Aircraft configuration in which the fuselage produces significant lift
US X-24A, M2-F3 and HL-10 lifting bodies
A lifting body is a fixed-wing aircraft or spacecraft configuration in which the body itself produces lift. In contrast to a flying wing, which is a wing with minimal or no conventional fuselage, a lifting body can be thought of as a fuselage with little or no conventional wing. Whereas a flying wing seeks to maximize cruise efficiency at subsonic speeds by eliminating non-lifting surfaces, lifting bodies generally minimize the drag and structure of a wing for subsonic, supersonic and hypersonic flight, or spacecraftre-entry. All of these flight regimes pose challenges for proper flight safety.
Lifting bodies were a major area of research in the 1960s and 70s as a means to build a small and lightweight crewed spacecraft. The US built a number of lifting body rocket planes to test the concept, as well as several rocket-launched re-entry vehicles that were tested over the Pacific. Interest waned as the US Air Force lost interest in the crewed mission, and major development ended during the Space Shuttle design process when it became clear that the highly shaped fuselages made it difficult to fit fuel tankage.
The lifting body had been imagined by 1917, in which year an aircraft with something like a delta wing plan form with a thick included fuselage was described in a patent by Roy Scroggs.[2] However at low airspeeds the lifting body is inefficient and did not enter mainstream airplane design.[citation needed]
Aerospace-related lifting body research arose from the idea of spacecraftre-entering the Earth's atmosphere and landing much like a regular airplane. Following atmospheric re-entry, the capsule spacecraft from the Mercury, Gemini, and Apollo series had very little control over where they landed. A steerable spacecraft with wings could significantly extend its landing envelope. However, the vehicle's wings would have to be designed to withstand the dynamic and thermal stresses of both re-entry and hypersonic flight. One proposal eliminated wings altogether: design the fuselage body to produce lift by itself.
The Martin Aircraft Company X-24 built as part of a 1963 to 1975 experimental US military program
NASA's refinements of the lifting body concept began in 1962 with R. Dale Reed of NASA's Armstrong Flight Research Center.[3] The first full-size model to come out of Reed's program was the NASA M2-F1, an unpowered craft made of wood. Initial tests were performed by towing the M2-F1 along a dry lakebed at Edwards Air Force Base California, behind a modifiedPontiac Catalina.[4] Later the craft was towed behind a C-47 and released. Since the M2-F1 was a glider, a small rocket motor was added in order to extend the landing envelope. The M2-F1 was soon nicknamed the "Flying Bathtub".
In 1963, NASA began programs with heavier rocket-powered lifting-body vehicles to be air launched from under the starboard wing of a NB-52B, a derivative of the B-52 jet bomber. The first flights started in 1966. Of the Dryden lifting bodies, all but the unpowered NASA M2-F1 used an XLR11 rocket engine as was used on the Bell X-1.[5] A follow-on design designated the Northrop HL-10 was developed at NASA Langley Research Center. Air flow separation caused the crash of the Northrop M2-F2 lifting body.[citation needed] The HL-10 attempted to solve part of this problem by angling the port and starboardvertical stabilizers outward and enlarging the center one.[citation needed]
Starting 1965 the Russian lifting-body Mikoyan-Gurevich MiG-105 or EPOS (Russian acronym for Experimental Passenger Orbital Aircraft) was developed and several test flights made. Work ended in 1978 when the efforts shifted to the Buran program, while work on another small-scale spacecraft partly continued in the Bor program.
The IXV is a European Space Agency lifting body experimental re-entry vehicle intended to validate European reusable launchers which could be evaluated in the frame of the FLPP program. The IXV made its first flight in February 2015, launched by a Vega rocket.[6]
Orbital Sciences proposed a commercial lifting-body spaceplane in 2010.[7] The Prometheus is more fully described below.
Aerospace applications
Lifting bodies pose complex control, structural, and internal configuration issues. Lifting bodies were eventually rejected in favor of a delta wing design for the Space Shuttle. Data acquired in flight test using high-speed landing approaches at very steep descent angles and high sink rates was used for modeling Shuttle flight and landing profiles.
In planning for atmospheric re-entry, the landing site is selected in advance. For reusable reentry vehicles, typically a primary site is preferred that is closest to the launch site in order to reduce costs and improve launch turnaround time. However, weather near the landing site is a major factor in flight safety. In some seasons, weather at landing sites can change quickly relative to the time necessary to initiate and execute re-entry and safe landing. Due to weather, it is possible the vehicle may have to execute a landing at an alternate site. Furthermore, most airports do not have runways of sufficient length to support the approach landing speed and roll distance required by spacecraft. Few airports exist in the world that can support or be modified to support this type of requirement. Therefore, alternate landing sites are very widely spaced across the U.S. and around the world. The Shuttle's delta wing design was driven by these issues. These requirements were further exacerbated by requirements that extended the Shuttle's flight landing envelope.
Nonetheless, the lifting body concept has been implemented in a number of other aerospace programs, the previously mentioned NASA X-38, Lockheed Martin X-33, BAC's Multi Unit Space Transport And Recovery Device, Europe's EADS Phoenix, and the joint Russian-European Kliper spacecraft. Of the three basic design shapes usually analyzed for such programs (capsule, lifting body, aircraft) the lifting body may offer the best trade-off in terms of maneuverability and thermodynamics while meeting its customers' mission requirements.
Burnelli General Airborne Transport XCG-16, a lifting body aircraft (1944)
Some aircraft with wings also employ bodies that generate lift. Some of the early 1930s high-wing monoplane designs of the Bellanca Aircraft Company, such as the Bellanca Aircruiser, had vaguely airfoil-shaped fuselages capable of generating some lift, with even the wing struts on some versions given widened fairings to give them some lift-generating capability. The Gee Bee R-1 Super Sportster racing plane of the 1930s, likewise, from more modern aerodynamic studies, has been shown to have had considerable ability to generate lift with its fuselage design, important for the R-1's intended racing role, while in highly banked pylon turns while racing.[10]Vincent Burnelli developed several aircraft between the 1920s and 1950 that used fuselage lift. Like the earlier Bellanca monoplanes, the Short SC.7 Skyvan produces a substantial amount of lift from its fuselage shape, almost as much as the 35% each of the wings produces.
Fighters like the F-15 Eagle also produce substantial lift from the wide fuselage between the wings. Because the F-15 Eagle's wide fuselage is so efficient at lift, an F-15 is able to land successfully with only one wing, albeit under nearly full power, with thrust contributing significantly to lift. In the summer of 1983, an Israeli F-15 staged a mock dogfight with Skyhawks for training purposes, near Nahal Tzin in the Negev desert. During the exercise, one of the Skyhawks miscalculated and collided forcefully with the F-15's wing root. The F-15's pilot was aware that the wing had been seriously damaged, but decided to try and land in a nearby airbase, not knowing the extent of his wing damage. It was only after he had landed, when he climbed out of the cockpit and looked backward, that the pilot realized what had happened: the wing had been completely torn off the plane, and he had landed the plane with only one wing attached. A few months later, the damaged F-15 had been given a new wing, and returned to operational duty in the squadron. The engineers at McDonnell Douglas had a hard time believing the story of the one-winged landing: as far as their planning models were concerned, this was an impossibility.[11]
In 2010, Orbital Sciences proposed the Prometheus "blended lifting-body" spaceplane vehicle, about one-quarter the size of the Space Shuttle, as a commercial option for carrying astronauts to low Earth orbit under the commercial crew program.[7] The Vertical Takeoff, Horizontal Landing (VTHL) vehicle was to have been launched on a human-rated Atlas V rocket but would land on a runway.[12] The initial design was to have carried a crew of 4, but it could carry up to 6, or a combination of crew and cargo. In addition to Orbital Sciences, the consortium behind the proposal included Northrop Grumman, which would have built the spaceplane, and the United Launch Alliance, which would have provided the launch vehicle.[13] Failing to be selected for a CCDev phase 2 award by NASA, Orbital announced in April 2011 that they would likely wind down their efforts to develop a commercial crew vehicle.[14]
Design principles of lifting bodies are used also in the construction of hybrid airships.
Lifting bodies have appeared in some science fiction works, including the movie Marooned, and as John Crichton's spacecraft Farscape-1 in the TV series Farscape. The Discovery Channel TV series conjectured using lifting bodies to deliver a probe to a distant earth-like planet in the animated Alien Planet.Gerry Anderson's 1969 Doppelgänger used a VTOL lifting body lander / ascender to visit an Earth-like planet, only to crash in both attempts. His series UFO featured a lifting body craft visually similar to the M2-F2 for orbital operations ("The Man Who Came Back"). In the Buzz Aldrin's Race Into Space computer game, a modified X-24A becomes an alternative lunar capable spacecraft that the player can choose over the Gemini or Apollo capsule.
The 1970s television programThe Six Million Dollar Man used footage of a lifting body aircraft, culled from actual NASA exercises, in the show's title sequence. The scenes included an HL-10's separation from its carrier plane—a modified B-52—and an M2-F2 piloted by Bruce Peterson, crashing and tumbling violently along the Edwards dry lakebed runway. The cause of the crash was attributed to the onset of Dutch roll stemming from control instability as induced by flow separation.[citation needed]
The episode "The Deadly Replay" (season 2 episode 8 aired 9/22/1974) features the HL-10 as a prop of the story.[16]
The Martin Marietta X-24 is an American experimental aircraft developed from a joint United States Air Force-NASA program named PILOT (1963–1975). It was designed and built to test lifting body concepts, experimenting with the concept of unpowered reentry and landing, later used by the Space Shuttle. Originally built as the X-24A, the aircraft was later rebuilt as the X-24B.
A reusable launch vehicle has parts that can be recovered and reflown, while carrying payloads from the surface to outer space. Rocket stages are the most common launch vehicle parts aimed for reuse. Smaller parts such as rocket engines and boosters can also be reused, though reusable spacecraft may be launched on top of an expendable launch vehicle. Reusable launch vehicles do not need to make these parts for each launch, therefore reducing its launch cost significantly. However, these benefits are diminished by the cost of recovery and refurbishment.
A spaceplane is a vehicle that can fly and glide like an aircraft in Earth's atmosphere and maneuver like a spacecraft in outer space. To do so, spaceplanes must incorporate features of both aircraft and spacecraft. Orbital spaceplanes tend to be more similar to conventional spacecraft, while sub-orbital spaceplanes tend to be more similar to fixed-wing aircraft. All spaceplanes to date have been rocket-powered for takeoff and climb, but have then landed as unpowered gliders.
The Boeing X-20 Dyna-Soar was a United States Air Force (USAF) program to develop a spaceplane that could be used for a variety of military missions, including aerial reconnaissance, bombing, space rescue, satellite maintenance, and as a space interceptor to sabotage enemy satellites. The program ran from October 24, 1957, to December 10, 1963, cost US$660 million, and was cancelled just after spacecraft construction had begun.
The Mikoyan-Gurevich MiG-105, part of the Spiral program, was a crewed test vehicle to explore low-speed handling and landing. It was a visible result of a Soviet project to create an orbital spaceplane. The MiG 105 was nicknamed "Lapot", for the shape of its nose.
Milton Orville Thompson, , better known as Milt Thompson, was an American naval officer, aviator, engineer, and NASA research pilot. He was one of twelve pilots who flew the North American X-15, an experimental spaceplane jointly operated by the United States Air Force and NASA.
The Boeing X-37, also known as the Orbital Test Vehicle (OTV), is a reusable robotic spacecraft. It is boosted into space by a launch vehicle, then re-enters Earth's atmosphere and lands as a spaceplane. The X-37 is operated by the Department of the Air Force Rapid Capabilities Office, in collaboration with United States Space Force, for orbital spaceflight missions intended to demonstrate reusable space technologies. It is a 120-percent-scaled derivative of the earlier Boeing X-40. The X-37 began as a NASA project in 1999, before being transferred to the United States Department of Defense in 2004. Until 2019, the program was managed by Air Force Space Command.
Dream Chaser is an American reusable lifting-body spaceplane developed by Sierra Space. Originally intended as a crewed vehicle, the Dream Chaser Space System is set to be produced after the Dream Chaser Cargo System cargo variant is operational. The crewed variant is planned to carry up to seven people and cargo to and from low Earth orbit. Sierra plans to manufacture a fleet of the spaceplane.
The Northrop HL-10 is one of five US heavyweight lifting body designs flown at NASA's 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. 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.
The NASA M2-F1 is a lightweight, unpowered prototype aircraft, developed to flight-test the wingless lifting body concept. Its unusual appearance earned it the nickname "flying bathtub" and was designated the M2-F1, the M referring to "manned", and F referring to "flight" version. In 1962, NASA Dryden management approved a program to build a lightweight, unpowered lifting-body prototype. It featured a plywood shell placed over a tubular steel frame crafted at Dryden. Construction was completed in 1963.
The Northrop M2-F2 was a heavyweight lifting body based on studies at NASA's Ames and Langley research centers and built by the Northrop Corporation in 1966.
The Orbital Space Plane (OSP) program was a NASA spaceplane concept in the early 2000s designed to support the International Space Station requirements for crew rescue, crew transport and contingency cargo transport. It was part of the Space Launch Initiative.
The HL-20 Personnel Launch System was a NASA spaceplane concept for crewed orbital missions studied by NASA's Langley Research Center around 1990. It was envisaged as a lifting body re-entry vehicle similar to the Soviet BOR-4 spaceplane design. Its stated goals were to achieve low operational costs, improved flight safety, and a possibility of landing on conventional runways. No flight hardware was built.
Not to be confused with the successful civilian airliner, the Douglas DC-3
The Lockheed Star Clipper was a proposed Earth-to-orbit spaceplane based on a large lifting body spacecraft and a wrap-around drop tank. Originally proposed during a United States Air Force program in 1966, the basic Star Clipper concept lived on during the early years of the NASA Space Shuttle program, and as that project evolved, in a variety of new versions like the LS-200.
Prometheus was a proposed crewed vertical-takeoff, horizontal-landing (VTHL) lifting body spaceplane concept put forward by Orbital Sciences Corporation in late 2010 as part of the second phase of NASA's Commercial Crew Development (CCDev) program.
Aircraft have different ways to take off and land. Conventional airplanes accelerate along the ground until reaching a speed that is sufficient for the airplane to takeoff and climb at a safe speed. Some airplanes can take off at low speed, this being a short takeoff. Some aircraft such as helicopters and Harrier jump jets can take off and land vertically. Rockets also usually take off vertically, but some designs can land horizontally.
A drop test is a method of testing the in-flight characteristics of prototype or experimental aircraft and spacecraft by raising the test vehicle to a specific altitude and then releasing it. Test flights involving powered aircraft, particularly rocket-powered aircraft, may be referred to as drop launches due to the launch of the aircraft's rockets after release from its carrier aircraft.
The HL-42 was a proposed scaled-up version of the HL-20 re-usable crewed spaceplane design, which had been developed from 1983 to 1991 at NASA's Langley Research Center but never flown. Like the HL-20, the HL-42 would have been launched into low Earth orbit mounted on top of a two-stage expendable rocket. At the end of the mission, it would have re-entered and glided to a runway landing.
SSC Demo-1, also known as Dream Chaser Demo-1, is the planned first flight of the Sierra Space robotic resupply spacecraft Dream Chaser to the International Space Station (ISS) under the CRS-2 contract with NASA. The demonstration mission is planned for launch no earlier than March 2025.
↑ "Orbital may wind down its commercial crew effort". NewSpace Journal. 2011-04-22. Retrieved 2011-04-25. CEO Dave Thompson said ... "I don't, at this time, anticipate that we'll continue to pursue our own project in that race. We'll watch it and if an opportunity develops we may reconsider. But at this point, I would not anticipate a lot of activity on our part in the commercial crew market."
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