Republic's unbuilt XP-47 project gave way to the XP-47B, shown, the first Thunderbolt.

Опытный истребитель XF5F-1 - конкурент самолета фирмы «Чанс Воут»
The Grumman XP-50 was based on the Navy's XF5F-1 but had a longer nose to house a nose wheel leg.

In the XP-40 pilot's outlook was somewhat improved.

AN AMERICAN "WET": The new Curtiss P-37 single-seater pursuit monoplane with 1,000 h.p. Allison liquid-cooled engine, the first American machine of its type to be fitted with anything but a radial for some years. It seems that the exhaust-driven blower is housed more carefully than in previous installations of the Allison.
In the Curtiss YP-37, the pilot sat behind the trailing edge.

Seversky's XP-41 was the final P-35 fitted with inward-retracting wheels and otherwise refined.

Delivery of 13 Republic YP-43 Lancers began in September 1940 and was completed in April 1941.

The first Republic YP-43 on landing approach with flaps down.

SOMETHING NEW IN COWLINGS: The Curtiss P-42 pursuit monoplane with an experimental installation of a two-row Pratt and Whitney with airscrew extension shaft. Cooling air enters through the scoop to the rear of and below the spinner and is exhausted through the adjustable gills.
The Curtiss XP-42 had a Twin Wasp radial with a long prop shaft to improve streamlining. Its top speed was 315 m.p.h. at 15,000ft.