A fleet of lifting bodies flown at the NASA Flight Research Center, Edwards, California, from 1963 to 1975 demonstrated the ability of pilots to maneuver (in the atmosphere) and safely land a wingless vehicle. These lifting bodies were basically designed so they could fly back to Earth from space and be landed like an aircraft at a pre-determined site. (In 1976 NASA renamed the FRC as the NASA Dryden Flight Research Center in honor of Hugh L. Dryden.)
In 1962, FRC Director Paul Bikle approved a program to build a lightweight, unpowered lifting body as a prototype to flight test the wingless concept. It would look like a "flying bathtub," and was designated the M2-F1. It featured a plywood shell, built by Gus Briegleb (a sailplane builder from El Mirage, California) placed over a tubular steel frame crafted at the FRC. Construction was completed in 1963.
The success of the Flight Research Center M2-F1 program led to NASA development and construction of two heavyweight lifting bodies based on studies at the NASA Ames and Langley research centers--the M2-F2 and the HL-10, both built by the Northrop Corporation, Hawthorne, California. The Air Force also became interested in lifting body research and had a third design concept built, the X-24A, built by the Martin Company, Denver, Colorado. It was later modified into the X-24B and both configurations were flown in the joint NASA-Air Force lifting body program located at Dryden.
The X-24B design evolved from a family of potential reentry shapes, each with higher lift-to-drag ratios, proposed by the Air Force Flight Dynamics Laboratory.
To reduce the costs of constructing a research vehicle, the Air Force returned the X-24A to Martin for modifications that converted its bulbous shape into one resembling a "flying flatiron" -- rounded top, flat bottom, and a double-delta planform that ended in a pointed nose.
First to fly the X-24B was John A. Manke, a glide flight on August 1, 1973. He was also the pilot on the first powered mission November 15, 1973.
Among the final flights with the X-24B were two precise landings on the main concrete runway at Edwards, California, which showed that accurate unpowered reentry vehicle landings were operationally feasible. These missions were flown by Manke and Air Force Maj. Mike Love and represented the final milestone in a program that helped write the flight plan for the Space Shuttle program of today.
After launch from the B-52 "mothership" at an altitude of about 45,000 feet, the XLR-11 rocket engine was ignited and the vehicle accelerated to speeds of more than 1,100 miles per hour and to altitudes of 60,000 to 70,000 feet. After the rocket engine was shut down, the pilots began steep glides towards the Edwards runway. As the pilots entered the final leg of their approach, they increased their rate of descent to build up speed and used this energy to perform a "flare out" maneuver, which slowed their landing speed to about 200 miles per hour--the same basic approach pattern and landing speed of the Space Shuttles today.
The final powered flight with the X-24B aircraft was on September 23, 1975. The pilot was Bill Dana, and it was also the last rocket-powered flight flown at Dryden. It was also Dana who flew the last X-15 mission about seven years earlier.
Top speed reached with the X-24B was 1,164 miles per hour (Mach 1.76) by Love on October 25, 1974. The highest altitude reached was 74,100 feet, by Manke on May 22, 1975. The X-24B is on public display at the Air Force Museum, Wright-Patterson AFB, Ohio.
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