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Spaceplane
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A spaceplane is a rocket plane designed to pass the edge of space. It combines some of the features of an aircraft and some of a spacecraft. Typically, it takes the form of a spacecraft equipped with wings.
Orbital spaceplanes The orbital spaceplanes successfully flown to date, the United States Space Shuttle and the Soviet Buran, have used their wings to provide aerobraking to return from orbit and to provide lift to allow them to land on a runway like conventional aircraft. Both these vehicles are still designed to ascend to orbit vertically under rocket power like conventional expendable launch vehicles. Each of these vehicles has a much smaller payload fraction than a ballistic design with the same takeoff weight. This is primarily due to the weight of the wings - around 9-12% of the weight of the atmospheric flight weight of the vehicle.
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A spaceplane is a rocket plane designed to pass the edge of space. It combines some of the features of an aircraft and some of a spacecraft. Typically, it takes the form of a spacecraft equipped with wings.
Orbital spaceplanes The orbital spaceplanes successfully flown to date, the United States Space Shuttle and the Soviet Buran, have used their wings to provide aerobraking to return from orbit and to provide lift to allow them to land on a runway like conventional aircraft. Both these vehicles are still designed to ascend to orbit vertically under rocket power like conventional expendable launch vehicles. Each of these vehicles has a much smaller payload fraction than a ballistic design with the same takeoff weight. This is primarily due to the weight of the wings - around 9-12% of the weight of the atmospheric flight weight of the vehicle. This significantly reduces the payload size, but the reusability is intended to offset this disadvantage.
Suborbital spaceplanes Other (suborbital) spaceplane designs use the vehicle's wings to provide lift for the ascent to space as well, in addition to the rocket. As of June 21, 2004, the only such craft to reach space have been the X-15 and SpaceShipOne. Neither of these craft were capable of entering orbit, and both began independent flight only after being lifted to high altitude by a carrier aircraft. NASA and Boeing are currently developing unmanned orbital spaceplane technologies as a low-cost alternative to expendable launch vehicles for satellite launches (see X-34, X-37, X-40A)
Atmospheric reentry Because spaceplanes designed for sub-orbital trajectories will not need to reach orbital speed, they will not need the kinds of thermal protection orbital spacecraft require during the hypersonic phase of atmospheric reentry. The Space Shuttle thermal protection system, for example, protects the orbiter from surface temperatures that could otherwise reach as high as -- well above the melting point of steel.
Single stage to orbit Future orbital spaceplanes may take off, ascend, descend, and land like conventional aircraft, providing true single stage to orbit capability.
Proponents of scramjet technology often cite such a vehicle as being a possible application of that type of engine, however pure rocket and turbojet designs have also been proposed and may be easier to design and build.
Other designs Various types of spaceplanes have been suggested since the early twentieth century. Notable early designs include Friedrich Zander's spaceplane equipped with wings made of combustible alloys that it would burn during its ascent, and Eugen Sänger's Silbervogel bomber design. Winged versions of the V2 rocket were considered during and after World War II, and when public interest in space exploration was high in the 1950s and 60s, winged rocket designs by Wernher von Braun and Willy Ley served to inspire science fiction artists and filmmakers.
The USAF invested some effort in a paper study of a variety of spaceplane projects under their aerospaceplane efforts of the late 1950s, but later ended these when they decided to use a modified version of Sänger's design. The result, X-20 Dyna-Soar, was to have been the first orbital spaceplane, but was cancelled in the early 1960s in lieu of NASA's Project Gemini and the U.S. Air Force's Manned Orbiting Laboratory program.
The Rockwell X-30 National Aero-Space Plane (NASP) was an attempt to build a scramjet vehicle, which failed due to technical issues.
The Multi-Unit Space Transport And Recovery Device (MUSTARD) was a concept explored by the British Aircraft Corporation (BAC) around 1964-1965 for launching payloads weighing as much as 5,000 lb. into orbit. It was never constructed.
The British Government began a project known as HOTOL whose ultimate goal would have been a spaceplane, but the project was cancelled due to technical and financial issues. The lead engineer from the HOTOL project has since set up a private company dedicated to creating a similar plane with a different engine, called Skylon. This vehicle would be capable of a single stage to orbit launch and would be far in advance of anything currently in operation. Whether or not the company will succeed in building such a craft remains to be seen.
In 1994 a design for a single stage to orbit peroxide/kerosene spaceplane called "Black Horse". This was notable in that it took off almost empty and underwent mid-air refuelling before burning for orbit.
The X-33 was a prototype made as part of an attempt by NASA to build a SSTO hydrogen fuelled space plane that failed when the hydrogen tank design proved to be unconstructable in the planned way.
The Roton was an unusual attempt to build a space plane. Several configurations were evaluated ranging from a helicopter ascent to a pure rocket ascent; all landings were to use a helicopter landing system. It failed due to funding issues.
Unconfirmed reportsThe March 5, 2006 edition of Aviation Week & Space Technology published a story purporting to be "outing" a highly classified US military two-stage-to-orbit spaceplane system with the code name Blackstar, SR-3/XOV among other nicknames. The alleged system, using an XB-70-like first-stage mothership, capable of mach 3, is said to launch an upper-stage wave-rider spaceplane capable of carrying small payloads and crews near to or into orbit or on skip-diving flights, ostensibly for reconnaissance and other missions, achieving surprise that cannot be attained by satellite. There has been considerable controversy over this story and its claims.
The Soviet Union supposedly developed the spaceplane Uragan in the 1980s. Intended as a follow-on to Spiral and a smaller sibling to Buran, the project was cancelled in 1987, a year before the first Buran flight. The project has never been confirmed by Soviet or Russian authorities, however.
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