Republic XP-47J Superbolt


1st Flight 1944

Crew 1



33.30 ft (10.15 m) Width:

40.78 ft (12.43 m) Height:

14.21 ft (4.33 m)


Empty Weight

9,663 lb (4,383 kg)

Max Take Off Weight

16,788 lb (7,615 kg)


1 x Pratt & Whitney R-2800-57C turbo, supercharged, air-cooled, radial piston engine developing 2,800 horsepower and driving a four-bladed propeller.


Max Speed:

505 mph (813 kph; 439 kts)

Service Ceiling:

44,997 feet (13,715 m; 8.52 miles)

Max Range:

1,072 miles (1,725 km; 931 nm)


4,900 ft/min (1,494 m/min)


6 x 0.50 calibre Browning heavy machine guns


A similar attempt to improve performance resulted in the XP-47J. Unlike the XP-47H, the sole XP-47J was a newly built airframe, with many changes to reduce weight. The aircraft was fitted with a 2,800 hp R-2800-57C engine with a CH-5 supercharger, housed in a redesigned streamlined cowling. Armament was reduced to six M2 Brownings.

The XP-47J was first flown on November 26, 1943, and on August 4, 1944, it became the first piston-engined fighter to exceed 500 mph, with a speed of 504 mph, making it the fastest Thunderbolt variant. A production version of the XP-47J was cancelled in favour of another Thunderbolt development, the XP-72, as were plans for installing an R-2800-61 engine with contra-rotating propellers.


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