The Fisher P-75 Eagle was a case study of the intricacies and issues related to aircraft development during wartime. Designed in the middle of World War II, the P-75 was an interceptor aircraft envisioned to take its place as more advanced than existing fighter aircraft at the time. But like its aspirational ideals, the project never really took off due to a myriad of technical and design errors.
The development of the P-75 Eagle was assigned to Fisher Body, the General Motors subsidiary, in response to a 1942 USAAF requirement for an interceptor with rapid climb and high performance. Fisher Body had gained experience from innovative car design and manufacturing, which it proposed to use in building a very different, state-of-the-art aircraft. This company had already made a huge contribution to the war effort through its production of parts for both the B-25 Mitchell and the B-29 Superfortress.
The P-75 Eagle was tailored around the Allison V-3420 engine, a 24-cylinder, 56-liter double V capable of over 2,500 horsepower. Its airframe contained elements from earlier aircraft to expedite production and cut costs. The tail assembly came from the Douglas SBD Dauntless, the wings from the Curtiss P-40 Warhawk, and the landing gear from the Vought F4U Corsair. The process was extremely troublesome.
Development of the P-75 was troubled. This airplane had really poor stability due to the poor weight distribution and bad center of mass. Test pilots who flew this plane reported really bad spin characteristics and aerodynamically unbalanced the aircraft. Rather well-conceived in its design, the Allison engine was too weak for the P-75. Often, overheating and failures in the coolant system took place.
Despite all sorts of modifications, redesigned tail, and new bubble canopy, the P-75 was never able to match requirements from the USAAF, which kept changing. By 1944, the USAAF had focused on long-range escort fighters like the P-51 Mustang, which had already proved its mettle in combat. With a raft of problems, the P-75 was thus redundant.
Project P-75 was ultimately canceled by the USAAF in October 1944 but retained some of the small number of finished units for experimental duty. On the whole, the P-75 Eagle failed at its stated goals but is an interesting footnote to the difficult conditions at that time for the development of aircraft and how important it was to have cohesive design and engineering.
Today, one of the surviving P-75 Eagles is preserved at the National Museum of the United States Air Force in Dayton, Ohio. It is a relic of an era and an ambitious but finally misguided experiment in aviation history.