Three of the five heavyweights -- X-24A (L), M2-F3 (C), & HL-10 (R)
A fleet of lifting bodies flown at the NASA Dryden Flight Research Center, Edwards, California, from 1963 to l975 demonstrated the ability of pilots to maneuver and safely land a wingless vehicle designed to fly back to Earth from space and be landed like an aircraft at a pre-determined site.
These unique research vehicles, with their unconventional aerodynamic shapes, were the M2-F1, M2-F2, M2-F3, HL-10, X-24A, and the X-24B.
Aerodynamic lift -- essential to flight in the atmosphere -- was obtained from the shape of their bodies. The addition of fins and control surfaces allowed the pilots to stabilize and control the vehicles and regulate their flight paths.
All but the M2-F1 were powered by the same type of XLR-11 rocket engine used in the famed Bell X-1 -- first aircraft to fly faster than the speed of sound. The M2-F1, a lightweight prototype, was unpowered.
The information the lifting body program generated contributed to the data base that led to development of today's space shuttle program.
Background
The original 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 NASA Ames Research Center, Moffett Field, Calif.NASA had earlier been investigating the problems associated with reentry of missile nose cones. H. Julian Allen, another Ames engineer, determined that a blunt shaped nose cone was a more desirable shape to survive the aerodynamic heating associated with reentry from space. Eggers found that by slightly modifying a symmetrical nose cone shape, aerodynamic lift could be produced. This lift would enable the modified shape to fly back from space rather than plunge to earth in a ballistic trajectory.
These studies led to the design known as the M-2, a modified half-cone, rounded on the bottom and flat on top, with a blunt, rounded nose and twin tail fins.
The Pioneering M2-F1
The M2-F1 being towed by Pontiac convertible
The M2-F1
More than 400 ground tows and over 100 aircraft tow flights were carried out with the M2-F1 before it was retired and gave way to more advanced versions of lifting bodies.
A historical artifact belonging to the Smithsonian's National Air and Space Museum, the M2-F1 is located at Dryden.
The Heavyweights
The success of Dryden's M2-F1 program led to NASA's development and construction of two heavyweight lifting bodies based on studies at NASA's Ames and Langley research centers -- the M2-F2 and the HL-10, both built by the Northrop Corporation. The "M" refers to "manned" and "F" refers to "flight" version. "HL" comes from "horizontal landing" and 10 is for the tenth lifting body model to be investigated by Langley.The Air Force later became interested in lifting body research and had a third design concept built, the X-24A, built by the Martin Company. 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.
M2-F2
The M2-F2 and its F-104 chase aircraft on final approach for landing
The first flight of the M2-F2 -- which looked much like the "F1" -- was on July 12, 1966. Thompson was the pilot. By then, the same B-52 used to air launch the famed X-15 rocket research aircraft was modified to also carry the lifting bodies into the air and Thompson was dropped from the B-52's wing pylon mount at an altitude of 45,000 feet on that maiden glide flight.
The M2-F2, weighed 4,620 pounds, was 22 feet long, and had a width of about 10 feet.
On May 10, 1967, during the sixteenth glide flight leading up to powered flight, a landing accident severely damaged the vehicle and seriously injured the NASA pilot, Bruce Peterson.
M2-F3
The M2-F3 after launch from the B-52
A reaction jet control system, similar to thrusters now used on orbiting spacecraft, was also installed to obtain research data about their effectiveness for vehicle control. First flight of the M2-F3, with NASA pilot Bill Dana at the controls, was June 2, 1970. It was a glide flight to evaluate changes in the vehicle's performance due to the modifications. The modified vehicle exhibited much better lateral stability and control characteristics than before. Over the next 26 missions, the M2-F3 reached a top speed of l,064 mph (Mach 1.6). Highest altitude reached by vehicle was 7l,500 feet on Dec. 21, 1971, the date of its last flight, with NASA pilot John Manke at the controls.
The M2-F3 is now on display in the National Air and Space Museum, Washington, D. C.
HL-10
The HL-10, pilot Bill Dana, and B-52 after lakebed landing
X-24A
The X-24A on lakebed
X-24B
The X-24B on a steep approach to a lakebed landing
First to fly the X-24B was Manke, a glide flight on Aug. 1, 1973. He was also the pilot on the first powered mission Nov. 15, 1973.
Among the final flights with the X-24B were two precise landings on the main concrete runway at Edwards 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 today's space shuttle program.
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 l,l00 mph 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 approach leg, they increased their rate of descent to build up speed and used this energy to perform a "flare out" maneuver and slow their landing speed to about 200 mph -- the same basic approach pattern and landing speed of today's space shuttles.
The final powered flight with the X-24B was on Sept. 23, l975. The pilot was Bill Dana, and it was also the last rocket-powered flight flown at Dryden. It was Dana who also flew the last X-15 mission about seven years earlier.
Top speed reached with the X-24B was l,l64 mph (Mach l.76) by Love. The highest altitude reached was 74,100 feet, by Manke.
The X-24B is on public display at the Air Force Museum, Wright-Patterson AFB, Ohio.
Don Nolan
NASA Dryden Flight Research Center
Edwards, Calif. 93523
(805) 258-3447
Don_Nolan@qmgate.dfrc.nasa.gov
Modified: February 2, 1994