XF-90
With the P-80A, Kelly Johnson gained a firm foothold in the production of a group of promising developments. From July 1945 they drew their attention to the development of technical specifications for the design of more sophisticated jet fighter, reflecting information from captured German studies of swept wing designs as a means of improving the transonic characteristics.
Within a short period they analyzed at least 65 different designs, including a version with tail "butterfly", with a wing with a W-shaped plan view (the inner part of the wing straight sweep, wing - with forward-swept), with three engines ( one on each wingtip and one in the fuselage) or swept-wing and one engine (this option had a great resemblance to the Hawker Hunter, which flew for the first time in the United Kingdom in July 1951). The benefits of this work and the use of their good reputation with the Air Force for the P-80 program allowed Lockheed in 1946 to be well aware of the answer to the requirement of the Air Force of the US Army (USAAF - United States Army Air Force) fighter-range, capable accompany the bombers and, if possible, to carry out airstrikes assault.
The ill-defined specification for long-range fighters, demanding combat range of 900 to 1,500 miles (from 1450 to 2415 km) and then decreased to 600 miles (965 km) and climb rate was increased from 35,000 feet (10,670 m) in 10 minutes subsequently amended to 50,000 feet (15,240 meters) for 5 minutes. This created a lot of problems for the team managed by the leading engineers of the project Don Palmer (Don Palmer) and Bill Ralston (Bill Ralston). Lockheed received on 20 June 1946 a contract for two prototype XP-90 (XF-90 after June 1948; Lockheed P-80 Model 090-32-01; 46-687 and 46-688). Lockheed was first developed fighter with delta wing.
However, tests carried out in a wind tunnel Caltech, Pasadena, resulted in a substantial re-design. Construction of the deltoid prototype was suspended, and already produced components were scrapped. A revised draft Lockheed Model 90 had swept wings, sharply pointed nose, two Westinghouse J34 engines and the proposed arms of six 20-mm guns. Axial turbojets was selected to provide additional security twin-engine configuration, had enough small diameter, through which were placed inside the fuselage to give the air from the side air intakes. Internal fuel capacity could be supplemented with tanks located under the wingtips wing panels, bringing the total capacity increased to 1665 US gallons (6303 liters).
Lockheed was the pioneer in the use of Almine 75ST, which was almost 25% stronger than standard aluminum alloy 24ST. The machine was built using large forgings and machined parts. As a result, the empty weight of the aircraft was more than 50% heavier than the corresponding parameter of the rival McDonnell XF-88. Both types use the same pair of turbojet engines and the project of Lockheed had a much worse power available. Thus by the time of its first flight XF-90, it was already doomed to failure.
Powered by two Westinghouse XJ34-WE-11 c pull 3,000 pounds (1361 kg), the first XF-90 (46-687) was collected approximately seven months after the McDonnell XF-88. The XF-90 was delivered to Edwards Air Force Base in preparation for its first flight, on 3 June 1949, under the management of Tony Levier (Tony LeVier). Although insufficient capacity of engines without afterburners gave disappointing performance, the XF-90 in April 1950 passed a test program with almost no problems.
To improve the characteristics of Lockheed, based on its experience with the modified second XP-80A, it was planning to use the engine with afterburning XJ34-WE-15, developing 3,600 lb (1633 kg) rated thrust and 4200 lb (1905 kg) of afterburner thrust. These engines were installed on the second plane, and they have been upgraded first. Designated as the XF-90A and fitted with uprated engines XJ34-WE-15 prototype began to explore the upper limit of their performance characteristics of the transonic and supersonic dive reached (May 17, 1950 in the dive was reached maximum speed in 1,12M). During the first of these supersonic flight is one of the XF-90A was almost lost because Tony Le Vieux experienced serious difficulties in getting out of a dive.
Achieving the maximum level flight speed 668 miles / hour (1075 km / h) in the XF-90A was a little later than the North American F-86A, which was already in service in parts of the US Air Force and received his baptism of fire in the skies of Korea. The company Lockheed has offered at least three other developments XF-90, which should have been equipped with a single Allison J33-A-29 (Lockheed Model 190-33-02), two Westinghouse J46-WE-2s (Model 290-34-03) and a General Electric J47-GE-21 (Model 390-35-02), respectively. However, each of these proposed version would entail serious redesign of the air intakes and the fuselage to accommodate larger the required air flow and the diameter of the power plant. Thus, because the engines that combine adequate traction with a maximum diameter, were not available for installation on the XF-90A.
In June 1950 the project lost to the Lockheed XF-88 and three months later the development of XF-90 was terminated. The second XF-90A was finally destroyed on the ground in 1952 during tests of the atomic bomb, held in Frenchmans Flat (Frenchman's Flat), Nevada. The next year already flightless first prototype was sent to the lab NACA in Cleveland, which intended to use it in a test of strength, paying tribute to the very robust design XF-90.
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