In the wild days of World War II, America was racing frantically to produce fighters that could outgun enemy planes. The Fisher P-75 Eagle was meant to be the new great interceptor—fast, brawny, and rapidly climbing into the heat of battle. Instead, it became a cautionary fable: grandiose, expensive, and in the end useless, leaving lessons instead of victories in its path.
The project started in 1942, when the Army Air Forces called for a fighter that would have outstanding climb. General Motors’ Fisher Body Division saw an opportunity to enter the field of aviation. Already known for designing automobile bodies and Sherman tanks, Fisher set out to design an impressive airplane of his own. To head up the project, they hired Don Berlin, an experienced designer who had worked on the Curtiss P-36 and P-40.
Fisher’s design was ambitious, possibly too ambitious. The proposal was to build the P-75 from existing components mixed and matched: P-40 Warhawk wings (ultimately replaced with Mustang wings), a Douglas SBD Dauntless tail, and F4U Corsair landing gear.
The engine was placed aft of the cockpit, powering contra-rotating propellers via long extension shafts—a design patterned after that of the Bell P-39. The objective was ambitious: to employ battle-proven components and produce a combat-capable aircraft in six months.
But airplanes aren’t cars, and what succeeds on an assembly line doesn’t necessarily take to the air. The Allison V-3420 engine, basically two V-1710 engines mated together, seemed great on paper but overheated and failed frequently in practice. The jury-rigged airframe created an unbalanced flying experience: iffy handling, herky-jerky spins, and slow roll rates. The center of gravity was askew, and the aircraft just didn’t get the job done.
As the war evolved, so did the role of the P-75. It was reconfigured as a long-range escort with greater fuel, a new tail, a bubble canopy, and a more powerful engine. These modifications, however, only weighed more, complicated, and cost more.
The military soon discovered it was easier and cheaper to upgrade tested warplanes such as the P-38 Lightning and the P-51 Mustang than to struggle with the P-75’s growing issues.
Flight testing was also tough right from the beginning. The prototype flew in November 1943 but showed instability and disappointing power. Test flights involved some crashes, including some with significant results. The aircraft never came close to its promised top speed, and its climb rate was mediocre at best.
The Army dropped the program by October 1944. The program produced no more than a few dozen prototypes, and they were mostly destroyed. All that remains today is one restored P-75 at the National Museum of the United States Air Force in Dayton, Ohio.
The Fisher P-75 Eagle is still an ugly warning to military planners and designers. It has been shown that piecing together pieces from different aircraft is not an alternative to careful, coherent design. Automobile mass production economics never directly apply to the intricacies of flying. Aviation historians have dubbed it the “champion” of “spare parts fighters,” a noble name for a project where haste and hubris met at great heights.
Ultimately, the P-75 is a lesson that true innovation requires harmony and planning, and that there are times when maintaining tried techniques is the key to war victory.
