HL-10 Lifting Body

The HL-10 was one of five aircraft built in the 

Lifting Body Research Program. It was a NASA 

design and was built to evaluate an inverted airfoil 

lifting body with a delta planform. The HL-10 was 

flown 37 times during the program and logged the 

highest altitude and fastest speed.

The other lifting body designs were the M2-F2, 

M2-F3 (rebuilt M2-F2 following a landing accident), X-24A and X-24B (the rebuilt X-24A with 

a different aerodynamic shape).

Wingless lifting bodies attained aerodynamic 

stability and lift from the shape of the vehicle. Lift 

resulted from more air pressure on the bottom of 

the body than on the top. Energy and aerodynamic 

lift are used for in-flight maneuvering and a powerless, glider-like landing.

Background

The idea of lifting bodies was conceived in 1957 

by Dr. Alfred J. Eggers Jr., then the assistant 

director for Research and Development Analysis 

and Planning at the National Advisory Committee for Aeronautics (NACA) Ames Aeronautical 

Laboratory (now NASA Ames Research Center) 

at Moffett Field, California.

The NASA Flight Research Center (now NASA 

Armstrong Flight Research Center), located at 

Edwards Air Force Base in California, was where 

the lifting body concept was originally tested 

with a plywood prototype built in late 1962 and 

designated the M2-F1. It featured a plywood shell, 

built by William "Gus" Briegleb who was a sailplane builder from Mirage Dry Lake in California, 

placed over a tubular frame built at the Flight Research Center. The M2-F1 was towed aloft, first 

behind a modified 1963 Pontiac Catalina convertible and then a C-47 aircraft, more than 100 times 

to validate basic lifting body stability and control 

characteristics. This led to establishment of the 

formal program that resulted in the HL-10 and its 

sister vehicles.

The contract for construction of the HL-10 and 

the M2-F2, first of the fleet of lifting bodies flown 

The HL-10 lifting body is seen in 1969 over Rogers Dry Lake, California. (NASA Photo)
FS-2015-07-050 AFRC

National Aeronautics and Space Administration

Armstrong Flight Research Center

P.O. Box 273

Edwards, California 93523

NASA Facts

at the Flight Research Center, was awarded to Northrop Corporation in June 1964. "HL" stands for horizontal landing and 

"10" refers to the tenth design studied by engineers at NASA 

Langley Research Center in Hampton, Virginia.

The HL-10 was delivered to NASA in January 1966. During the next 10 months it was instrumented and prepared for 

flight. The HL-10 and the M2-F2 were tested in wind tunnels 

at Ames before research flights began. First flight of the HL10 was 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.

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 

William H. "Bill" Dana flew the vehicle to 90,030 feet, the 

highest altitude reached in the program.

Typical Flight Profile

During a typical lifting body flight, the B-52 flew to a height 

of about 45,000 feet and a launch speed of about 450 mph. 

The research vehicle was attached to the pylon mount on the 

right wing between the fuselage and inboard engine pod.

Moments after being dropped, the XLR-11 rocket engine 

(same type engine used in the Bell X-l) was ignited by the 

pilot. Speed and altitude increased until the engine was shut 

down by choice or fuel exhaustion, depending on the individual mission profile. The lifting bodies normally carried enough 

fuel for about 100 seconds of powered flight and routinely 

reached altitudes of 50,000 to 80,000 feet and speeds above 

Mach 1. 

Following engine shutdown, the pilot maneuvered the vehicle through a simulated return-from-space corridor into a 

preplanned approach for a landing on one of the Rogers Dry 

Lake runways at Edwards Air Force Base. A circular approach 

was used to lose altitude during the landing phase. On final 

approach, the pilot increased his rate of descent to build up 

energy. At about 100 feet altitude, a "flare out" maneuver 

dropped air speed to about 200 mph for the landing.

The HL-10 helped develop energy management and landing 

techniques used presently with the space shuttle orbiters. The 

lifting body is on display at the entrance to NASA Armstrong 

Flight Research Center.

Specifications

•	 Dimensions: Length, 22 feet, 2 inches; width, 15 feet, 7

	 inches; height, 11 feet, 5 inches; minimum weight, 5,265

	 pounds; maximum weight, 9,000 pounds (with water ballast

tanks full).

•	 Controls: Elevons between vertical and center fins for pitch

and roll control. Split rudder on center fin for yaw and 

speed control. All surfaces used in three-axis stabilizeraugmenter system.

•	 Power: One XLR-11 four-chamber rocket engine fueled by

ethyl alcohol and liquid oxygen, producing maximum of 

	 6,000 pounds of thrust; built by Reaction Motors Inc.

•	 Auxiliary Power: Silver zinc batteries provided electrical power for the control system, flight instruments, radios, 

cockpit heat and stability augmentation system. To assist in 

pre-landing flare, four throttleable hydrogen peroxide rockets provided up to 400 pounds of thrust.

•	 Landing Gear: Main gear was a modified T-38 system that

retracted manually and lowered by nitrogen pressure. Nose 

gear was a modified T-39 nose gear that retracted manually 

and lowered with nitrogen pressure.

•	 Pilot Ejection System: Modified F-106 system.

HL-10 is shown on Rogers Dry Lake in 1966 with its subsonic 

control surface configuration. (NASA Photo)