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The North American XB-70A Valkyrie

Posted in America, Aviation, Historical articles, History, Weapons on Tuesday, 2 April 2013

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This edited article about aviation originally appeared in Look and Learn issue number 217 published on 12 March 1966.

XB-70A Valkyrie, picture, image, illustration

North American XB-70A Valkyrie by Wilf Hardy

An expectant hush fell over the crowd gathered at Air Force Plant 42, Palmdale, California, as the big hangar doors rumbled smoothly open. From the gloom inside came the whine of a diesel tractor moving forward. The moment had come for the roll-out ceremony of the mighty North American XB-70A Valkyrie.

Out into the sunlight of that May day in 1964 came a needle-sharp, black-topped snout and cockpit, then the jutting foreplane on a long, gleaming white fuselage sixteen feet above the ground. The fuselage drooped a full eighty feet ahead of the towing tractor linked to the nose-wheels.

Even though technical drawings and artists’ impressions had been available for some time, the towering XB-70A was stunning in its sheer size and streamlined, white beauty. The tubular fuselage blended into a sharply-swept delta wing sprouting two rudders. Beneath the wing was the great box housing the six engines and the undercarriage, the engine air-intakes gaping deep and wide.

In design and technology the XB-70A was and still is as far ahead of today’s aircraft as they are ahead of those of the second World War! The XB-70A flies at 2,000 m.p.h. at 70,000 feet, and is designed so that at this speed it rides the supersonic – triplesonic shock-wave it creates like a speedboat riding its foaming bow-wave.

The aircraft made its first flight on September 21, 1964, in the hands of North American Aviation’s pilot Al White and the United States Air Force project test pilot, Colonel Joseph Cotton. Flanked by supersonic T-38 jet-trainer chase planes, the Valkyrie blasted into the air on its six monster engines. The main feature of the flight was to be acceleration through the sound barrier – a mere nibble at the aircraft’s speed capability.

But the flight was dogged by faults from the start. The main-wheel units refused to retract, so supersonic speed was impossible. Then one of the six engines ran wild and had to be shut down. And the landing showed up a third fault – the powerful brakes on one pair of main wheels locked solid.

The red and white chase planes, dwarfed by the mighty delta wing, edged in close to guide the test pilots down by calling off the feet as the runway came up under the wheels. As the XB-70A touched down there was a scream of tortured metal and a spurt of flame and smoke as the two locked wheels were literally ground into dust. The pilots handled the situation coolly and skilfully, and the aircraft itself was undamaged.

These defects were quickly put right and there are now two XB-70As at the Edwards Air Force Base test centre where, by mid-January 1966, they had completed nearly 100 hours in the air. Both have flown at their designed Mach 3 speed, and the day is in sight when the aircraft will be flown at a sustained Mach 3 for 30 minutes.

Flying at 70,000 feet the crew of two pilots enjoy a “shirt-sleeve” environment. Their cabin is a sealed, pressurized capsule, and each pilot’s seat is a capsule within the cabin. If there is a pressure failure, two “clamshell” doors snap shut to seal the pilot in with his own oxygen and emergency controls, with which he can control the throttles and trim the aircraft for an emergency descent. Back at low altitude, the capsules can be re-opened or rocket-ejected for escape by parachute.

The XB-70A flies at speeds which generate heat enough to render ordinary aircraft metals as useless as plasticine, so the giant plane is constructed of stainless steel, titanium and nickel which take heat at a searing 630 deg. F. in their stride. The exacting requirements for the aircraft mean that many manufacturers had to make colossal technical leaps forward to meet them – research which benefits in many fields far from aircraft engineering.

Designed originally as a bomber, the Valkyrie is now gathering information for the designers of tomorrow’s peaceful, 2,000 m.p.h. supersonic transport planes. Its steel and titanium construction, advanced cooling systems, its multitude of automatic engine and flight controls and its refined fuels, are all signposts to the future.

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