Comparison of Fighter Roll Rates at 10kft

[ST_ami7b5]

^^ Looking forward to Rata.

[GOAT-ACEOFACES]

One soviet design could outroll Fw for sure.I-16.Comparing this little devil to any plane make them "sluggish" and "unresponsive"

Looking at the NACA test, the P36 was pretty impressive too

[Brano]

...everything was sluggish and unresponsive to soviet pilots transiting from I-16 to whatever new fighter it was.Being it Lagg3, Yak1 or MiG3.But ofcourse,mostly with lagg3 it is an holy words to follow and we all now have to belive that this plane moved like brick thrown into water.Still it does circles on surface of water even it is squared

[=FB=VikS]

One thing to note - about P-40 vs P-40 rollrate:

 

[GOAT-ACEOFACES]

One thing to note - about P-40 vs P-40 rollrate:

Thanks VikS!

 

That is some good info.. Now I just have to figure out a way to capture all this kind of info in the graph legend

 

I see the note says the P-40F had a Merlin engine, do you have any 'idea' as to why? Some kind of custom plane custom engine testing? Because, I was under the impression that all the P-40s had Allisons? Except for some that went to Russia, where I seem to recall them installing a different motor.

[Finkeren]

I seem to recall that the P-40F was a specific request by the British as a stop-gap solution for a Packard-Merlin engined Lend-Lease fighter before the Mustang arrived on the scene. Ironically only a few of them ever served with the RAF, as most equipped USAAF squadrons during and after Operation Torch. I think a few of them went to the USSR as well.

 

IIRC the F was considered overweight and sluggish in handling but fairly fast and it was often lightened by removing armour and some of the guns.

Edited February 12, 2015 by Finkeren

[GOAT-ACEOFACES]

Agreed, I also seem to recall reading about Curtis trying to get back into favor, about the time that the Britts selected N American's P-51 over the P-40.. Curtis was trying all sorts of things, and I if I remember correctly, about the time the testing showed the benefits of the Merlin in the P-51, Curtis figured they would stick on in the P-40 to see if what they get.. Not sure though how all that played out timeline wise.

[MiloMorai]

Thanks VikS!

 

That is some good info.. Now I just have to figure out a way to capture all this kind of info in the graph legend

 

I see the note says the P-40F had a Merlin engine, do you have any 'idea' as to why? Some kind of custom plane custom engine testing? Because, I was under the impression that all the P-40s had Allisons? Except for some that went to Russia, where I seem to recall them installing a different motor.

 

The P-40L also used a RR motor.

Edited February 12, 2015 by MiloMorai

[JtD]

Yep, the RR Merlin was used on a quite a few P-40, with about 2300 produced.

[GOAT-ACEOFACES]

So, was that a special order for the RAF? or were there some P40Fs with Allison and some with Merlins?

[JtD]

No, it was a primarily a USAF plane, to be exact it used the V-1650, a license built Merlin. I think checking wiki or something might be more efficient than continued Q&A.

Edited February 12, 2015 by JtD

[MiloMorai]

No, it was a primarily a USAF plane, to be exact it used the V-1650, a license built Merlin. I think checking wiki or something might be more efficient than continued Q&A.

 

There is also, http://www.joebaugher.com/usaf_fighters/p40.html

[GOAT-ACEOFACES]

Ah, good stuff, so in summary, there were not two types of F, one with an Allison and one with a Merlin, or any other model.. Except maybe those few that went to Russia, where I think they swapped out the motors with something else

[NZTyphoon]

The P-40F used the V-1650-1, which was a single-stage engine, similar to the Merlin XX (from  IPMS Stockholm  ):

 

 

P-40F - In USAF service the type received the name Warhawk. The engine was exchanged once more, this time to he vastly superior Roll-Royce Merlin 28 (later Packard Merlin V-1650-1) with a single-stage supercharger built into the P-40D airframe . With the new engine the carburettor air intake on top of the cowling was removed.

The first 699 production aircraft were designated only P-40F, after which the subtype numbers were introduced to keep track of modification introduced directly in production. The "dash numbers" were assigned according to the system: -1, -5, -10, -15, -20 and so on, with interval of 5. Thus the first P-40Fs were retroactively treated as P-40F-1, and subsequent modifications were designated P-40F-5, P-40F-10, P-40F-15, P-40F-20. Actually the official designations carried an additional suffix -CU indicating Curtiss production facilities, like P-40F-10-CU, but we'll omit it here for clarity.

The P-40F-5 and later production models had the rear fuselage lengthened with over 2 feet to improve directional stability. Of note is that only fin and rudder were moved back, the horizontal tailplane remained in the same position.

 

Kittyhawk Mk. II - of over 1300 P-40Fs produced, 150 were supplied to Britain under Lend-Lease and designated Kittyhawk Mk. II, in common with the later P-40L model. The RAF didn't actually use their Mk. IIs  - 80 were returned to USAAF for Tunisian campaign, 100 went to Soviet Union, and a handful was handed over to Free French AF in Africa.

 

 

AFAIK the 100 P-40Fs supplied to the Soviets kept their V-1650s.

Edited February 13, 2015 by NZTyphoon

[GOAT-ACEOFACES]

Well I learned something about Allison, I knew Packard had a license to produce British engines for the P-51, but I didn't know Allison had one too. Thanks for the info guys! Oh, and JtD, I would rather here if from you and others here over most if not all the wikie pages out there! I just trust you guys more than wikie nut jobs!

[MiloMorai]

Well I learned something about Allison, I knew Packard had a license to produce British engines for the P-51, but I didn't know Allison had one too. Thanks for the info guys! Oh, and JtD, I would rather here if from you and others here over most if not all the wikie pages out there! I just trust you guys more than wikie nut jobs!

 

Graham White's book Allied piston Engines of WW2 doesn't mention Allison making V-1650 Merlins.

 

Wiki is not to bad unless certain people have any input.

[GOAT-ACEOFACES]

Graham White's book Allied piston Engines of WW2 doesn't mention Allison making V-1650 Merlins.

Interesting, well the AHT graph 29 that VikS provided clearly states it was a Merlin in the P-40F, I think it was JtD that 1st noted it was licences? But looking back at it, I may have mistakenly assumed it was Allison, my bad..

 

Long story short, And back on topic!

 

The good news is, the AHT graph 29 VikS provided puts to rest any of the Dubious claims by Celestiale and less crediable claims by FalkeEins and Crump.

 

Wiki is not to bad unless certain people have any input.

Bingo! My point exactly.. Than again, I seem to recall some of the nut jobs getting the wikie edit abilities being pulled!

[GOAT-ACEOFACES]

After going through the report, I'm curious how you arrived at the conclusion it's inaccurate other than you simply don't think it's right?  You mention the shape of the curve but wouldn't you have to have data from other tests with known control inputs to make this claim.  Since NACA was doing this test strictly on the ailerons, knowing that rudder (and elevator) inputs would confuse the results, wouldn't they do what they could to minimize error?  If they didn't, or couldn't, wouldn't it then be difficult to take any NACA test at  face value?

Chutter,

 

You are a wise man to question the self proclaimed experts when they ask you to disregard the true experts..

 

Especially when the self proclaimed experts ask you to believe the true experts make a common sense (read basic and obvious) mistake! And provide no proof other than the self proclaimed experts 'opinion'..

 

In this case, Crump, the self proclaimed expert is asking us to disregard the roll rate testing done by the NACA, the true experts. And the only thing Crump is providing as proof is some ambiguous reference to 'the curves' which you yourself pick up on when reading Crump's reasoning for disregarding the P-40 roll rate values from the NACA test.

 

Sadly, when you asked Crump to explain he reasoning, all you got from Crump was more fluff, not facts.

 

Where Crump provided us with his version of history (read opinion) of the NACA testing procedures at the time of test. Once again, providing no proof other than his self proclaimed experts 'opinion'..

 

In summary Crump is not only asking us to believe the NACA test procedures were so lax at the time of the testing that they used rudder during a dedicated aileron effectiveness test, Crump is also asking us to believe that the NACA pilots and engineers were so incompetent that they didn't even realize that the use of rudders has an effect on the roll rates. Which, as you noted, would corrupt the aileron effectiveness test results.

 

Well, as noted, you are a wise man to question the self proclaimed experts because as it turns out..

 

Crump was WRONG!

 

When he said

 

Not really, you just have to put the report in the context of history in the timeline it occurred.  The NACA was in a transitional period until late 1942 when stability and control standards were adopted.  They adopted those standards because everyone was on a different page and not everyone understood what was important to measure or define and what wasn't.

 

Because as most wise men would expect the NACA knew what they were doing, as noted in the NACA 715 document, i.e.

 

 

From this documented 'proof' (read NOT opinion) we can see that the 'real' time-line shows the NACA had roll rate test procedures in place prior to 1940 and therefore they were all on the same page and understood what was important to measure and the NACA knew rudder has an effect on roll rates.

[Crump]

 

 

One thing to note - about P-40 vs P-40 rollrate:

 

That is pretty good.

 

The reason for the pre-war P-40 roll rate (being a higher rate at a faster speed) is unknown.

 

Sure is unknown....nobody measured the pilots rudder input, LOL.

 

 

 

From this documented 'proof' (read NOT opinion) we can see that the 'real' time-line shows the NACA had roll rate test procedures in place prior to 1940 and therefore they were all on the same page and understood what was important to measure and the NACA knew rudder has an effect on roll rates.

 

 

That is quote is correct.  They did institute (to inaugurate; initiate; start:) a program to study flying qualities well before the war.  They just did not adopt any standard until late 1942.  That is a fact.

 

Once more, rudder fixed means fixed in the trim position....in otherwords a co-ordinate roll.

 

If the test was done IAW the standards adopted in 1942.....

 

It would include a rudder deflection measurement.

 

It is that simple.

 

[GOAT-ACEOFACES]

In light of the excerpts from NACA 715 document that ACE-OF-ACES provided.. I have to admit I was wrong about the NACA not being on the same page, and not understanding what was important to measure during a roll rate test, and it is also clear that the NACA understood the use of rudder would affect the roll rates. In light of this, I also have to admit I was wrong to imply that the roll rate data from the NACA STABILITY AND CONTROL SUB-COMMITTEE document data 16th Nov 1942 was suspect, which is the same roll rate data show in AHT. Sorry for the confusion I caused in this thread.

Fixed that for ya!

[GOAT-ACEOFACES]

All kidding aside..

 

The NACA was in a transitional period until late 1942 when stability and control standards were adopted.

 

And

 

They did institute (to inaugurate; initiate; start:) a program to study flying qualities well before the war.  They just did not adopt any standard until late 1942.  That is a fact.

 

Even if that is true..

 

The NACA document that contains the P-40 roll rate data, i.e.

 

STABILITY AND CONTROL SUB-COMMITTEE. AERONAUTICAL RESEARCH COMMITTEE. Comparison of Aileron Control Characteristics as determined in Flight Test of P-36, P-40, 'Spitfire' and 'Hurricane' Pursuit Airplanes. By William H. Phillips

 

Is dated November 16th 1942

 

Now, I think everyone can agree that November 1942 qualifies as LATE 1942

 

Therefore, by your own admission Crump..

 

The NACA was abiding by their stability and control standards as spelled out in the NACA 715 document when they did the P-40 roll rate test.

[Crump]

 

 

he NACA was abiding by their stability and control standards as spelled out in the NACA 715 document when they did the P-40 roll rate test.

 

So where is the standard rudder deflection measurement??

 

It is not present nor does the test conform to the standard required.

 

The flight testing took place before the report was prepared and published. 

[GOAT-ACEOFACES]

So where is the standard rudder deflection measurement??

 

It is not present nor does the test conform to the standard required.

 

The flight testing took place before the report was prepared and published.

So, now you are disagreeing with yourself?

 

ROTFL!

 

Well.. while you are arguing with yourself about how LATE is LATE and/or why the document wasn't prepared BEFORE the testing was done..

 

LOL!

 

Allow me to point out that you are WRONG in saying the test didn't conform to the NACA 715 standards..

 

Take a look at the document containing the P-40 roll rate data, i.e.

 

STABILITY AND CONTROL SUB-COMMITTEE. AERONAUTICAL RESEARCH COMMITTEE. Comparison of Aileron Control Characteristics as determined in Flight Test of P-36, P-40, 'Spitfire' and 'Hurricane' Pursuit Airplanes. By William H. Phillips

 

Clearly they followed the test procedures listed in the NACA 715 document..

 

How do I know this you ask?

 

Simple!

 

Just look at the bottom of page 2 and you will see they listed NACA 715 as a reference!

 

As for where is the 'standard rudder deflection measurement'..

 

Clearly you have never read, let alone written an official statement of work!

 

If you had, you would know the difference between words like WILL and SHALL..

 

Referring to the NACA 868 page you provided..

 

Looking at the section titled Presentation of data.

 

Note that NO WHERE does it say SHALL DO

 

All it does is give recommendations, i.e.

• The test results may be plotted in the form of a time history..
• should be used..
• may have to be considered..
• Plots usually are made to show..
• the test should be made with the..

Words like may be, should be, may have to, usually, should be are NOT words that constitute REQUIREMENTS!

 

Therefore a time history plot showing all the variables is NOT A REQUIREMENT!

 

Which should have been clear in light of the FACT that they list 10 variables but only plotted 6 in their example! 

 

As a mater of FACT a time history plot itself is NOT A REQUIREMENT!

 

The NACA 868 lists other options, note where is says..

• Another very useful plot is one in which the..

In summary

The lack of a time history plot does not equate to variables NOT being recorded during the test, let alone equate to the test not abiding by the procedures listed in the NACA 715 document.

[Crump]

 

 

In summary The lack of a time history plot does not equate to variables NOT being recorded during the test, let alone equate to the test not abiding by the procedures listed in the NACA 715 document.

 

In summary, it is not correct data. 

[Crump]

After going through the report, I'm curious how you arrived at the conclusion it's inaccurate other than you simply don't think it's right?  You mention the shape of the curve but wouldn't you have to have data from other tests with known control inputs to make this claim.  

 

The fact the roll rate is faster and extends to a higher velocity than typical curves for the P-40 is a pretty good indicator.   What is certain is the data presented is very optimistic and also very worthless without the rudder deflection measurements.

 

 

Aerodynamic coupling effects keep rolling from being a one-degree-of-freedom proposition. Rolling moments come with yawing moments attached, and those yawing moments affect roll behavior.

 

 

 

 

 

Since NACA was doing this test strictly on the ailerons, knowing that rudder (and elevator) inputs would confuse the results, wouldn't they do what they could to minimize error?  If they didn't, or couldn't, wouldn't it then be difficult to take any NACA test at  face value?

 

This is why a standard was published.  Without the rudder measurements, it is guesswork....

 

What is equally certain is the team who did the report "thought" it was useful.  It does not mean it is actually useful data, though.

 

 

In fact there is a significant number of these early reports which are just an interesting read and nothing more.

 

You have to sort through the data with knowledge of how things work and understand that stability and control engineering was still a burgeoning science back then.  That was the whole point of the NACA standards.  

 

Only two nations during the war adopted stability and control standards.

 

If you know the history, some of the reports are very interesting.  For example, the exact mechanism that caused the elevator to lose effectiveness at high speed was hotly debated at the time.

 

In August of 1943 the NACA set out to answer that debate.

 

 

In a parallel development, a  month earlier, the Germans were investigating the same thing!

 

Edited February 14, 2015 by Crump

[JtD]

The early P-40 data appears to have been tested to a maximum of 230mph/30lb stick force. 30lb stick force were not reached at 230mph, only 19.5. If it was then extrapolated to 230*SQRT(30/19.5), it gets me to 285mph, which is exactly what NACA has as well in their chart, or 230*SQRT(50/19.5)=368mph, which matches the first posts chart. Just saying, feel free to ignore.

[NZTyphoon]

The 1943 NACA document on aileron flight test procedures states:

 

 

Rudder position is measured only to check on the correctness of the piloting technique. For this reason no great effort need be made in the interests of exactness. If the pilot is experienced in the technique involved, the measurement of rudder position may be dispensed with.  [page 4, para 2 "Rudder Position".]

 

In other words, NACA's policy was not to state the rudder deflection measurements, except where the test pilot was inexperienced, because such information was not essential when writing reports on roll rates.

[Crump]

Easy question to answer NzTyphoon.

 

The NACA found out that although pilots were reliable and truthful people.....measure everything because sometimes their perception and reality does not align.

 

The early standards did not require measurement.  They did leave it up to the pilot to meet the defined conditions of coordinated rolls.  

 

 

When all was said and done.....

 

Measuring the rudder position is extremely important.  It simply has too much influence on roll rate.

 

[GOAT-ACEOFACES]

In summary, it is not correct data.

 

That is your opinion, and your welcome to it..

 

Just not sure which Crump I am currently speaking with?

 

Because the Crump I was original speaking with said the following..

 

The NACA was in a transitional period until late 1942 when stability and control standards were adopted.

 

And

 

They just did not adopt any standard until late 1942.  That is a fact.

 

But this 'current' version of Crump is NOW saying he 'feels' November 16th 1942 does NOT qualify as LATE 1942..

 

Which is the date of the document that contains the P-40 roll rate data, and a reference to the NACA 715 document as two the procedures used during the testing!

 

So, just to keep things straight, I am going to use the following in further correspondence

 

CrumpA = November 16th 1942 does qualify as LATE 1942.

CrumpB = November 16th 1942 does NOT qualify as LATE 1942.

 

Agreed?

[Crump]

 

 

But this 'current' version of Crump is NOW saying he 'feels' November 16th 1942 does NOT qualify as LATE 1942..

 

So you think they just passed one set of standards and never revised it?

[GOAT-ACEOFACES]

The early standards did not require measurement.  They did leave it up to the pilot to meet the defined conditions of coordinated rolls.

 

That is not accurate..

 

Based on the NACA document Typhoon provided, neither EARLY (pre 1942) or LATE (1943) required the measurement of the rudder, i.e.

 

 

So, as you can see, the NACA experts here don't put as much importance on rudder measurements as you do,..

 

Which most likely stems from the fact that the NACA engineer and test pilots where aware of the fact that rudder affects roll rates.

 

Something you are asking us to believe was NOT the case, in that is the only way your argument would make any sense!

 

So you think they just passed one set of standards and never revised it?

 

No, on the contrary

 

The NACA document that Typhoon provided was review!

 

Hope that helps!

[GOAT-ACEOFACES]

Measuring the rudder position is extremely important.  It simply has too much influence on roll rate.

At first CrumpB I thought you were just arguing for the sake of arguing..

 

But..

 

I am going to give you the benefit of the doubt and treat this post of yours as a teachable moment..

 

Because I believe I have found the root cause of your confusion!

 

Based of your recent replies..

 

It is clear to me that you are confusing MEASURING with PRESENTING..

• MEASURING is what was done DURING the testing.
• PRESENTING is what was done AFTER the testing (post test).

You are operating under the following FALSE impression..

 

The NACA report did not PRESENT the VARIABLE therefore the NACA testing did not MEASURE the VARIABLE.

 

Which brings us back to the NACA 868 document you referenced as proof..

 

As I pointed out to you earlier, words mater!

 

With that in mind, I am going to post two different ways of saying something and than ask you what is different about the two ways I said it..

• The test results may be plotted in the form of a time history..
• The test results must be plotted in the form of a time history..

Question

 

Of the two, which one gives the report writer the OPTION to display the results in the form of a time history, and which one REQUIRES the report writer to display the results in the form of a time history.

 

Keeping in mind, that CASE 1 is how it is worded in the PRESENTATION section of the NACA 868 document you provided..

 

Hope that helps!

 

PS pay close att to the colors!

[Crump]

Aces,

 

There is a 36% difference in helix angle between the data on your made up chart and the P-40F data included on the NACA chart.

 

The non-dimensional value for Helix angle in your data is .081 at 300 mph IAS for sustained roll rate at full aileron deflection.

 

The P-40F is .060 under the same condition.

 

Non-dimensional helix angle is good indicator of roll data.  Do you really think the same wing and aileron suddenly achieved a 36% higher helix angle??

 

Just asking.;....

[Crump]

The P-40 is still a very agile aircraft.  Only the P-63, Spitfire, and FW-190 are more agile.

[Crump]

Here is the answer.

 

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

 

Wing weapons....the distance between the wings center of gravity and the aircraft's center of gravity (Yd) shifted increasing roll drag.  I still do not think that alone accounts for a 36% decrease in helix angle.

[JtD]

If the helix angle was non-dimensional, it wouldn't be different between speeds. The P-40F achieved in excess of 0.82 at low speeds.

Also wing and aileron weren't the same between the tests, they were just similar.

Edited February 14, 2015 by JtD

[Crump]

 

 

If the helix angle was non-dimensional,

 

MMMMM,  Lets follow your logic..

 

A coefficient of lift is non- dimensional yet it changes from stall to cruise flight quite dramatically..... 

 

https://rotorhead8900.files.wordpress.com/2011/11/angle-of-attack.png

[Crump]

 

 

The ONLY way your argument would make an sense is if the NACA engineers and test pilots did NOT realize the use of rudder would affect the roll rate.

 

 

Spoken like a man without any flying experience.....

 

Seriously, even today many pilots do not know what the heck a rudder is for or what a coordinated roll even looks like Aces.

Edited February 14, 2015 by Crump

[GOAT-ACEOFACES]

MMMMM,  Lets follow your logic..

Better yet, lets sum up your logic! 

 

And I can sum it up in one simple statement!

 

And that is..

 

The ONLY way your argument would make any sense is if the NACA engineers and test pilots did NOT realize the use of rudder would affect the roll rate.

 

Sorry, but that is just silly!

 

And that is why your argument has no merits

 

Spoken like a man without any flying experience.....

 

Spoken like a man who disregards all the DOCUMENTED PROOF proof that disagrees with his OPINION!

Edited February 14, 2015 by ACEOFACES

[messermeister]

Some food for though, since this thread is derailing the usual way: Phillips' CB was originally issued in August 1942. It's a summary of previous tests (i.e. nothing new was tested for issuing the report). The tests for the Hurricane and Spitfire were co-authored by Phillips, and are well known (debated to death in the net, usually with "particular" conclusions), issued as WR L-565 and L-334 respectively.

 

Since Phillips was also co-author of Confidential MR AAC, May 31 1941 Measurements of the Flying Qualities of a Curtiss P-40 Airplane (AC No. 39-160), there is a good chance that the data presented in this debated came from there. From the date of the report, flight test must have been done in early 1941 or late 1940, so there is a chance that the methodology was different than when the Hurricane, Spitfire or P-40F tests were done (and might explain the shape of the curves). So, the report in question should end the speculation (it's not available in the NASA ntrs server, BTW  ).