There can be few examples of machines that are so far advanced of their predecessors, yet were as completely useless as the B-70 Valkyrie. It was designed as a replacement for the Boeing B-52 in the late 1950s. Half a century on, the B-52 is still flying, whereas the Valkyrie never even saw service.

The Proposal

In 1954, at the height of the Cold War, The US Air Force issued an official requirement for a new bomber to replace the Boeing B-52 Stratofortress; that had only just taken to the air two years ago. It originally planned two planes. The first would be a nuclear-powered plane that would cruise at sub-sonic speeds and could make a dash faster than the speed of sound over the target. The other was for a conventional sub-sonic bomber.

Over time the proposals were changed. The nuclear option was binned as the technology was too expensive and the thought of any accidents with an airborne reactor was too hideous to contemplate. The final requirement demanded a plane that could cruise at Mach 3¹ or above, at a height of 72,000ft for a range of 10,000 miles. It should weigh no more than 490,000lbs.

Obviously, this was far in advance of technology of the time (the propeller driven B-36 was still in service), yet the first flight was expected by 1961. Boeing and North American submitted designs. North American won the competition with their XB-70² proposal in 1958 and an order was placed where the first operation wing would be operation from 1965.

The Design

No plane that came before looked like the XB-70. No plane that has come after resembles it. It was a long, sleek arrow that looked like it was more influenced by a paper dart than a real aircraft. It was 196' 6" long. Behind the pointed nose and cockpit were a set of small canard wings. The main wing was of a delta shape with wings swept back 65 degrees and the furthest third of each wing could be hydraulically folded downwards at cruising speed. There were twin vertical tail-planes.

The plane was designed to fly at high speed; over Mach 3. Once at speed, the Valkyrie would ride its own shockwave, which increased its efficiency. This effect, know as 'compression lift' was helped by the down-turned wing tips. The nose was titanium and the skin was made from a stainless steel honeycomb.

There were six General Electric YJ93 engines, all mounted in a box under the fuselage. The cockpit was designed for four people: the pilot, co-pilot, bombardier and defensive systems person.

The big problem of the XB-70 was that even at Mach 3, it was a sitting duck. It was true that no Russian fighter at the time could hope to intercept it, but there was no need. As it went so quickly, it generated massive amounts of heat and was therefore a beacon for any infrared-guided missile. The design of the body meant that it had an even larger radar cross-section than a B-52. Because of the nature of its high-speed flight, it was not at all manoeuvrable. It was a plane that was easy to spot and easy to track and therefore easy prey for Surface to Air Missiles (SAMs).

Political Football

When the B-70 project was announced, it captured the public imagination; however as President Eisenhower's reign continued, the Valkyrie fell rapidly out of favour. The main reason for this was that intercontinental ballistic missiles (ICBM) were becoming available to both superpowers. ICBMs put any target in Russia just a button-push away. They were much cheaper to build and research than a manned bomber. They required less manpower to run, and they couldn't be shot down.

More funds were being ploughed into ICBMs rather than into manned planes. In 1959 the F-108 Rapier fighter was cancelled. This project was being run alongside the Valkyrie. It was intended that the Rapier, essentially a scaled down, two-engined version of the Valkyrie, would act as the bomber's fighter escort. The planes would have shared a lot of systems. The development costs of all of these systems were now going to be totally lumped on the B-70 project.

Eisenhower decided to cut the B-70 project. At the end of 1959, the Air Force announced that it was no longer looking to acquire a fleet of these planes, and would instead be getting just one prototype. John F Kennedy was running for President in 1960 and he attacked Eisenhower for falling behind the Russians in technology. This caused the Air Force to announce in August 1960 that the B-70 was back on the table and that 12 prototypes were ordered.

When JFK came to power he found out that the Russians were not as advanced as he had been led to believe³, and that there was no 'missile gap'. He cut the B-70 project to just a research programme, and asked for just three prototypes.

The XB-70A flew on 21 September, 1964; it was painted white and was not designed to carry any weapons. The test was satisfactory, as were further tests, which saw the plane pass the Mach 2 barrier. At the time, it was the heaviest plane to have ever flown, weighing in at 550,000lb.

A second prototype was launched on 17 July, 1965. It carried a few improvements over the first example. The first example hit Mach 3 in October, 1965. The second hit Mach 3 for over half an hour on 19 May, 1966. During its flight it flew from Utah to California in 18 minutes.

The Final Flight

The second prototype XB-70A was appearing at a photoshoot for planes powered by General Electric engines near Barstow in California. It was flying in formation with, among others, an F-104N Starfighter. Flying at 25,000 feet, the fighter pilot flew too near the XB-70A's wing and his plane was caught in a vortex which drew it into the wing of the bomber. The fighter burst into flames and its pilot was killed instantly. The Valkyrie had lost a rudder and plunged into a spin. One pilot managed to eject, but was seriously injured in landing. The other couldn't get out of his seat due to the g-forces.

The other prototype continued to test before it was sent to NASA to help research on the aborted American supersonic transport (SST) project. It flew to Wright Patterson Air Force Base in Dayton, Ohio on 4 February, 1969, where it was put on display in the US Air Force museum.

When the military were trying to justify the B-70's existence, they proposed the RS-70. This was the reconnaissance/strike version of the Valkyrie. By providing the ability to perform reconnaissance roles, and be recalled when on a mission, it could do two things a missile couldn't. The problem was that being a giant glowing beacon, it wasn't exactly sneaky enough for a reconnaissance plane. It didn't stop the production run of 60 of these RS-70s being planned.

Although the RS-70 was announced just after the U-2 flown by Gary Powers was shot down over Russia, it was still thought that high altitude reconnaissance planes were a better bet than the RS-70. The ideal stealthy, high-altitude Mach 3 reconnaissance plane was actually on the drawing-board at the time. Based on the A-11 and YF-12 prototypes, the RS-71 would have been the perfect plane for the role. Except that President Lyndon Johnson got a bit muddled and announced the new plane as the SR-71, the Super Blackbird. His staff quickly covered up the error by designating the new plane as a strategic reconnaissance plane! At least that is the most popular story; doubts remain over how correct this is because it is difficult to see where the SR-71 would have stored its weaponry.

The fact that the B-70 bomber was easy prey for SAM missiles at the time did not stop the Russians designing a Mach 3 capable interceptor, the MiG-25 Foxbat⁴. Even though the B-70 was cancelled, the MiG-25 went into full production and served the Soviet Air Force as a reconnaissance/strike aircraft.

It's worth mentioning that although the Russians tried to develop a rival to the B-70, they did not produce a supersonic heavy bomber at the time. The Tupolev Tu-16 'Badger', Tupolev Tu-85 'Barge' and the Tupolev Tu-95 'Bear' were all too slow and the Tupolev Tu-22 'Blinder' was much smaller. The nearest they got was the Tupolev Tu-125 project that was cancelled in 1962. Various US intelligence reports which made the US Air Force believe that some Russian test planes were actually in service may have given support to the Valkyrie project.

At $700million per prototype, the Valkyrie was one of the most expensive planes ever produced. It was also one of the most extraordinary. In terms of performance, armament and range, it lived up to its expectations; however the nature of warfare changed. Its inability to perform at low levels, combined with its vulnerability at high altitude and its high cost compared to missiles meant that there was no reason for it to exist.

It would be the 1980s before the US Air Force had a supersonic heavy bomber in service, in the shape of the B-1B Lancer.