11 May 1964: At Air Force Plant 42 near Palmdale, a small city in the high desert of southern California, the first prototype North American Aviation XB-70A-1-NA Valkyrie, 62-0001, was rolled out. More than 5,000 people were there to watch.
In August 1960, the U.S. Air Force had contracted for one XB-70 prototype and 11 pre-production YB-70 development aircraft. By 1964, however, the program had been scaled back to two XB-70As and one XB-70B. Only two were actually completed.
The B-70 was designed as a Mach 3+ strategic bomber capable of flying higher than 70,000 feet (21,336 meters). Like its contemporaries, the Lockheed Blackbirds, the Valkerie was so advanced that it was beyond the state of the art. New materials and processes had to be developed, and new industrial machinery designed and built.
The XB-70A is a very large aircraft with a canard-delta configuration, built primarily of stainless steel and titanium. It has twin vertical fins combining the functions of stabilizers and rudders. The XB-70A Valkyrie prototype is 193 feet, 5 inches (58.953 meters) long, including the pitot boom, with a wingspan of 105 feet, 0 inches (32.004 meters) and overall height of 30 feet, 9 inches (9.373 meters). The canard span is 28 feet, 10 inches (8.788 meters). The canard has flaps, while the delta wing used multiple separate elevons for pitch and roll control.
The delta wing has an angle of incidence of 0° and its leading edges are swept to 65.57°, with 0° sweep at the trailing edge. The wings have a maximum of 2.60° negative twist at the tips. The wings of 62-001 have no dihedral, but the second B-70, 62-0207, had 5° dihedral. The total wing area is 6,297.8 square feet (585.1 square meters).
The canard also has 0° of incidence and dihedral. Its leading edge is swept aft 31.70°, while the trailing edge sweeps forward 14.91°. The canard has a total area of 415.59 square feet (38.61 square meters). The flaps can be lowered to 20°.
The vertical fins have a height of 15 feet (4.572 meters). The leading edges are swept 51.77° and the trailing edges, 10.89°.
The B-70 was designed to “surf” on its own supersonic shock wave (this was called “compression lift.”). The tips of the delta wing folded down as much as 65° for increased stability.
The first prototype, 62-001, had an empty weight of 250,817 pounds (113,769 kilograms) in July 1964. Its maximum taxi weight was 542,029 pounds (242,526 kilograms). 62-0207 had an empty weight of 253,601 pounds (115,031 kilograms) when calculated 28 May 1965, before its first flight. It had the same maximum taxi weight as -001.
The XB-70A is powered by six General Electric YJ93-GE-3 engines, grouped together in the tail. These are single-spool, axial-flow, afterburning turbojet engines, which have an 11-stage compressor section and 2-stage turbine. The YJ93-GE-3 is rated at 22,000 pounds of thrust (97.86 kilonewtons), and 31,000 pounds (137.90 kilonewtons) with afterburner. A special high-temperature fuel, JP-6, is required. The engine is 19 feet, 7.0 inches (5.969 meters) long, 4 feet, 7.0 inches (1.397 meters) in diameter, and weighs 5,200 pounds (2,359 kilograms).
In flight testing, the XB-70A reached a maximum of Mach 3.08 and 2,020 m.p.h. (3,251 kilometers per hour) with a sustained altitude of 74,000 feet (22,555 meters).
Fuel capacity was 46,745 gallons (176,950 liters), giving the bomber a potential range of 4,288 miles (6,901 kilometers).
The B-70 was designed to carry two B-53 two-stage radiation-implosion thermonuclear bombs in its internal bomb bay. A maximum of fourteen smaller weapons could be carried.
XB-70A-1 62-0001 first flew 21 September 1964, and exceeded Mach 3 for the first time on its 17th flight, 14 October 1965. Its final flight was 4 February 1969.
The second XB-70A-2-NA , 62-0207, was destroyed in a midair collision. The third Valkyrie, XB-70B-NA 62-0208, was cancelled before completion.
62-0001 is in the collection of the National Museum of the United States Air Force. It has made 83 flights with just 160 hours, 16 minutes, total flight time.
© 2018, Bryan R. Swopesby