The XP-47B was first flown on May 6, 1941. It was powered by a 1,960 hp XR-2800-21 engine and featured an elliptical wing, an all-metal construction (except for the fabric-covered control surfaces), and a hinged canopy. The main landing gear retracted inward into the wings, telescoping nine inches to clear the underside of the fuselage, and the steerable tailwheel was fully retractable. With a loaded weight of 12,086 lb, the XP-47B was almost twice as heavy as its competitors. Performance was higher than expected with a maximum speed of 412 mph. Only 171 were completed as P-47B's before production switched to the P-47C. The aircraft's nickname, Thunderbolt, was created by Republic's Director of Military Contracts, C. Hart Miller.
Sub-variants and modifications:
XP-47B, single prototype powered by a 1,960 hp XR-2800-21 engine.
P-47B-RE, 171 aircraft powered by a 2,000 hp R-2800-21 engine with other modifications.
RP-47B, designation originally applied to a handful of P-47B modified into photo-reconnaissance aircraft with a camera mounted in the port intercooler vent. Later applied to all P-47Bs in 1944 to denote its status as restricted from combat.
XP-47E. The final P-47B was converted in September 1942 into a prototype for a high-altitude variant as the XP-47E. Modifications included a pressurized cockpit with a hinged canopy. The project was canceled due to increased emphasis on low-level operations over Europe

XP-47E-Thunderbolt Ser. 41-6065 left side view at factory Farmingdale NY.

XP-47E-Thunderbolt Ser. 41-6065 Last P-47B converted.

XP-47E-Thunderbolt Ser. 41-6065 front view R-2800-59 engine, a pressurized cockpit with a hinged canopy, Farmingdale NY.

XP-47E-Thunderbolt Ser. 41-6065 left side view in snow factory field Farmingdale NY.

XP-47E Thunderbolt Ser. 41-6065 left rear 3-4 view at factory field in snow Farmingdale NY.

XP-47E Thunderbolt Ser. 41-6065 left front 3-4 view at factory field Farmingdale NY.