29 November 1957: The third production Boeing B-52A-1-BO Stratofortress strategic bomber, 52-003, was flown from Boeing’s Seattle plant to the North American Aviation facility at Air Force Plant 42, Palmdale, California, to be modified to carry the new X-15 hypersonic research rocketplane.
Modifications began on 4 February 1958. A pylon was mounted under the bomber’s right wing. A large notch was cut into the trailing edge of the inboard flap for the X-15’s vertical fin. A 1,500 gallon (5,678 liter) liquid oxygen tank was installed in the bomb bay.
A station for a launch operator was installed on the upper deck of the B-52 at the former electronic countermeasures position. A series of control panels allowed the panel operator to monitor the X-15’s systems, provide electrical power, and to keep the rocketplane’s liquid oxygen tank full as the LOX boiled off during the climb to launch altitude. The operator could see the X-15 through a plexiglas dome, and there were two television monitors.
After modifications were completed at Palmdale, 52-003 was flown to Edwards Air Force Base, 14 November 1958.
NB-52A 52-003 is on display at the Pima Air and Space Museum, Tucson, Arizona.
21 September 1964: The first prototype North American Aviation XB-70A-1-NA Valkyrie, serial number 62-0001, flown by Chief Test Pilot Alvin S. White and Colonel Joseph F. Cotton, U.S. Air Force, made its first flight from Air Force Plant 42, Palmdale, California, to Edwards Air Force Base.
Originally a prototype Mach 3 strategic bomber, 62-0001 (also known as AV-1) and it’s sister ship, XB-70A-2-NA, 62-0207, (AV-2), were built and used by the Air Force and NASA as high-speed research aircraft. The third Valkyrie, XB-70B-NA 62-0208 (AV-3), was never completed.
The B-70 was designed as a high-altitude Mach 3 strategic bomber armed with thermonuclear bombs. The XB-70A is 196 feet, 6 inches (59.893 meters) long with a wingspan of 105 feet (32.004 meters) and an overall height of 30 feet, 8 inches (9.347 meters). It weighs 231,215 pounds (104,877 kilograms) empty and has a maximum takeoff weight of 534,792 pounds (242,578 kilograms).
The XB-70’s delta wing had a total area of 6,297 square feet (585.01 square meters). it had a sweep of 58.0° at 25% chord. The angle of incidence was 0° and the wing incorporated 3.0° negative twist. There was no dihedral. (The second XB-70 had 5° dihedral.) The outer wing panels could be lowered as much as 60° to increase longitudinal stability in high speed flight.
The XB-70A was powered by six General Electric YJ93-GE-3 single-spool, axial-flow turbojet engines, which used an 11-stage compressor and two-stage turbine. The engine required a special heat-resistant JP-6 fuel. It had a maximum continuous power rating of 28,000 pounds of thrust (124.55 kilonewtons) at 6,825 r.p.m. The YJ93-GE-3 was 19 feet, 8.3 inches (6.002 meters) long, 4 feet, 6.15 inches (1.375 meters) in diameter, and weighed 5,220 pounds (2,368 kilograms).
The XB-70A had a maximum speed of Mach 3.1 (2,056 miles per hour, or 3,309 kilometers per hour). At 35,000 feet (10,668 meters), it could reach Mach 1.90 (1,254 miles per hour, or 2,018 kilometers per hour), and at its service ceiling of 75,550 feet (23,012 meters), it had a maximum speed of Mach 3.00 (1,982 miles per hour, or 3,190 kilometers per hour). The planned combat range for the production bomber was 3,419 miles (5,502 kilometers) with a maximum range of 4,290 miles (6,904 kilometers).
North American Aviation XB-70A Valkyrie 62-0001 made 83 flights with a total of 160 hours, 16 minutes flight time. 62-0001 is on display at the National Museum of the United States Air Force, Wright-Patterson Air Force Base, Ohio.
17 July 1989: The first Northrop B-2A Spirit, 82-1066, took off from Air Force Plant 42, Palmdale, California, on its first flight. The crew was Northrop Chief Test Pilot Bruce J. Hinds and Colonel Richard Couch, U.S. Air Force. The top secret “stealth bomber” prototype landed at Edwards Air Force Base 1 hour, 52 minutes later.
After completing the flight test program, -1066 was placed in storage until 1993, awaiting upgrade to the Block 10 operational configuration. In 2000 it was again upgraded to the Block 30 standard. It is now named Spirit of America and assigned to the 509th Bomb Wing at Whiteman Air Force Base, Missouri.
The Northrop B-2A Spirit is an advanced technology long-range heavy bomber. It can perform both tactical or strategic missions. It features extremely low radar observabilty. The bomber features the “flying wing” concept, pioneered by the Northrop XB-35 in 1946. In addition to its “stealthy” configuration, the B-2A is also highly aerodynamically efficient.
The B-2A has a crew of two pilots. According to data released by the U.S. Air Force, the bomber is 69 feet (21.0 meters) long, with a wingspan of 172 feet (52.4 meters) and height of 17 feet (5.2 meters). Its empty weight is 160,000 pounds (72,575 kilograms), with a maximum takeoff weight is 336,500 pounds.
Th B-2A is powered by four General Electric F118-GE-100 turbofan engines. The F118 is a non-afterburning two-spool axial-flow turbofan with a single stage fan section, 11-stage compressor (2 low- and 9 high-pressure stages) and 3-stage turbine (1 high- and 2 low-pressure stages). It is rated at 19,000 pounds (84.5 kilonewtons) thrust. The F118-GE-100 is 100.5 inches (2.553 meters) long, 46.5 inches (1.181 meters) in diameter and weighs 3,200 pounds (1,451 kilograms).
The maximum speed of the B-2A is “high subsonic,” and its range is “intercontinental.” The service ceiling is 50,000 feet (15,240 meters).
The B-2A can carry a variety of conventional or thermonuclear bombs, including sixteen 2,000 pound (907 kilogram) bombs, or two GBU-57 Massive Ordnance Penetrators.
Northrop produced twenty-one B-2As between 1987 and 2000. The first operational bomber was delivered in 1993. One was destroyed when it crashed on takeoff at Anderson AFB, Guam, 23 February 2008.
17 July 1965: At Air Force Plant 42, Palmdale, California, the second North American Aviation B-70 Valkyrie prototype, XB-70A-2-NA 62-0207, took off on its maiden flight enroute Edwards Air Force Base where it would continue the flight test program with its sister ship.
The Valkyrie was designed as a Mach 3+ strategic bomber, capable of flight above 70,000 feet (21,336 meters), with intercontinental range. It’s altitude allowed it to avoid interceptors of the time, but improvements in radar-guided surface-to-air missiles increased its vulnerability. Ultimately, though, political decisions ended the B-70 program.
62-0207 was flown just 46 times, for a total of 92 hours, 22 minutes of flight. Changes to the aircraft corrected the deficiencies discovered in testing the Number 1 XB-70A, 62-0001. The most visible change was 5° dihedral added to the wings for improved stability. On 16 April 1966, 62-0207 reached its maximum design speed, Mach 3.08, which it sustained for 20 minutes.
Less than one year after its first flight, 8 June 1966, the Valkyrie was involved in a mid-air collision with a Lockheed F-104N and crashed just north of Barstow, California. North American’s B-70 test pilot, Al White, was seriously injured and co-pilot, Major Carl Cross, USAF, was killed. NASA test pilot Joe Walker, flying the F-104, was also killed.
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° of twist. 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 canard 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 outer 20 feet (6.096 meters) of each wing could be lowered to a 25° or 65° angle for high speed flight. Although this did provide additional directional stability, it actually helped increase the compression lift, which supported up to 35% of the airplane’s weight in flight.
The first prototype, 62-001, had an empty weight of 231,215 pounds (104,877 kilograms), and its maximum takeoff weight was 521,056 pounds (236,347 kilograms).
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 has a normal power rating of 17,700 pounds of thrust (78.734 kilonewtons); military power, 19,900 pounds (88.520 kilonewtons); and maximum power, 28,000 pounds (124.550 kilonewtons). All ratings are at 6,825 r.p.m. and are continuous. A special high-temperature fuel, JP-6, is required. The engine is 19 feet, 8.3 inches (6.002 meters) long, 4 feet, 6.15 inches (1.375 meters) in diameter, and weighs 5,220 pounds (2,368 kilograms).
62-0001 had a cruise speed of 1,089 knots (1,253 miles per hour/2,016 kilometers per hour) at 35,000 feet (10,688 meters), and maximum speed of 1,721 knots (1,980 miles per hour/3,187 kilometers per hour) at 79,050 feet (24,094 meters)—Mach 2.97. During flight testing, the XB-70A reached a maximum of Mach 3.08 (1,777 knots) with a sustained altitude of 74,000 feet (22,555 meters).
Fuel was carried in 11 internal tanks in the wings and fuselage and the maximum capacity was 43,646 gallons (165,218 liters), giving the bomber a combat range of 3,786 nautical miles (4,357 statute miles/7,012 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 prototype, 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.