Horraantii 1937, USAAC waxay ku amartay Curtiss inay ku habboonaato mid ka mid ah P-36 mashiinka cusub ee Allison V-1710 oo leh 1,150 hp (860 kW). Waxaa loo qoondeeyay Curtiss XP-37, diyaaradda ayaa adeegsatay diyaaradda asalka ah ee Model 75 oo leh radiators oo lagu rakibay dhinacyada jirka ee ku wareegsan mashiinka. Qalabka duulimaadka ayaa loo raray meel fog oo gadaal ah si loogu sameeyo qol loogu talagalay radiators iyo nidaamka turbo bulky bulbocharger, iyo dheelitirka diyaaradda.
Sanadkii 1939