By Peter W. Merlin
Historian, NASA Dryden Flight Research Center
As the morning of Sept. 23, 1975 dawned over the Southern California high desert, a team of engineers, technicians and flight crew busily prepared for what would be the last chapter in a flight research program that had spanned more than a dozen years – the final rocket-powered flight of the X-24B, the last of the wingless lifting bodies.
But that final flight came with a twist of sartorial humor, courtesy of NASA research pilot William H. “Bill” Dana and the David Clark Co., manufacturers of the high-altitude pressure suit he would wear on the mission.
The X-24B was one of a series of wingless lifting body research vehicles flown by NASA’s Flight Research Center – now the Dryden Flight Research Center – in a joint program with the Air Force at Edwards Air Force Base, Calif., from 1963 to 1975. Tested only within the atmosphere, the lifting bodies allowed pilots to demonstrate the ability to maneuver and safely land wingless spacecraft following re-entry from space.
Because of their bulbous shapes, several early configurations were described as “flying bathtubs” or “finned potatoes.” In 1972, one of the craft – the X-24A – was rebuilt as the X-24B with a more stable external configuration designed by the Air Force Flight Dynamics Laboratory. Because the X-24B had a rounded top, flat bottom and double-delta planform, it was sometimes called the “flying flatiron.” Powered by an 8,400-pound-thrust rocket engine, the X-24B reached a top speed of 1,164 mph and a maximum altitude of 74,130 feet during its two years of research flights.
The craft were carried to launch altitude beneath the wing of a modified B-52 bomber. Following engine burnout, the pilot guided the vehicle to a glide landing on the dry lakebed at Edwards. The X-24B also made two landings on a concrete runway, demonstrating that accurate, unpowered landings were operationally feasible for returning spacecraft.
On the morning of the X-24B’s final mission, Dana emerged from the life support van in his white pressure suit – required for flights above 50,000 feet. In striking contrast, his boots were bright pink and adorned with yellow daisies. The non-standard footwear resulted from the occasion when Dana was fitted for a new pressure suit during the earlier HL-10 lifting body flight research project.
The David Clark Co. had agreed to supply NASA with white A/P-22S-2 pressure suits and black boots for the lifting body pilots. The Air Force used the same suit, but with white boots for SR-71 crews. At the fitting, Dana found his suit had white boots, which he opined were not sufficiently masculine for a test pilot.
“I might as well wear pink boots,” he said, a comment that was not lost on the David Clark technicians.
When Dana’s suit was delivered, it came with standard black boots. But the David Clark Co. technicians, remembering Dana’s earlier comment, also thoughtfully provided a second pair – pink with adhesive flower decals. To his credit, Dana not only wore the boots on his next HL-10 flight, but again during his final X-24B flight.
The final X-24B mission began with the lifting body being carried aloft beneath the wing of the mothership. Upon reaching launch altitude over the nearby town of Lancaster, the X-24B dropped away from the B-52. Dana flipped the switches to ignite the four rocket chambers, but one failed to fire. Dana adjusted his climb angle to accommodate a three-chamber flight profile, a contingency for which he had trained in the simulator.
Even without the fourth rocket chamber, the X-24B reached a speed of 780 mph – about Mach 1.157 – and climbed to an altitude of 58,000 feet. Dana successfully performed a series of maneuvers to meet the mission’s research objectives. The flight, and the lifting body flight research program, ended with the X-24B’s landing on Rogers Dry Lake.
Afterward, the X-24B team posed in front of their aircraft for a final group portrait. Dana, still clad in his pressure suit, was front and center – wearing pink boots festooned with yellow daisies. It was a whimsical finish to one of the most significant flight research programs ever conducted at NASA’s Dryden Flight Research Center.
For more information about NASA Dryden Flight Research Center and its research projects, visit: https://www.nasa.gov/centers/dryden
PHOTO EDITORS: A high-resolution photo to support this release is available for downloading from the NASA Dryden web site at: https://www.nasa.gov/centers/dryden/news/newsphotos/index.html
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