P-40 turn rate/Flight model check

[ZachariasX]

[...]

The P-40 pretty much has the same Spin behaviour as a J-3 Cub flown from the Rear without Passenger, just a bit quicker.

 

Funny you mention the Cub in that context. I don't know of an aircraft that flys better than a Cub. So "erratic stall" is not something I would have put in context with that aircraft. But thinking of it, it does really come around quickly in the loadout you mentioned. But you have to pull it by the hair as well as kick it in the crotch to flip in a spin...

[Guest deleted@83466]

The stall characteristics shouldn't be so mysterious, since they are described right there in the widely available P-40 pilot training manual published by the USAAF

 

"The stalling speed of the P-40 is approximately 84 mph with wheels and flaps down, about 90 mph with wheels and flaps up.  (These speeds vary slightly among individual airplanes.) 

 

But you can stall the P-40 at any speed, in any position, if you don't coordinate your controls properly.

 

If a high-speed stall develops it usually snaps the airplane.  Unless you ease back pressure on the stick immediately, the plane goes into a spin.  Avoid high speed stalls.  They are dangerous--to you and your airplane.

 

Low-speed stalls, on the other hand, are as safe as they were in your AT-6 and are an important part of your P-40 training...."

[Dave]

I am very pleased with the FM update to the extent that I have been able to test it thus far (P40 handling is much more consistent with first hand accounts).

 

Regarding the stall and spin behaviour, I have discussed personally the stall characteristics of the P40 with pilots who flew or fly it. They all agree that the low speed stall (the one we all practiced repeatedly when converting to type) is benign and preceded by plenty of buffet. According to them, during such a stall you have to be out of balance for any spin to develop. If you let the spin develop it is upright, not fast, and easily recovered using neutral stick and full opposite rudder (like every aircraft I have flown) as long as you begin recovery before about 3 revolutions. If you allow the spin to fully develop, as in many other aircraft, all the control surfaces will stall and it will be much harder to recover, and require significantly more altitude to do so.

 

Warnings about sudden stalls and violent spins in this type are all with respect to accelerated stalls, and stalls when severely out of trim (yaw) - which makes plenty of sense due to the likelihood of a much higher delta in airspeed between each wingtip.

[ACG_KaiLae]

Currently the engine is the biggest problem with the P-40, followed by some of the FM behaviors, like not needing to stand on the right rudder in dives. Stall behavior doesn't seem to be out of wack. 

[Dave]

Currently the engine is the biggest problem with the P-40, followed by some of the FM behaviors, like not needing to stand on the right rudder in dives. Stall behavior doesn't seem to be out of wack. 

 

I think you mean left rudder.

[Dave]

A Stable Aircraft doesn't Spin in a stable manner. Overly Stable Aircraft don't spin, Unstable Aircraft Spin Stable. 

 

 

Cessna 172 (an exceedingly stable aircraft) spins beautifully stably. No wild oscillation in pitch or angular velocity. Easily recovered even from fully developed spin.

PC-9A - quite agile in pitch and roll whilst being sufficiently stable for advanced pilot training - spins quite quickly and rolls inverted on spin entry (typically to the left) - has a noticeable oscillation in angular velocity with a distinct nose down attitude once established in the spin.

 

Unless there is some translation problem here this doesn't gel with your assertion. By "stable spin" do you mean deeply stalled spin? And by "unstable" aircraft do you mean in pitch or roll or both? If you are talking about aircraft with rearward CoG I might agree. I'd be more inclined to say that spins can be harder to recover in aircraft with rearward CoGs due to a reduced nose down attitude tending to hold the aircraft stalled in the spin.

 

 

 

Edit: Source - I have done plenty of spin-recoveries in each.

Edited September 5, 2017 by Dave

[FTC_Riksen]

Hey Dave when are you gonna get rid of that unconfortable wooden stool mate? lol

[Venturi]

I think you mean left rudder.

 

 

Right now, it does take almost full trim left to keep her centered in a dive, which is correct.

Hey Dave when are you gonna get rid of that unconfortable wooden stool mate? lol

 

Dave is a right gentleman and we have spoken on TS many times. Unfortunately he is an aussie, but I wouldn't hold that against him and I would take him at his word.

 

[19//Moach]

wooden stool.... been there, done that....

 

 

except that it was my MSFF joystick (v1, not that fancy v2 stuff) sitting on the stool, between my legs, while I sat a horrible half-broken (more than half) office chair in front of a 19" CRT eyeball-blaster-zap-gun... 

 

can't say those were the "good ole' days" because  that would contradict the oxford definition of the word "good".... but that was over ten years ago, nowadays, I use THIS instead, very gladly too, by the way...

 

 

 

 

as for the P40, I'm not sure what substances have been abused here, but the "old  crate" has a marked need for LEFT (the other right) rudder when on a dive, and calls for some 20%-ish right hand trim on a slow, high powered climb...  this is perfectly in agreeance with historical records and accounts, that "one can tell the P40 pilots by their muscular left leg" - since that's what did the heavy pushing whenever the plane was put on a dive...

 

or maybe they said that about their right legs, referring to the pressure needed on takeoff and climbout...  anyways, whichever leg it was, all of it is wonderfully modelled now 

 

 

 

 

left open for debate - the engine still massively overcools and the startup procedure includes correctional steps for overpriming that make it take twice as long to complete...

 

discuss   ( round 1, FIGHT! )

Edited September 5, 2017 by 19//Moach

[Venturi]

Also, the coolant flaps do not significantly reduce the aircraft's speed when fully open - even though in the manual, the coolant flaps must be placed in neutral position at max for anything approaching cruise speed and above. Opening them at high speeds will damage them.

 

The coolant flaps must also be fully open on the ground, or the engine will almost immediately overheat. Conversely, with airflow, the flaps never need to go more than halfway except in a slow speed, high power situation. Like a max effort climb or slow speed dogfight.

Completely agree regarding engine overcooling. Obviously.

[Dave]

Hey Dave when are you gonna get rid of that unconfortable wooden stool mate? lol

 

Soon I hope. I have designed a simpit based around the P51D airframe blueprints I have but seem to be too readily distracted by playing BoX to get off my sore arse and fabricate it. Maybe the arrival of my Rift today will spur me to finish it.

 

 

As you can see I've made an effort to pad it but after an hour or so you feel every grain in that wood - trust me.

Edited September 6, 2017 by Dave

[Dave]

Right now, it does take almost full trim left to keep her centered in a dive, which is correct.

 

Yep. Was pointing out that as you increase speed you need left rudder not right. The FM treatment seems very good to me now. Even required trim settings, and their control effectiveness, are as I would expect. Even the skating rink ground handling and incorrect strut compression on take off roll (it was the wrong strut - ie they had the aircraft torquing in the wrong direction) has been fixed.

 

It's not a stellar climber or speed demon - and that is accurate. I think some of my subjective perception of improvement is also due to the relative turn performance improvement against the 109s. I can now employ period correct maneuvers in engagements against 109s and they actually work.

 

The 2.012 update has transformed both the P40 and the game as a whole for me such that I no longer want to delete it from my PC.

 

Edit: Oh - and you will no longer have to suffer me complaining in MP about the previously rampant stabiliser abuse. Yay for you.

Edited September 6, 2017 by Dave

[Guest deleted@83466]

 

Unfortunately he is an aussie,

 

 

 

That's why god created alcohol, especially when they start singing 80's pop songs.

 

[Guest deleted@83466]

From the book "Fire in The Sky" 

 

(Sammy Pierce 49th FG)

"I dove Number 42 to the point where airspeed indicator went all the way around, the manifold pressure went to the stop and the RPM went 300 past normal maximum.  Even using full left rudder trim, standing on the left rudder, and using left aileron, the torque caused the P-40 to want to roll to the right.  But it stayed together, and kept flying, even though the rudder had to be replaced.  Several times we took some fairly good hits that didn't really affect the flying or performance"

Edited September 6, 2017 by Iceworm

[BlitzPig_EL]

Diving is one the the in game P40's great assets.

 

It can dive at speeds that will have the Russian planes shedding parts.

[216th_Lucas_From_Hell]

It can dive at speeds that will have the Russian planes shedding parts.

So 500km/h?

[BlitzPig_EL]

 

Well over 450mph.

 

You have to be careful on the pull out, but yeah, it can be done.

 

Diving is one of the reasons I usually won't fly the La-5.   It's just too easy to shed an aileron, or two...  

[216th_Lucas_From_Hell]

One too many shredded ailerons in all Soviet aircraft while diving. The one that hurt the most was a bounce on Wings of Liberty - took the LaGG-3 to cover a front-line objective from level bombers, flew patiently to 6000m, spotted a pair of dimwits in 109s flying at 4000m as if they were on top of the world. Textbook approach, turned to put the sun behind me, gained some speed for good measure and rolled over to being the dive. The controllers started locking up so I failed to execute minor corrections and missed the shot, then one aileron went, shortly followed by the second one, and with bits and pieces falling out and a canopy that refused to open my LaGG-3 lawndarted beyond 700km/h into the steppe with the pilot in it.

 

Just how much altitude does one need to recover from such a dive in the P-40?

[BlitzPig_EL]

Good question, I'm usually so busy at the time that I just do it and not pay too much attention to the dials.

 

[Farky]

Well, I totally forgot that I have "Test of XP-40 airplane in NACA Full-scale tunel". And yes, maximum lift coefficient is there. So, there you go -

 

https://www.sendspace.com/file/ajs29p

 

I'm not sure for how long will this link be active, if you will need this report upload again, just let me know.

[unreasonable]

CLmax chart from that:

 

 

 

Looks like about 1.35 clean on that chart....  1.32-1.35 in game.  Pity this did not come up earlier in the P-40 thread, might have saved some people a huge amount of angst.   Not sure how anyone can reconcile that with an 88mph stall speed.

[ACG_KaiLae]

What's the bottom axis there? I'm also curious how you can reconcile the above, with other listed facts given about the aircraft. I'm not saying the chart is wrong, but the weight seems to have been driving the high numbers. Also not saying the weight is wrong either, just would like to know why standard calculations are so far off. Also, there's listed PEC information for the stall speed region for a P-40B that would support the slower stall speed. Which is again, suggestive but not decisive. I'm wondering why all of the data points don't really agree?

 

With regards to remaining details left on the plane to correct, they're all engine related, such as displayed oil pressure, cooling system, warning lights, etc.  We should probably begin to collect information on that for improvement. Also, I'm still curious about the flight manual saying that MP went down as RPM increased until a certain height was reached and then it reversed?

Edited September 13, 2017 by Kai_Lae

[unreasonable]

The bottom axis is the angle of attack - it is the same chart as every other CL chart - and in the report the scale is on the next page. You can cut and reassemble the two to see the match. The peak CL (FG up) is at about 18 degrees.

 

The weight is not and has never been the main issue: the formula we have been using for calculating CLmax shows that a change in weight is exactly proportionally matched by a change in the CLmax, and since the alleged weight "discrepancies"  are anyway rather small they will have a small impact on calculated CLmax.  Anyway, the weight allegations have been fully answered by Farky in the P-40 thread: he thinks the weight in game is right and I agree.

 

The issue is the stall speed - since this is squared in the formula, the result is much more sensitive to the stall speed input.

 

The problem here is quite simply the conversion of an IAS from a manual into the TAS that the formula uses.  

 

If you use Venturi's preferred PEC and come up with a TAS lower than the manual IAS - or even equal - you get a very high CLmax. So high that the P-40 is in fact a wonder-plane. A much, much higher CLmax than that of the Spitfire Vb as measured by the RAE, who really ought to know better than anyone else, and which uses a very similar airfoil. Higher even than the airfoil CLmax, according to the data we have. Ie it is physically impossible and nonsense.

 

The only remaining explanation is that the stall TAS is actually a few mph higher than the manual's IAS. This is entirely understandable when you take into account the PEC error caused by the angle of attack, which Venturi's calculations do not do - or at least he has been unable or unwilling to answer my request that he show how they incorporate angle of attack effects. It is consistent with the RAE Spitfire results.

 

In other words, the game is right according to the data we have, IAS is not > TAS (edit at the stall), and the PEC of P-40 at stall speed is not -ve but +ve. This measured CLmax supports that conclusion.

 

The problems in the game had nothing to do with the CLmax in the first place, but I believe came from:

 

a) a slightly low critical AoA: if it was 18 degrees on this chart, the original stall AoA in the Tech spec notes was given as 14 degrees. This is what the tech specs still say, but Hans DD notes said that this angle had been increased in the last release. I think it will be a while before the team do a new set of robot tests to replace all the tech spec numbers.

 

b) The whole FM issue relating to roll/yaw coupling, (or perhaps something else) which the new FM appears to have solved, according to the reports.

Edited September 13, 2017 by unreasonable

[Venturi]

It is quite obvious that wing airfoil CLmax is not the same as airplane CLmax, a conclusion I came to some time ago.

[unreasonable]

It is quite obvious that wing airfoil CLmax is not the same as airplane CLmax, a conclusion I came to some time ago.

 

Hardly any great insight, since this is stated in NACA documents that have been posted as well as text books.  Additionally, in every case that I can recall, the plane CLmax is lower than the airfoil CLmax - or the wing CLmax, since these are not the same thing.

 

Anyway, the fact is that the only whole plane CLmax for a P-40 variant that I have seen posted on this site or anywhere else gives a value of about 1.35 - the game is within 1% of that. 

[ACG_KaiLae]

Actually, there's a 3rd factor, which was that they had gotten lift induced drag incorrect, which meant the more you turned the worse it got.

[Venturi]

Additionally, in every case that I can recall, the plane CLmax is lower than the airfoil CLmax - or the wing CLmax, since these are not the same thing.

 

And what instances are those, precisely? Because to my knowledge, you have posted ZERO examples, whereas I have actually done quite a bit of work on this and posted them here. In fact, such examples are available in the NACA test of whole airplane CLmax'es I have already posted in source documents.

 

Your attempts at discrediting me are obvious and petty, and do not require a response on my end.

[unreasonable]

And what instances are those, precisely? Because to my knowledge, you have posted ZERO examples, whereas I have actually done quite a bit of work on this and posted them here. In fact, such examples are available in the NACA test of whole airplane CLmax'es I have already posted in source documents.

 

Your attempts at discrediting me are obvious and petty, and do not require a response on my end.

 

I remember my Granny telling me never to do for someone else what they are quite capable of doing for themselves.

 

The point of this forum subsection is nothing to do with discrediting anyone, it is purely to do with discovering the truth through sharing data and having ideas subjected to analysis. It is no discredit to anyone to put forwards an idea or argument that is proved to be wrong. What does bring discredit is ignoring requests for clarification, refusing to engage in the substance of an opposing argument and casting aspersions about other peoples' motives.

 

For the record, I have not posted a specific document showing that aircraft CLmax lower than airfoil CLmax because all of the NACA documents have been posted already in this forum, mostly by JtD. I regard it as common knowledge which does not need constant references to sources, somewhat like the fact that the moon is smaller than the earth.   Even Crump agreed that plane CLmax must be less than airfoil CLmax: he even posted an extract from one of his textbooks stating just that.   I do not recall a single example of a document, including all the NACA test documents, showing aircraft CLmax higher than that of the wing or airfoil.  Indeed I am not even sure if it is physically possible, unless the rest of the aircraft minus the wings has a higher CLmax than the airfoil, which seems somewhat improbable.

 

If you can point me at one of the NACA sources that shows a plane CLmax higher than that of it's airfoils, please do so. I cannot find one.

[BlitzPig_EL]

Theoretical question.  If the fuselage and empenage  of an aircraft do produce some small amount of lift independent of the airfoil, would it be additive to the number produced by the wings to produce the total CL number?

 

I know it seems obvious, but so many things that seem obvious in aviation theory simply are not so.

Edited September 13, 2017 by BlitzPig_EL

[unreasonable]

Theoretical question.  If the fuselage and empenage  of an aircraft do produce some small amount of lift independent of the airfoil, would it be additive to the number produced by the wings to produce the total CL number?

 

I know it seems obvious, but so many things that seem obvious in aviation theory simply are not so.

 

Not sure how much to go into to answer that, so here is a stab at it...

 

The lift is additive - from the fuselage or the horizontal stab, for instance, although there is a bit of a problem as the area used in calculation is a wing reference area.  So if you add to the lift quantity but not change the area, CL will be higher.    

 

In measuring a whole plane's CLmax all of the lift of all surfaces is taken into account, based on a standard wing reference area.

 

[ Cl = L / (A * .5 * r * V^2)     see https://www.grc.nasa.gov/www/K-12/airplane/liftco.html  for a fairly clear explanation in case you have not seen that before.]

 

So for an aircraft you would need to know the total lift of wings plus fuselage etc.  We can estimate that because in level flight, lift = weight by definition.   CL is at the maximum at Vmin stall - so if we know Vmin, (in TAS!), we can calculate CLmax.

 

Wing tip downwash reduces wing CL compared to the airfoil maximum. In addition, the interactions of the surfaces of wings, fuselage etc, having manufacturing imperfections, gun ports, dust on surfaces etc all change the aerodynamics for the worse, hence the plane CLmax never reaches the theoretical limits of the airfoil.  One NACA report - from memory, as I cannot recall which one it was - says tests show this adds up to at least a 0.2 reduction for a plane in good nick with gaps filled, etc, and can be much more than that for a service plane.  So a plane with airfoils having a CLmax of 1.55 might easily have a measured CLmax of 1.35 

[JtD]

Well, I totally forgot that I have "Test of XP-40 airplane in NACA Full-scale tunel". And yes, maximum lift coefficient is there. So, there you go -

 

https://www.sendspace.com/file/ajs29p

 

I'm not sure for how long will this link be active, if you will need this report upload again, just let me know.

Awesome, 20 pages or so late, still - thanks a lot for sharing it.

 

I just had a really quick look at the curve unreasonable posted - two issues caught my eye - first, the low speed, meaning low Reynolds number and two, the removed propeller. An increase of the Reynolds number typically increases the maximum lift coefficient slightly and not having the prop mounted, producing a little slipstream, would also trend to give slightly lower clmaxes than you would get in a flight test.

I'll the NACA2200 series airfoil data for Reynold number influence and I'll also have to read through the report to see if/how they corrected the wind tunnel data.

 

Finally, we're getting there.

[Venturi]

Theoretical question.  If the fuselage and empenage  of an aircraft do produce some small amount of lift independent of the airfoil, would it be additive to the number produced by the wings to produce the total CL number?

 

I know it seems obvious, but so many things that seem obvious in aviation theory simply are not so.

 

Here is your answer:

 

[BlitzPig_EL]

Ah yes, lifting bodies.

 

Saw a couple of them, and some wind tunnel models of them, at the NMUSAF at Wright Field last week when I was there.

 

Still I don't think any of "our" planes fit that category, though they are still interesting in their own right.

[Venturi]

No, but it make a point.

[JtD]

Getting back to the Reynolds number - increasing the speed from the measurement speed of 50 mph to a more reasonable 1g stall speed of around 90mph, Reynolds number increases from about 3 to about 5.5. As at this higher number the boundary layer is more turbulent, the airflow is more resistant to separation from the wing surface and will at higher angles of attack increase the maximum lift coefficient.

 

Unfortunately I didn't find anything on the NACA 2200 series airfoil in particular, but there is quite a bit of general info, and it covers quite a variety of airfoils. They are very different from each other, but they all share an increase of the clmax of at least 0.1 when increasing Reynold number from 3 to 5.5. The ones I consider most similar, with an equal amount of camber, increase about 0.11 average. I'd consider it save to add this to at least the 1.32 of the first peak at 15°, so we'd end up at 1.43 @ 16°.

I've been wondering why we had a 'double stall' shape on this curve, which would be fairly annoying in real life - very hard for the pilot to bring the plane to the actual limit. Unfortunately, it is not being discussed. Anyone with a good explanation? Could it be a stall of the tail fin, happening prior to the stall of the main plane?

Speaking of the tail fin, we shouldn't forget that the elevator was in neutral position, and putting it up into a pitch-up position would reduce the clmax a bit, as they provide about 6% the total lifting surface. But then I went with 1.32 instead of 1.35 already, so this is probably covered.

 

Anyway, 1.43 is pretty much what I'd expect from the P-40, in fact an exact figure I've stated previously as a common sense ballpark. Happy to see the wind tunnel data is getting extremely close to this.

[Venturi]

I'd have to see what a 90mph stall at 8100lbs results in as far as CLmax for the airplane. But do agree this is more in the realm of reality. I do think that most manuals would specify stall speed with engine on at idle. I also think that 8100lbs is a good weight for this as we are talking +/- 2mph for stall at this TAS, depending on load, per manual.

 

With a maximum all-flight types weight of 8500lbs I believe the manual would have a lower weight for the stall speed with that +/- TAS figure, than maximum all flight types weight.

 

I do not buy that the manual's stall airspeed has any AoA instrument error built in. I think the only instrument error paid attention to is the PEC (and only occasionally), and that the aircraft stall speed was determined by trailing instrument method. Per the period US Army testing reports I have already posted. In other words, the whole AoA-pitot issue while maybe a problem in reality is not a problem in the game. Since we have no errors like that simulated. And I believe the original stall speeds were not determined from ASI, but rather from the trailing instrument method, with at most, calculated PEC corrections from higher airspeeds.

 

In other words 90mph TAS in clean configuration at 8100lbs, with engine on and idling, is my best thought given all the evidence.

[unreasonable]

I do not see it as probable that a manual would give a figure for stall speed that was not what the pilot sees on his cockpit instruments, at least if the manual is serving the function of pilot's notes.  What would be the point? It would be dangerous to give the pilot a number from a trailing pitot measurement when he has to read a number from a conventional installation. 

 

8100lbs at 90 mph = CLmax 1.66

 

I doubt that very much.

 

To get JtD's ballpark of 1.43 at 8100lbs you need 97mph.

[Farky]

Talking about stall speed in manuals - I know only one pilot's manual for P-40E/E-1 with power off stall speed and that is RAF manual AP 2014A. It states : "Stalling speeds are as follows: Undercarriage up and flaps up - 92 I.A.S.". It also states : "The above stalling speeds are subject to plus or minus 2 m.p.h., depending on load".

 

 

With a maximum all-flight types weight of 8500lbs I believe the manual would have a lower weight for the stall speed with that +/- TAS figure, than maximum all flight types weight.

 

I think that stall speed in manual will be somewhere between minimum and maximum weight and maximum permissible weight of P-40E was up to 9500 lbs.

 

 

And I believe the original stall speeds were not determined from ASI, but rather from the trailing instrument method, with at most, calculated PEC corrections from higher airspeeds.

 

If you mean by that "stall speeds in manuals were determined from trailing instrument method", that will be extremely dangerous for pilots. Stall speeds in manuals are ALWAYS in IAS (INDICATED airspeed), you must tell the pilot speed he sees, obviously.

 

[Venturi]

1. Nowhere does it say power off that I have read. Anywhere.

 

2. If ASI is the stall speed and we are using the manuals then it should be 90mph TAS stall (-2mph adjustment for PEC). That is 5mph too high in game. So I am glad you agree with me. Especially since you think pitot ASI is accurate enough at stall to be critical.

 

3. Manuals state maximum maneuvering weight is 8500lbs. Maximum permissible overload is 9500 but no maneuvering allowed. I have already posted the source try using search.

 

Thanks a lot for your input but you have provided no further evidence to contradict the existing multiple sources which give TAS stall speeds from 86-90mph.

[Farky]

1. Nowhere does it say power off that I have read. Anywhere.

 

 

Right. But since in USAAF pilot's manual for P-40D and E (TO No. 01-25CF-1, issued April 10th 1943) is power on stalling speed for clean airplane 85 mph IAS, i think that is safe to say that 92 mph IAS in RAF manual is for power off stall.

 

 

2. If ASI is the stall speed and we are using the manuals then it should be 90mph TAS stall (-2mph adjustment for PEC). That is 5mph too high in game. So I am glad you agree with me. Especially since you think pitot ASI is accurate enough at stall to be critical.

 

 

I don't know if TAS stall speed should be 90 mph, that is not point of my post at all. What i know is that Air speed indicator in cockpit should show at stall speed aproximately 88 - 92 mph IAS. It doesn't, BUT it doesn't matter, IF other planes in game got the same kind of "error". And it looks like they do, same standard is used for all airplanes. At the end of the day, it's really about mutual differences, not accurate numbers.

 

What I am saying is this - theory that stall speed in manuals was determined by the trailing instrument method is wrong, it doesn't make sense. That's it. And this isn't about accuracy of IAS at all (i don't know if you mean airspeed indicator or airspeed indicated by ASI). Stall speeds in manuals were determined by flight tests, you should read in cockpit same stall speed you read in manual. Any other way can be and will be deadly.

 

 

3. Manuals state maximum maneuvering weight is 8500lbs. Maximum permissible overload is 9500 but no maneuvering allowed. I have already posted the source try using search.

 

 

I don't get your point here, airplane with weight 9500 lbs can't stall ?

 

You actually mean Australian technical order, not manuals. Anyway, I know RAAF "Kittyhawk Instructions No.1 - Limitations to be observed during flying", i don't need search for that. Btw, in first issue (April 10th 1942) of thi technical order is "Normal weight for all forms of flying = 8000 lbs" and for "Maximum weight for straight flying and gentle turns = 8845 lbs". And also "STALLING - Flaps and Undercarriage up = 86 M.P.H.". 

 

 

Thanks a lot for your input but you have provided no further evidence to contradict the existing multiple sources which give TAS stall speeds from 86-90mph.

 

 

Shiny, because that wasn't my point. Do I have to agree or disagree all the time? I hope not.