Turn rate hierarchy correlation from actual flight tests

[Gaston]

    Hello everyone,

    From a series of British and American tests (most available on the Mike Williams WWII aircraft performance site), I made the following correlations in turn rates, all using the same A6M5 Zero as the "link" benchmark between many of the various tests:

   If the A6M5 Zero turns 2000°:

                                             -The F6F-5 turns 1550° (A6M5 gains 360° in 3.5 X 360°)

                                             -The F4U-1D turns 1550° (same as F6F-5)

                                             -The P-38L turns 1330° (A6M5 gains 360° in 2 X 360°)

                                             -The P-51D turns 1100°-1190° (A6M5 gains 360° in LESS than 2 X 360°)

                                             -The P-47D Bubbletop turns 997° (A6M5 gains 360° in 1.5 X 360°)

                                             -The FW-190A-5 turns 1162° (F6F-5 gains 360° in 3 X 360°): Despite this being roughly equal to the P-51D, it is made using a fully disassembled and re-built captured machine, whose aileron performance in this US Navy test was then contested by British evaluators in an official wartime document: Aileron performance DID affect low-speed sustained turn performance on the FW-190A...

                                              Official British test have the FW-190A-4 pegged as "equal" in sustained turn rate to the P-38G, and the FW-190A-4 could also out-turn the Spitfire Mk V in sustained horizontal turns, as seen in this combat account:

        http://img30.imageshack.us/img30/4716/jjohnsononfw190.jpg


                                              The P-38G was pitted against a Spitfire Mk XIV in mock combat, which failed to shake it from its tail in repeated attempts, so a turn rate of 1300°-1400° (vs 2000° on the A6M5) does not seem implausible for both the early-mid FW-190A's and the P-38G.

                                             The newly-built FW-190A-8Ns flying today are also confirmed by their pilots as being superior in turns to the P-51D, but inferior to the Yak-3.

                                             At least one FW-190A-8 Western ace claims to have regularly observed a gain of 360° in 2 X 360° against a P-51D at low speed and very low altitude (on the deck), but that would result in a turn rate of 1650°, which means the A6M5 Zero would require almost 5 X 360° to gain 360° on the FW-190A-8, which seems a bit much to me: The FW-190A-8 is described as a large advance in turn performance on the earlier models, but even then a turn rate of 1450°-1500° versus the A6M5's 2000° seems more reasonable.

                                            The P-47D Razorback could beat another, not rebuilt, FW-190A-5 in turns above 250 MPH indicated, but was soundly beaten by the FW-190A-5 below that speed. This still suggests a much better performance than what is displayed by the 1000 lbs heavier Bubbletop above. The Me-109G was very close in turn rate to the P-51D in many combat accounts, yet the 109G was much inferior-turning to a Needle-prop P-47D Razorback in Luftwaffe captured tests (On Special Missions: KG 200). The Needle-prop P-47D Razorback probably ranges from 900° or less below 250 MPH to 1300° above, but to what extent it can sustain this turn rate at higher speeds is hard to say. See the test here:

                          http://img105.imageshack.us/img105/3950/pag20pl.jpg

 

                                            Note that the use of flaps may be a temporary help against a wider tuning radius aircraft like the Me-109G (for a P-38 for instance), but against a smaller turning radius aircraft, the use of flaps actually ACCELERATES the gain of the smaller-radius opponent... I doubt flaps are a panacea that would significantly jumble the above hierarchy, since what they gain you in radius you lose, and more, in speed, unless the speed is so low that the engine has enough reserve power to keep speed constant. (But then torque becomes troublesome...)

                                           What does remain unresolved in the above tests is how the P-47D Razorback, especially with a Paddle-blade prop, would actually do in turns against a P-51D. Correlating their performance against the Me-109G in 1200 combat reports on the Mike Williams site absolutely confirms the turn superiority of the P-47D Razorback to both the Me-109G and the Merlin P-51, especially to left, as does the German captured test evaluations of the Needle-prop P-47D Razorback against both of them (but a P-51B or C in this instance).

                                           The Navy tests unfortunately pegs the FW-190A-5 and the P-51D as equals in sustained turns, but the mass of evidence elsewhere does favor even the earlier FW-190As at low speeds and low altitudes at least... Later FW-190A-8s were much improved.

                                           Note that all the data correlated here is from many repeated tests by many different pilots, except for the benchmark A6M5 Zero, which was always flown by the same pilot. The use of flaps was also widely tried in many different tests on all US fighters, and was found to make little or no difference against the tighter-turning A6M5...

                  Gaston

   P.S. A link to the Mike Williams site: http://www.wwiiaircraftperformance.org/

                  G.

[Widewing]

   
                                              Official British test have the FW-190A-4 pegged as "equal" in sustained turn rate to the P-38G, and the FW-190A-4 could also out-turn the Spitfire Mk V in sustained horizontal turns, as seen in this combat account:

If you read the account, you will notice that Johnson claims to be "greying out" during the vertical turning contest. That says much more than you apparently realize.

Johnson's fight was at speeds where G loading on the pilot is the limiting factor. At high speed, a P-51 could match a Zero in a turn. Had the fight been slower, where no more than 3g could be pulled, the Spitfire Mk.V would have easily out-turned the 190.

Another factor is that the 190 pilot sat in a semi-reclining seat, which increased the g loading the pilot could sustain before greying out.

In mid 1944, 8th AF pilots were being outfitted with G-suits. This gave the pilots an advantage as they could pull up to between 0.5g and 0.8G more loading than a typical Luftwaffe pilot. Pushing up the threshold of G-lock is no minor consideration.


My regards,

Widewing

[Chalenge]

You say the zero turns 360 on a P-47 within 1.5 turns but a zero turns 360 on a P-51 in 2 turns and then you say the P-47 out turns a P-51? I dont follow the logic.

[Saxman]

I'm assuming it's how many degrees each aircraft turns in the time it takes the Zero to turn 2000?

[StLouis]

If you read the account, you will notice that Johnson claims to be "greying out" during the vertical turning contest. That says much more than you apparently realize.

Johnson's fight was at speeds where G loading on the pilot is the limiting factor. At high speed, a P-51 could match a Zero in a turn. Had the fight been slower, where no more than 3g could be pulled, the Spitfire Mk.V would have easily out-turned the 190.

Another factor is that the 190 pilot sat in a semi-reclining seat, which increased the g loading the pilot could sustain before greying out.

In mid 1944, 8th AF pilots were being outfitted with G-suits. This gave the pilots an advantage as they could pull up to between 0.5g and 0.8G more loading than a typical Luftwaffe pilot. Pushing up the threshold of G-lock is no minor consideration.


My regards,

Widewing

^^ What he said.

[Chalenge]

I'm assuming it's how many degrees each aircraft turns in the time it takes the Zero to turn 2000?

Yes and obviously the P-51 is doing a better job at degrees turned than the P-47 is.

[Krusty]

See rule #4

[Saxman]

Rule #4 quote

[Gaston]

    Yes, I picked 2000°  as an arbitrary reference point. In the time it takes the A6M5 Zero to turn 2000°, the others do x degrees in a sustained way: Sustained turns implies a G loading of 3-4 Gs where pilot endurance to Gs is not the dominant factor...

    If you read the Johnny Johnson account, it is VERY clear these are turns sustained for a long time, several 360s, horizontally: Everything in Johnny Johnson's wording is very indicative of Medium-slow speed turning: The vertical bank, the low altitude, with diving only at the end of a losing turning contest: "It was only a matter of time", and most importantly the complete lack of diving PRIOR to the combat.

    Greying out actually confirms to me the fight was not at high speeds, as the Spitfire's light elevators could easily induce BLACKING out above 300-350 MPH...

   Quote: Challenge
"You say the zero turns 360 on a P-47 within 1.5 turns but a zero turns 360 on a P-51 in 2 turns and then you say the P-47 out turns a P-51? I dont follow the logic."

    -Yes the BUBBLETOP P-47D is worse-turning than the P-51D Mustang, but the linked FW-190A-5 comparison test (Which FW-190A-5 I speculate performed much better than the US Navy test, P-51D-equalling, fully-rebuilt 190A-5...) shows the P-47D RAZORBACK (1000 lbs lighter) to be competitive at high/medium speeds with even an untampered with FW-190A-5, something I consider far too impressive a performance for the Razorback to be similar performing to a Bubbletop...

   This is further confirmed by the fact that the German captured tests, and about 600 P-47 combat reports, describe the Razorback as CLEARLY better-turning than the Me-109G in medium/high-speed turns with needle blade prop, extending to low-speed turns with the paddle-blade prop (post Jan '44)... Neither German captured tests, or 700 P-51 combat reports, are as clear about that for the P-51, especially against later 109s, except for a very good speed retention in LEVEL turns for the American fighter (giving the P-51 a turn rate (not radius) advantage low on the deck, where there is no downward spiral to help the non-MW-50 109G).

   I reason that if the Bubbletop P-47D is slightly worse than the P-51D in sustained level turns, then it must be MUCH worse than the Razorback also...

   I don't really know why it is, but it seems a logical deduction that the P-47D Razorback turns better than the P-51D and its own Bubbletop cousin.

   But to get the proper relationship, it must first be accepted that the FW-190A turned significantly better at low speeds than the Me-109G, or no wartime account makes any sense... To ALL participants directly involved with these aircrafts, it was no mystery that the FW-190A turned better at sustained low speeds than the Me-109G. (This is contradicted only once by a sentence in a La-5 Rechlin evaluation, in which a MW-50 equipped Me-109G is compared to a FW-190A at unknown speed, but probably I would assume above 250 MPH, and this would tend to support the notion that Me-109Gs with MW-50 could match or beat in turns, at some speeds, some of the FW-190A versions. Note MW-50 was considered by Hartmann to be essential to Me-109G competitiveness in late '44, but was not that widely available)

   In addition, very late-war combat accounts make it clear the later Bubbletop P-47Ds could not compete in turns at all with later FW-190A-8s: Typical November-December 1944 quote: " Three P-47s were turning on the deck with one lone 190, going nowhere fast..." These types of comments do not really occur in early 1944, where the P-47D/FW-190A parity appears much greater...

   How much better was the Razorback in turns to the Bubbletop is unfortunately not clear to me, although I do remember reading a P-51B/P-47D Razorback flight comparison somewhere that would be of interest here, if I could find it... It was with a B model Mustang however, so the continuity vs the P-51D is again not clear... It probably did NOT say the P-47D Razorback out-turned the P-51B, or I would have remembered it... It did say the P-47D Razorback out-accelerated the P-51B in dives, completely contradictory to to what the later Bubbletop vs P-51D said in the Zero evaluations tests... I think this could be due to the Paddle-blade prop creating extra drag in a dive compared to a needle-blade, but it still seems strange to me...

   It would be interesting to find a P-47D Razorback vs Merlin P-51 evaluation to clarify the picture...

   Gaston

   

   

[Jabberwock]

The RAF disagrees with your assessment:

http://www.wwiiaircraftperformance.org/sl-wade.html

http://www.wwiiaircraftperformance.org/wade-turning.jpg

You seem to consistently ignore the effect that speed has on both the relative rate and radius of turn for various aircraft.

[Chalenge]

I think the primary problem is the mixing of anecdotal and empirical evidence the way I read the post. You cant mix the two and then come away with any hard evidence at all yet you are trying to draw conclusions that way.

[Karnak]

Gaston,

If Johnson was greying out, they were going way, way above sustained turn speeds.  He wasn't blacking out because he wasn't pulling into a blackout, not because he couldn't.

No WWII fighter, not the Fw190, not the Spitfire and not the A6M, could maintain greater than a 3g turn, and a 3g turn is not going to being greying you out.

[bozon]

While this is an impressive literature study, it is doomed to produce meaningless results. Different tests are done at different conditions and have different meanings to their results. You normalize all the results in terms of degrees per second (dps), but is doesn't say anything about the turn radius or G loads.

There is a difference between measuring the time it takes a plane to turn until it covered a certain direction change and two planes flying in a circle around each other to see who gains. In the first case, each will try to be close to its own corner speed (lowest speed that allows max G). In the second they need to match turning radius or this becomes meaningless as a "turn rate" measure, but some combination of rate and radius instead.

These tests have only a qualitative meaning.

[JunkyII]

If you read the account, you will notice that Johnson claims to be "greying out" during the vertical turning contest. That says much more than you apparently realize.

Johnson's fight was at speeds where G loading on the pilot is the limiting factor. At high speed, a P-51 could match a Zero in a turn. Had the fight been slower, where no more than 3g could be pulled, the Spitfire Mk.V would have easily out-turned the 190.

Another factor is that the 190 pilot sat in a semi-reclining seat, which increased the g loading the pilot could sustain before greying out.

In mid 1944, 8th AF pilots were being outfitted with G-suits. This gave the pilots an advantage as they could pull up to between 0.5g and 0.8G more loading than a typical Luftwaffe pilot. Pushing up the threshold of G-lock is no minor consideration.


My regards,

Widewing

man i wish i could have your brain for this game

[Gaston]

   Quote Jabberwock: "The RAF disagrees with your assessment:

http://www.wwiiaircraftperformance.org/sl-wade.html

http://www.wwiiaircraftperformance.org/wade-turning.jpg

You seem to consistently ignore the effect that speed has on both the relative rate and radius of turn for various aircraft."

 
  Prolonged sustained turns are basically ALL medium-low speed turns, eventually anyway... It is the basic standard used in all WWII tests... This is why the FW-190A is said to out-turn the Me-109G, even though the Me-109G is much better-turning above 250 MPH, as is the P-51, despite both having much heavier elevators... As this P-47D comparison test shows, the FW-190A had terrible handling immediately above 250 MPH:

   http://img105.imageshack.us/img105/3950/pag20pl.jpg

  
   This terrible high speed handling is confirmed by innumerable tests and assesments by all sides, I'll only quote the Russian experience:

   "The FW-190A will inevitably offer turning combat at minimum speed"

   "The FW-190A is more maneuverable than the BF-109 in horizontal maneuvers"

   "The FW-190A does not like vertical maneuvers"

   E. Brown: "Care must be taken not kill speed by "sinking" during dive pull-outs..." AND the above-linked  P-47D high-speed debacle...

   It doesn't get much plainer than this...

  
  Quote: ""The RAF disagrees with your assessment:"

  And you seem to ignore that I DID say the BUBBLETOP P-47D ("Thunderbolt II" in RAF speak) IS a poorer turner than the P-51D, as I quoted myself several times in the Zero relative turn tests (997° to the Mustang's 1100°-1190°). It is the 1000 lbs lighter and DIFFERENT-shaped RAZORBACK P-47D that I think turns better than a P-51D, and the RAZORBACK is confirmed by German captured tests as turning better than their Me-109G (which is itself pretty close to a Merlin P-51)...

  I have repeated the above point several times already... Obviously you must have skipped over some paragraphs...

  Note the Germans in those same test did NOT say the P-51B out-turns their Me-109G, and instead insisted on the fact that one of their pilots got killed in a stall-turn with the P-51B... Hmmm... They STILL liked better the Mustang's speed and acceleration, but the Razorback was probably a bit below specs on top-end power...

  Johnny Johnson mentions greying-out at the beginning of his battle ONLY. He then mentions several complete AND CONSECUTIVE 360° turns "on opposite sides of an ever-decreasing circle". VERTICAL bank so NO diving (and no diving prior to the battle either)... He could have done  more than greying out?: " I asked the Spitfire V for all she had" but: "It was only a matter of time" ie: for the FW-190A to gain a tail position on him.... He knew that pulling a tighter turn would only stall him or lose him more speed, and thus get him killed sooner...

  There is no ambiguity possible in this exceptionally detailed battle. It is prolonged level and sustained turning at medium then lower speeds... People are so bewildered by this article some have even resorted to calling Johnson's "vertical turns" as meaning something other than a vertical bank... A "vertical" vertical turn would have been called a loop.... In those days "vertical turn" for a vertical bank was common parlance.

  But it does illustrate how desperate people get to not read what is in plain sight...

  Direct comparisons to the P-47D Razorback would still be of interest, but they appear rare compared to the "Thunderbolt II"...

   Gaston