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.
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.
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)
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.
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 Gemini and the U.S. Air Force's Manned Orbiting Laboratory program.
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 in advance of anything currently in operation. Whether or not the company will succeed in building such a craft remains to be seen.
The content of this page is retrieved from http://en.wikipedia.org/wiki/Spaceplane under GFDL
