually the aircraft will need manual input. It is also stated in the Zero report that constant attention is needed on the rudder. The Fw190 has almost no trimming tabs on the controls and in my limited experience of powered aircraft without trimming tabs you cannot be hands off and always have to stay in control

It is a similar story when you gave me a list of books that said that the Me109 could turn with the Spitfire, I have checked two of them out and they don't seem to say what you said they say. I did ask where they did agree with your statement, but there was no reply.

I have asked for a list of the flight tests or reports from test establishents/test pilots that say that the SPit was difficult or dangerous or uncomfortable to fly. You stated that you had these but as we have discovered it only referred to the prototype and that was fixed in first production.

You have a habit of being very very selective over what you state and often don't read the papers in their entirity before forming a picture, I can give a number of examples if you so wish.

Take the regs you just quoted. I am pretty sure that MIL-F-8785 is to do with the rolling of an aircraft so what has this to do with longatudinal stability?
I could be wrong on this so if you could confirm this I would appreciate it. However it again from memory it calculated the characteristics of five different types of aircraft from transports to fighters defining what was acceptable for each.
However I cannot help suspect that you are trying to impress and blind us with a list of regs rather than concentrate on what is correct.

Like the 100 octane threads, Crumpp has struck out again.