Glider (sailplane)

A sailplane or glider is a type of glider aircraft used in the sport of gliding. Sailplanes are aerodynamically streamlined and are capable of soaring in rising air.

Sailplanes (or "sports gliders") benefit from producing the least drag for any given amount of lift, and this is best achieved with long, thin wings, a fully faired narrow cockpit and a slender fuselage. Aircraft with these features are able to climb efficiently in rising air produced by thermals or hills. Sailplanes can glide long distances at high speed with a minimum loss of height in between.

Gliders have rigid wings and either skids or undercarriage. In contrast hang gliders and paragliders use the pilot's feet for the start of the launch and for the landing. These latter types are described in separate articles, though their differences from sailplanes are covered below. Gliders are usually launched by winch or aerotow, though other methods: auto tow and bungee, are occasionally used.

All sailplanes soar, but some gliders do not soar and are simply engineless aircraft towed by another aircraft to a desired destination and then cast off for landing. Military gliders (such as those used on D-Day) are single-use only, and are abandoned after landing, having served their purpose.

Motor gliders are gliders with engines which can be used for extending a flight and even, in some cases, for take-off. Some high-performance motor gliders (known as "self-sustaining" gliders) may have an engine-driven retractable propeller which can be used to sustain flight. Other motor gliders have enough thrust to launch themselves before the engine is retracted and are known as "self-launching" gliders. Another type is the self-launching "touring motor glider", where the pilot can switch the engine on and off in flight without retracting their propellers.

Sir George Cayley's gliders achieved brief wing-borne hops from around 1849. In the 1890s Otto Lilienthal built gliders using weight shift for control. In the early 1900s the Wright Brothers built gliders using movable surfaces for control. In 1903 they successfully added an engine.

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