Vultee submitted a proposal in response to a U.S. Army Air Corps request for an unusual configuration. The Vultee design won the competition, beating the Curtiss XP-55 Ascender and the Northrop XP-56 Black Bullet. Vultee designated it Model 84, a descendant of their earlier Model 78. After completing preliminary engineering and wind tunnel tests, a contract for a prototype was awarded on 8 January 1941. A second prototype was ordered on 17 March 1942. Although it appeared to be a radical design, performance was lackluster, and the project was canceled.
Flight tests of the first prototype, 41-1210, began on 15 January 1943. Trials showed performance to be substantially below guarantees. Simultaneously, development of the XH-2470 engine was discontinued. Although the Allison V-3420 engine could be substituted, that required substantial airframe changes. Projected delay and costs resulted in a decision to not consider production buys.
The prototypes continued to be used in an experimental program until problems with the Lycoming engines and lack of spare parts caused termination. The second prototype, 42-108994 (but mistakenly painted as 42-1211) equipped with an experimental GE supercharger, made ten flights before it was relegated to a “parts plane” to keep the first prototype in the air
The Republic Aviation Corporation was an American aircraft manufacturer based in Farmingdale, New York, on Long Island. Originally known as the Seversky Aircraft Company, the company was responsible for the design and production of many important military aircraft, including its most famous products: World War II's P-47 Thunderbolt fighter, the F-84 Thunderjet and F-105 Thunderchief jet fighters, as well as the A-10 Thunderbolt II close-support aircraft.