In many ways the P-47B was a development model of the Thunderbolt. In the summer of 1940 the original lightweight design for the P-47 had been cancelled, and the new massive radial engined version approved. In many ways similar to the earlier XP-44 Rocket, which in its later versions was to have used the same Pratt & Whitney R-2800 engine adopted for the Thunderbolt, the prototype XP-47B first flew on 6 May 1941.
The XP-47B closely resembled the production aircraft. The main differences were in the cockpit, which was entered through a hinged door on the left side of the aircraft, and on the control surfaces, which were fabric covered. After extensive tests, the prototype was lost in a crash on 8 August 1942. The prototype recorded a top speed of 412 mph.
A year after the first flight of the prototype, the first production aircraft was accepted by the USAAF (26 May 1942). The production aircraft differed from the prototype in having a full sliding canopy, replacing the hinged door. It was also appreciably faster, with a top speed of 429 mph.
The P-47B was issued to the 56th Fighter Group in June 1942. They would be the only unit to use this model. Lessons learned by the 56th FG would be used on the P-47C.
The most important of these lessons was that the fabric covered control surfaces were inadequate. On the P-47B they were replaced by metal covered surfaces, and the change was incorporated in all later versions.
The pilots of the 56th FG also learned a series of valuable lessons in how to handle the massive P-47. It was twice the size of anything they had flown before, with very different strengths and weaknesses. Even one of its main strengths, its speed in the dive, could be a danger for novice pilots, who often failed to exit from the dive in time to avoid a crash. The P-47B was not considered combat ready, and had been replaced by the P-47C by the time the 5th FG was sent to Europe. 170 P-47Bs were completed before the designation was changed.
Engine: Pratt & Whitney R-2800-21
Max Speed: 429 mph at 27,800ft
Span: 40ft 9.25in
Length: 35ft 4in
Range: 550 miles at 25,000ft, 835 miles at 10,000ft