The first production P-47B (41-5895) was really a specially-built second prototype. It was delivered to the Army on December 21, 1941, and was immediately dispatched to Wright Field for testing. The XP-47B remained with the manufacturer. The first four P-47Bs from production (41-5896/5899) were delivered in mid-March of 1942, only eight months after the XP-47B prototype had first flown. These planes were used for an extensive test program by various agencies.
Numerous problems soon presented themselves as the test program advanced. 41-5899 crashed on Salisbury golf course on Long Island on March 26, 1942, killing Republic test pilot George Burrrell. Examination of the wreckage showed that part of the tail assembly had broken off in flight. This accident resulted in restrictions being placed on P-47B flying while the cause of the structural failure was under investigation. At altitudes above 30,000 feet, the ailerons tended to snatch and freeze, the cockpit canopy could not be opened, and control forces became excessive. The fabric covering for the elevators was often found to be ruptured after high speed flights, the aerodynamic pressures having caused it to balloon out and burst. These problems caused further P-47 acceptances to be delayed until May of 1942.
The problem of the freezing ailerons and the ruptured elevators was solved by having these control surfaces being fully metal-covered on all subsequent P-47Bs. Some time elapsed before metal-covered elevators and ailerons could be incorporated into production machines, and deliveries went forward with the understanding that appropriate modifications would be completed later. Most earlier P-47Bs were eventually modified to take metal-covered control surfaces, and the earlier restrictions on flight were removed. In addition, the ailerons were revised in shape and were fitted with blunt noses, which largely alleviated the excessive control force problem. Balanced trim tabs were adopted to reduce rudder pedal loads.
The stuck cockpit canopy problem was solved by replacing the original hinged canopy by a rearward sliding hood. This change meant that the dorsal radio antenna had to be redesigned and moved further aft to accommodate the rearward-sliding hood. This innovation is believed to have been applied to P-47B serial number 41-5896 onward.
A windshield defroster was introduced with P-47B number 41-5951. Beginning with 41-5974, major changes were made in control surface movement limitations and tailplane incidence. New landing gear tires were introduced from 41-5974 onwards. Modified link ejector chutes were added to the guns on 41-6016 and subsequent aircraft.
The production P-47B was fitted with a production R-2800-21 engine of 2000 hp. The engine drove a 12-foot 2-inch diameter Curtiss Electric C542S-A6 propeller. An increase in the amount of internal equipment raised the empty, normal loaded, and maximum loaded weights to 9346, 12,245, and 13,360 pounds respectively. Consequently, the climb to 15,000 feet now took 6.7 minutes rather than the promised five. However, the increased power of the production-ready engine provided an increase in level speed to 429 mph at 27,000 feet.
At one time, it had been hoped that it would be possible for the RAF to test the Thunderbolt in combat in the Middle East, but production difficulties caused the British Air Ministry to be informed in September 1941 that it was probably not a good idea to do this until all the bugs had been wrung out of the design.
P-47Bs were first issued in mid-1942 to the 56th Fighter Group. This group was chosen to be the first recipient of the P-47B because it was based near New York City and hence located near the Farmingdale plant where Republic engineers could be easily called upon to help in ironing out problems as they arose. The P-47Bs of the 56th Fighter Group were used largely for stateside testing and operational training, and very few ever went overseas.
The 56th Fighter Group found the process of working up to its new mounts rather difficult--13 pilots and 41 aircraft were lost in accidents. By the end of June, the 56th FG had damaged or wrecked half of its aircraft. Many of the crashes were the result of pilot inexperience, but a significant number were caused by loss of control during high-speed dives. After a rudder was ripped from a P-47B in flight, an order was issued on August 1, 1942, restricting the speeds to 300 mph or lest, forbidding violent maneuvers, and stipulating that fuel be carried in the rear tank.
Later, the 80th Fighter Group was moved to Farmingdale with the intention that it too would begin training on P-47s.
The last P-47B was delivered in September 1942. Serial numbers of the 170 P-47Bs constructed were 41-5895/6065. A total of 171 were built.
The last example of the P-47B series (41-6065) was converted during manufacture in September 1942 as the XP-47E with a pressurized cockpit and a hinged canopy. However, increased emphasis on low-level operations over Europe lead to the cancellation of plans to introduce this pressurized Thunderbolt into production.
XP-47F was the designation given to another P-47B airframe (serial number 41-5938) which was used to test a new larger-area wing with a laminar-flow aerofoil. It flew for the first time on September 17, 1942. No production was undertaken.
The P-47B was strictly used for test and training, and was never sent into combat. The designation of the P-47B was changed to RP-47B in 1944, where the R stood for *Restricted*, which meant that it was not to be used for combat.