Gliders or Sailplanes are heavier-than-air aircraft primarily intended for unpowered flight. See also gliding and motor gliders for more details.

Terminology

A "glider" is an unpowered aircraft. The most common types of glider are today used for sporting purposes. The design of these types enables them to climb using rising air and then to glide for long distances before finding the next source of lift. This has created the sport of gliding, or soaring. The term "sailplane" is sometimes used for these types, implying a glider with a high soaring performance. In addition to high-performance sailplanes, the term 'glider' also encompasses hang gliders and paragliders. Like sailplanes these can use upwardly moving air to soar but differ in not having a fuselage, control surfaces or a control column. Descriptions of these variants are in separate articles and so the rest of this article is only about conventional gliders and sailplanes.

Although many gliders do not have engines, there are some that use engines occasionally (see Motor glider). The manufacturers of high-performance gliders now often list an optional engine and a retractable propeller that can be used to sustain flight if required; these are known as 'self-sustaining' gliders. Some can even launch themselves and are known as 'self-launching' gliders. There are also 'touring motor gliders', which can switch off their engines in flight though without retracting their propellers. The term "pure glider" (or equivalently, but less commonly "pure sailplane") may be used to distinguish a totally unpowered glider from a motorized glider, without implying any differential in gliding or soaring performance.

History

In China, kites rather than gliders were used for military reconnaissance. However the Extensive Records of the Taiping Era (978) suggests that a true glider was designed in the 5th century BC by Lu Ban, a contemporary of Confucius. There is also a report from the History of Northern Dynasties (659) and Zizhi Tongjian (1084) that Yuan Huangtou in Ye made a successful glide, taking off from a tower in 559.Beishi 19 and Zizhi Tongjian 167:
quote: Ye]], capital of the Northern Qi. Yuan Huangtou was the only one who survived from this flight, as he glided over the city-wall and fell at Zimo western segment of Ye safely, but he was later executed."

Abbas Ibn Firnas invented the first weight shift aircraft (hang glider) and is also claimed as the inventor of the first manned glider in 875 by fixing feathers to a wooden frame fitted to his arms or back. Written accounts at the time suggest that he made a ten minute flight. Abbas was seriously injured in the resulting crash.