P-40 turn rate/Flight model check

[19//Moach]

(...)

 

 

What it basically tells us is that the P-40 needs to get the Bf-109 low and slow.  The P-40 can turn at airspeeds the Bf-109 cannot even fly.  That being said, if the Bf-109 stays in his envelope, he matches the P-40 and even has a slight advantage in Rate of Turn at his best turn speed.

 

it seems to me, however, the P40 as is ingame, is not capable of matching this expected behavior

[Crump]

1150 Are obviously Horsepower

 

 

The analysis above uses Allison data for 52"Hg.  If the VVS was only getting 1150hp out of their P-40E then the performance will be adjust accordingly:

 

 

 

 

 

 

The lower power used by the VVS really hurts the P-40E performance.  The Bf-109F4 has some definitive maneuvering advantages.

 

 

it seems to me, however, the P40 as is ingame, is not capable of matching this expected behavior

 

It is using the lower power settings as per the VVS operating instructions and not the full power Allison authorized.  That needs to change if the airplane is going to be the competitive fighter it was in the early war in the west.

 

It is no wonder the P-40 in VVS service was considered a second rate fighter. 

Using the VVS power settings, the P-40E has a very narrow margin of superior turn performance over the Bf-109F4.  In reality, the fight will probably be over before the P-40 pilot could set the conditions he would win.

[19//Moach]

in which case, this does seem to support the ingame conditions - where the P40 is not capable of holding up in a fight with a 109 unless he has a considerable tactical advantage

 

I have read reports from VVS usage of the P40 stating their losses were actually very high - and indeed it was so that the plane was preferred for ground attack, just as it is in game

 

 

the many accounts I have of pilots saying it would out-turn the 109 in a flat contest were from the western front - perhaps the russians were "using it wrong"?

[Crump]

http://lend-lease.airforce.ru/english/articles/romanenko/p-40/

 

It does kind of seem to fit the VVS description.

[MiloMorai]

"From information gathered from interrogations of shot down German pilots from II and II/JG 5 (A. Jakobi, H. Bodo, K. Philipp, and W. Schumacher), it was learned that they considered the Tomahawk to be a serious enemy (they placed only the Bf-109F and the Airacobra above it). The relatively limited success of Soviet pilots was due primarily to their adherence to defensive tactics and insufficiently decisive attacks."

 

"Altogether the VVS VMF USSR received 360 P-40s of all models from 1941-1945, and lost 66 in combat (18 percent), the lowest loss percentage among fighters of all types."

 

http://lend-lease.airforce.ru/english/articles/romanenko/p-40/

Edited October 29, 2016 by MiloMorai

[Crump]

 

 

The Kittyhawk was considered an "average" aircraft in the Soviet VVS, better than the I-15, I-16, and Hurricane, but not as good as the P-39, Yak, or Lavochkin.

 

 

 

 

Gradually (as a result of subsequent losses) these were replaced by the P-40E and -K. Later two paths emerge: If the regiment did not particularly distinguish itself in combat (greater losses and lesser victories), it was transferred to PVO and received the P-40M and -N. If it achieved notable combat success, it became a guards regiment and was rearmed with the P-39, Yak-7 and -9, or La-5. 

 

 

http://lend-lease.airforce.ru/english/articles/romanenko/p-40/

[Stig]

Was the P-40 considered an above average aircraft on the Western front?

[Crump]

Question is did the VVS increase the limitations of the P-40E series they had in use and if so when?

[II./JG77_Manu*]

 

 

The P-40 can turn at airspeeds the Bf-109 cannot even fly.

That is not true in the game. P40 stalls out before the 109 in a slow ongoing turn 

 

 

The Kittyhawk was considered an "average" aircraft in the Soviet VVS, better than the I-15, I-16, and Hurricane, but not as good as the P-39, Yak, or Lavochkin.

If only this would be true in game. I16 miles better and more effective then the Kitty 

[Crump]

 

 

hat is not true in the game. P40 stalls out before the 109 in a slow ongoing turn 

 

Then it does not appear to be correct.  We have to prove that.  Can we get some measured data from in the game and we can submit a bug report.  

 

Some film would great showing the stall speed under the same conditions for the Bf-109F4 and the P-40E.

 

Aircraft set up for both test:

 

Take 100% fuel and full ammunition for the weapons.

 

Altimeter set to sea level on a standard day NOT nearest airfield.

 

 

Test procedures:

 

 

 Film is a power off FULL stall test.  That means we take the stall to the point the airplane departs controlled flight.  It is not minimum controllability but actual departure we are looking for...

 

Again, altimeter at sea level on a standard day.  

 

Take the aircraft up to 3000 meters altitude.  Put the airplane in slow flight about 20 kph above the stall point.  Maintain altitude and heading (+ or - 10 degrees).  Reduce power to idle and gently pull back the stick slowing the aircraft at a rate of about 2kph per second.  It does not have to be exact, just do not be faster than 2kph/sec.  Use rudder to maintain heading and keep the wings level.  If that cannot be done, record it, do it a couple of times and then use ailerons to keep the wing level for the next run.

 

Note the speed that the airplane DEPARTS not when you think you have no control but the moment the airplane is making large uncommanded movements and you are just along for the ride.

 

Try and do at least two runs, the more you do the better the data. 

[andyw248]

"Altogether the VVS VMF USSR received 360 P-40s of all models from 1941-1945, and lost 66 in combat (18 percent), the lowest loss percentage among fighters of all types."

 

In its first paragraph, the article states: "In all, the USSR received 247 P40C (Tomahawk IIB) and 2,178 P-40E, -K, -L, and -N aircraft from 1941 through 1944" (for all branches, not just the VMF). Just making sure we keep the complete picture in mind.

Edited October 30, 2016 by andyw248

[Dakpilot]

Was the P-40 considered an above average aircraft on the Western front?

 

One has to always remember that the version we have is the P-40 E many of the successful combat reports are from later models which had considerable structural/design and engine differences from E model.

 

Not saying the P -40 in game is right or wrong but there is a lot of 'generalization' when discussing P-40 performance/history 

 

Cheers Dakpilot

[Stig]

I agree, Dak, and I will add that the reputation even the later models of the P-40 has taken with it from WWII is based in large part on inflated claims. In the end, the expectations people have to this plane are not likely to be fulfilled, no matter how close the devs get to modelling it right.

[Venturi]

It is very simple, if the engine cannot be used as it was historically, you will not get historical performance, even if everything else is right.

[303_Kwiatek]

Not true

 

http://yarchive.net/mil/p40.html

[Crump]

The P-40E was a good fighter and every bit the equal of the Bf-109E series.  It is kind of outclassed by the Bf-109F4 and FW-190's in the game.

 

 

 

It is very simple, if the engine cannot be used as it was historically, you will not get historical performance, even if everything else is right.

 

Han posted the VVS data used in the game.  I would think that the VVS received the latest updates from Allison as part of their support package.  In other words the VVS should have been able to use the latest power limitations like every other allied user of the P-40 series did.

 

It would be nice if someone on the Russian side of things could confirm that.  Without it, we have no data and no proof to ask for any change in modeling the VVS export variant.

 

If we get to the west or the Pacific, then the power must be changed to be representative.

Edited October 30, 2016 by Crump

[Venturi]

The engine is not the entirety of the situation. The P40E also does not handle low speeds as it should. I am not sure if it is the wing, or the total lack of acceleration at even low speeds. But in the game I would feel much more comfortable handling a 109E at 150kph and low alt in a turn, than handling a P40E under the same circumstances, and I am not sure that is right. The 109 is much more forgiving, and I am not sure that is right. As Joe said, "I could throw that thing around like a big kite". The P40 certainly does not feel that way right now.

 

I remember in the recent past, someone in the dev team writing as an aside, "We will probably look at the P40 again in the future to fix some things" when the P40 was first early-released. I still think that needs to be done, and I think the time to do that is NOW before other allied birds come into play.

[Venturi]

The spin characteristic of the P-36 was entirely different from that of the P-40; the spin/ snap roll of the P-36 was quite violent. I was unable to snap or spin any of the P-40B's that I had flown although I tried without success. The difference was due to a cuff place [placed] on the wing root of the P-40, but absent on the P-36.

Spin recovery for the P-36 was the standard NACA recovery. Flat spin recovery was pro spin: full aileron into the spin, stick full back, and rudder into the spin. When the [nose] dropped and normal spin developed, [standard] NACA recovery was used. [i reckon this is the spin recovery I was taught: power off, neutralize the stick, and kick full opposite rudder to the airplane's rotation. Once the plane stops spinning, be ready to counteract if it begins to spin in the other direction. Then pull back hard to recover from the dive.--DF]

However the P-40 had a vicious tumble (end over end) if a stall was entered into at a nose high position of about 60 degrees above the horizon. To recover from the tumble you reduced power and went along for the ride with all controls in neutral. After about 12,000 feet the nose settled into a vertical dive from which recovery was normal. -Erik Shilling http://www.warbirdforum.com/p40spin.htm

 

P40 Wing airfoil: NACA 2215 at root tapering to NACA 2209 near tip

P40 Wing area: 236 sq. ft.

 

Source: Curtiss P-40: Snub-nosed Kittyhawks and Warhawks, Osprey publishing

 

The first and second was the result of the lack of power. What we did was simple. First drawback we removed by holding higher RPM. We always flew it with increased RPM. Second: we took (wing-installed) guns off. That was it. Fighter became "on par". It all depended of yourself, the most important thing was not to be lazy, to work more intensive with the throttle. Truth to be told, engines were "burning away" from our unusual settings. They would last up to 50 hours, often shorter. They would usually clock up to 35 hours and then be replaced. -General-Major Nikolay Gerasimovich Golodnikov (retired) 

 

And of your intensive work with throttle would do "abracadabra" (translator's. note: according to Golodnikov, Tomahawk—but not Kittyhawk—woud sometimes tumble "head over heels", depending of the throttle or harsh stick movement!). Allies found many drawbacks of "Tomahawks", but "abracadabra" was not mentioned. Why?

Golodnikov: I don't know, but "Tomahawk" had that drawback.http://www.warbirdforum.com/russp40.htm

Edited October 30, 2016 by Venturi

[Stig]

Whether or not the P-40 is modelled correctly or not ( and it very likely isn't 100% correct) is a moot point. Same with the engine settings, for however much the RL pilots over boosted the engine doesn't change the results that the P-40 actually achieved. Once you begin stripping away the over claims and start comparing to actual enemy losses, you see that the even RL P-40 doesn't live up to the hype surrounding it. 

[=362nd_FS=Hiromachi]

 

 

Not true http://yarchive.net/mil/p40.html

I'm sorry but this is not a reliable source, Erik Shilling was AVG pilot but his combat experience is limited even if compared to his AVG buddies. He never flew any other of the aircraft he is speaking of except for P-40B (and CW-21 if that matters), he did not have a chance to compare them, most of this is just repeating intelligence reports and experiences of other pilots. As much as one can admire his pilot skills and life adventures (which I do) as well as good will, his knowledge is limited - which you can pretty much see when he brings Zero to comparison, all the number he has come from one of the interviews with S. Sakai. Unfortunately there is a huge legend blown out of proportion about AVG, if anyone dares to touch it he is forever prohibited from getting close to those guys (like quite a few historians learnt later on).   

 

Venturi, in regard to flight characteristics, just look up for "Measurements of the Flying Qualities of a Curtiss P-40 Airplane" by William Hewitt Phillips, Army Air Corps, May 31, 1941. This should pretty much answer most of the questions, even though it would rather represent P-40B which is one heck lighter than P-40E. 

[Venturi]

I have two sources who have extensive time in the Tomahawk saying exactly the same thing.

 

Thanks for your input.

[=362nd_FS=Hiromachi]

What I mean is that "Measurements of the Flying Qualities of a Curtiss P-40 Airplane" is a NACA document, a series of tests with more of a scientific approach and thus providing graphs, tables and numbers to back up all the conclusions. I'd not underestimate its importance here, though one must admit it is very hard to find. It's not available in NASA archives and back in the day I also could not find it via National Archives and Records Administration, but it must be somewhere. Especially as it was one of the first reports Phillips made on the matter of flying qualities which led to creation of stability and control-ability requirements, affecting many of the US WW2 aircraft.

 

http://history.nasa.gov/monograph12/ch4.htm

FIGURE 4.3. Curtiss P-40 airplane. This airplane at the start of the war was lightly armed and underpowered compared to British and German fighters. Its flying qualities were satisfactory except for the usual heavy aileron control forces. Stalling characteristics were poor in some conditions. The airplane had a particularly bad tendency to ground loop, which was found to be caused by asymmetrical stalling of the wing in the three-point attitude. This problem was cured by extending the tail-wheel strut so that the airplane remained unstalled on the ground.

Edited October 30, 2016 by =LD=Hiromachi

[JtD]

Is it available by now? Last time I checked, it wasn't.

[=362nd_FS=Hiromachi]

It's not available on NASA website, but there must be some reason why its not. I'd at least hope that someone would make an effort and contact archives guys about it, not to mention that copies of it might be held in other places. It's much easier to do for US citizen than someone from Europe or Russia. 

[JtD]

I contacted them some years ago and still came up empty handed. I agree, a US citizen might stand a better chance.

[=362nd_FS=Hiromachi]

Hmm, I found few of the documents of NACA, not available online, in various archives and units. To my surprise some of it was held in London National Archives, Kew. As a matter of fact I just went right now to see what they got and I found this: "Curtiss P-40 aircraft: measurement of flying qualities" with reference number DSIR 23/12268. However its dated for 1943, which is not a date of original document. However it might be a date when copy reached Britain, I'm not sure. There are two other P-40 related reports, one concerns rudder and tail fin design and other compares aileron characteristics with Hurricane, Spitfire and P-36. 

Yet its possible that this is jewel we are looking for. 

 

I'd actually request copying details, but it takes time and most importantly they dont send a CD or small paper but big size A3 scans which cost 1.4 British Pound per page (or something like that) and after last shopping I promised them I'm not going to give them even a penny for that rip off prices. 

[ACG_KaiLae]

Was the P-40 considered an above average aircraft on the Western front?

It was considered to be very average. Overall it should play king kinda similar to the lagg-3, but with different performance pluses and minuses.

 

Right now it's not remotely close to average.

I contacted them some years ago and still came up empty handed. I agree, a US citizen might stand a better chance.

What's this thing I need to send a FOIA for?

[JtD]

I'd actually request copying details, but it takes time and most importantly they dont send a CD or small paper but big size A3 scans which cost 1.4 British Pound per page (or something like that) and after last shopping I promised them I'm not going to give them even a penny for that rip off prices.

Nice find. Did that copy thing years ago for all they had on the Hurricane, back then it was .40 a page which was still very expensive. I don't get why they don't digitalize it first time someone pays them for a copy/scan. No better way to preserve knowledge than a world wide distribution. Now it's probably cheaper to go there in person, it just takes more time.

 

What's this thing I need to send a FOIA for?

I don't remember, not even what that is, and right now too buisy to check again.

[=362nd_FS=Hiromachi]

 

 

Now it's probably cheaper to go there in person, it just takes more time.

We will need a British volunteer   

[Bert_Foster]

I have around 11files of the RAAF Kitthyawk trials from the UK Archives. This one "RAF Brief Handling trials on Kittyhawk I" is perhaps the most relevant to this discussion:

 

 

https://dl.dropboxusercontent.com/u/53314365/AVIA_734_Report_783__Part_17%5B1%5D.pdf

 

Max speed trials ... data with Stub exhausts and Flame damping ... may also be of use:

 

https://dl.dropboxusercontent.com/u/53314365/AVIA_734_Report_783__Part_14%5B1%5D.pdf

 

Other files including Cooling trials and External stores performance trials etc

Edited October 30, 2016 by Bert_Foster

[ACG_KaiLae]

I don't remember, not even what that is, and right now too buisy to check again.

FOIA stands for freedom of information act. Any citizen can demand that the government produce a record of anything as long as it is not secret, since it is public property. This would seemingly apply. Depending on how much work they have to do to find it, it can be expensive. It's a common tool of news organizations.

[Farky]

 

Venturi, in regard to flight characteristics, just look up for "Measurements of the Flying Qualities of a Curtiss P-40 Airplane" by William Hewitt Phillips, Army Air Corps, May 31, 1941. This should pretty much answer most of the questions, even though it would rather represent P-40B which is one heck lighter than P-40E. 

 

This test was conducted with P-40 39-160 (5th production P-40), almost totally different airplane then P-40E. A.&A.E.E. Boscombe Down reports on Kittyhawk (A.&A.E.E./783, 17 parts) are much better. Or Kittyhawk files in National archives of Australia. Btw - when you compare data from these sources with the game, you'll find that many things do not match.

 

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

My 2 cents -

I like FM of most of airplanes in game (they seem believable), but there is one exception - P-40E. Let leave aside engine limits for now. This airplane wasn't at low speeds unstable piece of crap like is it in game. Behavior during the sideslip is a joke, typical characteristics of a P-40 in dive are also absent, you are not able outturn even Bf 109E. This FM needs major overhaul.

[Felix58]

Interesting discussion on the P40, and a prelude to a similar one on the P39 Airacobra i suggest!

 

The P39, in Soviet hands, had many engine issues early due to the poor quality of oil used.   Once they improved the oil quality many of the issues were solved.

 

Wondering if all lend-lease aircraft suffered performance downgrade versus performance in Western hands due to lower standard of fuel, oil and lubricants; maintenance, etc.   It appears that the Soviets received lend-lease aircraft with english manuals and had no english speakers!  With the P39 a French pilot who spoke english provided an interpretation to a Soviet pilot who spoke French when they were assembling the aircraft!

 

Comparing western performance/observations with Soviet needs a little caution I suggest.

[ACG_KaiLae]

Getting back to the topic of the OP, is there any way to prove or disprove what we have in game?

[-WILD-AlbinoHA5E]

Getting back to the topic of the OP, is there any way to prove or disprove what we have in game?

There is a dubious number of 19 seconds for a horizontal turn, which I find very hard to believe, at least when using Military Rating of 42"@3000.

Back when 56"+ could be used for 2 Minutes it would do that.

If they change the Wing Polar it may change, but as of now it requires a lot of Teamwork to get those Freedomcals on target.

[Crump]

Getting back to the topic of the OP, is there any way to prove or disprove what we have in game?

 

YES!!  

 

It has already been pointed out what the first step needed in testing the P-40 and identifying the issue.

 

 

There is a dubious number of 19 seconds for a horizontal turn, which I find very hard to believe, at least when using Military Rating of 42"@3000.

Back when 56"+ could be used for 2 Minutes it would do that.

If they change the Wing Polar it may change, but as of now it requires a lot of Teamwork to get those Freedomcals on target.

 

It is not hard to determine the performance of a P-40E and what its turn times should be given some good measured data.  There is already plenty of good real world data but what we need is measured game performance data to compare.

 

My suggestion is first determining the power off clean CLmax and then the sustainable load factor at velocity.

That data can then be matched to real world data.

 

Again, that was suggested long ago and when nobody responded to take any concrete action.....the thread devolved into a history discussion.

 

It would be fantastic too If someone could find good measured airfoil data on the NACA 2215 airfoil.  

That turn time of 19 seconds is probably not dubious given the conditions of flight.

Edited November 8, 2016 by Crump

[ACG_KaiLae]

Ok, when I get a chance I'll look into it and see what I can find out. Will post video, please give feedback.

[Crump]

I will  do that and sounds good.

[ACG_KaiLae]

Is there someone else who could also do this independently from me so we can compare information? Also, interestingly, the DD123 data says that the P-40's stall speed is about the same than the 109 F4.

Edited November 8, 2016 by Kai_Lae

[ACG_KaiLae]

Ok I tried to grab some data, but screwed up the power off part. Will try again tonight. One question though is with power off, in order to get the slow speed decrease specified, you basically need to be in a dive. Is this right?