Republic XP-47H Thunderbolt

Republic History XP-47H Thunderbolt

Like many of the American fighters that victorious in World War II (1939-1945), the Republic P-47 Thunder was the subject of many experiments, modifications, and derivatives for additional power and a high-performance airframe. The P-47D became the final production model during the war, and the promising but untapped P-47M was limited to just 130 before the company developed its successor, the P-47N - it received expanded fuel reserves to better cope with a wide range of The scope of the Pacific Theatre.

A more radical transition between these more dramatic forms, the XP-47H was a postwar attempt to transform the "Jug" into a fast, inline-engined fighter.

The XP-47H was born out of two P-47D-15-RA production aircraft (Razorback models) dedicated to testing the promised new Chrysler XI-2220-11 16-cylinder inverted-V inline liquid-cooled engine up to 2,500 horsepower. The planes were pulled from the Republic's Evansville, Indiana, production line that was set up to meet heavy industry's need for Thunderbolts during the American War.

The H model more or less retained the P-47D's form and function, but the new and extremely complex Chrysler engine installation meant that the P-47D's rather simple airframe had to be significantly modified to accommodate the powerplant.

As a test bed, the fighter was stripped of all weapons and "military" equipment. Unlike the "open" radial-piston air-cooled engine installed on the original D model, the XP-47H features an all-new front section molded around a liquid-cooled inline engine. The nose is very pointed as the trimmer adapts to the general shape of the aircraft. The engine drives a four-bladed propeller unit and causes the nose section to extend significantly forward into the cockpit - limiting the pilot's forward view.

Beneath the nose is a radiator intake designed to suck in air as the plane accelerates, which gives the modified Thunderbolt a lower-than-normal side profile, making the larger plane appear larger.

All other physical characteristics of the Model D are preserved, including the main aircraft with elliptical wings, the empennage with fins and the tail tow landing gear (retractable). The pilot sits amidships under a heavily framed canopy that slides back onto the side rails.

The Razorback Thunderbolts' raised fuselage spine limited visibility to the critical tail of the aircraft - which was later remedied by the wartime bubble-like canopy design.

The Chrysler Inline proved to be more trouble than it was ultimately worth, and delays to the project naturally delayed the XP-47H program. As a result, the Model H prototype did not enter service until July 1945, and even then the axial compressor attached to the engine was not in operation, so a GE CH-5 turbo was used.

As the project progressed slowly, engineers were optimistic about a top speed of 490 mph - making the Model H one of the fastest piston-powered fighters of the war. However, quick testing showed that the XP-47H was a dead-end project - doomed to failure due to its questionable engines, sporadic development successes and the end of the Pacific War in August 1945.

During testing, the Model H recorded a maximum speed of 414 miles per hour, well below the expected performance gain and without weapons or military equipment.

The project was eventually abandoned by the Republic despite substantial investment in fighter jets.

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