G l i d i n g
Is a recreational activity and competitive sport in which pilots fly un-powered aircraft known as gliders or sailplanes. Properly, the term gliding refers to descending flight of a heavier-than-air craft, whereas soaring is the correct term to use when the craft gains altitude or speed from rising air. When soaring conditions are good enough, experienced pilots can fly hundreds of kilometres before returning to their home airfields, and occasionally flights over 1,000 kilometres are made. However, if the weather deteriorates, they may need to make a forced landing, also known as “landing out”, but motorglider pilots can avoid this by starting an engine.While many glider pilots merely enjoy the sense of achievement, some competitive pilots fly in races around pre-defined courses. These competitions test the pilots’ abilities to make best use of local weather conditions as well as their flying skills. Local and national competitions are organized in many countries and there are also biennial World Gliding Championships.

Powered aircraft and winches are the two most common means of launching gliders. These and other methods (apart from self-launching motor-gliders) require assistance from other participants. Gliding clubs have thus been established to share airfields and equipment, train new pilots and maintain high safety standards.

H i s t o r y
The development of heavier-than-air flight in the half-century between Sir George Cayley’s coachman in 1853 and the Wright brothers mainly involved gliders (see aviation history). However, the sport of gliding only emerged after the First World War as a result of the Treaty of Versailles, which imposed severe restrictions on the manufacture and use of single-seat powered aircraft in Germany. Thus, in the 1920s and 1930s, while aviators and aircraft makers in the rest of the world were working to improve the performance of powered aircraft, the Germans were designing, developing and flying ever more efficient gliders and discovering ways of using the natural forces in the atmosphere to make them fly farther and faster. The active support of the government ensured a ready supply of experienced aviators ready to be trained in warplane operation when the treaty was abrogated in preparation for World War II by the Third Reich - though for most of the participants, their sport had no military overtones.

The first German gliding competition was held at the Wasserkuppe in 1920, organized by Oskar Ursinus. The best flight lasted two minutes and set a world distance record of 2 km. Within ten years, it had become an international event in which the achieved durations and distances had increased greatly. In 1931, Gunther Grönhoff flew 272 km (169 miles) from Munich to Czechoslovakia, further than had been thought possible.

In the 1930s, gliding spread to many other countries. In the 1936 Summer Olympics in Berlin gliding was a demonstration sport, and it was scheduled to be a full Olympic sport in the 1940 Games. A glider, the Olympia, was developed in Germany for the event, but World War II intervened. By 1939 the major gliding records were held by Russians, including a distance record of 748 km (465 miles).

During the war, civilian gliding in Europe was largely suspended. Although some military operations in WWII involved military gliders, they did not soar and so are unrelated to the sport of gliding. Nonetheless, several German fighter aces in the conflict, including Erich Hartmann, began their flight training in gliders.

Gliding did not return to the Olympics after the war, for two reasons: first, the shortage of gliders following the war; and second, the failure to agree on a single model of competition glider. (Some in the community feared doing so would hinder development of new designs.) The re-introduction of air sports such as gliding to the Olympics has been occasionally proposed by the world governing body, the FAI, but this has been rejected on the grounds of lack of public interest.

In many countries during the 1950s a large number of trained pilots wanted to continue flying. Many were also aeronautical engineers. They started both clubs and manufacturers, many of which still exist. This stimulated the development of both gliding and gliders; for example, the Soaring Society of America grew from 1,000 members then to its present total of 12,500. The increased numbers of pilots, greater knowledge and improving technology helped set new records, so that the pre-war altitude record was doubled by 1950, and the first 1,000-km (621 statute miles) flight was done in 1964. New materials such as glass fiber and carbon fiber, advances in wing shapes and airfoils, electronic instruments, GPS and improved weather forecasting have since allowed many pilots to make flights that were once extraordinary. Today over 500 pilots have made flights over 1,000 km.

Instead of Olympic competition there are the World Gliding Championships. The first event was held at the Wasserkuppe in 1937. Since WWII it has been held every two years. There are now six classes open to both sexes, plus three classes for women and two junior classes. Germany, the sport’s birthplace, is still a center of the gliding world: it accounts for 30% of the world’s glider pilots, and the three major glider manufacturers are still based there. However the sport has been taken up in many countries and there are now over 116,000 active glider pilots, plus an unknown number of military cadets. Each year many other people experience their first glider flight. It does not matter whether the countries are flat or mountainous, hot or temperate, because gliders can soar in most places.

S o a r i n g
Glider pilots can stay airborne for hours by flying through air that is ascending as fast or faster than the glider itself is descending, thus gaining potential energy. The most commonly used sources of rising air are

• thermals (updrafts of warm air);
• ridge lift (found where the wind blows against the face of a hill and is forced to rise); and
• wave lift (standing waves in the atmosphere, analogous to the ripples on the surface of a stream).

C r o s s - c o u n t r y
The distance that a glider can fly for each meter it descends is expressed as its lift-to-drag ratio (L/D). Depending on the class, this can be between 44:1 and 70:1 in modern designs. This performance combined with regular sources of rising air enables gliders to fly long distances at high speeds. The record speed for 1,000 km is 169.7 km/h (621 statute miles at 105 miles/h). Even in places with less favorable conditions (such as Northern Europe) most skilled pilots complete flights over 500 km (310 miles) every year.Glider pilots are required to stay within gliding range of their home airfield for their early solo flights. Cross-country flights are allowed when they have sufficient experience to find sources of lift away from their home airfield, to navigate and to land elsewhere if necessary. As the performance of gliders improved in the 1960s, the concept of flying as far away as possible became unpopular with the crews who had to retrieve the gliders. Pilots now usually plan to fly around a course (called a task) via turn-points, returning to the starting point.

In addition to just trying to fly further, glider pilots also race each other in competitions. The winner is the fastest, or, if the weather conditions are poor, the furthest round the course. Tasks of up to 1,000 km have been set and speeds of 120 km/h are not unusual.

Initially, ground observers confirmed that pilots had rounded the turn-points. Later, the glider pilots photographed these places and submitted the film for verification. Today, gliders carry secure GNSS Flight Recorders that record the position every few seconds from GPS satellites. These recording devices now provide the proof that the turn-points have been reached.

National competitions generally last one week, with international championships running over two. The winner is the pilot who has amassed the greatest number of points over all the contest days. However, these competitions have as yet failed to draw much interest outside the gliding community for several reasons. Because it would be unsafe for many gliders to cross a start line at the same time, pilots can choose their own start time. Furthermore, gliders are not visible to the spectators for long periods during each day’s contest and the scoring is complex, so gliding competitions have been difficult to televise.In an attempt to widen the sport’s appeal, a new format, the Grand Prix, has been introduced. Innovations introduced in the Grand Prix format include simultaneous starts for a small number of gliders, tasks consisting of multiple circuits, and simplified scoring. There is decentralized Internet based competition called the Online Contest where pilots upload their GPS data files and are automatically scored based on distance flown. 7,800 pilots worldwide participated in this contest in 2006.

From: http://en.wikipedia.org/wiki/Gliding