The Bell XP-77
development was initiated by the United States Army Air Corps
during World War II
to produce a simplified 'lightweight' fighter aircraft
using so-called "non-strategic" materials. Despite being innovative, the diminutive prototype
proved tricky to handle and the project was canceled when the XP-77 did not deliver its projected performance.
Design and development
The project with the Bell Aircraft Corporation was initiated in October 1941. Originally a design study for the P-39, the XP-77 was intended to be a small, light fighter much in the mold of the 1930s air racers. The aircraft featured a single-engine, low-wing monoplane with mainly wood construction, equipped with tricycle landing gear, a Bell trademark that bestowed good ground handling. A sleek bubble canopy also provided great visibility in all directions except forward (a key requirement for a fighter).
While originally conceived using an air-cooled 500 hp Ranger XV-770-9 twelve-cylinder engine with a supercharger, the prototypes were delivered with the unsupercharged XV-770-7 engine due to engine development delays. The planned armament was one 20 mm cannon and two 0.5 inch machine guns, with the option of either a 300 lb bomb or 325 lb depth charge.
The project suffered numerous delays, many for correction of excess weight issues. The first XP-77 flew 1 April 1944
at Wright Field
. These trials revealed vibration problems due to directly mounting the engine to the airframe, without vibration isolation. The long nose and rear-mounted cockpit inhibited visibility relative to operational aircraft of the time.
The XP-77 proved to be difficult to fly and despite flying without guns or armour, it did not come up to the expected performance estimates mainly because it was woefully underpowered. Further trials were conducted at the A.A.F. Proving Ground at Eglin Field with the second aircraft, which was destroyed when it entered an inverted spin while attempting an Immelmann, and the pilot bailed out. The development was terminated in December 1944.
Specifications (Bell XP-77)
- Green, William. War Planes of the Second World War, Volume Four: Fighters. London: MacDonald & Co. (Publishers) Ltd., 1961 (Sixth impression 1969). ISBN 0-356-01448-7.
- Green, William and Swanborough, Gordon. WW2 Aircraft Fact Files: US Army Air Force Fighters, Part 1. London: Macdonald and Jane's Publishers Ltd., 1977. ISBN 0-356-08218-0. Pages 25-26.
- Jane, Fred T. "The Bell XP-77." Jane’s Fighting Aircraft of World War II. London: Studio, 1946. ISBN 1-85170-493-0.
- Winchester, Jim. The World's Worst Aircraft: From Pioneering Failures to Multimillion Dollar Disasters. London: Amber Books Ltd., 2005. ISBN 1-904687-34-2.