06/23/2025. Remarks by Johan Visschedijk: "Only four months after the USAAC ordered the YP-39 Service trials aircraft, the Army awarded the first production contract on August 10, 1939. This one, which received USAAC approval on October, 12, covered eighty examples of Bell Model 13 (s/n 40-2971 to 40-3050) and, were at first designated P-45 Airacobra, although this was changed to P-39C and P-39D prior to the delivery of the first production aircraft. These variants were almost identical to the YP-39 with the exception of the engine which was a 1,l50 hp Allison V-1710-35.

Twenty aircraft were built as P-39Cs (Model 13) (s/n 40-2971 to 40-2990) and the first of them flew in January 1941. These were followed by sixty P-39Ds (Model 15) (s/n 40-2991 to 40-3050, c/n 15-1 to 15-60). In comparison to the P-39C, the P-39D incorporated several improvements, the two 0.30 in (7.62 mm) nose machine guns were deleted and four guns of similar caliber were installed in the wings, an under-fuselage strong-point enabled the carrying of a jettisonable fuel tank, a 300 lb (136 kg) M-31 bomb or a 600 lb (272 kg) M-32 bomb. The fuel tanks were now self-sealing but their capacity was reduced to 120 gal (454 l), some armor was added and a small fillet was added at the root of the vertical fin.

Further orders covered 394 P-39Ds, 186 P-39D-1s and 158 P-39D-2s, in all, a grand total of 798 P-39Ds was produced. The P-39D-1 was the variant which was due to be delivered to Great Britain under Lend-Lease. These aircraft were armed with a 20mm M1 cannon and incorporated a small dorsal fillet. P-39D-2s were also Lend-Lease aircraft equipped with a 1,325 hp V-1710-63 engine. Most of the D-ls and D-2s were delivered to the USSR and some dozens were taken in charge by USAAC squadrons. Most of these were later modified for the ground attack role with additional armor under the fuselage and K-24 and K-25 cameras in the fuselage thus becoming P-39D-3s (26 ex-P-39Ds) and P-390-4s (11 ex-P-39D-1s).

The Bell P-39 Airacobra history will be continued in the next update.