Republic P-47 Thunderbolt variants

XP-47 (AP-10) In response to a USAAC requirement for a new fighter aircraft, Republic Aviation engineer Alexander Kartveli proposed the AP-10 lightweight high-altitude interceptor on August 1, 1939. As originally proposed, the AP-10 was to have been powered by a 1,150 hp Allison V-1710-39 12-cylinder inline engine and have an armament consisting of two nose-mounted .50 in (12.7 mm) M2 Browning machine guns. Maximum speed was estimated to be 415 mph, while gross weight was to be 4,900 lb. Expecting the USAAC to reject the XP-47 for the more suitable Curtiss XP-46, Republic canceled the XP-47 and XP-47A and Kartveli began an extensive redesign of the aircraft. == Razorback Thunderbolts ==

P-47B On June 12, 1940, Kartveli submitted the redesigned AP-10 to the USAAC. The new aircraft was much larger than the original, and the inline engine was swapped for a turbo-supercharged Pratt & Whitney R-2800 Double Wasp 18-cylinder radial engine. Only 171 of the original order were completed as P-47Bs before production switched to the P-47C. Later applied to all P-47Bs in 1944 to denote its status as restricted from combat. XP-47F Another P-47B was fitted with a larger-area laminar-flow wing as the XP-47F. The XP-47F was first flown on September 17, 1942, but project was ultimately canceled when the aircraft crashed and no production aircraft followed. P-47C Several improvements were incorporated into the Thunderbolt starting with the 172nd production aircraft on September 14, 1942. The resulting P-47C featured a redesigned metal rudder, as the original fabric-covered unit was prone to tail flutter which frequently led to crashes. A revised oxygen system was fitted, as were new SCR-274-N and SCR-515-A radios. The main external difference between the P-47B and C was the upright antenna mast, which replaced the B's forward-swept mast. but with two additional cowl flaps (for a total of five) on each side (this was absent on early aircraft, making them indistinguishable from P-47Cs). Internal changes included extra cockpit armor and changes to the turbo-supercharger exhaust system. Sometimes referred to as the P-47D-1-RA. • P-47D-1-RE, Farmingdale equivalent of the late-P-47D-RA. 105 built. 446 built. Some aircraft were fitted with Malcolm Hood canopies to improve visibility. The first delivery of a Curtiss-Wright-built P-47G was in December 1942. XP-47J 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 canceled in favor of another Thunderbolt development, the XP-72, as were plans for installing an R-2800-61 engine with contra-rotating propellers. == Bubbletop Thunderbolts ==

XP-47K/L A common complaint from P-47 pilots was that the razorback cockpit limited rearward visibility. In response to these complaints, Republic fitted a bubble canopy from a Hawker Typhoon onto a P-47D-5-RE in July 1943. Designated XP-47K, the aircraft's new canopy improved visibility greatly. Another "bubbletop" prototype was modified from a P-47D-20-RE as the XP-47L, differing from the XP-47K in that it had an increased fuel capacity. For reasons unknown, the first production bubbletop Thunderbolts were not given a new variant letter, instead they were a continuation of the P-47D line. • P-47D-30-RA, Evansville equivalent of the D-30-RE. 1,800 built. 1,816 P-47Ns were built in six production blocks, with orders for an additional 5,934 aircraft being canceled after VJ Day. The final P-47 rolled off the production line in December 1945. Sub-variants • XP-47N, prototype converted from the third YP-47M. • P-47N-1-RE, initial production block. Fitted with a new dorsal fin along with other minor changes. 550 built. • P-47N-5-RE, with the tail warning radar of the P-47D-40-RE, rocket launcher stubs, and minor changes to the radio. Later aircraft were fitted with 2,800 hp R-2800-73 engines. 550 built. • P-47N-15-RE, with an R-2800-73 engine, a S-1 bomb release, a K-14 gun sight, and a redesigned pilot seat. 200 built. • P-47N-20-RE, with changes to the radio and fuel system. 200 built. • P-47N-20-RA, Evansville equivalent of the N-20-RE. 149 built. The final Thunderbolt built, s/n , was from this production block. • P-47N-25-RE, fitted with either the R-2800-73, R-2800-77, or R-2800-81. The cockpit floor and tailwheel linkage were redesigned, along with other minor changes. 167 built. • F-47N, designation applied to all P-47Ns in service in 1947 when the USAAF broke off from the Army and became the United States Air Force. == Further developments ==

XP-72 (AP-19) Developed in parallel with the Republic XP-69, the AP-19 was proposed by Alexander Kartveli as a replacement for the P-47. The aircraft was a development of the bubbletop P-47D, but was to be powered by 3,450 hp Pratt & Whitney R-4360-13 Wasp Major 28-cylinder radial engine driving contra-rotating six-bladed Aeroproducts propellers and armed with six M2 Brownings. The USAAF ordered two prototypes on June 18, 1943. The first prototype, with a four-bladed propeller due to delayed delivery of the intended unit, was first flown on February 2, 1944, and the second prototype with the intended propeller followed on June 26 of that year. The second XP-72 crashed early in the test program, but the USAAF was impressed with its performance and placed an order for 100 production P-72 aircraft with R-4360-19 and four 37 mm cannons in place of the Brownings. However, this order was canceled as the war neared its end. == Summary of serial numbers ==