The North American Aviation XB-70 Valkyrie was the prototype version of the proposed B-70 nuclear-armed deep penetration bomber for the United States Air Force's Strategic Air Command. Designed in the late 1950s, the Valkyrie was a large six-engined aircraft able to fly at beyond Mach 3 at an altitude of 70,000 ft (21,000 m), which would have allowed it to avoid interceptors, the only effective anti-bomber weapon at the time.
Two XB-70 prototypes were built for the U.S. Air Force. The aircraft program's high development costs, and changes in the technological environment with the introduction of effective high-altitude anti-aircraft missiles, led to the cancellation of the B-70 program in 1961. Although the proposed fleet of operational B-70 bombers was never built, the XB-70A aircraft were used in supersonic test flights from 1964 to 1969, performing research for the design of large supersonic aircraft. One prototype crashed following a midair collision in 1966; the other is on display at the National Museum of the United States Air Force in Ohio.
Specifications (XB-70A)
Data from USAF XB-70 Fact sheet[91]
General characteristics
- Crew: 2
- Length: 185 ft 10 in (56.6 m)
- Wingspan: 105 ft 0 in (32 m)
- Height: 30 ft 9 in (9.4 m)
- Wing area: 6,296 ft² (585 m²)
- Airfoil: Hexagonal; 0.30 Hex modified root, 0.70 Hex modified tip
- Empty weight: 210,000 lb (93,000 kg)
- Loaded weight: 534,700 lb (242,500 kg)
- Max takeoff weight: 550,000 lb (250,000 kg)
- Powerplant: 6× General Electric YJ93-GE-3 afterburning turbojet
- Dry thrust: 19,900 lbf[68] (84 kN) each
- Thrust with afterburner: 28,800 lbf[69] (128 kN) each
Performance
- Maximum speed: Mach 3.1 (2,056 mph, 3,309 km/h)
- Cruise speed: Mach 3.0 (2,000 mph, 3,200 km/h)
- Range: 3,725 nmi (4,288 mi, 6,900 km) combat
- Service ceiling: 77,350 ft (23,600 m)
- Wing loading: 84.93 lb/ft² (414.7 kg/m²)
- lift-to-drag: about 6 at Mach 2[92]
- Thrust/weight: 0.314
(WIKIPEDIA)
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