XB-70 — The Valkyrie Survivors

The B-2 Spirit bomber is controversial due to its price tag of $1-billion to $2-billion per aircraft. Pundits point to the good that could be done with the money from just one of these aircraft. Military buffs wonder if the USAF will ever risk these expensive aircraft in combat, and how the public would react to the loss of just one airplane. Given that nothing is really new due to history repeating itself, all of these questions have played out before in the late 1950s and early 1960s under the umbrella of Weapons System 110, the B-70 Valkyrie bomber.

The problem faced by the USAF is that Soviet radar, interceptors, and missiles had developed to the point where it was questionable if any of the B-36 Peacemakers would survive to make it to their primary targets in the event of World War 3. Several interim bombers were built, including the B-47 (the all-jet bomber), the B-52, and the B-58 (Mach 2 medium bomber). It was hoped that these interim bombers could fly a bit higher and faster, giving the US a fighting chance to win WWIII until the US could field the ultimate Mach 3 bomber. The theory was that this Mach 3 bomber would fly so fast and so high that nothing could shoot it down. This project became Weapons System 110, the chemical powered bomber program.

The requirements for the B-70 were extreme. It has to cruise at Mach 3 at an altitude of at least 70,000 feet, have a range of at least 7,500 miles with a payload of at least 50,000 pounds. Further, the crew had to work in shirtsleeve comfort while the aircraft had to operate using existing B-52 hangars and runways. Many thought that this was simply impossible, especially in the age of slide rules and drafting boards. The biggest challenge was heat. Air friction would cause the skin to heat to several hundred degrees baking the entire airframe on each flight. To solve this problem techniques were adapted such as a honeycomb skin, titanium structural components, embedding metal in the tires, and cooling the fuel. The most remarkable design element of the Valkyrie is the folding wings. During flight, the outer 20 feet of each wing could be dropped between 25 and 65 degrees. This trapped the supersonic shock wave under the fuselage, resulting in the Valkyrie being able to ride its shock wave much like a surfer rides a wave with a surfboard.

The first Valkyrie, Air Vehicle 1, first flew on September 21, 1964. While there were many complex teething problems, the USAF was able to work the problems one at a time. But it eventually became apparent that AV/1 was flawed due to a lack of experience in working with the honeycomb materials. Air Vehicle 2 was a far better aircraft. It first flew on July 17, 1965. It accumulated 46 flights as the primary research aircraft until disaster struck on June 8, 1966. While flying in formation with 4 other jets, an F-104 struck the Valkyrie breaking off its two vertical rudders. The Valkyrie flew on for a few more seconds, then went into a snap-roll and fell out of the sky, killing the co-pilot and destroying a $750-million aircraft.

AV/1 was outfitted with new instrumentation and took over the research program that AV/2 had started, first for the USAF, and later for NASA. NASA needed the data to support the supersonic transport project. AV/1 eventually accumulated 83 flights. But the Mach 2.5 speed limit was a handicap for the NASA research. Coupled with loss of USAF funding, the cancellation of the SST, and the need for funding to support the war in South-east Asia, AV/1 was sent to the USAF Museum on February 4, 1969.

The key factor that lead to the death of the B-70 program was the same factor that resulted in the birth of the program. That is the mission had changed. By the early 1960s, the Soviet Union had developed air defense systems that could successfully attack high-flying bombers. As a result, the bombing mission was changed to be a low-level mission, flying in under the radar. The B-52 could adapt to that role, as did the B-58, but the B-70 could not be adapted to be a low-level penetrator. As a result, the B-52 soldiers on having been in service for over 50 years as an interim solution, while the remarkable B-70 has been almost forgotten by history.