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4 hours ago, Collimatrix said:

 

As far as I know, only the FW-190 had the automatic lean/rich adjustment for the throttle, it wasn't a feature of German aircraft generally.
 

Which is amusing, as the vast majority of German radial engines of that era, were the result of BMW licensing Pratt & Whitney designs.

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A few years late, but have to say this was a great OP I wish I'd stumbled on sooner (plus a pretty epic flamewar). Fascinating for those of us who don't work on or aspire to design aircraft but want to understand the choices designers made. Hope it is not too late to add something to the conversation.


1. Some more fighters with outer wing fuel tanks:

2. Some more points worth mentioning:

  • Airframes that were arguably heavier and stronger than optimal for pure air-to-air or economy of production (most US fighters, Fw 190, Typhoon/Tempest) had an advantage when converted to fighter-bombers, since you could hang more bombs on them without breaking. (Of course if you were optimising for load carrying you would also make the wings bigger for more lift, with a drag penalty, which is one reason bombers and transports tend to be slower than fighters even unloaded.)
  • The distinction between maximum speed and initial acceleration is important in a dive as well as level flight. E.g. the Spitfire had AFAIK the best critical Mach number of any WW2 prop plane, but didn't pick up speed very quickly in a dive due to its lightness.
  • Re the earlier civilised discussion on the P-38, the following critical Mach numbers from Wings on My Sleeve by Eric Brown may be of interest:
    P-38 0.68
    P-47 0.71
    Me 109 0.75
    Fw 190 0.75
    P-51 0.78
    Spitfire 0.83 (?)
  • If you want to use your plane on a carrier, you need extra weight (strength for basically controlled crash landings), bigger wings (more lift for short takeoff runs & slower landing/stall speeds), and better visibility illustrated e.g. in the "hump" on the Sea Fury at the cost of some drag (similar to the move to from razorback to bubble canopies in general). The poor forward visibility mentioned on the Fw 190 would have been a problem.

3. And finally push back a little on a few statements:

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The heavy [twin-engine] fighters had a major, inherent disadvantage in terms of top speed. This is because twin engined prop fighters have three big lumps contributing to frontal area...

This isn't obvious from the data: leaving aside the Lightning which is granted as an exception, the Me 110 was competitive in top speed (it was the manouverability that killed it as a day fighter), the Whirlwind was as fast as the Spitfire with less powerful engines and the Mosquito and DH Hornet were faster with the the same power. Same for the Tigercat vs the Bearcat. Geometrically, too, the pilot can't hide completely behind the engine in a single engine fighter that needs a minimum level of visibility.

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Maximum dive speed is also a function of drag and thrust

Theoretically yes but practically didn't all a/c (not just US ones) develop excessive control forces, hit critical Mach, or simply break apart before that point? AKA "why dive bombers needed dive brakes".

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The design requirements for turn rate were very difficult to reconcile with the design requirements for climb rate.

Again, not obvious as a major problem: aircraft with good power-weight and moderate wing loadings (no I don't have E-M charts for them all!) like the Spitfire, Zero, Oscar, early 109s were pretty good at both, even if there is a marginal tradeoff. Even the J2M given as an example of a fighter completely optimised for climb was not that bad a turn fighter: "the Raiden, despite not being designed for maneuverability, still had a lower stall speed than the Hellcat, and could turn tighter." There is a much more obvious tradeoff between climb and turn performance on the one hand, and dive on the other, based on weight, seen most notably in Japanese or really anyone else vs most US fighters.

Edited by hobbes154
Edited for clarity
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1 hour ago, hobbes154 said:

A few years late, but have to say this was a great OP I wish I'd stumbled on sooner (plus a pretty epic flamewar). Fascinating for those of us who don't work on or aspire to design aircraft but want to understand the choices designers made. Hope it is not too late to add something to the conversation.


1. Some more fighters with outer wing fuel tanks:

  • (some) CorsairsChance-Vought-F4U-Corsair-Cutaway-Drawin
  •  

 

 

Just a note on the Corsair wing tanks. They did not work well. They had a tendency to leak at the fold point. The pilots did not like them, even though they came with C/O2  purging system.  The wing tanks were only found on the -1 and -1A birds. When they -1D went into production, they were eliminated, since it could carry up to three drop tanks.  You would think instead  of dropping them, they would have fixed the leaking problems, and given the the Corsair some extra range! 

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Regarding the turn rate/climb rate question... I tried to find some info about bi-planes becase before WW2 those were generally rated to have high-climb rate combined with great turning abilities. I found following numbers (without guarantee): Fiat CR.32 (1934) 9,2 m/s; Gloster Gladiator (1937) 11,5 m/s; Fiat CR.42 (1938) 11,7 m/s; Grumman F-3F (1936) 14 m/s; Polikarpov I-15 (1934) 14,3 m/s; Polikarpov I-153 (1939) 15 m/s; Avia B-534-IV (1937) 15 m/s; Avia B-634 (1936) 16 m/s (not produced aerodynamically cleaned version but still with fixed gear). 

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