Just something to think about here...
My uncle started out with the P-36 and as the war got underway in the Pacific, was assigned briefly to the P-39 and then the P-38 for the duration.
He hated the P-39 with a passion and spoke highly of the P-38. However, his passion was the P-36 and said that had it been armed better, it would have been a deadly adversary to the A6M NOT because of speed but it's ability to hold it's energy in a turn. His thoughts on engaging an adversary were that speed allowed you the luxury of dictating when and where you confronted the enemy but being able to out perform the adversary was #1.
In otherwords, you can be the fastest ride on the block, but that doesn't mean sh!t unless you can take down your opponent...
Dave - my point is that the thread was about "Which Performance Attributes Were Most Critical"
My observation about your uncle's comments are twofold. First, after flying the P-38 would he have chosen a 'new P-36' with better armament? Second, would he have liked to fight the A6M with a P-38 absent turbosuperchargers. That version of a P-38 doesn't do well against any front line adversary as the P-322 would not have (and RAF recognized such) done well against anybody. The Difference? Top speed across the entire performance envelope, which in turn drove excess power available over drag for climb and turn performance - given the same wing and gross weight.
I am fully aware that maneuverability is extremely important, but for WWII increase in speed (and Range) was driving US fighter designs. The aircraft that failed to achieve the AAF spec on speed failed to become front line fighters. For the USN, speed was important but Carrier Qual/low speed handling characteristics were equally important - which is why the USN held back on F4U and initially gave them to USMC. The Brits on the other hand, looked at F4F and Martlet, looked at F4U - and said 'no brainer'.
Case in point - when the P-51 was upgraded with the Merlin, the handling characteristics suffered as well as relative turn rate maneuverability comparisons versus the P-40 and P-39. At no time was NAA asked to re-design the P-51B/D wing to restore turn comparison or increase climb via increased wing area. They ultimately achieved both by reducing the weight of the P-51H and reducing the drag while increasing HP - and speed.
The F4F could close on an F4U in less than a full turn - but lost every other attribute for combat usefulness. The A6M was arguably the best fighter in the world in 1942 and brutalized everything we put up against it - because its speed was near equal but had every other maneuver attribute except dive in its favor (possible exception P-36 according to your uncle). When our much faster fighters arrived in PTO, the tables were turned even though the Zero still held most of the maneuverability advantages in a dogfight - if our fighters chose to engage. The Tactics were modified to capitalize on the big advantage - Speed.
To your uncle's example, the P-36C was the last production ship with top speed of 313mph, W/L of 24psf and max climb rate of 3400 fpm. The A6M mod zero-21 of 1941 was about the same overall performance, much heavier firepower, edge to P-36 for dive.. good match.
Take it to Europe or Russia and see how it does against the 109F which was 80mph faster, But had a greater W/L, same ROC, greater dive speed and greater firepower? P-36, like the P-39, like the P-40 could all out turn the 109F/G - but how did they perform against the front line German (or A6M) until the P-47, P-51 and P-38 arrive in numbers.
My point, which I am sure will elude the other guy in this debate, is that Speed requirement was first or near first on the Specs and RFP's. Top Speed drives the aerodynamics and thus the wing airfoil and fuselage lines as well as Power plant. If Power plant a given (i.e. Allison for in-line until 1942 when Merlin was 'possible, or R-2800 for radial fighters after P-36 and F4F were obsolete). Range drives aerodynamics, weight, fuel load, W/L and AR. Take off and landing drives wing area, flap considerations, empennage sizing - and also increases weight and drag, thereby lowering speed for same power available.
Requiring iterations and design compromises regarding the secondary factors. For USN lading speed and takeoff length was Not secondary - but landing speed over the fantail Did drive empennage and flap and wing area - necessitating compromise of top speed absent those considerations.
But picking big wing, high AR and big fuel load increases drag, lowers climb and turn and lowers top speed. BTW, the F6F was a leap over the F4F but fell short of the F4U except for turn rate.
My only point is that designing a single engine Fighter during WWII focused on the initial attributes of top speed attainable while factoring in the Range/fuel load/AR/GW on one hand and Flap Area, elevator and rudder for low speed mandates on the other.
Neither the AAF nor USN started with Max Turn Rate or even Max Climb rate as those attributes, after optimal fuselage and wing design were conceived, could then be factored in by sacrificing top speed in your conceptual design - or reach an unacceptable Speed capability and start major compromises on Range or Ceiling (both MUCH more important that Rate of Turn and Climb(both of which is driven by Excess Power available, Lift CL, Wing area and Drag).
BTW the P-38 Spec was driven by 1.) Top Speed, and 2.) Rate/time of Climb and 3.) Ceiling which is why only a fat wing, twin turbosupercharged engine configuration would work in 1938. The Fat Wing compromised top speed later on as well as controllability in a dive - both of these learning experiences translated into a better design with the F7F, even though the F7F also had to build Carrier Qual into wing/flap, GW and tail design that the P-38 didn't have to worry about.
Thanks, Dave for the anecdote from your uncle..