Gliding competitions

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Duo Discuses en masse waiting for the start of a glider competition at Vaumeilh airfield near Sisteron.

Some of the pilots in the sport of gliding take part in gliding competitions. These are usually racing competitions, but there are also aerobatic contests and cross-country distance competitions. Many other pilots enjoy flying cross-country just for its own sake without racing.

1 History of competitions
2 Present day
3 Levels of competition
4 A competition day
5 Tactics
6 Water ballast
7 Scoring
8 Grand Prix
9 Online Contest
10 Aerobatics
11 See also
12 References

[edit] History of competitions

In the early days, the main goal was to stay airborne for as long as possible. However flights lasted for days and pilots killed themselves by falling asleep. This type of contest was then abandoned.

From the earliest days of gliding there was also 'free distance' flying. Pilots launched themselves from a hill top, attempting to glide as far as possible. Once pilots learned to exploit ridge lift and thermals, flights could be extended further. Eventually they mastered flying from thermal to thermal, resulting in ever longer retrieves. As the pilots and gliders became better, the winner of a competition day might fly so far that he could not get back to the competition site for the next day. Turn-points were therefore used. Those pilots who managed to fly all the way to the turnpoint and back would score the same distance as for free distance flights. When pilots and gliders became even better, most of the pilots would complete the task. Points were then awarded for speed.

Initially observers would be stationed at the turn-points to verify that the pilots rounded the them. Later on, pilots used cameras to photograph to prove they have rounded each turn-point. Today, pilots use GPS flight recorders to log their positions to prove that the task was correctly completed.

[edit] Present day

Modern gliding competitions now comprise closed tasks where everyone races on an aerial route around specified turn-points, plus start and finish points, that brings everybody back to base. The weather forecast and the performance of the gliders, as well as the experience level of the pilots, dictate the length of the task. Today, most of the points are speed points. Nowadays, the rule is to set the task so that all pilots have a fair chance of completing it.

With the advent of GPS, also new types of task were introduced such as speed or distance tasks within assigned areas, and speed or distance tasks with pilot-selected turnpoints. However tasks over a fixed course are still often used. In the European Gliding Championships in 2005, a task of 1,011 km was set in the open class; the longest task in an international competition.

[edit] Levels of competition

Regional contests are usually the first contests that a pilot enters. These are usually handicapped, this means that allowances are made if the pilot's glider does not have the performance of the latest models. Having succeeded in one or more of these competitions, pilots can gain a high enough ranking to enter national championships. Most of these are not handicapped. (See Glider Competition Classes.) Thereafter international competitions are available for the most ambitious pilots: the European Gliding Championships, and the World Gliding Championships. There are now six classes open to both sexes, plus three classes for women and two junior classes. There is also the prestigious Barron Hilton Cup, which is an invitation event for the top pilots.

[edit] A competition day

Regional gliding contests generally last about a week, while international contests last two. Early in the day a weather forecaster will discuss the conditions with the 'task-setter'. Once the task has been decided, a briefing is held to describe the task, the forecast weather and any airspace restrictions. Before this, the pilots will have prepared their gliders and moved them onto the grid ready for launching. Launching takes places when the director believes that the gliders can easily stay airborne. Launching all the gliders usually takes less than an hour.

[edit] Tactics

No-one can start until twenty minutes after the last competitor has launched. After that each pilot can decide when to start. A maximum height is defined below which a valid crossing of the start line must be made, and so most pilots aim to climb higher and then fly through the start line at the maximum specified height at the maximum speed that their gliders can withstand. However the pilot's first decision is deciding when to start. By starting just after rivals, a pilot will be able to keep in them in sight. By following them a skilled pilot should be able to catch up because it will not be necessary to stop at the places where earlier starters have failed to find lift. Thereafter the later starter should be able to keep them in sight and cross the finish line at about the same time, thus completing the course faster. However various tactics are used to shake off pursuers, such as doubling back after a start and starting again. Only the last start counts. However sometimes when the weather is deteriorating, there is no advantage in waiting too long before starting. The best pilots are therefore also good weather forecasters.

The biggest single deciding factor on how fast a glider can fly around a given task is the strength of the lift. The best pilots will reject weaker lift and press on to the next source of lift to maximise their chances of finding stronger lift. However this runs the risk of getting too low and not finding any lift at all. The ability to identify the strongest lift by looking at the weather conditions and the terrain is one of the main factors that determines the winners. Having found lift, the best pilots quickly find the center where the rate of climb is strongest.

It is often possible to fly efficiently by not stopping in the areas of rising air but merely slowing down. As the glider leaves the lift the pilot speeds up. This technique is known as 'dolphining'. If the conditions are right, the glider can gain enough energy from each source of lift and maintain its overall height for long distances without circling. Windy days are good for this, as the thermals often line up into cloud streets, enabling the pilot to race without having to turn. Choosing a straight course may not be the best tactic if a slight diversion can keep the glider in rising air for longer, or at worst keep out of the strongly sinking air.

Another key tactical decision is what to do with the water ballast. Competition pilots usually launch with ballast, even though they sometimes have to dump it before the start. However it is possible that conditions may improve and so sometimes keeping the ballast throughout the task may be advantageous. Nevertheless heavier glider will be at a disadvantage if weak conditions persist and so sometimes dumping the water during the task may be the better choice.

The last decision will be when the glider is high enough to reach the finish. Taking an unnecessary climb wastes time and there are no additional points gained for arriving any higher at the finish. However the higher glider will be able to cruise back faster and so if strong lift is available it may be better to take the final climb higher than the minimum height required to get home.

[edit] Water ballast

An LS4 glider crossing the finish line of a competition at high speed. It is jettisoning water that has been used as ballast.

It may seem counter-intuitive, but pilots put water ballast into compartments in the wings to make their planes heavier. Modern gliders can take large quantities of water (a Nimbus-3, for example, can hold 272 kg). The objective is to increase the speed, while maintaining the same gliding angle. The downside is that the glider will climb more slowly in thermals.

If, for example, a glider's weight is increased by 50% by water ballast, then the forward speed together with its sink rate will also increase by about 50%. However the sink rate alone may only increase from 0.5m/s to 0.8m/s. The 0.3m/s increase in sink rate only results in a 10% loss in climb rate if the glider flies in a thermal that rises by a speed of 3m/s (which is common). The time lost in climbing more slowly is then more than recouped by the increased speed to the next thermal. However if the thermals are weaker, it may be better to fly without ballast.

The airframe of a glider is not designed to withstand the stresses of a hard landing while the glider is loaded with water. Consequently, pilots start emptying the ballast tanks shortly before the gliders cross the finish line so they are empty when they land. This results in spectacular images when competition pilots cross the finish line at low altitude.

[edit] Scoring

Each glider carries a device for recording its GPS position every few seconds. This provides evidence that the start, turn-points and finish have been legitimately reached. The winner on each competition day is the fastest and can have a maximum score of 1000 points. This can be devalued if very few gliders get around the task. (The reason being that if only a few gliders get round the task, then luck was probably a key factor.) The scores are then assigned according to the speed relative to the winner. A small proportion of the maximum score is given for the distance covered so that competitors who do not complete the task, will get a score. In some competitions, handicapping is used and so further factors are applied before determining each pilot's score for the day.

[edit] Grand Prix

In an attempt to widen the appeal of gliding contests, a new format contest, the Grand Prix, has been introduced.^[1] Innovations introduced in the Grand Prix format include simultaneous starts for a small number of gliders, tasks consisting of multiple circuits, and simplified scoring.

[edit] Online Contest

Also gaining popularity in recent years is an informal internet competition called the Online Contest (OLC)^[2] 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.

S-1 Swift - modern aerobatic glider

[edit] Aerobatics

Aerobatic competitions are held regularly.^[3] In this type of competition, the pilots fly a program of maneuvers (such as inverted flight, loop, roll, and various combinations). Each maneuver has a rating called the "K-Factor".^[4] Maximum points are given for the maneuver if it is flown perfectly, otherwise points are deducted. Efficient maneuvers also enable the whole program to be completed with the height available. The winner is the pilot with the most points.