The Republic P-43 "Lancer" was an all metal low wing monoplane. It was the first production model made by Republic after it emerged from the bankruptcy of Seversky Aircraft.
A stubby little plane, the Republic P-43 was the predecessor to the successful P-47. It was used mainly in China. It was developed from the P-35. It was powered by a Pratt & Whitney R-1830-49 14-cylinder air-cooled radial engine, and the plane was armed with 4 0.50 in Browning Machine Guns.
- AP-4: The AP-4 was a private venture undertaken by the then Seversky Aircraft. In March 1939, an order for 13 evaluation aircraft was received, designated YP-43. These aircraft were delivered between September 1940 and May 1941.
- P-43: Standard production model. Identical to the YP-43. 54 built.
- P-43A: R-1830-49 engine upgrade 0.30in wing mounted guns replaced with 0.50in guns.; 80 built.
- P-43A-1: Chinese Lend-Lease version. 125 built, of which 51 were actually delivered. 1x.50in gun in each wing, two in nose. One centrepoint for fuel tank or 200lb bombs. Basic armor and fuel tank protection added. Briefly used by the American Volunteer Group.
- P-43B/C/D: Photo-recon versions. Converted from '43A and '43A-1 versions respectively.
The P-43 started life as a privately funded design of the Republic Aviation Corporation which had recently formed from the remains of Seversky Aviation. AP-4 was the designation of this project, which was a single seat fighter with a turbo-supercharger. An order of 13 aircraft for testing was received under YP-43.
Several sources have stated that the USAAC ordered these planes despite knowing that they were inferior in order to keep the newly founded Republic in business whilst they developed the aircraft that would become the P-47 Thunderbolt.