McDonnell Aircraft Corporation Model 1

Back in 1938 McDonnell founded his own company after having worked for the Martin company. The company was founded officially on 6th July 1939 in St. Louis, Missouri and soon, they submitted various designs to the United States Army Air Corps and the United States Navy. Those proposals didn't led to any order, but thanks to them, McDonnell was included in the list of USAAC's request data for R40-C in February 1940.
R40-C requested an unorthodox design capable of reaching the 450mph (724km/h) but 525mph (845km/h) were preferred, plus other features present in the XC-622 specification. McDonnell's candidate for that requeriment was their Model 1 (their first design) which was officialy proposed on 11th April 1940.
It was expected to be powered by either Allison V-3420 B2, Pratt & Whitney H-3130, Pratt & Whitney X-1800-A2G or Wright R-2160, all of the liquid cooled. Regardless of the engine, it was expected to be buried in the fuselage aft the pilot. The power of the engine was transmitted via extension shafts to a pair of four blades, two speed propellers set in a pusher configuration. The expected armament were two 0.30in calibre machine guns plus other two 20mm cannons, but it changed various times during the design process. However it was always a combination of two to four machine guns and one to four cannons.
The X-1000 and R-2160 designs didn't fill the expectations of the XC-622 specification and were dropped from the R40-C competition, while those powered by a two-stage supercharger for the H-3130, did achieve the requirements. It was however rejected due to the complicated manufacturing process as it was expected that 42 months were needed only to develop the engine and power drives for the model 1. Furthermore, it was the heaviest of the submitted models and it ranked poorly, in the 21st and 22nd of the 26 submitted candidates. It was, however, interesting enough for the USAAC to buy a wind tunnel model on 6th June 1940 for 3000$ which was the first sale of the McDonnell company to the USAAC.
The competition for the R40-C was won by the Vultee XP-54 Swoose Goose, the Curtiss XP-55 Ascender and the Northrop XP-56 Black Bullet which all of them had pusher configuration engines and resulted to be filled with too many technical difficulties to be massly manufactured. The Model 1 served, however, as the basis for the McDonnell XP-67 Moonbat which even if it wasn't a success, it was built and flew.

Sources:
1. https://oldmachinepress.com/2012/09/07/mcdonnell-aircraft-corporation-model-1/
2. http://www.centennialofflight.net/essay/Aerospace/McDonnell/Aero31.htm