Na mbido 1937, USAAC nyere Curtiss iwu ka ọ gbanwee otu P-36 ka ọ bụrụ ihe ọhụrụ nke mmiri mmiri na-eme ka ọ dịkwuo elu Allison V-1710 engine na 1,150 hp (860 kW). A na-akpọ Curtiss XP-37, ụgbọelu ahụ jiri ụgbọelu ụgbọelu 75 mbụ na radiators arụnyere n'akụkụ nke fuselage gburugburu engine ahụ. A na-ebugharị kokpiiti ahụ n'azụ azụ iji mee ohere maka radiators na usoro turky bulbocharger, na iji mee ka ụgbọelu ahụ nwee nguzozi.
Afọ 1939