NASA Dryden and the Space Shuttles

NASA research pilot John Manke worked through his prelaunch checklist while the X-24B lifting body hung beneath the wing of a modified B-52 cruising at an altitude of 45,000 feet over California’s Mojave Desert. When the countdown reached zero, the X-24B – its narrow delta shape and flat belly had earned it the nickname the “flying flatiron” dropped away.

Seconds later, Manke ignited the vehicle’s four chamber XLR11 rocket engine and climbed to a peak altitude of 60,000 feet. As the craft nosed over, he scanned the desert below looking for a narrow gray strip of concrete near the edge of Rogers Dry Lake at Edwards Air Force Base.

Because lifting bodies have a very low lift-to-drag ratio some pilots felt the experience was akin to flying a brick all previous landings had been made on the 44 square mile lakebed expanse where there was significant margin for error. But this flight on Aug. 5, 1975 would be different and for the first time, a lifting body would touch down on Edwards' 15,000-foot-long, 300 foot wide concrete runway. Manke was aiming to make a precise landing on a spot about a mile down the airstrip.

Seven minutes after launch from the B-52, the X-24B was lined up for final approach. Manke touched down precisely on target moments after lowering the landing gear. The demonstration proved that a low lift-to-drag vehicle like the lifting bodies or the coming space shuttle could approach from high altitude or low-Earth orbit and land like a conventional airplane.

Early manned spacecraft designs enabled ballistic entry into the atmosphere, similar to that of a missile warhead. This type of entry resulted in high G-loads and intense heating due to atmospheric friction. Hence, Mercury, the first U.S. manned space vehicle and the only one to use a strictly ballistic entry trajectory, was designed so a single crewmember could lie on his back facing away from the direction of flight. Final deceleration was achieved through use of a parachute, and the capsule landed in the ocean.

Though a capsule could carry a human into space, it had to return to Earth beneath a parachute for an ocean splashdown; a lifting body allowed a pilot to fly home and land on a runway. Advantages of the lifting-body design included reduced mission costs (because the expense of an ocean recovery was eliminated) and greater cross-range maneuvering capability.

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