Glider

Gliders are heavier-than-air aircraft primarily intended for un-powered flight.

Major manufacturers of gliders

• DG Flugzeugbau GmbH
• Schempp-Hirth GmbH
• Alexander Schleicher GmbH & Co
• Rolladen-Schneider Flugzeugbau GmbH (taken over by DG Flugzeugbau)
• Scheibe-Flugzeugbau GmbH

Instrumentation and other technical aids

Gliders are equipped with an altimeter, compass and an air-speed indicator, and often with a radio, though in some countries the radio is not compulsory. In European countries with crowded airspace there are also proposals that all gliders should fly with anti-collision devices such as transponders but this is still uncertain.

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Much more than in other types of aviation, glider pilots depend on an instrument known as a variometer (a very sensitive vertical climb indicator), which measures the climb or sink rate of the plane. This enables the pilot to detect rising and sinking air. Both mechanical and electronic 'varios' are usually fitted to a glider. The electronic variometers produce a beeping noise of variable amplitude and frequency depending on the strength of the lift, so that the pilot can concentrate on watching for other traffic, on navigating and on the weather. (Refer to the variometer article for more information). Rising air is announced to the pilot as a rising tone which the pilot may choose to react to by turning the sailplane to circle in the lift. Alternately descents are announced with different tone and the pilot will typically accelerate to escape the sink as soon as possible. The same instrument will often also suggest an ideal speed when flying straight after allowing for factors such as water ballast, headwinds/tailwinds and insects on the leading edges of the wings.

Related Topics:
Variometer

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Sailplane variometers are often fitted with devices such as the "MacCready Ring" to indicate the optimal speed to fly for given conditions. These devices are based on the mathematical theory developed by Paul MacCready. MacCready theory solves the problem of how fast a pilot should cruise in between thermals, given both the average lift the pilot expects in the next thermal climb, as well as the amount of lift or sink he encounters in cruise mode.

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Soaring flight computers, in combination with PDAs and specialized soaring software, have been specifically designed for sailplane use. Using GPS technology these tools are able to:

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• Provide the glider's position in 3 dimensions by a moving map display
• Alert the pilot to nearby airspace restrictions
• Indicate contest task position along with managing required course direction and distance
• Show airports within gliding distance (ignoring sink/lift)
• Calculate and display information to help in remaining aloft
• Determine wind direction and speed at current altitude
• Show historical lift information
• Create a secure GPS log of the flight, required for contest flying

...and a host of other soaring related data.

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The flight computer's GPS log may be replayed on specialized computer software to analyse past flights, including watching one or more gliders fly together in a two or three dimension 3-D view. The 3-D representation is shown here with a typical topographical background showing map details such as roads, cities and airports. The glider ("CD") has just executed a series of tight thermalling turns in the Austrian Alps. Other backgrounds might be a satellite image or an FAA sectional map.

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Glider markings

To distinguish gliders in flight, large numbers/letters are sometimes put on the fin and wings. Because these numbers were once needed by ground-based observers in competitions, these are known as "competition numbers". They are in addition to the glider's registration and are assigned by national gliding associations. They are useful in radio communications between gliders and so they are often the glider's call-sign.

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Modern gliders are mainly white but some have bright patches painted on them in an attempt to improve their visibility to other aircraft.

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Aerobatic gliders

Another - less widespread - form of gliding is aerobatics. In this type of competition, the pilot fly a program of maneuvers (such as inverted flight, loop, roll, and various combinations). Each maneuver has a rating called the "K-Factor." This number of points is given if the maneuver is flown perfectly, otherwise a number of points is subtracted. The winner is the pilot with the highest sum of points in each skill based category.

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Motor gliders

Some sailplanes ("self-launching motor gliders") are equipped with propellers that retract into the fuselage. The motor is powerful enough to allow these gliders to launch independently. Recently electric self-launchers such as the Antares have been developed. Others ("self-sustaining motor gliders," also referred to as "turbo" or "sustainer" gliders) are equipped with motors just powerful enough to allow the glider to climb slowly but they must be launched like unpowered gliders. A third type, termed touring motorglider, has a conventional layout with a motor and propellor on the front of the aircraft.

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The most important point in favor of powered gliders (retractable engine high-performance types) is that it helps pilots to avoid outlandings. Outlandings, while they are not necessarily dangerous, can be an expensive and time-consuming nuisance for competitive pilots who need to be back home at a set time. Another consideration is that a retrieve crew is needed on stand-by. However the sense of achievement in completing a difficult cross-country is lessened if an engine has been available.

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Some people argue that an engine makes the aircraft safer, because the pilot can avoid storms, and can go on to an airstrip to land. An opposing view is that motor gliders are against the spirit of the sport, and, more importantly, that they sometimes give pilots a false sense of security. Even in a motor glider, it is important never to be out of gliding range of a 'landable' area.

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More recently, pilot licensing terms have changed in Europe. Powered gliders are now categorized into gliders with retractable propellers/engines, which can be flown with an ordinary glider pilot license (GPL), and touring motor gliders (TMG), which require a specific license extension to the standard GPL. In the United Kingdom, where gliding is regulated by the British Gliding Association, pilots of self-sustaining gliders, like those of pure gliders, do not have to be licensed with the United Kingdom Civil Aviation Authority.

Related Topics:
Glider pilot license - TMG - United Kingdom Civil Aviation Authority

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In the United States, a private glider pilot certificate allows the pilot to fly unpowered gliders, self-launching motor gliders (including touring motor gliders and gliders with retractable enginesor propellors) and sustainer motor gliders. An instructor must provide instruction and sign the logbook of the pilot to authorize the launch method, which may be by airplane towing, ground launch (winches, bungee, auto tow, etc.) or, in the case of a suitable motor glider, by self-launching.

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