The XB-70A Valkyrie was arguably one of the most beautiful aircraft in history. Its sweeping lines and gracefully curved fuselage remind the viewer favorably of the determined stance of a trumpeter swan in flight. As Simppa has noted below, the program was terminated before production for several reasons.

For one, there was indeed a crash of a prototype. However, this was not due to a flaw in the design; during a photo flight, one of the accompanying observer aircraft ventured too near the port wingtip of the XB-70 and was caught in the vortex of disturbed air rushing around the outside of the canard (known as wake turbulence). The F-104 was sucked over the top of the larger plane's wing, rolling to the right, and struck one of the Valkyrie's two vertical stabilizers. After being swept over the top of the larger aircraft, the F-104 struck the other vertical stabilizer as well, killing its pilot, Joe Walker. The Valkyrie continued to fly straight on for a few moments before starting to gently roll to the right; when the flight crew attempted to recover the aircraft, it had lost too much aerodynamic performance and stability and went into a nasty spin, progressing to a flat spin, and struck the desert killing the copilot, who was unable to eject in time. The pilot escaped.

There is a series of photographs of the event taken by another photo plane; they are easily found in any large-format book which concerns the XB-70.

This, however, was not the primary reason the airplane was cancelled. At the time, the war in Vietnam was ramping up, and military spending was in a crunch in order to pay for expanded operations in the Southeast Asian theater. The XB-70 would have been enormously expensive to produce, and (much like the B-1 and B-2 were at first) would have been useless in conventional bombing operations. The then-current bomber project, the B-52 series, was readily adaptable to the conventional role and was (with the introduction of the B-52H) becoming the standard heavy bomber for the Air Force's conventional needs. This was most efficient, as its sisters the B-52D and B-52G remained in the force as the nuclear bomber platform, allowing for common maintenance and supply.

Finally, the XB-70 had been designed and built on the notion that 'the bomber will always get through,' a notion born from the performance of the Boeing B-29 Stratofortress, which was able to fly high enough and fast enough to avoid interception by fighters - and with nuclear gravity bombs, the resultant accuracy loss wasn't really relevant. However this notion of airborne invulnerability had recently been dealt a sharp blow by the downing of Francis Gary Powers and his U-2 spyplane by a Soviet SAM. Once it became clear that despite the Mach 3+ speed of the XB-70 it remained vulnerable to surface-fired missiles and modern jet interceptors, the airplane began to look less and less like a capable platform given its somewhat limited bombload and high expense. During this time, the approved nuclear bombing doctrine switched to low altitude penetration and terrain-following, a maneuver the slower but less wing-loaded B-52s were more adept at. The XB-70's enormous swept delta wing meant that it was unsuitable, ungainly and extremely inefficient to fly at low speeds and altitudes.

And so the airplane was never built. It is really a pity; it was a stunning airplane.

There is a postscript, however; even without serving, the XB-70 served. The Soviet Air Force had a fairly good idea of what the XB-70 was capable of, and it scared them quite badly. In point of fact, the missiles that had downed Powers, while able to reach the altitudes of the XB-70, were not very useful against high-speed targets, and the USSR had no interceptors which could operate at the altitude of the U-2 much less the Valkyrie's performance envelope.

As a result, they began a crash program to defeat the Valkyrie. The result was the Mikoyan-Gurevich MiG-25, code-named by NATO the Foxbat. This interceptor was designed for one thing: speed. Capable of Mach 3+ operation, it had limited endurance, limited armament, mediocre maneuverability and poor maintenance characteristics. However, it was the only airplane in general service which could have caught and engaged a Valkyrie at full honk. It set numerous records; the U.S. tried for years to beat its time-to-altitude record, set with a production MiG-25. The mark was bested with the F-15 Streak Eagle, a purpose-built speed version of the F-15 fighter. All nonessential systems were stripped off the aircraft, lightweight substitute parts were emplaced in some cases, and the aircraft was run up to full throttle while bolted to the runway. The explosive bolts were detonated and the Streak Eagle, engines already at full output, barely beat the MiG-25's time to altitude record.

Then the MiG-25 took it back, and keeps it to this day.

The effort required to design and build the MiG-25 was massive, however; and these planes really weren't much use for anything else save reconnaissance. In this sense, the XB-70 contributed quite nicely to the economic front of the Cold War.

During the early 1960s, the NASA Flight Research Center was involved in support of the national Supersonic Transport Program (SST). Two prototype Mach 3+ high altitude bombers, built by North American Aviation for the Air Force, became available for SST research with the cancellation of their intended military program. The XB-70A Valkyrie was the largest experimental aircraft, measuring 190 feet in length, with a wing span of 105 feet and standing 33 feet in height. The aircraft had a delta wing and hinged wing tip that could be folded down to a 65 degree angle to improve stability at the aircraft's supersonic speeds of up to Mach 3. At this speed the Valkyrie was designed to ride its own shock wave.

Unfortunately program got several serious setbacks including crash of other prototype which caused death of two pilots. After that whole project was abandoned... (Originally created under wrong name : Fri Apr 28 2000 at 10:16 utc)

Other matters of note and corrections concerning the Valkyrie XB-70A:

The two prototypes produced, known as AV/1 (Air Vehicle/1) which bore tail number 20001 and AV/2 which bore 20207, were subtly different aircraft. AV/1 was constructed using extensive wind tunnel testing and some 18 months worth of computer modeling (remember, this is the 1960's), while AV/2 incorporated many design modifications that were made after testing of AV/1. These included changes to the canards, the nose and other minor structural, aerodynamic, and control aspects of the craft.

Problems with the AV/1 were manifold, owing to the number of new technologies and construction methods employed. These ranged from the first large scale use of honeycombed reinforced surface panels to a hydraulic system that operated at 4000psi, some 35% higher pressure than any other aircraft at the time. The problems with the honeycomb surface panels were so severe that they separated in flight the first time the plane broke Mach 3, after only one short foray to its maximum speed, AV/1 had a speed limit placed upon it: Mach 2.5 (1,850 mph/2980 kph).

AV/2 was plagued by fewer gremlins. It performed exceptionally, cruising in excess of Mach 3 without any difficulties. Even after the possibility of production was ruled out, it was obvious that AV/2 would be an ideal test bed for technologies necessary for a supersonic transport (SST) as well as general sonic boom research.

On the morning of June 8th, 1966, AV/2 performed a few passes over some recording instruments at Mach 1.4, 32,000ft above sea level. Then, at the request of GE it joined a formation of 4 other aircraft powered by GE; an F-4 Phantom II, an F-104 Starfighter, a T-38 Talon and an F-5 Freedom Fighter (also known as the F-5 Tiger). The aircraft flew in close formation for some 45 minutes, with the photographers constantly requesting a tighter formation; then just as formation was being broken for return to Edwards Airforce Base disaster struck. The F-104 that had been flying off of the XB-70's starboard wingtip was caught in the wake vortices generated by the massive delta wing. It was hurled into the wing and then carried with the airflow up over the back of the aircraft, where it smashed into both vertical stabilizers (tails). The pilot of the F-104, Joseph A. Walker, was killed instantly.

The XB-70 continued to fly for roughly another minute before it too lost control. The pilot, Al White, was able to eject safely, though he was injured in the 33G impact to which he was subjected upon landing. Carl Cross, the co-pilot who was making his first XB-70 flight, died when the XB-70 impacted in a flat spin in the desert just north of Barstow, California.

To this day, you can find parts of that XB-70 littering the desert.

Log in or register to write something here or to contact authors.