Firstly
Vincenzo, thanks for the info on Italian fighters early on this tread. And thanks for the link to the French handbook on Hawk 75A.
FAF used Hawk 75A longer as 1-line fighter than Fiat G.50, but that was at least partly because G.50 was technically a problem child.
Hawk 75A and Fiat G.50 had both very strong airframes which usually meant that they could absorb lot of battle damage,
On horizontal manoeuvrability of FAF fighters in 42, Fokker D.XXI was worst, it was tip staller and lost energy rapidly in turns. The Mercury engined version (which was the better one) needed 25 – 28 sec for 360deg turn. On the other hand its controls remained light even at high speed but same was true also for G.50, Hawk 75A and B-239.
HoHun
I wonder why in your graphs P-36 got its max speed at so low altitude. According to Wagner's American Combat Planes both P-36C and P-36A had their max speed at 3048m (10000 ft), also according to Finnish tests CU-572 (an A-3 but with 87oct fuel, not 100 oct) achieved its max speed (c. 434km/h) at 3570m when using automatic fuel/air mixture and at appr. 2300m when using over rich mixture (c. 436,5 km/h). French manual gave critical altitude for H-75A-1 as 4000m and according to "Detail specifications for Curtiss Hawk 75-A Airplane" the critical altitude of a H-75A with P&W Twin Wasp S3C3-G geared engine was 4650m.
Juha