The HL-10 Lifting Body is seen here in flight over Rogers Dry lakebed. Like the other lifting bodies, the HL-10 made a steep descent toward the lakebed, followed by a high-speed landing. This was due to the vehicle's low lift-over-drag ratio. The first 11 flights of the HL-10 were unpowered, flown to check the vehicle's handling and stability before rocket-powered flights began using the XLR-11 rocket engine.
The HL-10, seen here parked on the ramp, was one of five lifting body designs flown at NASA's Dryden Flight Research Center, Edwards, California, from July 1966 to November 1975 to study and validate the concept of safely maneuvering and landing a low lift-over-drag vehicle designed for reentry from space.
The HL-10 was one of five heavyweight lifting-body designs flown at NASA's Flight Research Center (FRC--later Dryden Flight Research Center), Edwards, California, from July 1966 to November 1975 to study and validate the concept of safely maneuvering and landing a low lift-over-drag vehicle designed for reentry from space. Northrop Corporation built the HL-10 and M2-F2, the first two of the fleet of "heavy" lifting bodies flown by the NASA Flight Research Center. The contract for construction of the HL-10 and the M2-F2 was $1.8 million. "HL" stands for horizontal landing, and "10" refers to the tenth design studied by engineers at NASA's Langley Research Center, Hampton, Va. After delivery to NASA in January 1966, the HL-10 made its first flight on Dec. 22, 1966, with research pilot Bruce Peterson in the cockpit. Although an XLR-11 rocket engine was installed in the vehicle, the first 11 drop flights from the B-52 launch aircraft were powerless glide flights to assess handling qualities, stability, and control. In the end, the HL-10 was judged to be the best handling of the three original heavy-weight lifting bodies (M2-F2/F3, HL-10, X-24A). The HL-10 was flown 37 times during the lifting body research program and logged the highest altitude and fastest speed in the Lifting Body program. On Feb. 18, 1970, Air Force test pilot Peter Hoag piloted the HL-10 to Mach 1.86 (1,228 mph). Nine days later, NASA pilot Bill Dana flew the vehicle to 90,030 feet, which became the highest altitude reached in the program. Some new and different lessons were learned through the successful flight testing of the HL-10. These lessons, when combined with information from it's sister ship, the M2-F2/F3, provided an excellent starting point for designers of future entry vehicles, including the Space Shuttle.
The HL-10 Lifting Body completes its first research flight with a landing on Rogers Dry Lake at Edwards AFB, California, on December 22, 1966. The HL-10 suffered from buffeting and poor control during the flight. Pilot Bruce Peterson was able to make a successful landing despite the severe problems. These were traced to airflow separation from the fins. As a result, the fins were no longer able to stabilize the vehicle. A small reshaping of the fins' leading edges cured the airflow separation, but it was not until March 15, 1968, that the second HL-10 flight occurred.
Air Force Major Peter Hoag stands in front of the HL-10 Lifting Body. Maj. Hoag joined the HL-10 program in 1969 and made his first glide flight on June 6, 1969. He made a total of 8 flights in the HL-10. They included the fastest lifting-body flight, which reached Mach 1.861 on Feb. 18, 1970.
A model of the X-66 aircraft with a wingspan of almost 6 feet was placed in the 12-Foot Low-Speed Wind Tunnel at NASA’s Langley Research Center in Hampton, Virginia on October 30, 2024. During the tests, the team captured measurements of forces such as lift and drag over many aerodynamic configurations and flight conditions.
A model of the X-66 aircraft with a wingspan of almost 6 feet was placed in the 12-Foot Low-Speed Wind Tunnel at NASA’s Langley Research Center in Hampton, Virginia on October 30, 2024. During the tests, the team captured measurements of forces such as lift and drag over many aerodynamic configurations and flight conditions.
Not every moment of a test pilot's day is serious business. In a moment of levity, NASA pilots Bill Dana (left) and John A. Manke try to drag Air Force test pilot Peter Hoag away from the HL-10 lifting body while Air Force Major Jerauld R. Gentry helps from the cockpit. These four men were the principal pilots for the HL-10 program. This was not the only prank involving the HL-10 and its pilots. Once "Captain Midnight" (Gentry) and the "Midnight Skulkers" sneaked into the NASA hangar and put "U.S. Air Force" on the aircraft using stick-on letters. Later, while Gentry was making a lifting-body flight, his 1954 Ford was "borrowed" from the parking lot, painted with yellow-green zinc-chromate primer, and decorated with large stick-on flowers about one foot in diameter. After Gentry returned from the flight, he was surprised to see what had happened to his car.
The HL-10 lifting body is seen here in flight over Rogers Dry Lake at Edwards AFB. After the vehicle's fins were modified following its first flight, the HL-10 proved to be the best handling of the heavy-weight lifting bodies flown at Edwards Air Force Base. The HL-10 flew much better than the M2-F2, and pilots were eager to fly it.
The four principal HL-10 pilots are seen here with the lifting body aircraft. They are, left to right; Air Force Major Jerauld R. Gentry, Air Force test pilot Peter Hoag, and NASA pilots John A. Manke and Bill Dana. All are wearing the pressure suits needed for flying above 50,000 feet.
NASA research pilot Bill Dana stands in front of the HL-10 Lifting Body following his first glide flight on April 25, 1969. Dana later retired as Chief Engineer at NASA's Dryden Flight Research Center, (called the NASA Flight Research Center in 1969). Prior to his lifting body assignment, Dana flew the X-15 research airplane. He flew the rocket-powered aircraft 16 times, reaching a top speed of 3,897 miles per hour and a peak altitude of 310,000 feet (almost 59 miles high).
The HL-10 Lifting Body completes its first research flight with a landing on Rogers Dry Lake. Due to control problems, pilot Bruce Peterson had to land at a higher speed than originally planned in order to keep the vehicle under control. The actual touchdown speed was about 280 knots. This was 30 knots above the speed called for in the flight plan. The HL-10's first flight had lasted 3 minutes and 9 seconds.
The HL-10 Lifting Body is seen here in powered flight shortly after launch from the B-52 mothership. When HL-10 powered flights began on October 23, 1968, the vehicle used the same basic XLR-11 rocket engine that powered the original X-1s. A total of five powered flights were made before the HL-10 first flew supersonically on May 9, 1969, with John Manke in the pilot's seat.
The HL-10 Lifting Body is seen here parked on Rogers Dry Lake, the unique location where it landed after research flights. This 1968 photo shows the vehicle after the fins were modified to remove instabilities encountered on the first flight. It involved a change to the shape of the leading edge of the fins to eliminate flow separation. It required extensive wind-tunnel testing at Langley Research Center, Hampton, Va. NASA Flight Research Center (FRC) engineer Bob Kempel than plotted thousands of data points by hand to come up with the modification, which involved a fiberglass glove backed with a metal structure on each fin's leading edge. This transformed the vehicle from a craft that was difficult to control into the best handling of the original group of lifting bodies at the FRC.
As shown in this photo of the HL-10 flight simulator, the lifting-body pilots and engineers made use of early simulators for both training and the determination of a given vehicle's handling at various speeds, attitudes, and altitudes. This provided warning of possible problems.
The HL-10, seen here parked on the ramp at NASA's Flight Research Center in 1966, had a radically different shape from that of the M2-F2/F3. While the M2s were flat on top and had rounded undersides (giving them a bathtub shape), the HL-10 had a flat lower surface and a rounded top. Both shapes provided lift without wings, however. This photo was taken before the HL-10's fins were modified.
John Manke is shown here on the lakebed next to the HL-10, one of four different lifting-body vehicles he flew, including the X-24B, which he flew 16 times. His final total was 42 lifting-body flights.
This photo shows the HL-10 in flight, turning to line up with lakebed runway 18. The pilot for this flight, the 29th of the HL-10 series, was Bill Dana. The HL-10 reached a peak altitude of 64,590 feet and a top speed of Mach 1.59 on this particular flight.