Role Lifting body technology demonstrator
Manufacturer Northrop
Designer Langley Research Center
First flight 22 December 1966
Retired 17 July 1970
Status On display, NASA Armstrong Flight Research Center
Primary user NASA
Number built 1

The Northrop HL-10 was one of five US heavyweight lifting body designs flown at NASA's Flight Research Center (FRC—later Dryden Flight Research Center) in 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.[1] It was a NASA design and was built to evaluate "inverted airfoil" lifting body and delta planform. It currently is on display at the entrance to the Armstrong Flight Research Center at Edwards Air Force Base.


Northrop Corporation built the HL-10 and Northrop 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, Virginia. Main gear was a modified T-38 system retracted manually,[1] and lowered by nitrogen pressure. Nose gear was a modified T-39 unit, retracted manually and lowered with nitrogen pressure. Pilot Ejection System was a modified F-106 system. 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 lbf (1.8 kN) of thrust.

Operational history

Cockpit of the HL-10 lifting body.

After delivery to NASA in January 1966, the HL-10 made its first flight on December 22, 1966, with research pilot Bruce Peterson in the cockpit. Although the XLR-11 rocket engine (same type used in the Bell X-1) was installed, the first 11 drops from the B-52 launch aircraft were unpowered 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).[1]

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 February 18, 1970, Air Force test pilot Peter Hoag piloted the HL-10 to Mach 1.86 (1,228 mph or 1,976 km/h). Nine days later, NASA pilot William H. "Bill" Dana flew the vehicle to 90,030 feet (27,440 m), which became the highest altitude reached in the program.[1]

During a typical lifting body flight, the B-52—with the research vehicle attached to the pylon mount on the right wing between the fuselage and inboard engine pod—flew to a height of about 45,000 feet (14,000 m) and a launch speed of about 450 mph (720 km/h).[1]

Moments after being dropped, the XLR-11 was lit by the pilot. Speed and altitude increased until the engine was shut down by choice or fuel exhaustion, depending upon the individual mission profile. The lifting bodies normally carried enough fuel for about 100 seconds of powered flight and routinely reached from 50,000 to 80,000 feet (15,000 to 24,000 m) and speeds above Mach 1.[1]

Following engine shutdown, the pilot maneuvered the vehicle through a simulated return-from-space corridor into a pre-planned approach for a landing on one of the lakebed runways on Rogers Dry Lake at Edwards. A circular approach was used to lose altitude during the landing phase. On the final approach leg, the pilot increased his rate of descent to build up energy. At about 100 feet (30 m) altitude, a "flare out" maneuver dropped air speed to about 200 mph (320 km/h) for the landing.[1]

Unusual and valuable lessons were learned through the successful flight testing of the HL-10. During the early phases of the Space Shuttle development program, lifting bodies patterned on the HL-10 shape were one of three major types of proposals. These were later rejected as it proved difficult to fit cylindrical fuel tanks into the always-curving fuselage, and from then on most designs focused on more conventional delta wing craft.

Unrealized space flight

According to the book "Wingless Flight", by project engineer R. Dale Reed, the HL-10 was considered to fly into space in the early to mid-1970s. Following the cancellation of the Apollo moon project, Reed realized that there would be substantial Apollo hardware left over, including several flight-rated command service modules (CSM) and Saturn V rockets.[2]

The proposal was to add an ablative heat shield, reaction controls, and other additional subsystems needed for crewed spaceflight to the HL-10. The now space-rated vehicle would have then been launched in the space for the Lunar Module on a Saturn V launch vehicle with an Apollo CSM. Once in Earth orbit, it was planned that a robotic extraction arm would remove the HL-10 from the rocket's third stage and place it adjacent to the crewed Apollo CSM spacecraft. One of the astronauts would then spacewalk from the Apollo and board the lifting body to perform a pre-reentry check on its systems.[2]

It was planned that there would be two flights in this program. In the first, the lifting body pilot would return to the Apollo and send the HL-10 back to earth uncrewed. If this flight was successful, the second launch would be involve a piloted landing at Edwards AFB. Reportedly, Wernher von Braun was enthusiastic about the mission, offering to prepare two Saturn Vs and Apollo Command Service Modules. However, he was overridden by the Flight Research Center director, and nothing came of the proposal.[2] Launching a Saturn V to low Earth orbit with a light payload would not be an efficient use of capability, and the Apollo program was ended mainly on cost grounds.[citation needed]

HL-10 flights

Flight #
Date Pilot Mach Velocity /km/h Altitude /m Duration Comments
HL-10 #1 December 22, 1966 Peterson 0.693 735 13,716 00:03:07 First HL-10 Flight
Unpowered glide
HL-10 #2 March 15, 1968 Gentry 0.609 684 13,716 00:04:03 Unpowered glide
HL-10 #3 April 3, 1968 Gentry 0.690 732 13,716 00:04:02 Unpowered glide
HL-10 #4 April 25, 1968 Gentry 0.697 739 13,716 00:04:18 Unpowered glide
HL-10 #5 May 3, 1968 Gentry 0.688 731 13,716 00:04:05 Unpowered glide
HL-10 #6 May 16, 1968 Gentry 0.678 719 13,716 00:04:25 Unpowered glide
HL-10 #7 May 28, 1968 Manke 0.657 698 13,716 00:04:05 Unpowered glide
HL-10 #8 June 11, 1968 Manke 0.635 697 13,716 00:04:06 Unpowered glide
HL-10 #9 June 21, 1968 Gentry 0.637 700 13,716 00:04:31 Unpowered glide
HL-10 #10 September 24, 1968 Gentry 0.682 723 13,716 00:04:05 Unpowered glide
XLR-11 installed
HL-10 #11 October 3, 1968 Manke 0.714 758 13,716 00:04:03 Unpowered glide
HL-10 #12 October 23, 1968 Gentry 0.666 723 12,101 00:03:09 1st powered flight
engine malfunction
landed Rosamond
HL-10 #13 November 13, 1968 Manke 0.840 843 13,000 00:06:25 3 tries to
light engine
HL-10 #14 December 9, 1968 Gentry 0.870 872 14,454 00:06:34 -
HL-10 #15 April 17, 1969 Manke 0.994 974 16,075 00:06:40 -
HL-10 #16 April 25, 1969 Dana 0.701 744 13,716 00:04:12 Unpowered glide
HL-10 #17 May 9, 1969 Manke 1.127 1,197 16,246 00:06:50 1st lifting body
supersonic flight
HL-10 #18 May 20, 1969 Dana 0.904 959 14,966 00:06:54 -
HL-10 #19 May 28, 1969 Manke 1.236 1,312 18,959 00:06:38 -
HL-10 #20 June 6, 1969 Hoag 0.665 727 13,716 00:03:51 Unpowered glide
HL-10 #21 June 19, 1969 Manke 1.398 1,484 19,538 00:06:18 -
HL-10 #22 July 23, 1969 Dana 1.444 1,350 19,446 00:06:13 -
HL-10 #23 August 6, 1969 Manke 1.540 1,656 23,195 00:06:12 1st four-
chambered flight
HL-10 #24 September 3, 1969 Dana 1.446 1,542 23,762 00:06:54 -
HL-10 #25 September 18, 1969 Manke 1.256 1,341 24,137 00:07:06 -
HL-10 #26 September 30, 1969 Hoag 0.924 980 16,383 00:07:16 -
HL-10 #27 October 27, 1969 Dana 1.577 1,675 18,474 00:06:57 -
HL-10 #28 November 3, 1969 Hoag 1.396 1,482 19,544 00:07:19 -
HL-10 #29 November 17, 1969 Dana 1.594 1,693 19,687 00:06:48 -
HL-10 #30 November 21, 1969 Hoag 1.432 1,532 24,165 00:06:18 -
HL-10 #31 December 12, 1969 Dana 1.310 1,402 24,372 00:07:08 -
HL-10 #32 January 19, 1970 Hoag 1.310 1,399 26,414 00:06:50 -
HL-10 #33 January 26, 1970 Dana 1.351 1,444 26,726 00:06:51 -
HL-10 #34 February 18, 1970 Hoag 1.861 1,976 20,516 00:06:20 Fastest lifting
body flight
HL-10 #35 February 27, 1970 Dana 1.314 1,400 27,524 00:06:56 Highest lifting
body flight
HL-10 #36 June 11, 1970 Hoag 0.744 810 13,716 00:03:22 Lift/Drag
powered approach
HL-10 #37 July 17, 1970 Hoag 0.733 803 13,716 00:04:12 Last flight

Aircraft serial number


The HL-10 is currently on display at the entrance of Armstrong Flight Research Center at Edwards, CA.

Specifications (Northrop HL-10)

NASA HL-10 Lifting Body Diagram

General characteristics


Fictional references

In the pilot movie, and an episode of The Six Million Dollar Man series, titled "The Deadly Replay", the HL-10 serial number 804 is identified as the aircraft flown by Col. Steve Austin when he crashed, leading to his transformation into a bionic man, and the HL-10 is also featured in this episode.[3] Other episodes and Martin Caidin's original novel, Cyborg, contradict this, however, by identifying Austin's aircraft as a fictional cousin of the HL-10, the M3-F5.[4] Further confusion is added by the fact that both the HL-10 and the M2-F2 are featured in the opening credits of the television show.

See also

Aircraft of comparable role, configuration, and era

Related lists


  1. ^ a b c d e f g "HL-10 Lifting Body fact sheet". Dryden Flight Research Center. NASA. Retrieved 2010-10-04.
  2. ^ a b c Reed, R. Dale; Darlene Lister (2002). Wingless Flight: The Lifting Body Story. University Press of Kentucky. ISBN 0-8131-9026-6. also available as a PDF file.
  3. ^ The Six Million Dollar Man: "The Deadly Replay". Written by Wilton Denmark. First broadcast on Nov. 22, 1974
  4. ^ Martin Caidin, Cyborg, Arbor House, 1972, and sequel works, plus the 1987 telefilm Return of the Six Million Dollar Man and the Bionic Woman