military-aircraft-xf-91

To compete with the Convair Model 8 (later F102 Delta Dagger) in a Air Force competition for a new high altitude interceptor with missile armament, Republic produced a radical design dubbed "Thundercepter". This featured a highly unusual swept wing of inverse chord and taper (wider and thicker at the tip than the root), which worked with leading edge slot to reduce the danger of low speed wing tip stall, The main landing gear units, located at the wing mid points, retracted out ward in to the tips. The wing also had a variable incidence system to allow a higher angle of attack for take off and landing. The XF-91 also used a mixed power plant. with a rocket engine providing 45 seconds of additional power via four chambers located above and below the jet nozzle. The first of two XF-91s flew in May 1949, and in December 1952 the type became the first American warplane to exceed Mach 1 in level flight. The conventional tail was later replaced by butterfly V tail for test purpose, but no production was undertaken.

Description	Specifications
Manufacturer: Republic	Length: 46 ft. 8 in.
First Flight: May 1949	Height: 18 ft. 1 in.
Model: XF-91	Wing Span: 31 ft. 3 in.
Crew: One	Wing Area:
Nickname: Thundercepter	Empty Weight: 19,000 lb.
Basic Role: High altitude interceptor prototype.	Max. Weight: 30,000 lb.
Other Versions: XF-91 interceptor prototype	Armament: Proposed air to air missiles.
Principal User: USA	Propulsion
Performance	Power Plant: General Electronic J47-GE-3 and one Reaction Motors XLR11-RM-9 rocket motor.
Range: 800 miles.	Horsepower: 5,200-lb reheated thrust and one 6,000-lb thrust .
Max. Speed: 730 mph or Mach 1.1 at 35,000 ft.	No. Of Engines: One
Ceiling: 55,000 ft.
Climb Rate: 44,250 ft. in less than 3 minutes 0 seconds.