On April 19, 1967, a spacecraft that looked somewhat like a fat, winged dart reentered the Earth’s atmosphere over the Pacific Ocean. As it dipped into the upper reaches of the ionosphere it began to glow and was surrounded by a fiery plasma. But rather than traveling in a straight line as most reentering spacecraft did, the glowing craft began banking at hypersonic speeds, finally slowing and deploying a parachute at a point more than 1,100 kilometers off its orbital path. A JC-130 aircraft grabbed its parachute lines high above the Pacific and the crew winched it inside. The experimental spacecraft, known as the X-23 PRIME, was not a classified project. According to the US Air Force, it was intended to test the ability of a spacecraft to travel crossrange from its entry orbit, something that many years later would be incorporated into the design of NASA’s space shuttle.
"Cold War American Spacecraft Projects and the “Paperclip” connection."
NASA Engineers Propose Combining a Rail Gun and a Scramjet to Fire Spacecraft