Republic XF-91 Thunderceptor

The Republic XF -91 Thunderceptor was an experimental interceptor of the U.S. aircraft manufacturer Republic. It is a single-seat all-metal aircraft with a hybrid drive of jet and rocket engine. Was based on the mid-wing monoplane, the Republic F - 84th

History

Initial studies of Alexander Kartweli ( who also designed the P -47 and F- 84) for XF -91 started in 1946. The machine was the first for the Abfangjagd developed aircraft that could fly faster than sound, the design saw a use to prior object -defense. To this end, several unusual interpretations were elected. Thus, the tread depth at the wing root of the swept with a 35 ° wing was lower than at the wing tips (he had there a width of 3.92 m), and its setting angle was in flight (especially for take off and landing ) by hydraulic jack screws between - 2 ° and 5.65 ° be changed continuously. This idiosyncratic wing shape resulted from the then limited experience with swept wings, their flight characteristics are not sufficiently constructive dominated especially in slow flight. For structural reasons, also the arrangement of the main landing gear was far out necessary - so there was the outline of the wing. To house the main landing gear had to be sufficiently thick wing, which explains the greater profile depth and thickness of the outer wing. This in reducing both the oscillation susceptibility of the wing and improved machine stability, especially in slow flight. As a side effect of this design engineers expected to reduce the air resistance in this critical area of the thin wing to the fuselage area. The two recovered in the wings outward shock struts each had two small wheels in tandem, the nose wheel went into the hull to back. In order to achieve the planned flight services a J47 jet engine was provided with an afterburner. As such, however, was not equipped with an afterburner available, Republic developed this yourself The afterburner was designed adjustable in power, the automatic system proved to be unreliable and so the scheme, curiously, according to instructions of the pilot by remote control was carried out from the ground. Another problem of the short life span was Nachbrennerbetriebes the inner outlet cuff only five hours. Since so a supersonic flight and the planned climb performance were not available, two rocket engines Curtiss -Wright XLR -27 were also scheduled. Since these were not available, instead of the four rocket engines XLR -11 engine of reaction were installed, the two above and below the jet engine.

The American military showed interest in the design and ordered two more than XP -91 labeled prototypes. The first machine left on 24 February 1949, the factory buildings in Farmingdale Long Iceland. The (for security to Edwards Air Force Base moved ) First flight of the XF -91 with Republic chief test pilot Carl Bellinger at the wheel was held on 9 May 1949. It was carried out a series of amazingly smooth flight tests in which the machine reached the first developed in the United States fighter aircraft type on December 9, 1952 supersonic. Reason for the delay was the late installation of the rocket engines that took place until the end of 1952. The second prototype flew tentatively similar to that of F- 86D with a V-tail and a Radarbug. However, there was no mass production of the proposed XF - 91A (normal ) and XF - 91B ( all-weather version similar to the second prototype ), since the flight time was limited to just 25 minutes. So it was ultimately up to the two prototypes after the Air Force had set the project in 1954. Overall, the design, especially the wing, as too heavy and the intended tactical performance proved was not achieved.

The first prototype ( USAF serial number 46-680 ) is on display at the National Museum of the United States Air Force, the second ( 46-681 ) was killed in 1951 after an engine damage.

Specifications

  • Length: 13.21 m
  • Wingspan: 9.52 m
  • Height: 5.51 m
  • Wing area: 29.73 m²
  • Empty weight: 7181 kg
  • Takeoff weight: 8424 kg
  • Max. Takeoff weight: 13,600 kg
  • Powerplant: one General Electric J47 -GE -3 with 23.2 kN of thrust without and 35.24 kN with afterburner four additional rocket motors Reaction Motors XLR11 -RM -9, each with 6.67 kN thrust
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