Historical perspective - Historical perspective

Frontiers September 2014 Issue

HISTORICAL PERSPECTIVE Speed surfer The XB-70 Valkyrie was designed to be a Mach 3 strategic bomber, but it ended up in a much different role By Mike Lombardi Fifty years ago, on Sept. 21, 1964, about 5,000 employees of North American Aviation and guests gathered at U.S. Air Force Plant 2 in Palmdale, Calif., to watch a six-engine, experimental military aircraft take off for the first time. It was unlike anything that had flown before—graceful, awe-inspiring and designed to surf its own shock wave at hypersonic speeds. The XB-70 Valkyrie was the embodiment of innovation and a testament to the talent nurtured under the leadership of North American founder Dutch Kindelberger, company president Lee Atwood and chief engineer Harrison Storms. That successful first flight of the 10 Frontiers September 2014 XB-70 represented an effort that began in 1954 when both Boeing and North American submitted designs for the Air Force Weapon System 110A competition. In December 1957, North American was named the winner. (North American is one of Boeing’s heritage companies.) The XB-70 was the prototype for a nuclear-armed bomber for the U.S. Air Force’s Strategic Air Command. It would fly three times the speed of sound at more than 70,000 feet (21,000 meters). At that altitude it would be able to evade interceptor aircraft. Even before the XB-70 was off the drawing board, however, advances in Soviet air defenses resulted in an emphasis on less-expensive intercontinental ballistic missiles as the mainstay of the U.S. nuclear forces. In April 1961, the Air Force cut back the B-70 to a research program. The second Valkyrie, XB-70A-2, flew in July 1965. As a research program, the XB-70s introduced many new technologies including a revolutionary design that relied on an aerodynamic theory called Compression Lift, which gave the Valkyrie additional lift from its own supersonic shock wave. At supersonic speeds, the outer wing panels hinged downward up to 65 degrees to improve directional stability. Just behind the cockpit were two large control surfaces, known as canards. North American came up with a steel honeycomb sandwich skin that


Frontiers September 2014 Issue
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