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).
Republic XP-47J Thunderbolt
Republic XP-47J Thunderbolt
Republic XP-47J Thunderbolt
Republic XP-47J Thunderbolt
Republic XP-47J Thunderbolt
Republic XP-47J Thunderbolt
Republic XP-47J Thunderbolt
Republic XP-47J Thunderbolt
Republic XP-47J Thunderbolt and Republic XP-47H Thunderbolt
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 Bell XP-83 was a United States prototype escort fighter designed by Bell Aircraft during World War II. It first flew in 1945. As an early jet fighter, its limitations included a lack of power and it was soon eclipsed by more advanced designs. The early jet fighters consumed fuel at a prodigious rate which severely limited their range and endurance.
In March 1944, the United States Army Air Forces requested Bell to design a fighter with increased endurance and formally awarded a contract for two prototypes on 31 July 1944.Bell had been working on its “Model 40” interceptor design since 1943. It was redesigned as a long-range escort fighter while retaining the general layout of the Bell P-59 Airacomet. The two General Electric-GE-5 turbojet engines were located in each wing root which left the large and bulky fuselage free for fuel tanks and armament. The fuselage was an all-metal semimonocoque capable of carrying 4,350 l of fuel. In addition, two 950 l drop tanks could be carried. The cabin was pressurized and used a small and low bubble style canopy. The armament was to be six 12.7 mm machine guns in the nose.
Early wind tunnel reports had pinpointed directional instability but the “fix” of a larger tail would not be ready in time for flight testing. The first prototype was flown on 25 February 1945, demonstrating that the aicraft was under-powered and unstable. The limited flight testing provided satisfactory flight characteristics although spins were restricted until the larger tail fin was installed. The second prototype did incorporate the extended tail and an aileron boost system. One unique characteristic was the XP-83’s refusal to slow down due to its sleek aerodynamic shape and lack of drag brakes. This meant that test pilots were forced to fly “stabilized approaches” (i.e. very long and flat landing approaches).
The first prototype was used in 1946 as a ramjet test-bed with an engineer’s station located in the fuselage behind the pilot. The second prototype flew on 19 October and was later scrapped in 1947. Apart from range, the XP-83 was inferior to the Lockheed P-80 Shooting Star and this led to the cancellation of the XP-83 project in 1947 (Ref.: 24).
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: One Pratt & Whitney R-4360-13 Wasp Major, rated at 3,450 h.p.
PERFORMANCE: 490 m.p.h. at 25,000 ft
COMMENT: The second prototype of the Republic XP-72, first flown on 26 June 1944, had Aero Products contra props in place of the four bladed propeller of the first prototype of the Republic XP-72.
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.
POWER PLANT: One General Electric T31-GE-1 turboprop engine, rated at 2,300 h.p. and one Allison J 33-GE-5 turbojet engine, rated at 703 kp
PERFORMANCE: 507 m.p.h. at 30,000 ft
COMMENT: The Consolidated Vultee XP-81was a development of the Consolidated Vultee Aircraft to build a single seat, long range escort fighter that combined use of both turbojet and turboprop engines. Although promising, the lack of suitable engines combined with the end of World War II doomed the project.
Two prototype aircraft were ordered on February 1944 that were designated XP-81. The engine selection was an attempt to couple the high-speed capability of the turbojet engine with the endurance offered by the propeller engine. The XP-81 was designed to use the General Electic TG-100 turboprop engine in the nose driving a four-bladed propeller and a General Electric J33 turbojet in the rear fuselage. The turboprop would be used for normal flight and cruising and the turbojet added for high-speed flight.
The first XP-81 was completed in January 1945 but because of developmental problems the turboprop engine was not ready for installation. A decision was then made to mount a complete Packard V-1650-7 Merlin engine package from a North American P-51D Mustang aircraft in place of the turboprop for initial flight tests. This was done in a week and the Merlin-powered XP-81 was sent to the Muroc airbase where it flew for the first time on 11 February 1945. During 10 flight test hours, the XP-81 displayed good handling characteristics except for inadequate directional stability due to the longer forward portion of the fuselage. This was rectified by enlarging the vertical tail.
While 13 Convair YP-81 pre-production aircraft had been ordered, the capture of Guam and Saipan eliminated the need for long-range, high-speed escort fighters and then, just before VJDay the contract was cancelled, after 85% of the engineering was completed. The YP-81 was to be essentially the same as the prototype but with a lighter and more powerful General Electric TG-110 (XT41) turboprop engine, the wing moved aft 0.25 m, and armament of either six 12.7 mm machine guns or six 20 mm cannon.
After the XP-81 was returned to Vultee Field, the TG-100 turboprop was installed and flight testing resumed, including the first flight by an American turboprop-powered aircraft on 21 December 1945. However, the turboprop engine was not able to produce its designed power; producing only the same output as the Packard Merlin (1,490 hp) with the resultant performance limited to that of the Merlin-engined version.
With the termination of hostilities, the two prototypes continued to be tested until 1947 when they were both consigned to a bombing range as photography targets (Ref.: 24).
Power Plant: One × Allison V-3420-23 liquid-cooled engine, rated at 2,885 hp driving three-blade contra-rotating propellers
Performance: 433 mph at 20,000
Comment: The disappointing results of the test program with the General Motors/Fisher XP-75 “Eagle” led to a complete re-design of the aircraft. Furthermore, in mid-1943, the need for long-range escort fighters became more urgent than fast climbing interceptors so a decision was made to order six more XP-75 airplanes modified for the long-range role. At this time, an order for 2,500 production aircraft was also let, but with the stipulation that if the first production version P-75A was not satisfactory the complete order might be canceled.
At the time, General Motors was busy in several projects towards the war effort, including the mass production of several different aircraft types, among them the Grumman TBM “Avenger”. Redesigns of the P-75A “Eagle” were introduced including a new outer wing section from the North American P-51 “Mustang”, a modified tail assembly, new “bubble” canopy, and a V-3420-23 engine that corrected most of the deficiencies by the time the first P-75A “Eagles” entered flight test in September 1944.
By this time, the Army Air Forces decided to limit the number of combat aircraft types in production and not enter into large-scale production of new types that might not be available before the war ended. As the twin-engine Lockheed P-38 “Lightning” and North American P-51 “Mustang” demonstrated excellent long-range capabilities the production run of the P-75A “Eagle” was substantially terminated on October 1944. Although the “Eagle” was given extensive media coverage prior to its first flight, being trumpeted as a “wonder plane”, it was decided to use the six completed production aircraft for experimental work and development of the V-3420 engine. As a result of these events, the P-75A did not complete formal performance trials due to termination of the production contract. Ultimately, only eight XP-75s and six P-75As were built (Ref. 24).
General Motors/Fisher P-75A “Eagle”
General Motors/Fisher P-75A “Eagle”
General Motors/Fisher P-75A “Eagle”
General Motors/Fisher P-75A “Eagle”
General Motors/Fisher P-75A “Eagle”
General Motors/Fisher P-75A “Eagle”
General Motors/Fisher P-75A “Eagle” and General Motors/Fisher XP-75 “Eagle
General Motors/Fisher P-75A “Eagle”
General Motors/Fisher P-75A “Eagle”
General Motors/Fisher P-75A “Eagle”
General Motors/Fisher P-75A “Eagle”
General Motors/Fisher P-75A “Eagle”
General Motors/Fisher P-75A “Eagle”
General Motors/Fisher P-75A “Eagle”
General Motors/Fisher P-75A “Eagle” and General Motors/Fisher XP-75 “Eagle
Scale 1:72 aircraft models of World War II
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