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XB-70 Valkyrie North American
XB-70 Valkyrie
Strategic Bomber Prototype
High-Speed Research Aircraft

DESCRIPTION:
The B-70 bomber program resulted from an Air Force requirement for a high-speed, high-altitude strategic bomber to replace the B-52. North American engineers utilized NACA studies dealing with optimum Mach 3-6 configurations to develop the winning B-70 design (find out more at the Aerospaceweb.org Hypersonic Waveriders site). The aircraft was shaped to remain within its Mach cone throughout the flight regime thereby reducing drag and increasing lift. The latter was accomplished by manipulating the high pressure of the shock wave beneath the wing to generate compression lift. In addition, the wing tips were designed to pivot downward up to 65 to increase this compression lift while also providing greater directional stability.

Unfortunately, budget cuts of the late 1950s and early 1960s gutted the XB-70 advanced bomber project, and only two unarmed aerodynamic prototypes were actually built. Despite their exceptional performance, the XB-70 program had been cancelled by the time the Air Force flight tests were completed. The two prototypes were then transferred to NASA as high-speed research aircraft to prepare the way for supersonic transports. Both Valkyries served in this function well, flying 129 missions to study the aerodynamic, control, and heating issues associated with flight at Mach 2 to 3.

Tragedy struck on the 95th flight, however, when an F-104 flew too close to the second XB-70 prototype during a photo shoot. The fighter became caught up in the giant bomber's trailing vortices and the two planes collided before falling to earth in a fatal crash. The sole remaining XB-70 Valkyrie continued to fly until 1969 when it was placed in the USAF Museum.

Construction had also started on a third XB-70 prototype that carried a crew of four and would have been much closer to the final production design. As managers struggled to keep the B-70 program alive, proposals were made to equip this third aircraft with even more extensive research capabilities than the earlier prototypes had received. Among the proposals were plans to use the aircraft as a high-altitude astronomical observatory, a recoverable first stage booster for launching payloads into orbit, a platform for launching anti-satellite weapons, a high-altitude commucations relay, a high-speed propulsion test craft, and a vehicle to test methods of reducing radar cross section. Although construction of this aircraft was well underway, it was cancelled prior to completion.

Despite its failure to go into production, the B-70 Valkyrie provided invaluable high-speed flight test data that helped to bridge the gap between supersonic and hypersonic travel. Information collected during its test flights is still used by engineers today.

Last modified 17 March 2012

HISTORY:
First Flight 21 September 1964
Service Entry

did not enter service

CREW: (XB-70A) two: pilot, co-pilot
(B-70A) four: pilot, co-pilot, navigator/bombardier, defensive systems officer

ESTIMATED COST:

$700 million (prototype)

AIRFOIL SECTIONS:
Wing Root 0.30 Hex (Mod)
Wing Tip

0.70 Hex (Mod)

DIMENSIONS:
Length 185.83 ft (56.69 m) without pitot tube
192.17 ft (58.63 m) with pitot tube
Wingspan 105.00 ft (32.03 m)
Height 30.75 ft (9.38 m)
Wing Area 6,298 ft (586.2 m)
Canard Area

415.6 ft (38.68 m)

WEIGHTS:
Empty 300,000 lb (136,365 kg)
Normal Takeoff 534,700 lb (243,045 kg)
Max Takeoff 542,000 lb (246,365 kg)
Fuel Capacity internal: unknown
external: unknown
Max Payload

20,000 lb (9,070 kg) planned for production B-70

PROPULSION:
Powerplant six General Electric J-93 afterburning turbojets
Thrust 180,000 lb (800.71 kN)
Fuel Type JP-6

PERFORMANCE:
Max Level Speed at altitude: 2,056 mph (3,310 km/h) at 73,000 ft (22,270 m), Mach 3.1
at sea level: unknown
cruise speed: 2,000 mph (3,200 km/h) at 72,000 ft (21,965 m), Mach 3.0
Initial Climb Rate unknown
Service Ceiling 77,350 ft (23,600 m)
Range typical: 3,725 nm (6,900 km) [XB-70]
typical: 6,600 nm (12,230 km) [B-70]
ferry: unknown
g-Limits unknown

ARMAMENT:
Gun none
Stations production model designed with 2 internal bomb bays
Air-to-Air Missile none
Air-to-Surface Missile none
Bomb up to 14 nuclear bombs planned
Other none

KNOWN VARIANTS:
XB-70A-1 First prototype that was capable of only Mach 2.5 due to structural and aerodynamic limitations
XB-70A-2 Second prototype with a redesigned wing, structural improvements, and improved hydraulics allowing flight at Mach 3, vehicle was lost after an in-flight collision
XB-70A-3 Proposed third prototype, cancelled during construction
B-70A Proposed production model; 200 were to be built, cancelled
RS-70A Proposed reconnaissance model; 150 were to be built, cancelled

KNOWN OPERATORS:

United States (US Army Air Force)
United States (NASA)

3-VIEW SCHEMATIC:

XB-70 Valkyrie


SOURCES:
  • Boeing North American XB-70 site
  • Campbell, John M. and Pape, Garry R. North American XB-70 Valkyrie: A Photo Chronicle. Atglen, PA: Schiffer Military History, 1996.
  • Donald, David, ed. The Complete Encyclopedia of World Aircraft. NY: Barnes & Noble, 1997, p. 698, North American B-70 Valkyrie.
  • Dryden Research Center Photo Gallery
  • Eggers, A. J. and Syvertson, Clarence A. Aircraft Configurations Developing High Lift-Drag Ratios at High Supersonic Speeds, NACA RM-A55L05, 1956.
  • Flight of the Valkyrie
  • Rees, Ed. The Manned Missile: The Story of the B-70. NY: Duell, Sloan, and Pearce, 1960.
  • Remak, Jeannette and Ventolo, Joe. XB-70 Valkyrie: The Ride to Valhalla. Osceloa, WI: MBI Publishing, 1998.
  • US Air Force Museum XB-70 site
  • Winchester, Jim. Concept Aircraft: Prototypes, X-Planes and Experimental Aircraft. San Diego, CA: Thunder Bay Press, 2005, p. 186-187, North American XB-70 Valkyrie.





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