POWER PLANT: One Pratt & Whitney R-2800-57C radial engine, rated at 2,800 hp
PERFORMANCE: 460 mph at 30,000 ft
COMMENT: The main role for the Republic P-47N was as an escort fighter for the Boeing B-29 Superfortress bombers flying raids on the Japanese home islands. But in the final stage of the war the P-47N was used very successfully as a ground attacker. App. 1.100 P-47N’s were equipped with zero-length rocket launchers for six or 10 rockets, depending on whether or not bombs or drop tanks were carried under the wings. In April 1945, the 318 Fighter Group was re-equipped on P-47N’s and operated from Ie Shima island, off the coast of Okinawa. Bombing and strafing missions were flown until the end of the hostilities (Ref.: 9).
POWER PLANT: One Allison V-1710-35 liquid-cooled Vee engine with single-stage supercharger, rated at 1,150 hp
PERFORMANCE: 360 mph at 15,000 ft
COMMENT: The Bell P-39 “Airacobra” was one of the main American fighter aircraft in service when the United States of America entered the World War II. Designed by Bell Aircraft, it had an innovative layout, with the engine installed in the center fuselage, behind the pilot, and driving a tractor propeller via a long shaft. It was also the first fighter fitted with a tricycle undercarriage. Although its mid-engine placement was innovative, the P-39 design was handicapped by the absence of an efficient turbo-supercharger, limiting it to low-altitude work. The XP-39 made its maiden flight on 6 April 1938 achieving 390 mph at 20,000 ft, reaching this altitude in only five minutes. A production order was placed and by the time of the Pearl Harbor attack, nearly 600 P-39s had been built. When P-39 production ended in August 1944, Bell had built 9,558. Most important variants were Bell P-39N and P-30Q, if which 4,773 have been built. The “Airacobra” saw combat throughout the world, particularly in the Southwest Pacific, Mediterranean and Russian theaters. But the “Airacobra” found itself outclassed as an interceptor and the type was gradually relegated to other duties. It often was used at lower altitudes for such missions as ground strafing (Ref.: 23).
POWER PLANT: One Chrysler XI-2220-11 inverted-Vee in-line engine, rated at 2,500 hp
PERFORMANCE: 414 mph
COMMENT: While the production of the Republic P-47 Thunderbolt had been emerging in ever-mounting quantities, Republic’s engineers had been investigating other ways in which the Thunderbolt could be improved. Two P-47D-15-RAs were assigned for testing the Chrysler XI-2220 engine, a 16 cylinder inverted-Vee liquid-cooled unit which transmitted its power to a propeller shaft by way of gears located midway along the crankshaft. The design was such as to produce an extremely finely-streamlined cowling of low frontal area, despite the engine’s ability to produce 2,500 hp. The converted aircraft were designated Republic XP-47H and remembered to a pre-war project, the Republic XP-69. Extensive redesign of the P-47 airframe was necessary to install the XI-2220-11 engine, with which was associated a General Electric CH-5 single-stage turbosupercharger in a modified installation in the rear fuselage. The first flight was not made until July 1945 and in one of the 27 flights a top speed of 414 mph had been recorded. The second XP-47H flew briefly after the war ended (Ref.: 9).
POWER PLANT: One Pratt & Whitney R-2800-57 Double Wasp radial engine plus one General Electric CH-5 turbosupercharger, rated at 2,800 hp at 32,500 ft
PERFORMANCE: 505 mph at 34,500 ft
COMMENT: In 1942 studies made by Republic culminated in proposals for a “lightweight” P-47 with an improved engine installation. Construction of two prototypes was authorized, but within a few weeks it became clear to Republic and the USAAF that the more radical development of the P-47 powered by a 3,000 hp Pratt & Whitney R-4300 Wasp Major, than proceeding as the Republic P-72 held greater promise than the P-47J within a similar timescale, and work on the latter project was limited to a single XP-47J. This sole prototype had a lightened wing structure, a more powerful variant of the R-2800 radial engine, driving a four-bladed propeller with a large spinner and a fan to assist the flow of cooling air through a narrow annulus around the spinner. A separate intake scoop beneath and behind the engine cowling provided air for the General Electric CH-5 supercharger in the rear fuselage. The first flight was made in November 1943, and on August 1944 a speed of 505 mph was recorded, at 34,450 ft. This was the highest known speed achieved up to that time in level flight by a propeller driven aircraft and established the XP-47J as one of the few such aircraft to have broken through the 500-mph “barrier” (Lit.: 9).
POWER PLANT: One Pratt & Whitney R-2800-53 engine, rated at 2,000 hp
PERFORMANCE: 414 mph
COMMENT: In 1940 the Curtiss Aircraft Company proposed a new design for the eventual replacement for the Curtiss P-40. The new aircraft, the Curtiss XP-60, went through a long series of prototype versions with different engines. Installation of the British Rolls-Royce Merlin engines led to the development of the XP-53, soon redesignated XP-60. Delayed deliveries of the Merlin engines necessitated the installation of Wright (XP-63C) as well as Chrysler (XP-60B) engines. To improve the performance of the XP-60C the engine was changed again, this time a Pratt & Whitney R-2800 with contra-rotating propellers was installed. During its first flight the results were generally satisfactory. Changing the contra-props into a four-bladed propeller led to the XP-60E. But the performance was poorly, too, and further work on this design was abandonded. (Ref.: 8)
POWER PLANT: Two Allison V-3420 engines, rated at 3,000 hp each
PERFORMANCE: 436 mph at 25,000 ft
COMMENT: The Lockheed XP-58 Chain Lightning was an American long-range fighter developed during WW II. Although derived from the successful Lockheed P-38 Lightning, the XP-58 was plagued by technical problems with its various engines that eventually led to the cancellation of the project. Initially, the design was powered by two Continental IV-1430 engines. In July 1940, Lockheed decided to switch to Pratt & Whitney XH-2600 engines as the aircraft would be underpowered with the Continental engine. However, soon Lockheed was advised the development of the XH-2600 engine was terminated. So again engine alternatives were needed and the design was changed to use two Wright R-2169 Tornado engines. In February 1943, use of another engine, the Allison V-3420, was necessary due to poor progress with the Tornado engine development. Parallel to this the design was revised as a second crew member was added and the defensive armament was changed. Two turrets, one upper and the other lower on the fuselage, each containing two .50 in machine guns, were installed and directed by a gunner in the rear fuselage. The XP-58 finally flew on 6 June 1944 for the first time, but after 25 test flights were completed and clarified many more problems further work on the XP-58 was reduced and in October 1944 the program was stopped and no further flights were done. The construction of the second prototype was abandoned. (Ref.: 23)
POWER PLANT: Two General Electric J33-GE 5 turbojets, rated at 1,835 kp each
PERFORMANCE: 522 mph at 15,700 ft
COMMENT: The early USAAF jet fighters consumed fuel at a great rate which limited their range and endurance drastically. In early 1944 the USAAF requested the Bell Company, who built the first American jet fighter, the Bell P-59 Airacomet, to design a fighter with increased endurance. A contract for two prototypes was awarded, but apart from range, the XP-83 was inferior to the Lockheed P-80 Shooting Star. So the XP-83 project was cancelled after the WW II. (Wikipedia)
POWER PLANT: One Pratt & Whitney R-4360-10, rated at 3,000 hp
PERFORMANCE: 432 mph
COMMENT: The estimated excellent performance of this aircraft, designed for the US Navy, was of great interest for the US Army Air Force, too. So the third (of three) prototype was delivered to the US Army Air Force and tested at Eglin Air Force base. But the advent of new jet fighters led to the cancellation of many wartime piston-engined projects. So consequently, the USAF lost interest in pursuing the project and the prototype was scrapped.
POWER PLANT: Wright R-2160-6 Tornado, rated at 2,500 h.p.
PERFORMANCE: 453 m.p.h.
COMMENT: This project was designed as a fast high altitude fighter capable of intercepting and destroying high altitude enemy bombers. The design incorporated new innovations such as a pressurized cabin, laminar flow wing, and contra-rotating propellers. A mock-up was built, but the project was cancelled because the Wright R-2160 42-cylinder engine was never produced. In 1944 Republic modified a two P-47D’s for testing Chrysler XI-2220 inverted-Vee liquid-cooled engines (Republic XP-47H). This made an extremely finely-streamlined cowling of low frontal area necessary similar that project shown here.