The Oxcart’s J-58 jet engines developed by Pratt and Whitney were finally delivered in 1963, Annie Jacobsen explains (in Area 51), but not without complications:
A host of new problems occurred when the engines were first powered up. In one instance, engineers suspected a foreign object was stuck in an engine’s heart, called the power plant, and was damaging internal parts. An X-ray showed the outline of a pen that had fallen into the engine’s cover, called a nacelle, during final assembly in Burbank. From then on, Lockheed workers got coveralls without breast pockets.
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The engines worked like giant vacuums. Once powered up on the tarmac, they sucked in every loose object lying around, including rocks and metal screws. As a solution, Area 51 workers took to sweeping and then vacuuming the runway before each flight. It was a tedious but necessary job.
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As the airplane reached higher speeds, the 500-plus-degree temperatures began melting electrical components, many of which had to be redesigned and rewired.
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In the case of the Oxcart, the sonic shock unexpectedly caused the fuselage to flex in such a way that many structural parts became dangerously compromised. These parts had to be redesigned and replaced.
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Every flight was like an operational mission, with navigators plotting a course and making maps days before as they worked to test the Oxcart’s inertial navigation system, or INS. “When you’re flying at that altitude and that speed, you need big checkpoints to validate information from the INS,” recalls navigator Sam Pizzo. “Any old geographical landmark, like a mountain or a river, would not do. The Oxcart traveled too fast. Pilots would have to look for landmarks on the scale of the Grand Canyon or the Great Lakes,” says the veteran navigator. “You can’t imagine what new territory this was for a navigator. No amount of experience can prepare you when you work on an airplane that goes two or three times as fast as anything you navigated for before.”