Going back to the first experiments, man has tried to fly by copying the wings of birds, bats, and to a lesser extent, insects. In 1917 however, a patent was filed by Roy Scroggs for an aircraft without wings at all. Instead of a flying wing, where the body is entirely wing, Scroggs proposed a fuselage shape where the fuselage would act as a low-aspect ratio delta wing. Flight testing allegedly took place in 1930, but the aircraft did not perform well, and it was damaged in an accident.
Interest in the idea, now called a “lifting body”, was reignited in the 1960s as the Space Race heated up, and NACA/NASA and the USAF began to look into building aircraft that could go into space and back and be maneuverable for the entire flight, as opposed to capsules like those used for Mercury and Gemini, which were launched on converted ICBMs and returned to Earth ballistically, with little to no control. While the X-15 proved the idea of a ‘space plane’ could work, but the plane faced incredible heat and drag, and a simpler design was desired.
In 1962 NASA began work at the Dryden Flight Research Center, with the M2-F1 (The “M” was NASA’s designation for ‘manned’ aircraft, the “F” for ‘flight version’) taking flight in 1963.
A joint effort by Dryden and local glider manufacturer Briegleb Glider Company, the M2-F1 was hand built from mahogany, was built for a budget of $30,000 ($254,000 today), and had the landing gear from a Cessna 150 (later traded for gear from a Cessna 180). As the M2 had no engine, a tow car was suggested, with a 421 Catalina Convertible being the ‘logical’ choice. Couched as the power-plant for a research vehicle, Congress signed off on the plan and a brand new Catalina, white, with a four-speed but no hubcaps or mufflers, was delivered fresh from Pontiac. The first test was not entirely successful, with the car not powerful enough to drag the M2-F1 aloft, and the vehicle more bounced from wheel to wheel than flew. The former issue was solved by taking the car to hotrodder Bill Straub to make improvements. A new transmission was fitted, as well as a roll bar and drag slicks. NASA also made modifications to the car, with radios and scientific instruments added, as well as painting the hood and trunk lid yellow, and adding NASA markings. Eventually, four hundred test flights of the M2 were completed, with the car maintaining 100mph for 30 seconds at a time, at 4mpg.
The 421 was eventually replaced by an ex-Navy R4D, allowing flights higher than 20 feet, and a small rocket motor was eventually added to boost the -F1 for longer flights. The craft survived its test program, and is now on display at the AFFTM at Edwards AFB.
The follow-on to the M2-F1, the M2-F2, was built by Northrop, and flew for the first time on 12 July 1966.
A “heavyweight” derivation of the previous design, the -F2 was powered by an XLR-11 rocket motor, and was carried aloft and dropped from NASA’s B-52 mother ships. The M2-F2 had a short career, with only 15 successful glide tests completed before the 10 May 1967 flight, which ended in a crash so spectacular that it was featured in the opening credits for “The Six Million Dollar Man”.
Pilot Bruce Peterson survived the accident (No estimate on how much his hospital stay cost...), though he lost his right eye due to a staph infection. Peterson continued flying for NASA and the USMC Reserves, and stayed on with Dryden until 1981, after which he was hired on with Northrop to work on the B-2 Spirit bomber program.
The M2-F2 was rebuilt (which had to have cost significantly more than six million dollars...) with changes informed by what data the -F2 had compiled. The renamed M2-F3 featured a third tail fin, which provided greater stability and reduced pilot-induced oscillation, a state which contributed to the crash of the -F2.
The M2-F3 completed 27 flights, eventually reaching speeds of Mach 1.6 and altitudes of 71,500 feet. The -F3 was fitted with an RCS system, similar to a space capsule, and provided a great deal of data about spaceflight. The M2-F3 was retired in 1973, and was donated to the Smithsonian, which placed it on display at the National Air & Space Museum.
Flying concurrently with the M2-F2/-F3, the HL-10 (Horizontal Landing, model 10), also built by Northrop, first flew on 22 December 1966. In comparison to the M2-F3, the HL-10 featured an inverted airfoil design on a delta planform. Costs were kept down by reusing some components; the main landing gear was from a T-38, the nose gear from a T-39, and an F-106's ejection seat. Thrust was provided by the same XLR-11 engine as the M2-F2/-F3, and four additional H2O2 rockets were used to pitch the nose up for the pre-landing flare. The HL-10 was judged to be the best flying Lifting Body by her pilots, and through 37 flights the craft achieved Mach 1.83 and a maximum altitude of more than 90,000 feet. After the end of the Apollo program, a proposal was circulated to launch the HL-10 (modified with a heat shield, RCS and life-support) along with a spare CSM into space on a Saturn V. Once in orbit, a robotic arm attached to the Command module would pull the HL-10 from the Saturn’s third stage, at which point one of the astronauts would space walk to the craft and run systems checks. At this point the crew would leave the HL-10 in orbit and return to Earth, then afterwards a second mission would be launched and again a pilot would spacewalk over, but this time the HL-10 would be deorberated and land back at Edwards. Wernher von Brown was highly enthusiastic about the idea, but NASA was unconvinced about the potential gains to be had versus wasting two Saturn Vs and two Apollo CSMs, so the idea was dropped. The HL-10 is now on display at the Armstrong FRC at Edwards AFB.
An outgrowth of the X-23 PRIME (Precision Reentry Including Maneuvering reEntry) research drone, the X-24 was operated under the joint NASA/USAF PILOT program. Like the other heavyweight lifting bodies, the X-24 was carried aloft by a B-52 and dropped, after which its XLR-11 rocket motor would fire, propelling the craft to speeds as high as Mach 1.52 and heights exceeding 70,000 feet. The X-24A proved to be somewhat unstable in flight, and was rebuilt into the X-24B.
The X-24B, nicknamed the “Flying Flatiron”, first flew in 1973 and provided data for NASA’s forthcoming STS program. After 36 flights, the X-24B was retired to the USAF Museum.
A minor footnote in the lifting body story, the SV-5J was a proposed jet-powered trainer for the X-24A, suggested by Chuck Yeager and built by Martin Marietta. One mockup and two flyable examples were built, but NASA and the USAF were uninterested, and test pilot Milt Thompson refused to fly one, even with the promise of a $20,000 bonus. One of the SV-5Js were modified to look like the X-24A, and is on display at the USAF Museum. The other is on display at the USAF Academy in Colorado Springs. The SV-5J mockup was supposedly used as a prop in several movies before being lost.
Sometimes described as a lifting body, the X-20 Dyna-Soar (“Dynamic Soarer”) was actually a delta-winged space-plane which used the lift generated by its wings to maintain a suborbital but exoatmospheric flight (hence “dynamic soarer”) in a maneuver called “skip-gliding”. Three X-20s were planned: Dyna-Soar I would be a purely research vehicle, while Brass-Bell (later Dyna-Soar II) would be a reconnaissance platform, and RoBo (later Dyna-Soar III) would be a strategic bomber.
Lack of funding, uncertainty over the launch vehicle(s), and competition from the Gemini-B/MOL program doomed the project though, and only a single mockup was constructed.
NASA would revisit the concept in 1995 with the X-38, a technology demonstrator for the Crew Return Vehicle program, which was looking to develop a “lifeboat” for the ISS. The CRV would have been transported to the station in a Shuttle’s cargo bay, then docked, ready to evacuate either an injured/sick crew member, or the entire compliment in case of disaster. A second crew launch/exploration version was also investigated that could be launched on an Ariane 5 lifter.
Two prototypes were built, V-131 and V-132, and were modified versions of the X-24A’s design. After several drops to validate the autonomous guidance system and the parafoil wing (the largest ever flown), V-131 was returned to Scaled Composites and a new aeroshell, an 80% version of the final shape, was added.
Drop tests with V-131-R and V-132 continued until 2001, and the V-201 orbital prototype was 90% complete when the program was canceled in 2002 due to spiraling costs with the ISS and CRV programs. V-131-R is on loan from NASA at the Evergreen Aviation Museum in Oregon, while V-132 is on loan to the Strategic Air Command & Aerospace Museum near Ashland, NE. The incomplete V-201 was left wrapped in netting on a modified boom-lift outside building B49 at the Johnson Space center.
Originally planed to launch crew to the ISS under NASA’s Commercial Crew Development program, the Dream Chaser is now being developed into a cargo carrier under the CRS-2 program, which has also contracted flights with Orbital ATK (now part of Northrop Grumman), Cygnus, and SpaceX. Cargo Chaser is modified with folding wings to fit within the 5m payload fairing on a ULA Vulcan lifter, and will also feature “Shooting Star” an expendable module that increases total cargo space, and can be filled with garbage from the station and jettisoned prior to reentry.
SNC is also continuing to work on a crewed version of the Chaser, partnering with the EU and UN for possible flights within 5 years.