The Berliner-Joyce XFJ was a prototype biplane fighter aircraft that first flew in May 1930. Designed by Berliner-Joyce Aircraft for the United States Navy, its lower wing, placed below the fuselage and just two feet above the ground, apparently gave it a tendency to ground loop when landing, and it was never ordered for production.
Berliner-Joyce had been formed in 1929, and had won a contract with the army for the Berliner-Joyce P-16. At the same time, they submitted a similar design to the Navy, modified to meet the differing requirements. The body was to be an all-metal monocoque, with the upper wing mounted on the top on the fuselage, and the lower wing slung on struts beneath the body.
The prototype, XFJ-1, was sent to Anacostia for testing after its initial flights, where the ground-looping habit was noted, and eventually resulted in a landing accident, necessitating return and repair. The company took the opportunity to add a Townsend ring cowling, and upgraded the engine from a 450-hp Pratt & Whitney R-1340C to a 500-hp R-1340-92 Wasp. This and other improvements boosted speed from 177 to 193 mph, and the Navy gave the reconstructed aircraft the designation XFJ-2. However, improved performance came at the expense of stability, and the ground loop problem persisted, and there was no interest in continuing with this design. Nevertheless, the prototype continued to be used for other tests for several years.
- Lloyd S. Jones, U.S. Naval Fighters (Fallbrook CA: Aero Publishers, 1977, ISBN 0-8168-9254-7), pp. 80-83