Republic XP-69 High-Speed, High-Altitude Single-Seat Fighter Concept
The Republic XP-69 fighter project was doomed with the demise of the Wright Tornado engine program in 1943.
Authored By Staff Writer; Content ©www.MilitaryFactory.com
Republic struck wartime gold with its successful P-47 "Thunderbolt" fighter. The Thunderbolt went down in American aviation lore as one of the classic designs to come out of the World War 2 period (1939-1945). It, along with a healthy stable of competing designs, helped to swing back the initiative in the air wars over Europe and the Pacific, leading to an ultimate resolution in the years-long conflict come 1945.
The P-47 was so critical to American wartime needs that it left little room for Republic to work on other promising ventures. Despite this, several projects were underway with the task of fulfilling various over-battlefield roles and, in July of 1941, the company pursued a new single-seat / single-engine high-altitude, high-speed fighter design in the "AP-18" and this performance aircraft was to fit either the in-development Wright "Tornado" or the Pratt & Whitney "Wasp Major" engine. The Tornado seemingly held the edge in terms of timetable and was backed by the Army since a contract was given in June of 1939.
To field the engine in a fighter form as quickly as possible, the Army contracted with Republic to produce an appropriate aircraft in short order. A pair of prototypes would be covered in the agreement with one showcasing a single propeller fit and another completed with a contra-rotating propeller. The Tornado engine was estimated to have an output of 2,500 horsepower with turbosupercharger installed but this also required a propeller unit with considerable diameter. In turn this would require a dimensionally large airframe and, to satisfy the high-altitude requirement, a pressurized cockpit was a must.
The proposed armament suit would revolve around a battery of 4 x 0.50 caliber Browning heavy machine guns paired with 2 x 37mm automatic cannons. All armament would be held in the wings so as to clear the arc of the spinning propeller blades at the nose.
The fuselage incorporated a slim, narrow appearance for aerodynamic efficiency. The early version had a raised dorsal spine which restricted rearward views while a later, more refined approach, incorporated a bubble-style canopy (as in late-P47 fighters). The wing mainplanes, with rounded tips as in the P-47, were set well-ahead of midships. The tail unit was conventional and settled on a single vertical fin with low-set planes. The undercarriage was to use a "tail-dragger" stance. It is suspected that the engine would have been placed aft of the cockpit to drive the propeller by way of a shaft running under the cockpit floor (as in the Bell P-39).
A wind tunnel model was constructed at three-quarter size of the expected aircraft and officially inspected by Army personnel in June of 1942. Republic began construction of the actual prototype by November of that year but, in 1943, continuing issues with the Tornado engine program affected all related aircraft programs like the XP-69 and Vultee's XP-68 proposal. Its eventual cancellation led to the cancellations of both fighter programs with nothing but a wind tunnel model and partially-built XP-69 prototype to show for Republic.
The XP-69 was officially cancelled on May 24th, 1943 and Republic moved on to more P-47 production and additional development as well as development of the promising XP-72 "Ultrabolt" which could possibly meet the same over-battlefield need as the proposed XP-69. In any event, the XP-72 did not see formal adoption nor serial production.