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JtD

Another look at turn times

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I've taken the data provided by the devs and put it in a table for a plausibility check. I've been calculating the overall efficiency of the aircraft in the sustained level turn at sea level.

 

Several odd things pop up:

  • The B109F-2 is clearly worse than all other Bf109's, even worse than the Bf109E-7. That's odd.
  • The LaGG-3 and both Yak-1's are miles ahead of the competition.
  • The I-16 performs very poorly, even for a design as chubby as it is.
  • The Ju87 performs extremely well for a design as draggy as it is.
  • The La-5, also evident from level flight, is draggy as heck. It can probably be attributed to a lot of leakage and inefficient cooling of the new engine installation, looking forward to later versions where these issues were solved.
  • I can't for the love of it figure out why the Mc202 and P-40E are as bad as they are. It strikes me as odd. Clearly, they have some not so aerodynamic features, but so do other aircraft.
  • Newer and updated flight models, like the Bf109G-4, Fw190A-3, Yak-1S129 are more efficient than older ones or previous versions. This indicates a global change in the FM philosophy.
  • I hope to see the other older FM's updated, so that we get a homogeneous set of FM's. It would probably reduce many of the oddities here to reasonable margins.

FAQ:

1) What is that efficiency you calculated?

 

 

I've taken the minimum theoretically required drag and divided it by the maximum theoretically available thrust. Since in any sustained level manoeuvre drag equals thrust, we know how much of the thrust goes into the physically necessary drag, and how much is wasted on all sorts of losses.

The theoretically minimum required drag is the pure lift induced drag, which I calculated in the third column from the right using ((2*lift²)/(1.225*Pi*speed²*span²)).

The theoretically maximum available thrust was calculated in the second column from the right using (power/speed).

The last column is the ratio of these two.

All sorts of losses for instance include the Oswald coefficient (wing efficiency), parasitic drag (shape drag, friction drag, internal drag) or propeller efficiency (typically around 85%), all to be found on aircraft.

 

 

2) What do I do with it and how does it compare to real life?

 

 

It doesn't. It's a statement about the aerodynamic quality of the aircraft in turning flight as modelled. Higher equals better. It's of no use to the pilot and there's no figure in historical documents that can be directly compared to it.

 

3) The speed figures appear to be given to the nearest 10km/h - how sensitive is your calculated efficiency?

 

 

I've changed the speeds to -10km/h and +10km/h the given value without changing anything else, and efficiency changed in the region of 3% over that 20km/h range.

 

4) What do you need the lift coefficient for?

 

 

I don't need it for calculating the efficiency, I just calculated it as a bonus because I was curious about it.

 

5) Did you compare the devs figures with in game tests?

 

 

Yes, I did it for some of the odder results, but I'm not systematically doing it every time the game or the developers figures receive an update. However, my own in game figures came close enough to the devs figures to consider them correct.

 

 

Note: Currently the power figures for the Spitfire come from real life data, not in game data. The devs haven't stated it in the data section.

 

bla002.jpg

Edited by JtD
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Mc202

This is surprising, I'm no engineer but if I understand your numbers properly Mc 202 doesnt seem to be an aerodynamically clean airframe here. And based on aircraft performance (as it was using same Db 601 Aa as Emil) it proved to be quite clean design, as it went to over 600 km/h while 109 E-3 with similar engine did 570 km/h (according to kurfurst.org). 

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Might make sense to test the turn rate of the questionable planes. I'll probably do that, but of course it would be best to have more than one guy doing it.

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This is surprising, I'm no engineer but if I understand your numbers properly Mc 202 doesnt seem to be an aerodynamically clean airframe here.

Obviously, there's no need to be an engineer to understand it. :) Mind you, step turns and level flight aerodynamics aren't quite the same, but still, the apparent high drag of the Mc202 is surprising.

 

Might make sense to test the turn rate of the questionable planes. I'll probably do that, but of course it would be best to have more than one guy doing it.

Biggest outliers for me are the I-16 and LaGG-3, which I have quick-tested in game. In left hand turns, I got 21s for the I-16, even worse than what the DD says, and 22.5s with the LaGG-3, pretty much in line with the DD. Maybe it simply isn't 3157kg in game, even if that figure is reasonable for an S29 LaGG-3.

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I'll test different weights then. Also will definately test the F-2 because that seems odd to me aswell. You did use boost on the I-16 in your test right?

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Quite possibly I didn't, was fiddling with the engine setting prior to turning I probably forgot to switch it back on...right hand turn with boost definitely on: 19.5s in my test. I had difficulties consistently flying it at 230, so I'd take this as a good match, again.

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Hm, i checked the F-2 and on first try i was able to complete a turn in a bit over 21 seconds, though at a slightly lower speed (around 260 km/h IAS). Same for the P-40 were i got less than 23 seconds on first try.

 

Also looking at the speeds in the description most fighters have the 270 km/h as best turn speed, which seems odd to me. I also don't see why the speed would differ between the LaGG-3 and La-5, but not between most other planes. So maybe those numbers are not 100% accurate.

Edited by Matt

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Bf109F-2 to the right gave me 23.7s (3 turns in 1:11.2 @ 40m @ 270km/h), rads on auto. Probably measurably better with rads closed, but not a couple of seconds. I don't think the 23.6 given is completely wrong.

WRT the P-40, the figure in the DD appears to be for 54" boost, which is less than 100% throttle. As you may know, 100% is more like 65" down low. It would give around 22.5s at the same speed for the same efficiency. Did you go with 100% or less? I haven't yet figured out how many % 54" are, will test the P-40 after I've done so.

 

All in all I haven't found anything so far suggesting the info is completely off, haven't tested flaps or anything, most aircraft only into one direction, but nothing out of the ordinary. Except for my blunder on that first I-16 check.

 

I noticed the dominant 270 as well, I don't know if it's actually the best turn speed, but a cl of around 1.2 seems to suggest it's not far off for any of these planes. At any rate, if you change that speed somewhat, the efficiency is not changing much, say 3% for 20km/h. You wouldn't want to change it more if you want to keep the cl within a reasonable best turn range.

The difference between LaGG and La can be down to aerodynamics (really poor on La-5, makes higher speeds less attractive, apparently really good on the LaGG-3, makes higher speeds more attractive) or the presence of the leading edge slats on the La-5. Or both.

 

If this forum is really in "developers assistance" I hope they can take something away from a topic for once. In terms of turning, the LaGG-3, I-16, Bf109F-2 and Mc.202 clearly require some attention, more than the other aircraft.

Edited by JtD

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I wonder P40 cause VVS test say 19.2 sec also pilots reported that it wasnt bad turner (if we dont compare it with Japanesse fighters). Still it has lower wingloading then some other fighters here

Edited by 303_Kwiatek

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WRT the P-40, the figure in the DD appears to be for 54" boost, which is less than 100% throttle.
 

OK, i misunderstood the "maximum possible power" and indeed tested with 100% throttle.

 

At ground level in a slow turn, it's basically 5% throttle increase for 5" boost increase and 54" should be around the 84-85% throttle position. Of course that's not exact, but should be good enough for a test comparison.

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A couple more Translated charts from the TSAGI book that might be of use:

 

VVSeeng_zps2th0rt1e.jpg

 

Pg1eng_zpspkzl56xc.jpg

 

Pg2eng_zpsq6dsugxn.jpg

 

 

Edited by Bert_Foster
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Apologies, I made one mistake calculating the drag (stupid typo) and I didn't catch it because I made a second mistake (thinking) in my plausibility check. L/D figures of the aircraft suggest efficiencies of 40%-75%, not 70% to 90% as written yesterday. In fact, more on the lower end of the 40-75% range, if you're looking at full scale aircraft. It lowers the expected values considerable. So for instance the LaGG-3 is not 'wrong' based on total value any more, just 'implausible' based on relative performance.

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Some more data about turn times of Eastern Front fighters:

 

http://juhansotahistoriasivut.weebly.com/results-of-the-soviet-turn-times-tests.html

 

 

Polikarpov I-15 (1934, 1,415 kg, 480hp M-22 - Soviet version of Bristol Jupiter, 2 or 4 x 7,62mm
    PV-1 mgs): 8 - 8.5 secs

Polikarpov I-15bis (1937, 1,640 kg, 764 hp/740 hp Shvetsov M-25V, 4 x 7,62mm PV-1 mgs):
    10.5 secs

Polikarpov I-153 "Chaika" (1939, 1,680 kg, 764 hp/740 hp Shvetsov M-25V, 4 x 7,62mm ShKAS
    mgs): 11.4 - 12.4 secs

Polikarpov I-153 "Chaika" (1939, 1,762 kg, 986 hp/789 hp Shvetsov M-62, 4 x 7,62mm ShKAS
    mgs): 11.4 - 12.4 secs
    Finnish tests 12 sec, radius 110m, maybe the most feared opponent to Fokker D. XXI
    pilots during Winter War, FiAF used war booty I-153s as a frontline a/c to autumn 44,
    during later part of the Continuation War (25 Jun 41 – 4 Sept 44) as recon fighter, last kill
    on 29 July 44, a P-39 from 773 IAP.

Polikarpov I-153 "Chaika" (1940, 1,902 kg, 1085 hp/887 hp Shvetsov M-63, 4 x 7,62mm ShKAS
    mgs): 14 secs

Polikarpov I-16 tip 29 (1940, 1,966 kg, 1085 hp/887 hp Shvetsov M-63, 2 x 7.62mm ShKAS +
    1 x 12.7mm UBS): 16-17 secs

Polikarpov I-16 tip 10 (1938, 1,716 kg, 764 hp/740 hp Shvetsov M-25V, 4 x 7.62mm mgs):
    16-18 or 16.5 secs

Yakovlev Yak-9 (1943, 2,873 kg, 1,193 hp/ 1,163 hp Klimov M-105PF, 1x20mm ShVAK +
    1x12.7mm UBS): 17 secs or 16 - 17 secs  or 17 - 18 secs
      Finns thought that Yak-9 was very manoeuvrable, there are many comments like that in
      the FiAF Bf 109G pilots’ combat reports

Polikarpov I-16 tip 28 (1939 - 40, 1,988 kg, 1085 hp/887 hp Shvetsov M-63, 2 x 7.62mm ShKAS
    + 2 x 20mm ShVAK): 17 - 19 secs


Yakovlev Yak 1B (1942, 2,884 kg, 1,193 hp/ 1,163 hp Klimov M-105PF, 1 x 20mm ShVAK +
    1 x 12.7mm UBS): 17 - 19secs or
19 secs depending the source.

Supermarine Spitfire F Mk IX (1944, 3,292 kg, 1,275 hp/1,380 hp Merlin 61, 2 x 20mm + 4 x
    7.7mm):  17.5 secs

Bell P-39D-2 (1,350 hp/1,135 hp Allison V-1710-63, 1x37mm+2x12.7mm+4x7.62mm):
   17.7-18.7 secs


Curtiss P-40C (3,390 kg, 1,055 hp Allison V-1710-33, 2x12.7mm+4x7.62mm): 18.0 secs mid

Yakovlev Yak-1 (1942, 2,900 kg, 1,193 hp/ 1,163 hp Klimov M-105PF, 1 x 20mm ShVAK + 1 x
    12.7mm UBS): 18-19 secs

Yakovlev Yak-9T (1943, 3,025 kg, 1,193 hp/ 1,163 hp Klimov M-105PF, 1x37mm NS-37 + 1 x
    12.7mm UBS): 18-19 secs.


Lavochkin LaGG-3 series 66 (1943, 2,990 kg, 1,193 hp/ 1,163 hp Klimov M-105PF, 1 x 20mm
    ShVAK + 1 x 12.7mm UBS): 18 - 19secs or
19 secs depending the source.
    this lightened version was IMHO better than series 28, a LW top ace, IIRC Barkhorn, told
    later that hardest fight he ever fought was a long duel against a LaGG-3 from a GIAP in
    1943/44, which ended when both disengaged simultaneously, so late over the Southern
    sector IMHO the LaGG must have been the lightened series 66 a/c.


Bell P-400/Airacobra Mk. I (1942, 3,556 kg, 1,150 hp V-1710-35, 1x20mm + 2x12.7mm +
    4 x 7.62mm) 18.2 secs

Bell P-400/Airacobra Mk. I (lightened) (1942, 3,324 kg, 1,150 hp V-1710-35, 1 x 20mm +
    2 x 12.7mm): 18.2 secs

Supermarine Spitfire LF. Mk IXE (1945, 3,351 kg, 1,320 hp/1,580 hp Merlin 66, 2 x 20mm +
    2 x 12.7mm): 18.5 secs

Bell P-39L-1-BE (1943, 3,616 kg, 1,325 hp V-1710-63, 1x37mm+2x12.7mm+4x7.62mm): 18.5 secs

Supermarine Spitfire Mk VB (1943, 2,920 kg, 1,130 hp/1,166 hp Merlin 46, 2 x 20mm + 4 x
    7.7mm): 18.8 secs


Curtiss P-40M-5-CU (1943, 3,958 kg, 1,200 hp/1,125 hp V-1710-81, 6x12.7mm): 18.8 secs

Supermarine Spitfire HF. Mk IX (1945, 3,338 kg, 1,475 hp Merlin 70, 2 x 20mm + 2 x 12.7mm):
    19 secs

Lavochkin LaGG-3 series 28 (1942, 3,055 kg, 1,085 hp/1,035 hp Klimov M-105PA, 1 x 20mm
    ShVAK + 1 x 12.7mm UBS): 19 secs
     Finns concluded that LaGG-3 turned more or less as well as 109G. When Finns tested a
     LaGG-3 against Hawk 75A, LeLv 32 (Fighter Wing/Jagdgruppe) used both in combat,
     conclusion was that if at the beginning of a mock combat LaGG-3 was behind Hawk 75A
     after only 1½ turns situation was reversed.

Lavochkin La-5 (1943, 3,208 kg, 1,676 hp/1,311 hp Shvetsov M-82, 2 x 20mm ShVAK): 19 secs

Bell P-39D (3,556 kg, 1,150hp Allison V-1710-35, 1x37mm+2x12.7mm+4x7.62mm): 19 secs

Bell P-39N-1 (1,420 hp/1,200 hp Allison V-1710-85, 1x37mm+2x12,7mm+4x7.62mm): 19 secs
     From the report of FiAF 3./HLeLv 34 on the actions during the hectic summer 44. “AC
     (P-39) is more or less as good as La-5 (at this stage means La-5Fs and FNs) but maybe less
     manoeuvrable.”

Yakovlev Yak-3 (1943, 2,697 kg, 1,272 hp/1,223 hp Klimov VK-105PF-2, 1x20mm+2x12.7mm):
    19 secs

Hawker Hurricane IIA (1941, 3,170 kg, 1,280 hp R-R Merlin XX, Vokes filter, 8x7.7mm
    Browning): 19-20 secs

Bell P-39Q-25-BE (1944, 3,547 kg, 1,420 hp/1,200 hp Allison V-1710-85, 1x37mm+2x12.7mm
    so without gunpods): 19-20 secs

Yakovlev Yak-1 (1941, 2,934 kg, 1,085 hp/1,035 hp Klimov M-105PA, 1 x 20mm ShVAK +
    2 x 7.62mm ShKAS): 19-20 secs

Yakovlev Yak-1 (1942, 2,917 kg, 1,193 hp/ 1,163 hp Klimov M-105PF, 1x20mm ShVAK +
    2 x 7.62mm ShKAS): 19-20 secs


Yakovlev Yak-7B (1942, 3,005 kg, 1,193 hp/ 1,163 hp Klimov M-105PF, 1x20mm ShVAK +
    2 x 12.7mm UBS): 19-20 secs
     Finns misidentified some Yak-7Bs as Spitfires, they were told that they might meet  
     Spitfires, and thought that these didn’t live up their high reputation

Yakovlev Yak-9D: (1943, 3,117 kg, 1,193 hp/ 1,163 hp Klimov M-105PF, 1x20mm ShVAK +
    1 x 12.7mm UBS): 19-20 secs

Yakovlev Yak-9M: (1944, 3,095 kg, 1,193 hp/ 1,163 hp Klimov VK-105PF, 1x20mm ShVAK +
    1 x 12.7mm UBS): 19-20 secs

Lavochkin La-5FN (1943, 3,305 kg, 1,825 hp/1,410 hp Shvetsov ASh-82FN, 2 x 20mm ShVAK):
    19 or 19.5 secs, depending on the source
     Finns thought that La-5F/FN was a bit better turner than 109G at low level. It was also the
     most dangerous opponent of FiAF Bf 109Gs during the heavy fighting in summer 44, even if
     one cannot find so many glowing appraisal on La-5 than on Yak-9 in FiAF 109G pilots’
     combat reports

Curtiss P-40E-1-CU (1942, 3,840 kg, 1,150 hp Allison V-1710-39,  6x12.7mm): 19.2 secs mid 

Bell P-39Q (1943, 3,495 kg, 1,420 hp/1,200 hp Allison V-1710-85, 1x37mm+4x12.7mm so with
    gunpods): 19.5 secs
    the subversion is not given, but the weight given is some 25kg lighter than the
    grossweight of Q-15-BE, see below, maybe Q-5-BE or a lightened plane.

Yakovlev Yak-1 (1942 Winter variant, heavier due to insulation, heating ducts etc): 19.5 secs

Messerschmitt Bf 109F-4 (2,902 kg, 1,331 hp/1,183 hp DB601E, 1x20mm MG 151/20 + 
    2x7.92mm MG 17): 19.6 - 20.5 secs

    Soviet max speed for the aircraft (624km/h at 6,500m) is on slow side, so maybe it
    had some problems

Messerschmitt Bf109F-2 (2,780 kg, 1,144 hp DB 601N, 1x15mm MG 151 + 2x7.92mm MG 17):
    19.6 secs (some sources 19.8) -20.5 NII

Hawker Hurricane IIC (1943, 3,455 kg, 1,319 hp Merlin XX, 4 x 20mm): 20 secs

Lavochkin LaGG-3 series 4 - 8, (3,280 kg, 1,085 hp/1,035 hp Klimov M-105PA, 1 x 20mm ShVAK
    + 1 x 12.7mm UBS + 2 x 7.62mm ShKAS): 20 secs
     Finnish tests for a war booty LaGG-3 series 4 (LG-1) with wings modified with slots: 23s
     with 40km/h speed loss, the same plane shot down a Soviet LaGG-3 from 415 IAP on 16
     Feb 44 after fairly long turning fight, the fight began as an head on meeting with 2
     escorting LaGG-3s against the LG-1. After a while after an head on pass one of the Soviet
     LaGGs disengaged but the other continued the turning fight until it was hit after which it
     tried disengage but the FiAF pilot followed and shot it down. So Finns were not altogether
     hopeless in flying early LaGG-3s, there were some other contacts with FiAF and Soviet
     LaGG-3s which ended without losses on either side. IMHO in early 44 Soviet LaGG-3s
     should have been at least series 28 or later.

Lavochkin La-5F (1943, 3,207 kg, 1,676 hp/1,311 hp Shvetsov M-82F; 2 x 20mm ShVAK): 20
    secs

    Finns thought that La-5F/FN was a bit better turner than 109G at low level, the high back
    La-5, which Finns called LaGG-5, was more or less equal to 109G-2 in low-speed turning
    fight at low level

Yakovlev Yak-9U (1944, 3,260 kg, 1,479 hp/1,430 hp Klimov VK-107A, 1x20mm ShVAK +
    2x12.7mm UBS): 20 secs

Bell P-39Q-10-BE (1943, 3,570 kg, 1,420 hp/1,200 hp Allison V-1710-85, 1x37mm + 4x12.7mm
    so with gunpods): 20-21 secs
    From the report of FiAF 3./HLeLv 34 on the actions during the hectic summer 44. “AC
    (P-39) is more or less as good as La-5 (at this stage means La-5Fs and FNs) but maybe less
    manoeuvrable.”

Lavochkin La-7 (1944, 3,232 kg, 1,824 hp/1,449 hp Shvetsov ASh-82FN, 2 x 20mm ShVAK): 20 -
    21 secs or 20.5 secs

Messerschmitt Bf 109G-2 (1942, 3,023 kg, 1,454 hp/1,233 hp DB 605A-1, 1 x 20mm MG 151 +
    2 x 7.92mm MG 17): 20-21.5 secs, middle 21 secs NII
    Finnish tests, also at 1,000m, 1,3 ata, sustained 22 secs, speed 360 km/h 3G


Messerschmitt Bf 109G-4 (1943, 1,454 hp/1,233 hp DB 605A-1, 1 x 20mm MG 151 +
    2 x 7.92mm MG 17): 20.5-21 secs


Hawker Hurricane IIB (1942, 3,352 kg, 1,319 hp Merlin XX, 2 x 20mm ShVAK + 2 x 12.7mm +
    6 x RS-82 rockets): 20.5 secs

Bell P-63A-10-BE (1945, 3,822 kg, 1,325 hp V-1710-93, 1x37mm + 2x12.7mm): 20.5 secs

Lavochkin LaGG-3 series 29 and 32 (3,150 kg, 1,193 hp/ 1,163 hp Klimov M-105PF, 1 x 20mm
    ShVAK + 1 x 12.7mm UBS): 21 secs or 22 secs  depending the source.   

    When Finns tested a LaGG-3, FiAF LG-3 was 35th serie aircraft, that Serie was the first
    with leading edge slats, against Hawk 75A, LeLv 32 (Fighter Wing/Jagdgruppe) used both
    in combat, conclusion was that if at the beginning LaGG-3 was behind Hawk 75A after
    only 1½ turns situation was reversed.

Yakovlev Yak-7A (1942, 2,935 kg, 1,085 hp/1,035 hp Klimov M-105PA, 1 x 20mm ShVAK + 2 x
    7.62mm ShKAS): 21-22 secs

Focke-Wulf FW 190A-5 (1942, 4,070 kg, 1,558 hp/1,440 hp BMW 801 D-2): 21 - 22 secs

Focke-Wulf FW 190A-8 (1944, 3,986 kg, 1,558 hp/1,440 hp BMW 801 D-2, 2x20mm +
    2x13mm): 21 - 22 secs
    without outer wing cannon and also otherwise lightened, because according to German
    documents weight should have been 4,272 - 4,395kg w/o a drop tank, different docus give
    different weights and appr. 4,100kg without outer wing cannon)

Hawker Hurricane IID (1944, 3,650 kg, 1,319 hp Merlin XX, 2 x 40mm [should also have 2 x
    7.7mm, removed or forgotten]): 22 secs

Lavochkin LaGG-3 series 1 - 3 (3,346 kg, 1,085 hp/1,035 hp Klimov M-105P, 3 x 12.7mm UB +
    2 x 7.62mm ShKAS): 22 secs

Lavochkin LaGG-3-37 (3,363 kg, 1,193 hp/ 1,163 hp Klimov M-105PF, Armed with a 37mm
    Sh-37 cannon and 1x12,7mm UBS). Also had leading edge slats: 22 secs
    Finns met these a/c in summer 44, one Soviet regiment equipped with these and Yak-9s was
    transferred from VVS Black Sea Fleet to VVS Baltic Fleet to reinforce Soviet attack forces,
    but I recall only comments on their good tactics and unusual camo from Finnish combat
    reports.
 
Focke-Wulf FW 190A-4 (3,989 kg, 1,706 hp/1,341 hp BMW801D, 4x20mm + 2x7.92mm): 22 -
    23 secs NII-VVS, 23 - 24 secs LII-NKAP


Focke-Wulf FW 190D-9 (4,197kg, 1,755 hp Jumo 213A, 2x20mm + 2x13mm): 22 - 23 secs,
    max speed achieved was 624km/h. Very near the German test results with the 6th series
    production Fw 190D-9 at Rechlin test center, which were at 3,000 rpm max. speeds 520
    to 530 km/h at sea level and 625 and 635km/h at 6,500m (about full throttle height,
    depending on engine adjustment). 3,000rpm means Steig- und Kampfleistung (climb and
    combat power) and with 3,250 rpm, speeds reached 540 and 550 km/h at sea level and
    645 and 655 km/h at 6,600m. This with Start- und Notleistung (Take-off and emergency
    power) with B4/87oct. fuel. Take-off weight was 4,350kg. Soviets didn't use MW50 or
    C3/96oct fuel in their 190D-9 tests. According to Focke-Wulf the top speed at Start u.
    Notleistung with B4 was 568 km/h at SL and 680 km/h at 6,600m.

Messerschmitt Bf 109G-2/R6 (1942, 3,235 kg, 1,454 hp/1,233 hp DB 605A-1, 3 x 20mm
    MG 151 + 2 x 7.92mm MG 17): 22.6 - 22.8 secs

Lavochkin La-5 (1942, 3,360 kg, 1,676 hp/1,311 hp Shvetsov M-82, 2 x 20mm ShVAK): 22.6
    secs


North American Mustang Mk I (1942, 3,884 kg, 1,150 hp Allison V1710-F3R, 4x12.7mm +
    4x7.62mm): 23 secs.
    Soviet tested one of those sent from GB (AG348 ) and the max. speed at 4,600m 587km/h,
    the designation used in some Soviet documents, NA-73, and the engine sub-type indicated
    that it was not P-51A but XP-51 in USAAF parlance. British A&AEE tests in spring 42 (AG351)
    595km/h at 4,572m, so almost the same speed.

MiG-3 (1941, 3,350 kg, 1,331 hp / 1,183 hp Mikulin AM-35A, 1x12.7mm UB +  2x7.62 mm
    ShKAS):  23 secs
    Finns: at lower level not very manoeuvrable on horizontal plane)


Messerschmitt Bf 109E-3 (1940, 2 x 20mm MG FF + 2 x 7.92mm MG 17):  23-26 secs with 1.33
    ata, max 5 min power setting
    The supercharger seemed to have malfunctioned at low level, which was very important for
    these tests made at 1000m. German specs give 18.92 sec for a sustained turn at SL for the
    Emil, at 5 min rating, w/o using the 1-min special low-alt augmented rating. British tests gave
    25 sec but the altitude was 12,000 ft, means 3,658m, so at higher altitude and so it should
    have taken a little longer than at 1,000m. British didn't notice any measureable difference
    between turning left or right.)

Lavochkin LaGG-3 series 23 (3,100 kg, 1,085 hp/1,035 hp Klimov M-105PA, 1 x 20mm ShVAK +
    1 x 12.7mm UBS + 6 x 82mm RS-82 rockets): 26 secs

Republic P-47D-10-RE (1944, 5,961 kg, 2,000 hp R-2800-63, 6(8)x12.7mm, 661km/h at
    8,500m): 26 secs

Yakovlev Yak-9DD (1944, 3,387 kg, 1,193 hp/ 1,163 hp Klimov VK-105PF, 1x20mm ShVAK +
    1 x 12.7mm UBS): 26 secs

Messerschmitt Bf 109E-3 (1940, 2,605 kg, 2 x 20mm MG FF + 2 x 7.92mm MG 17): 26.5-29 secs
    at 1.26 ata
    The supercharger seemed to have malfunctioned at low level, which was very important for
    these tests made at 1,000m. German specs give 18.92 secs for a sustained turn at SL for the
    Emil, at 5 min rating, w/o using the 1-min special low-alt augmented rating.

Republic P-47D in 1945: 27-28 secs

Messerschmitt Bf 110C-4 (1940, 6,510 kg, 2 x 20mm MG FF + 4 x 7.92mm MG 17 + 1 x
    7.92mm MG 15): within 30 secs

Edited by 303_Kwiatek
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The developers have updated their figures, most notably they've changed the turn time for the Yak-1S69 and added Bf109G4 and Yak-1S127. I've also found some minor typos in my table. I suspect an error in the Bf109G-4 data, they state the turn was flown at combat power, but it looks as if emergency was used. It would end up at 34% this way and make sense in relation to the G-2. It would explain why the aerodynamically less clean and heavier aircraft turns better.

I've also sorted the table from highest to lowest efficiency.

post-627-0-63168500-1483792997_thumb.jpg

Edited by JtD
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Care to summarize what are the three most important or odd conclusions to be drawn from that table?

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Pretty similar to what I said in the initial post, however, as the Yak is now allegedly turning two seconds faster than previously stated, it's as odd as the LaGG-3.

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Interesting to see the data collected like that JtD. When I compare to the numbers I get in my C++ simulation it does not look too bad:

 

I get the following numbers for stationary turn times at 1 Km altitude with combat power:

 

Fw-109A3: ca 23 s                      (7.4% less than Il-2)

Me-109F4: ca 19.7s                   (3% less than IL-2)

Me-109E4: ca 18.4s                   (11% less than IL-2 E7. However, note I have E4 not E7 modeled!)

Me-109G2: ca 20.2s                  (10% less than IL-2)

Yak-1 s69: ca 20.1s                    (5.5% less than IL-2)

 

So IMHO IL-2 looks pretty good actually: I’m just a tad more optimistic that’s all. OTOH what counts more than the absolute number is the relative performance and with the exception of the G2 and F2 those look pretty good actually if you translate my number up ca 5%! (I don’t have the F2 modeled but looking at the power- and wing loading 23.6 looks way too pessimistic to me.)

 

The P-40 is a bit special in that my estimate is based on 1150 hp whereas the table says 1470 hp so I have two figures for the P-40:

 

P-40E with 1150 hp: ca 25.1s                             (3.2% more than IL-2)

P-40E with 1470 hp: ca 21.7s                             (11% less than IL-2)

 

Now I don’t think it so strange that the P-40 has such a long turn time if you look at the wing- and power loading: It's not that far from the G2 in terms of wing loading: The G2 gets 186 kg/sqm while the P-40 comes in at 174 Kg/sqm. However, the G2 is way ahead on the power loading: With a power loading of 0.44 hp/kg as opposed to the P-40E at 0.3 hp/Kg at 1150h to 0.38 at 1470 hp.

 

For fun I did a third calculation giving the P-40 the same power loading as the G2 (0.44) and unsurprisingly with the same power loading both come in a ca 20 s. So the P-40 is simply hampered by the laws of physics: It’s a pretty heavy plane but if it simply had the same power loading as the lighter G2 it too would do well in terms of turn times.

 

Concerning the deviation of the G2 and the F2: I think Venturi had a good theory about this in another thread: The different planes are most likely done by different developer teams so this could explain why some planes deviate. Hopefully the developers are already thinking about this though and the question in which direction to go: Improve the G2 and F2 turn times or tune down the others?

 

Maybe would be good to start thinking about a report on the F2 though? 23.6 s seems way too high IMHO. Then there is the P-40E of course: I thought it was 1150 hp that was modeled IL-2? However, if it is 1470 hp as the table says then for sure 24.3 seems way too pessimistic as well.

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Holtzauge your calculations look really good. Still wonder about P40 and VVS data clamied about 19-20 sec turn time ( p40 got lower wing loading then contemporary dunno also about cl max). As you said G2 and F2 looks in BOS not good. As for G2 we got VVS data which showed average 20 sec (depend left or right ) but i cant find any historical data for F2.

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Well, I agree there is something off with some of the Russian turn times: While many make sense, there are a couple that really stick out: the P-40E turn time is listed at 19.2 s which seems very optimistic. Also note that the Me-109E is listed as doing a 360 turn in 26.6 to 29.4 s which is also really weird. So something is obviously off here. Question is what?

 

Regarding the F2: I don't have the numbers (P/W and W/S) in front of me but I would assume they are pretty close to the F4 and if so they should be just about the same.

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These AIS figures must be rounded to the nearest 10kph - ie +/- 2% of 270 - since the turns were measured at "boosted power" rather than a set speed. Interesting that they were all so close - all but 3 recorded as 270kph.

 

Obviously I have no idea how or if in your model the speed, or radius which I assume you calculate from the speed+time, affects the results.

 

So I am wondering if the approximation for the speed makes a material difference: having been sensitized to sensitivities.  

 

edit - bleh.

Edited by unreasonable

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Turn times have to be carefully interpreted, after all a Ju-52 can out turn an FW-190 at sea level (albeit at a slower speed)  ;)

 

Cheers Dakpilot

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But it is aerodynamically only as efficient as an I-16, both at 24% (updated post #16). I'd say the relation between Fw and Ju is quite OK.

 

Holtzauge, your figures are for 1km, developers figures for sea level. It makes your figures quite a bit more optimistic than the Il-2 ones. But the relative performance looks pretty much as one would expect.

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These AIS figures must be rounded to the nearest 10kph - ie +/- 2% of 270 - since the turns were measured at "boosted power" rather than a set speed. Interesting that they were all so close - all but 3 recorded as 270kph.

 

Obviously I have no idea how or if in your model the speed, or radius which I assume you calculate from the speed+time, affects the results.

 

So I am wondering if the approximation for the speed makes a material difference: having been sensitized to sensitivities.  

 

edit - bleh.

 

I'm not sure how you mean corrected for power? If you mean the slipstream effect that is at least covered in my model: For example Me-109G2 stall speed is in my model is 165 KM/h power off and 153 Km/h at Steig& Kampfleistung. As to the calculation of max turn rate, this works by calculating the stall line then iterating the power limited curve until the thrust matches the drag and then you will see the max turn rate at the intersection of the two. I can also print out so-called doghouse charts where you see the turn rate as a function of speed.

 

But if you mean that they specify a particular speed, I think that that just defines at what speed you have the max turn rate ingame at the given power level so that is OK and in that sense they do not need to be corrected.

 

 

Turn times have to be carefully interpreted, after all a Ju-52 can out turn an FW-190 at sea level (albeit at a slower speed)  ;)

 

Cheers Dakpilot

 

True, if you slow down and turn fight a Ju-52 in a Yak it'll probably come back bite you in the @ss!

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But it is aerodynamically only as efficient as an I-16, both at 24% (updated post #16). I'd say the relation between Fw and Ju is quite OK.

 

Holtzauge, your figures are for 1km, developers figures for sea level. It makes your figures quite a bit more optimistic than the Il-2 ones. But the relative performance looks pretty much as one would expect.

 

OK, I see. I always calculate for 1 Km because a lot of the times the figures are given for 1 Km. I believe the Russian numbers are for that altitude and I guess it makes sense since if you want to max out the turn rates you are basically at stall so it would be sensible to keep some altitude as a margin.

 

Concerning the level of optimism, I agree that that makes the Il-2 numbers a bit on the low side in general then. In addition, looks like my numbers are closer to the Russian table estimates as well (excepting the P-40 and Me-109E of course). Its a bit strange that the Il-2 turn times are lower than mine given that Il-2 seems to be more optimistic on climb times than me in general. For example, my G2 turn estimate is higher but my climb estimate is around 18-19 m/s at low altitude (1.3 ata) which I believe is lower than what you see in Il-2.

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At Holtzauge: sorry I was referring to JtD's original table. You can either fix the power and measure the speed, or fix the speed and see what power you need. Cannot do both. In the Tech Specs the turn times are given as being done at boosted power, so the speeds given must be measured. 

 

Since the times given are all in multiples of 10kph, they must be rounded. So I was wondering if JtD's calculations are particularly sensitive to the implied +/- 2% error in the speed number.

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No, they are not. I answered that in post #8...maybe it would make sense to update the first post with current figures and the FAQ instead of distributing the information all over the discussion.

Edited by JtD

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Sorry, missed that.  Your update/FAQ idea is a good one: forums are a horrible format to store information except as a sticky. There will always be some idiot who misses some detail.  :blush:

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No need to feel bad unreasonable: I missed that part with the same speed being given in the table :unsure: : However it turns out that the best turn rates are in my calculations close for the F4 (273 km/h), the Yak (276 Km/h) and reasonable for the G2 (284 Km/h) but for the E4 (255 km/h) and A3 (315 Km/h) it's a bit of a difference. OTOH it does not look like it makes that much of a difference: The A3 turns at 25 s at 280 Km/h, and the G2 at 20.9 and the E4 at 18.7s at 270 Km/h so it does not look like it makes that much of a difference.

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Holtzhauge, does your turn time model take into account induced drag as JtD mentions?

 

If so how are you finding the drag numbers, wing polars only?

 

Sorry if already posted.

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Holtzhauge, does your turn time model take into account induced drag as JtD mentions?

 

If so how are you finding the drag numbers, wing polars only?

 

Sorry if already posted.

 

Yes, it takes the induced drag into account as well as the so-called Oswald factor e,  i.e. the deviation from the perfect elliptical distribution. I'm not assuming e as a constant but as a variable of Cl and Mach. Also, the propeller efficiency is not constant, so while the efficiency is around 0.8 at high speed, it is lower at climb and turn speeds. In addition, the efficiency drops at higher altitudes since the air gets thinner and the blades need a higher aoa to absorb the power which lowers the efficiency even more. I'm not claiming my model is a 100% right but I have been tuning it over the years and have more than 20 different planes modeled and once you get a few IRL data points to tune with it turns out that the predictions tab pretty well for the others. When it comes to things like polars, propeller efficiencies its interesting to note that when you reverse engineer the performance, there does not seem to be that much difference between the level of technology in axis and allied designs. As an example, there seems to be little to choose between a German 3 blade prop with bigger wider blades and an allied 4 bladed prop with a slightly lower solidity. Same goes for the wings: the important thing seems to be the wing loading and aspect ratio. The model itself is a bit more complicated since it takes into account Mach effects as well, both in terms of drag, buffet limits on lift and propeller efficiencies due to prop tip speeds etc. However, as I said before, the interesting thing is that in terms of performance it looks like this is basically determined by the wing- and power loading and not provenance which also makes sense if you assume that allied and axis designers where about as good at their job which also seems like a reasonable assumption. 

 

Maybe this was a bit long winded but this is why I have been saying earlier that I think the P-40 has a bit of an uphill struggle when it comes to the physics: When you look at the wing loading in combination with the power loading it does not come out that strong which is the reason I find it hard to believe that it was good at sustained turn fights. OTOH it does have a lower wing loading than a Me-109 so for sure it should be able to out turn it momentarily and I guess theoretically a scissors with a P-40 would be suicide since in addition to the lower wing loading, it rolled better. In addition if a P-40 suckered a Me-109 into slowing down sufficiently he could probably win the turn fight that way.

Edited by Holtzauge

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Interesting. I would like to see a screenshot of the output of this program and the input parameters. Which wing polar are you using since we do not have the 2215 airfoil data?

 

RE P40E, we already know 1150hp is most likely not the power level used by the VVS pilots and others in combat. It is also unclear to me how heavy the P40E was actually given the manifold different loading options. Additionally the CLmax and critical angle of attack are not clear, which would influence drag for any given Cl.

 

Another thing to consider is stick forces. Not everyone could put 50lbs lateral force with 2" elbow clearance and this has a real impact.


^ CLmax and critical angle of attack potentially varying even within 22xx series.

Edited by Venturi
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Trying to decode what this table actually means. Efficiency is expressed as a ratio like this: "empircal result / theoretical" and then given as a %.

 

JtD, are you taking into account dev numbers here and deriving overall airplane efficiency with them? I am not sure I have seen this done before.

 

Maybe you've already explained this and I've missed it. What are your parameters for efficiency here, IE is this table for % efficiency in turning time?

 

Are you then, finding an overall theoretical "turn time" to start with?

 

If so, my question is the same as the one posed to Holtzhauge, IE what numbers are you using and how are you calculating theoretical turn time? Are you then using official dev figures? If so which ones, IE wing polar for P40E is not known, so how can you derive theoretical drag?

 

Obviously the "empirical result" found is the dev's figures for turn time, but that is irrelevant as it is empirical (and obviously not always the same result we can actually achieve in game).

 

Again, my point is how you are getting the theoretical figures to derive an efficiency, which is expressed as an empirical result / theoretical result and given as an efficiency.


I note your Cl for the P-40 is 1.10. ^

I assume you mean CLmax? If so this seems a very low number given the published stall speeds and weight range.

post-16698-0-03617500-1483805985_thumb.jpg

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Interesting. I would like to see a screenshot of the output of this program and the input parameters. Which wing polar are you using since we do not have the 2215 airfoil data?

 

RE P40E, we already know 1150hp is most likely not the power level used by the VVS pilots and others in combat. It is also unclear to me how heavy the P40E was actually given the manifold different loading options. Additionally the CLmax and critical angle of attack are not clear, which would influence drag for any given Cl.

 

Another thing to consider is stick forces. Not everyone could put 50lbs lateral force with 2" elbow clearance and this has a real impact.

^ CLmax and critical angle of attack potentially varying even within 22xx series.

 

Well when it comes to wing profiles that is taken care of in the Clmax estimate which is different for each aircraft and again, a function of Cl and Mach. The wing profile will also affect the Cdo estimate and when it comes to the polar or L/D factor, this again seems to be mainly influenced by the wing loading and aspect ratio together with the Oswald factor which as I said before is modeled as a function of both Cl and Mach. I know JtD also has a turn estimate program in Excel and I'm sure he will agree that you can do pretty well in the estimates using this as a base.

 

However, there was one aircraft that required a bit of TLC in my modeling and that was the Mustang: In this case you have a laminar profile with a so-called low drag bucket where you have a very good L/D ratio on the wing profile but once you get to a higher Cl, like when turning, you drop outside the bucket and get a substantial drag penalty. Other than that, IMHO it is the same as with the propellers: while the wing profiles, propeller blade numbers etc. varied, the wing performance in terms of L/D ratio on both axis and allied planes was mainly determined by the choice of wing loading and wing span together of course with the wing profile and slats or washout which to a large extent determined the Clmax.

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Trying to decode what this table actually means...

All the physically necessary drag is the lift induced drag. Every other bit of drag is just waste - be it efficiency figures like the Oswald coefficient or the parasitic drag, both skin friction and shape drag, and what not else. All waste.

Likewise, physically thrust is shaft power output divided by speed. However, again in practice there are considerable losses with the airscrew.

In all sustained, level flight manoeuvres drag equals thrust. So comparing the theoretical lift induced drag from the flight parameters with the theoretical thrust produced from the engine, we can see how much of the engine output is wasted.

 

Basically:

 

theoretical, pure induced drag + all sorts of aerodynamic losses = theoretical thrust - airscrew losses

or

theoretical, pure induced drag + all sorts of aerodynamic losses + airscrew losses = theoretical thrust

 

The third column from the right is that theoretical, pure induced drag ((2*lift²)/(1.225*Pi*speed²*span²)).

The second column from the right is that theoretical thrust (power/speed).

The efficiency then is the ratio of that theoretical, pure induced drag divided by that theoretical thrust.

efficiency = ((2*lift²)/(1.225*Pi*speed²*span²))/(power/speed)

 

It's a statement about the aerodynamic quality of the aircraft in turning flight. It's of no use to the pilot and there's no figure in historical documents that can be directly compared to it.

 

But I don't need any information for that besides what is in the table, and even there wing area is added as a bonus so that I can calculate lift coefficient as a bonus. I only need turn time, speed, weight, span and engine power, which all are developers figures.

I can then go on and make up my mind on some things. For instance, if the P-40 was modelled as efficiently as the Yak, it would have a turn time of 20s, not 24s. A Macchi would match the Yak figures at 19s. Do you know why the Yak would be so much more efficient then the P-40 or the Mc202 in a sustained turn? I don't, I just don't see it.

---

I have no clue about what I need to explain, so if the above didn't help, let me know.

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What are your parameters for efficiency here, IE is this table for % efficiency in turning time?

 

He is using induced drag.  It is his own creation and parameter loosely based on science.

 

It has no relation to any actual aircraft efficiency factor. 

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That answers my questions thank you JtD. I agree it is strange, some of the findings. A professional aero engineer recently related to me that "the major problem with sims of this type is that they do not treat drag correctly. And therefore they do not get real results."

 

Since this gentleman is widely respected in his community and states he has worked with a few very famous firms, I tend to take him at his word.

Edited by Venturi

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Let me make a few observations.

 

The loss of thrust from the propeller and the overall drag in a turn for an airplane, including form drag, are unknowns right now, but may be responsible for reductions / overestimations in airplane turning performance in the sim.

 

There is no easy way to determine the unknowns of total turning airframe drag or turning propellor inefficiency, if using the formula(steady state) of "thrust=drag".

 

(Although certainly one could find the straight line value for propellor inefficiency easily enough, and substitute it in?)

 

What you do in your spreadsheet instead, is calculate the lift necessary to turn a plane in the time given by the devs, with the dev given wing area, weight, and power. You then find the induced drag for the wing, only, which that amount of lift would generate, using a generic formula. You then divide the drag by the thrust to generate your "efficiency".

 

Since in a level steady state condition, thrust=drag, this "efficiency" score is actually an indirect way of looking at airscrew thrust losses and / or the overall drag of the plane in a turn, which itself includes many variable forms of drag.

 

A lower "efficiency" score infers that a airplane has a higher airscrew inefficiency, higher airframe turning drag, or some combination of the two.

 

I am glad you have done this, because it closely follows the chain of logic I also had in another hotly contested thread a little while back on turn-induced "near stall / max effort turns" drag.

Edited by Venturi

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Here is a relevant recent quote from my aerodynamicist friend:

 

----

 

"Just in case you are modeling for maneuver combat, the drag factors always dictate a lower effective CLmax in a banked stall.

 

The Free body equation of Thrust = Drag for level flight at cruise or above velocities do not include much cooling drag or form drag due to angle of attack or trim drag for control surface deflection. At 160-200mph for tight and level (same altitude) turns, the form drag for high AoL banked turns is as much as the parasite drag for level flight. These factors drive Power Required to significantly higher % of Power available.

 

That is why 'Gamers' miss the mark."

 

The unknowns you are treating with here, one of which is mentioned, above, seem very significant and widely underdiscussed.

Edited by Venturi
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