Fisher P - 75 Eagle The General Motors / Fisher P - 75 Eagle was a fighter aircraft designed by the Fisher Body Division of General Motors Corporation . Development started in September 1942 in response to United States Army Air Forces requirement for a fighter possessing an extremely high rate of climb , using the most powerful liquid - cooled engine then available , the Allison V - 3420 . The program was cancelled after only a small number of prototypes and production aircraft had been completed , as it was no longer required in its original role , could not be quickly deployed , and possessed no significant advantages over aircraft already in production . Design and development . In October 1942 , the contract for two prototypes , designated XP - 75 , was signed with the Fisher Body Division of GM . The design concept was to use the outer wing panels from the North American P - 51 Mustang , the tail assembly from the Douglas A - 24 ( SBD ) , and the undercarriage from the Vought F4U Corsair in a general layout much as in the Bell P - 39 Airacobra with the engine located amidships with the propeller driven through an extension shaft . At an early design stage , however , Curtiss P - 40 Warhawk outer wing panels were substituted for the P - 51 panels . In mid - 1943 , the need for long - range escort fighters became more urgent than fast climbing interceptors so a decision was made to order six more XP - 75 airplanes modified for the long - range role . At this time an order for 2 , 500 production aircraft was also let , but with the stipulation that if the first P - 75A was not satisfactory the complete order might be canceled . At the time , General Motors was busy in several projects towards the war effort , including the mass production of several different aircraft types , including the Grumman TBF Avenger . Some sources claim that the P - 75 was the result of a scheme to get General Motors out of being forced to build Boeing B - 29 Superfortress es ; the P - 75 project being a " high - priority " project to help GM avoid the added strain of Superfortress production . Bearing the name , " P - 75 Eagle " was significant as the designation harkened back to the French 75 gun in World War I , considered a symbol of defeating the Germans . The " Eagle " was given extensive media coverage prior to its first flight , being trumpeted as a " wonder plane " . Operational history . Powered by a V - 3420 - 19 24 - cylinder engine rated at 2 , 600 hp driving co - axial contra - rotating propellers , the XP - 75 flew for the first time on 17 November 1943 . The second XP - 75 flew shortly thereafter , with all six long - range XP - 75s entering the test program by the spring 1944 . The test program brought up numerous teething problems , including miscalculation of the fighter ’ s center of mass , failure of the engine to produce its expected power , inadequate engine cooling , high aileron forces at high speed , and poor spin characteristics . Redesigns were introduced into the long - range XP - 75s including a modified tail assembly , new " bubble " canopy , and a V - 3420 - 23 engine that corrected most of the deficiencies by the time the first P - 75A Eagles entered flight test in September 1944 . By this time , the Army Air Force decided to limit the number of combat aircraft types in production and not enter into large - scale production of new types that might not be available before the war ended . As the twin - engine Lockheed P - 38 Lightning , along with the single - engine Republic P - 47 Thunderbolt and P - 51 Mustang , demonstrated excellent long - range capabilities , the production run of the P - 75A Eagle was substantially terminated on 6 October 1944 . It was decided to use the six completed production aircraft for experimental work and development of the V - 3420 engine . As a result of those events , the P - 75A did not complete formal performance trials due to termination of the production contract . Ultimately , only eight XP - 75s and six P - 75As were built .