Curtiss-Wright XP-55 Ascender Pursuit Fighter Prototype
The XP-55 was a novel attempt at a pusher-prop aircraft design, though hampered by less-then-stellar performance.
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The XP-55 Ascender was an unorthodox attempt by the Curtiss-Wright company that produced just three prototype models. Answering a United States Army Air Corps call for unconventional aircraft designs, the XP-55 fit the bill with its pusher engine mounted at rear, swept-back wings and forward canard mountings. Less-then-stellar flight testing results and mechanical delays with the expected powerplant would eventually doom the project and leave two surviving prototypes (one would later be lost at an air show).
The XP-55 was a single-seat single-engine design. The pusher-type engine was mounted to the extreme rear and differed from traditional pull designs with the engine mounted at front. This left the pilot with a commanding forward view. Wings were highly swept which was another departure from the straight wing designs that continued on in jet fighter developments well into the Korean War. First drawings and scale models were completed and assessed as early as 1940 to which the Army Air Corps needed more convincing. As a result, Curtiss took it upon itself to produce a flyable full scale model - this one to be designated in-house as the CW-24B. The test aircraft differed some from the final three prototypes developed from the granted contract of 1942. The test bed flew with a Menasco C68-5 powerplant, whereas the final prototype models were fitted each with the Allison V-1710 engine. Initially, the XP-55 was to utilize an entirely new engine design in the form of a Pratt & Whitney design known as the X-1800. But developmental issues with the powerplant forced Curtiss to use an existing - yet proven - model instead.
Armament for the XP-55 was originally drawn up to include a pair of 20mm cannon to go along with twin 12.7mm (.50 caliber) machine guns. This arrangement was revisited and revised to a quad .50 caliber array during the testing phase and this standard armament stayed with the life of the program. The design offered up benefits in this way in that the armament could be fully fitted into the nose assembly, seeing it that the engine was now mounted behind the cockpit seating area, opening up the nose to more spacious armament. Firepower could also be more concentrated in this fashion as opposed to a combination of wing and nose-mounted armament.
The XP-55 would go on to feature a host of interesting design elements. For Curtiss, it would become its first design to feature a powered tricycle landing gear assembly (though fixed on the initial test models). The absence of a true rudder resulted in smaller vertical surfaces mounted far off onto the wings. The use of forward canards was also revolutionary as was the ejection system - the propeller had to be jettisoned before the pilot could eject himself, ensuring the pilot would not eject and hit the spinning propeller system at rear by accident. It should be noted that designs similar to this were also being trialed by the Japanese (in the J7W1 Shinden) and Germans (in the Henschel P.75) during the Second World War and was by no means unique to American aircraft design efforts.
The final verdict on the XP-55 rang in hard when it was realized that the system could not match the performance available to contemporary and traditionally-designed fighters. Additionally, the latter years of the Second World War were already bringing about the advent of jet-propulsion effectively negating any more development or advances in propeller systems research. As such, the series was limited in production totals and became the stuff for aviation aficionados and museum buffs.