XB-70 Valkyrie: Right Plane – Wrong Time
In the mid-1950s, the United States and the former Soviet Union were embroiled in the “Cold War.” Both countries were poised with nuclear weapons capable of effectively ending civilization as we know it. The United States’ nuclear force consisted of nuclear-armed missiles, submarines, and aircraft. The primary strategic aircraft were the venerable B-52 Stratofortress and the B-58 Hustler. Both were capable of striking deep into the Soviet Union with air-to-air refueling.
The Soviets, however, had developed ground-to-air missiles capable of reaching the B-52 at its maximum cruise altitude. The military wanted an aircraft that could fly higher (70,000 feet) and faster (Mach 3.0) than the B-52 out of range of Soviet missiles. Initial concept designs began in 1955. After several preliminary design cycles, North American was eventually issued a contract in 1958 for two aircraft. The new bomber was designated the XB-70 and named the “Valkyrie.”
North American won the contract principally as the result of an obscure wind tunnel experiment conducted in 1956 that described “compression lift” from the supersonic shock wave created by the nose of the aircraft. The aircraft was designed so that this shockwave was formed under the belly of the aircraft creating additional lift at supersonic speeds. They also designed drooping outer wing panels that folded down in flight to maintain the shockwave under the center of the aircraft.
Engineering was not the problem—politics and military doctrine were. Late in the 1950s, President Eisenhower favored Intercontinental Ballistic Missiles (ICBMs) as less expensive and more reliable for hitting Soviet targets and he opposed XB-70 program. At that point, the program was cut to a single prototype, and further development of advanced systems ceased.
But the program was not dead yet. During the 1960 presidential campaign, John F. Kennedy’s campaign said that the Republicans were weak on defense. He endorsed the B-70 program (garnering votes from North American’s California based employees) and the Air Force switched the program to a full development program and awarded North American a contract for the XB-70 prototype and 11 YB-70 developmental aircraft. Kennedy took office in January 1961, became convinced that the ICBMs were a better defense, and canceled the XB-70 program, except to fund the aircraft as an experimental platform for testing a Mach 3 aircraft. There were just enough funds to complete three prototype aircraft.
XB-70 Air Vehicle (AV) No. 1 was officially rolled out on May 11, 1964, and AV No.2 was completed October 15, 1964. The third aircraft was never built.
The first flight of AV No. 1 was September 1964. It was flown to Edwards AFB where it would undergo further testing. This first flight, however did not go smoothly. Just after takeoff, one of the engines had to be shut down, and there was a landing gear malfunction. This meant that the flight had to be made with the landing gear extended. Repairs were made, and the aircraft made another local test flight near Edwards AFB.
The Flight Test Program
The XB-70 first went supersonic at just Mach 1.1 on its third flight, and the outer wing panels were partially lowered to check operation. The aircraft went through a series of generally successful test flights over the next year, and on October 14, 1965 reached a speed of Mach 3.02 at 70,000 feet—its original design goal. After early proving flights, AV No.2 Exceeded Mach 3 for 20 minutes. The following month it reached Mach 3.06 and maintained that speed for 30 minutes, traveling a total of 2,400 miles in 91 minutes.
In 1966, AV No. 2 was selected for a joint NASA/USAF program for measuring the intensity of its sonic boom. It was equipped with a suite of sensors and it flew it’s first test on June 6, 1966 at a speed of Mach 3.05. Two days later at the beginning of the second test, it was flying in formation with three other aircraft for a photo flight. An F104 fighter chase plane clipped the XB-70’s wingtip and rolled up over and back down on the other XB-70 wing. The aircraft crashed into the desert. One XB-70 pilot was able to eject. The other pilot and the F-104 pilot were killed.
AV No.1 continued in its role as a test aircraft making a total of 83 flights. Its last flight was on February 1969 when it flew from Edwards AFB to Wright Patterson AFB where it was turned over to what is now the US Air Force Museum.
Valkyrie AV-1 (AF Ser. No. 62-0001) is on display at the National Museum of the United States Air Force at Wright-Patterson AFB. For many years, XB-70 No.1 was crammed into a hangar with dozens of other experimental and test aircraft as part of the Air Force Museum. Today, the XB-70 and the other members of the research collection are displayed in a spacious new building.