Gliding

A recreational activity and competitive sport where individuals fly unpowered aeroplanes? usually called gliders? or sailplanes?. Gliders are initially launched into the air either by being towed behind a powered aircraft or a ground based winch. Once airborne flight is sustained either, most commonly, by thermals?, localised updrafts of rising air which pilots learn to spot from cloud formations, ridge lift generated by air forced to rise over ground features, or, in the case of high altitude gliding, wave. Wave lift, setup by standing waves in air masses, has allowed gliders to achieve altitudes in excess of 30,000feet/10 000m.

Glider aircraft are designed to have very high lift-to-drag ratios, approaching 60:1 in the case of modern competition gliders, and to retain this efficiency over the widest possible speed envelope. With this in mind, they have very narrow bodies and very long, narrow wings. Some gliders are actually equipped with motors, usually retractable into the fuselage, some with minimal power, just enough to allow the glider to slowly climb without thermal assistance if necessary to reach a landing area safely. Others are equipped with motors powerful enough to allow the glider to launch itself.

While recreational glider enthusiasts enjoy the freedom, scenic views, and sheer enjoyment of controlling the planes, others concentrate on building their own craft, while still others compete in competitive events where the goal is to fly a circuit around certain geographical points, or areas, as quickly as possible. These competitions test the pilot's (and the copilot, in two-seater gliders) ability to recognise and make use of local weather conditions as well as their navigational abilities.

The sport is enjoyed in many countries, not only those offering large areas of relatively flat, unpopulated land but also those where the terrain provides more challenging flying.

A more minimalistic variation of the sport is hang gliding, where instead of a fully-fledged plane with full control surfaces and an enclosed cockpit the craft used is basically a fabric flying wing.