Gliding is a recreational activity and competitive sport in which pilots fly un-powered aircraft known as gliders or sailplanes. Recreation or fun is the expenditure of time in a manner designed for therapeutic refreshment of one's Body or Mind. Sport is an Activity that is governed by a set of rules or Customs and often engaged in competitively Overview Fixed-wing aircraft range from small training and recreational aircraft to Wide-body aircraft and military cargo aircraft. Terminology A "glider" is an unpowered Aircraft. The most common types of glider are today used for sporting purposes 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. ^[1] 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. ^[2] However, if the weather deteriorates, they may need to land elsewhere, but motorglider pilots can avoid this by starting an engine. See Also Glider A Motor Glider is a Fixed-wing aircraft that can be flown with or without engine power

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. Some of the pilots in the sport of Gliding take part in gliding competitions. Local and national competitions are organized in many countries and there are also biennial World Gliding Championships. The World Gliding Championships is a gliding competition held every two years or so by the FAI Gliding Commission. ^[3]

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.

Contents 1 History 2 Soaring 2.1 Thermals 2.2 Ridge lift 2.3 Wave lift 2.4 Other sources of lift 3 Launch methods 3.1 Aerotowing 3.2 Wire launching 3.2.1 Winch-launching 3.2.2 Auto-tow 3.3 Bungee launch 4 Cross-country 4.1 Maximizing speed 4.2 Badges 4.3 Landing out 4.4 Use of engines 5 Aerobatics 6 Hazards 7 Challenges for the gliding movement 8 Learning to glide 9 Related air sports 10 See also 11 References 12 Further reading 13 External links

History

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). Sir George Cayley 6th Baronet ( December 27, 1773 &ndash December 15, 1857) sometimes known as "the father of Aerodynamics" was WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout Aviation history deals with the development of mechanical Flight, from the earliest attempts in Kite -powered and gliding flight to powered Heavier-than-air flight However, the sport of gliding only emerged after the First World War as a result of the Treaty of Versailles,^[4] which imposed severe restrictions on the manufacture and use of single-seat powered aircraft in Germany. World War I (abbreviated WWI; also known as the First World War, the Great War, and the War to End All The Treaty of Versailles was one of the peace treaties at the end of World War I. The term Weimar Republic ( ˈvaɪmarɐ repuˈbliːk is used by historians to signify the democratic and Republican period of Germany from 1919 to 1933 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. World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including Nazi Germany and the Third Reich are the common English names for Germany under the regime of Adolf Hitler and the National Socialist German Workers

The first German gliding competition was held at the Wasserkuppe^[5] in 1920,^[6] organized by Oskar Ursinus. The Wasserkuppe ( German for "water peak" is a high Plateau (elevation 950 m or 3100 ft the highest peak in the Rhön Mountains within Carl Oskar Ursinus ( March 11 1877 &ndash July 6 1952) was a pioneer of The best flight lasted two minutes and set a world distance record of 2 km. ^[6] 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. Munich (München; Minga is the capital city of Bavaria, Germany. Czechoslovakia may also refer to what is now the Czech Republic and Slovakia. ^[6]

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. The 1936 Summer Olympics, officially known as the Games of the XI Olympiad, an International Multi-sport event which was held in 1936 in Berlin Berlin is the capital city and one of sixteen states of Germany. A demonstration sport is a sport which is played in order to promote itself most commonly during the Olympic Games, but also at other sporting events The anticipated 1940 Summer Olympics, officially known as the Games of the XII Olympiad and originally scheduled to be held from September 21 to October 6 A glider, the Olympia, was developed in Germany for the event, but World War II intervened. The DFS Olympia Meise (German "Olympic Tomtit" was a Sailplane designed for Olympic competition based on the DFS Meise. By 1939 the major gliding records were held by Russians, including a distance record of 748 km (465 miles). Russia (Россия Rossiya) or the Russian Federation ( Rossiyskaya Federatsiya) is a transcontinental Country extending ^[6]

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. Military gliders (an offshoot of common gliders) have been used by the military of various countries for carrying troops and heavy equipment (see Glider infantry Nonetheless, several German fighter aces in the conflict, including Erich Hartmann, began their flight training in gliders. A flying ace or fighter ace is a military aviator credited with shooting down several enemy Aircraft during aerial combat Erich Alfred "Bubi" Hartmann (19 April 1922 &ndash 20 September 1993 also nicknamed " The Blond Knight of Germany " by friends and " The Black

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. )^[6] 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. The term Air sports covers a range of aerial activities such as Aerobatics Ballooning General aviation The Fédération Aéronautique Internationale (FAI is the world governing body for Air sports and Aeronautics and Astronautics world records ^[7]

In many countries during the 1950s a large number of trained pilots wanted to continue flying. Many were also aeronautical engineers. Aerospace engineering is the branch of Engineering behind the design construction and science of Aircraft and Spacecraft. They started both clubs and manufacturers, many of which still exist. Abbott-Baynes Sailplanes Ltd Abrial Abrial A-12 Bagoas Abrial A-2 Vautour Advanced 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 Soaring Society of America (SSA was founded at the instigation of Warren E 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 achieved in 1964. ^[6] 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. Fiberglass (also called fibreglass and glass fibre see Spelling differences) is material made from extremely fine Fibers of Glass. WING "ESPN 1410" is a commercial AM radio station in Dayton Ohio operating with 5000 watts at 1410 kHz with studios offices and transmitter located on David Basic concept of GPS operation A GPS receiver calculates its position by carefully timing the signals sent by the constellation of GPS Satellites high above the Earth Today over 500 pilots have made flights over 1,000 km. ^[8]

Instead of Olympic competition there are the World Gliding Championships. The World Gliding Championships is a gliding competition held every two years or so by the FAI Gliding Commission. The first event was held at the Wasserkuppe in 1937. ^[6] 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. Competition classes in Gliding, as in other sports mainly exist to ensure fairness in competition Germany, the sport's birthplace, is still a center of the gliding world: it accounts for 30% of the world's glider pilots,^[9] and the three major glider manufacturers are still based there. Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. Abbott-Baynes Sailplanes Ltd Abrial Abrial A-12 Bagoas Abrial A-2 Vautour Advanced However the sport has been taken up in many countries and there are now over 116,000 active glider pilots,^[10] 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.

Soaring

Main article: Lift (soaring)

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. Potential energy can be thought of as Energy stored within a physical system ^[11] 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). A thermal column (or thermal) is a column of rising Air in the lower altitudes of the Earth's atmosphere. Ridge lift (or 'slope lift' is created when a prevailing Wind strikes a geologic obstacle that is large and steep enough to deflect the wind upward In Meteorology, lee waves, are atmospheric Standing waves. The most common form is mountain waves, which are atmospheric internal Gravity A standing wave, also known as a stationary wave, is a Wave that remains in a constant position Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five

Ridge lift rarely allows pilots to climb much higher than about 600 m (2,000 ft) above the terrain; thermals, depending on the climate and terrain, can allow climbs in excess of 3,000 m (10,000 ft) in flat country and much higher above mountains;^[12] wave lift has allowed a glider to reach an altitude of 15,447 m (50,671 ft). ^[13] In a few countries, gliders may continue to climb into the clouds in uncontrolled airspace, but in many countries the pilot must stop climbing before reaching the cloud base (see Visual Flight Rules).

Thermals

Thermals are streams of rising air that are formed on the ground through the warming of the surface by sunlight. A thermal column (or thermal) is a column of rising Air in the lower altitudes of the Earth's atmosphere. ^[14] If the air contains enough moisture, the water will condense from the rising air and form cumulus clouds. A cumulus cloud' is a type of Cloud with noticeable vertical development and clearly defined edges Once a thermal is encountered, the pilot usually flies in circles to keep the glider within the thermal, so gaining altitude before flying off to the next thermal and towards the destination. This is known as "thermalling". Climb rates depend on conditions, but rates of several meters per second are common. Thermals can also be formed in a line usually because of the wind or the terrain, creating cloud streets. Cloud streets are rows of cumulus or cumulus-type Clouds aligned parallel to the low-level wind These can allow the pilot to fly straight while climbing in continuous lift.

When the air has little moisture or when an inversion stops the warm air from rising high enough for the moisture to condense, thermals do not create cumulus clouds. In meteorology an inversion is a deviation from the normal change of an atmospheric property with altitude Without clouds or dust devils to mark the thermals, the pilot must use his skill and luck to find them using a sensitive vertical speed indicator called a variometer that quickly indicates climbs or descents. A dust devil is a strong well-formed and relatively long-lived whirlwind, ranging from small (half a meter wide and a few meters tall to large (over 10 meters wide and over The term Variometer also refers to a type of tunable Electrical Transformer A variometer (also known as a rate-of-climb indicator Typical locations to find thermals are over towns, freshly ploughed fields and asphalt roads, but thermals are often hard to associate with any feature on the ground. The plough ( American spelling plow; both plaʊ is a Tool used in Farming for initial cultivation of soil in preparation for sowing seed Asphalt ( is a sticky black and highly viscous liquid or semi-solid that is present in most crude Petroleums and in some natural deposits sometimes termed asphaltum Occasionally thermals are caused by the exhaust gases from power stations or by fires. A power station (also referred to as generating station, power plant or powerhouse) is an industrial facility for the generation of

As it requires rising heated air, thermalling is only effective in mid-latitudes from spring through into late summer. During winter the solar heat can only create weak thermals, but ridge and wave lift can still be used during this period.

Ridge lift

A ridge soaring pilot uses air lifted up the sides of hills. Ridge lift (or 'slope lift' is created when a prevailing Wind strikes a geologic obstacle that is large and steep enough to deflect the wind upward It can also be augmented by thermals when the slopes also face the sun. ^[15] In places where a steady wind blows, a ridge may allow virtually unlimited time aloft, though records for duration are no longer recognized because of the danger of exhaustion. ^[16]

Wave lift

The powerfully rising and sinking air in mountain waves was discovered by a glider pilot, Wolf Hirth, in 1933. In Meteorology, lee waves, are atmospheric Standing waves. The most common form is mountain waves, which are atmospheric internal Gravity ^[17] Gliders can sometimes climb in these waves to great altitudes, though pilots must use supplementary oxygen to avoid hypoxia. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Chronic Hypoxia is a pathological condition in which the body as a whole ( generalized hypoxia) or region of the body ( tissue hypoxia) is deprived of adequate This lift is often marked by long, stationary lenticular (lens-shaped) clouds lying perpendicular to the wind. Lenticular clouds are stationary lens-shaped Clouds that form at high altitudes normally aligned at right-angles to the wind direction ^[18] Mountain wave was used to set the current altitude record of 50,699 feet (15,453 m) on August 29, 2006 over El Calafate, Argentina. El Calafate is a little village in Patagonia, Argentina. It is situated in the southern border of Lake Argentino, in the southwest part of the Santa For a topic outline on this subject see List of basic Argentina topics. The pilots were Steve Fossett and Einar Enevoldson, who were wearing pressure suits. James Stephen Fossett (born April 22 1944 missing September 3 2007 declared legally dead February 15 2008 On September 3 2007 Fossett was reported missing after ^[19] The current world distance record of 3,008 km (1,869 statute miles) by Klaus Ohlmann (set on 21 January 2003)^[20] was also flown using mountain waves in South America. Klaus Ohlmann, born 1952 in Neustadt Germany is a German glider pilot who has established 36 world records approved by FAI. Events 1189 - Philip II of France and Richard I of England begin to assemble troops to wage the Third Crusade. Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. South America is a Continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a

A rare wave phenomenon is known as Morning Glory, a roll cloud producing strong lift. The Morning Glory cloud is a rare meteorological phenomenon observed in Northern Australia 's Gulf of Carpentaria. Pilots near Australia's Gulf of Carpentaria make use of it in springtime. The Gulf of Carpentaria is a large shallow sea enclosed on three sides by northern Australia and bounded on the north by the Arafura Sea (the body of water that lies Spring is one of the four Temperate Seasons Spring marks the transition from Winter into Summer. ^[21]

Other sources of lift

The boundaries where two air masses meet are known as convergence zones. For convergence zones of sonars see Sonar#Sound_propagation. Convergence zone usually refers to a region in the atmosphere where two prevailing ^[22] These can occur in sea breezes or in desert regions. A sea-breeze (or onshore breeze) is a Wind from the sea that develops over land near coasts In a sea-breeze front, cold air from the sea meets the warmer air from the land and creates a boundary like a shallow cold front. A cold front defined as the leading edge of a cooler and drier mass of air Glider pilots can gain altitude by flying along the intersection as if it were a ridge of land. Convergence may occur over considerable distances and so may permit virtually straight flight while climbing.

Glider pilots have been able to use a technique called "dynamic soaring",^[23] where a glider can gain kinetic energy by repeatedly crossing the boundary between air masses of different horizontal velocity. Dynamic Soaring is a Gliding technique used to gain Kinetic energy by repeatedly crossing the boundary between air masses of significantly different horizontal The kinetic energy of an object is the extra Energy which it possesses due to its motion However, such zones of high "wind gradient" are usually too close to the ground to be used safely by gliders. In common usage wind gradient, more specifically wind speed gradient or wind velocity gradient,or alternatively shear wind,is the vertical

Launch methods

Gliders, not having engines, use various methods to take off. Glider pilots who want to use the different types of launch methods must be in current practice in each. Licensing rules in some countries differentiate between aerotows and ground launch methods, due to the widely different techniques. In most countries one is required to obtain a glider pilot license (GPL or certificate before acting as pilot of a Glider.

Aerotowing

Aerotows normally use single-engined light aircraft, although motor gliders have also been permitted to tow gliders. The PA-25 Pawnee was a very popular Agricultural aircraft produced by Piper Aircraft between 1959 and 1982 See Also Glider A Motor Glider is a Fixed-wing aircraft that can be flown with or without engine power The tow-plane takes the glider to the desired height and place where the glider pilot releases the rope^[24]. A weak link is often fitted to the rope to ensure that any sudden loads do not damage the airframe of the tow-plane. Airframe means the mechanical structure of an Aircraft and as generally used does not include the engines

During the aerotow, the glider pilot keeps the glider in one of two positions behind the tow-plane^[25]. This position can either be the "low tow" position, just below the wake from the tow-plane, or the "high tow" position just above the wake. Wake turbulence is Turbulence that forms behind an aircraft as it passes through the air ^[26] In Australia the convention is to fly in low tow, whereas in the United States and Europe the high tow prevails. For a topic outline on this subject see List of basic Australia topics. The United States of America —commonly referred to as the ^[27] One aerotow variation is to attach two gliders to one tow-plane, using a short rope for the high towed glider and the long rope for the low tow.

Wire launching

Winch-launching

Gliders are often launched using a stationary ground-based winch mounted on a heavy vehicle. A winch is a mechanical device that is used to pull in (wind up or let out (wind out or otherwise adjust the " Tension " of a Rope or Wire rope ^[28] This method is widely used at many European clubs, often in addition to aerotowing. The engine is usually a large diesel, though hydraulic fluid engines and electrical motors are also used. A diesel engine is an Internal combustion engine which operates using the Diesel cycle (named after Dr Hydraulic fluids are a large group of fluids used as the motive medium in Hydraulic machinery. An electric motor uses Electrical energy to produce Mechanical energy. The winch pulls in a 1,000 to 1,600 m (3,000 to 5,500-foot) cable, made of high-tensile steel wire or a synthetic fiber, attached to the glider. The cable is released at a height of about 400 to 700 m (1,300 to 2,200 feet) after a short and steep ride.

The main advantage of a winch launch is its lower cost, but the launch height is usually lower than an aerotow, so flights are shorter unless the pilot can quickly make contact with a source of lift within a few minutes of releasing the cable. Although there is a risk of the cable breaking during this type of launch, pilots are trained to deal with this.

Auto-tow

Another launch method, the "autotow", is rarer nowadays. The Long Mynd in Shropshire, England, is a part of the Shropshire Hills Area of Outstanding Natural Beauty. ^[29] The direct towing method requires a hard surface, a powerful vehicle and a long steel cable. After gently taking up slack in the cable, the driver accelerates hard and the glider rises like a kite to as much as 400 m (1300 ft) if there is a good headwind and a runway of 1. A headwind is a Wind that blows against the direction of travel of an object A runway ( RWY) is a strip of land on an Airport, on which Aircraft can take off and land. 5 km (1 mile) or more. This method has also been used on desert dry lakes.

A variation on this is the "reverse pulley" method in which the truck drives towards the glider that it is launching with the cable passing around a pulley at the far end of the airfield, with an effect similar to a winch launch.

Bungee launch

Bungee launching was widely used in the early days of gliding, and occasionally gliders are still launched from the top of a gently sloping hill into a strong breeze using a substantial multi-stranded rubber band, or "bungee". A bungee cord is an elastic cord composed of one or more elastic strands forming a core covered in a woven sheath usually of nylon or cotton ^[30] For this launch method, the glider's main wheel rests in a small concrete trough. The hook normally used for winch-launching is instead attached to the middle of the bungee. Each end is then pulled by three or four people. One group runs slightly to the left, the other to the right. Once the tension in the bungee is high enough, the pilot releases the wheel brake and the glider's wheel pops out of the trough. The glider gains just enough energy to leave the ground and fly away from the hill.

Cross-country

The distance that a glider can fly for each meter it descends is expressed as its lift-to-drag ratio (L/D). In Aerodynamics, the lift-to-drag ratio, or L/D ratio ("ell-over-dee" in the US "ell-dee" in the UK is the amount of lift generated Depending on the class, this can be between 44:1 and 70:1 in modern designs. Competition classes in Gliding, as in other sports mainly exist to ensure fairness in competition This performance combined with regular sources of rising air enables gliders to fly long distances at high speeds. ^[31] The record average speed for 1,000 km is 169. 7 km/h (621 statute miles at 105 miles/h). ^[32] Even in places with less favorable conditions (such as Northern Europe) most skilled pilots complete flights over 500 km (310 miles) every year. Northern Europe is a term for the northern part of Europe. The United Nations defines Northern Europe as (Finland ^[33]

Glider pilots are required to stay within gliding range of their home airfield for their early solo flights as student pilots. 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. A waypoint is a reference point in physical space used for purposes of Navigation.

In addition to just trying to fly further, glider pilots also race each other in competitions. Some of the pilots in the sport of Gliding take part in gliding competitions. ^[34] 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^[35] and average 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. The International Gliding Commission (IGC is the international governing body for the sport of Gliding. Basic concept of GPS operation A GPS receiver calculates its position by carefully timing the signals sent by the constellation of GPS Satellites high above the Earth ^[36] 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. FAI World Grand Prix Gliding Championships are competitions for gliders that is both more spectacular and more easily understood by the public than conventional Gliding ^[37] 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^[38] where pilots upload their GPS data files and are automatically scored based on distance flown. The Aerokurier Online Contest (OLC a worldwide decentralized Soaring competition for Glider, Hang glider, and Paraglider pilots 7,800 pilots worldwide participated in this contest in 2006. ^[39]

Maximizing speed

Soaring pioneer Paul MacCready is usually credited with developing a mathematical theory for optimizing the speed to fly when cross-country soaring,^[40] though it was first described by Wolfgang Späte (who later became famous for flying Messerschmitt Me 163 Komet rocket fighters with the Luftwaffe late in World War II) in 1938. Paul B MacCready Jr ( September 25, 1925 - August 28, 2007) was an American Aeronautical engineer. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout ^[41] The speed to fly theory allows the optimal cruising speed between thermals to be computed, using thermal strength, glider performance and other variables. Speed to fly is a principle used by soaring pilots when flying between sources of lift usually Thermals Ridge lift and wave. It accounts for the fact that if a pilot flies faster between thermals, the next thermal is reached sooner. However at higher speeds the glider also sinks faster, requiring the pilot to spend more time circling to regain the altitude. The MacCready speed represents the optimal trade-off between cruising and circling. Most competition pilots use MacCready theory to optimize their flight speeds, and have the calculations programmed in their flight computers. The greatest factor in maximizing speed, however, remains the ability of the pilot to find the strongest lift. ^[42]

On cross-country flights where strong lift is forecast, pilots fly with water ballast stored in tanks or bags in the wings and fin. WING "ESPN 1410" is a commercial AM radio station in Dayton Ohio operating with 5000 watts at 1410 kHz with studios offices and transmitter located on David The fin tank is used to reduce trim drag by optimizing the center of gravity, which typically would shift forward if water is stored only in the wings ahead of the spar. ^[43] Ballast enables a sailplane to attain its best L/D at higher speeds but slows its climb rate in thermals, in part because a sailplane with a heavier wing loading cannot circle within a thermal as tightly as one with a lower, unballasted wing loading. But if lift is strong, typically either from thermals or wave, the disadvantage of slower climbs is outweighed by the higher cruising speeds between lift areas. Thus, the pilot can improve the speed over a course by several percent or achieve longer distances in a given time. ^[43] If lift is weaker than expected, or if an off-field landing is imminent, the pilot can jettison the water ballast by opening the dump valves.

Badges

Achievements in gliding have been marked by the awarding of badges since the 1920s. The International Gliding Commission (IGC is the international governing body for the sport of Gliding. ^[44] For the lower badges, such as the first solo flight, national gliding federations set their own criteria. Typically, a bronze badge shows preparation for cross-country flight, including precise landings and witnessed soaring flights. Higher badges follow the standards set down by the Gliding Commission of the Fédération Aéronautique Internationale (FAI). The International Gliding Commission (IGC is the international governing body for the sport of Gliding. The Fédération Aéronautique Internationale (FAI is the world governing body for Air sports and Aeronautics and Astronautics world records ^[45] The FAI's Sporting Code defines the rules for observers and recording devices to validate the claims for badges, which are defined by kilometers of distance and meters of altitude gained. ^[46] The Silver-C badge was introduced in 1930. ^[44] Earning the Silver Badge shows that a glider pilot has achieved an altitude gain of at least 1,000 m, made a five-hour duration flight, and has flown cross-country for a straight-line distance of at least 50 km: these three attainments are usually, but not invariably, achieved in separate flights. The Gold and Diamond Badges require pilots to fly higher and further. A pilot who has completed the three parts of the Diamond Badge has flown 300 km to a pre-defined goal, has flown 500 km in one flight (but not necessarily to a pre-defined goal) and gained 5,000 m in height. The FAI also issues a diploma for a flight of 1,000 km and further diplomas for increments of 250 km.

Landing out

If lift is not found during a cross-country flight, for example because of deteriorating weather, the pilot must choose a field and 'land out'. ^[47] Although inconvenient and often mistaken for "emergency landings", landing out (or "outlanding") is a routine event in cross-country gliding. An emergency landing is an unplanned Landing made by an Aircraft in response to a crisis which either interferes with the operation of the aircraft or involves The pilot has to choose a field where the glider can be landed safely, without damaging property such as crops or livestock. ^[48]

The glider and the pilot(s) can be retrieved from the field using a purpose-built trailer. Alternatively, if the glider has landed in a suitable field, a tow-plane can be summoned to re-launch the aircraft (as long as the property owner gives permission). The glider pilot typically pays for the time the tow-plane is in the air, both to and from the field, so this alternative can become expensive.

Use of engines

To avoid the inconvenience of landing out, some gliders are motor gliders, optionally fitted with a small engine and a retractable propeller, adding both weight and expense. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout See Also Glider A Motor Glider is a Fixed-wing aircraft that can be flown with or without engine power Two principal categories of engine are used: more powerful ones for 'self launching,' which makes the glider independent of a tow plane, and less powerful 'sustainer' engines that can prolong flight but are not powerful enough for launching. However, engines have to be started at a height that includes a margin that would still allow a safe landing-out to be made, if the engine were to fail to start. ^[49]

In a competition, starting the engine ends the soaring flight. Gliders without an engine are lighter and, as they do not need a safety margin for an engine-start, they can safely thermal at lower altitudes in weaker conditions. So, pilots in unpowered gliders may complete competition flights when some powered competitors cannot. ^[50] Conversely, motor glider pilots can start the engine if conditions will no longer support soaring flight, while unpowered gliders will have to land out, away from the home airfield, requiring retrieval by road using the glider's trailer. Opinions differ whether difficult flights, where an engine was always available, are as satisfying as flights in pure gliders.

Aerobatics

Aerobatic competitions are held regularly. The Swift S-1 is a single seat aerobatic Glider manufactured by Swift Ltd. Aerobatics is the demonstration of flying maneuvers for Training, Recreation or Entertainment. ^[51] 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". ^[52] 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.

Hazards

Gliders, unlike hang gliders and paragliders, surround the pilot with a strong structure, so most accidents cause no injuries,^[53] but there are some hazards. History See also History of hang gliding Summary: Hang gliding existed in China perhaps by the 4th century AD according to the writing of the Paragliding is a recreational and competitive flying sport A paraglider is a free-flying foot-launched Aircraft. ^[54] Though training and safe procedures are central to the ethos of the sport, a few fatal accidents occur every year, almost all caused by pilot error. ^[53] In particular there is a risk^[55] of mid-air collisions between gliders, because two pilots might choose to fly to the same area of lift and so might collide. Because of this risk, pilots usually wear parachutes. A parachute is a device used to slow the motion of an object through an atmosphere by creating drag. To avoid other gliders and general aviation traffic, pilots must comply with the Rules of the Air and keep a good lookout. General aviation (abbr GA) is one of two categories of Civil aviation. In several European countries and Australia, the FLARM warning system is used to help avoid mid-air collisions between gliders. For a topic outline on this subject see List of basic Australia topics. FLARM is an electronic device to selectively alert pilots to potential collisions between Aircraft. ^[56]

Challenges for the gliding movement

Gliding as a sport faces challenges in the years ahead. ^[57] These include:

• Time pressures on participants: gliding typically takes whole days, which many people today find harder to devote. As a result the average age of glider pilots is increasing
• Airspace: in many European countries the growth of civil aviation is reducing the amount of uncontrolled airspace
• Competition from other activities: there is now a greater variety of similar sports such as hang gliding and paragliding that may attract potential glider pilots. Airspace means the portion of the atmosphere controlled by a particular country on top of its territory and Territorial waters or more generally any specific three-dimensional Civil aviation is one of two major categories of flying representing all non- Military aviation, both private and commercial Uncontrolled airspace is an aviation term to describe Airspace where an Air Traffic Control (ATC service is not deemed necessary or cannot be provided for practical History See also History of hang gliding Summary: Hang gliding existed in China perhaps by the 4th century AD according to the writing of the Paragliding is a recreational and competitive flying sport A paraglider is a free-flying foot-launched Aircraft.
• Lack of publicity: without coverage by television, many people are unaware of competitive gliding.
• Increasing costs, due to higher costs of fuel and insurance, and due to greater regulation requiring equipment such as new radios or transponders. Radio is the transmission of signals by Modulation of electromagnetic waves with frequencies below those of visible Light. In Telecommunication, the term transponder (short-for Trans mitter-res ponder and sometimes abbreviated to XPDR XPNDR TPDR or TP has the following meanings

Learning to glide

Most clubs offer trial lessons to people interested in learning to glide. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout National gliding associations have contact details for their member clubs. The sport of Gliding is managed in each country by national gliding associations, subject to governmental aviation authorities to varying degrees Because most gliders are designed to the same specifications of safety, the upper weight limit for pilots, after allowing for a parachute, is usually 103 kg (228 pounds). People over 193cm (6’ 4’’) will also have problems. The pupil flies with an instructor in a two-seat glider fitted with dual controls. ^[58] The instructor performs the first launches and landings, typically from the back seat, but otherwise the pupil manages the controls. Some clubs offer courses over several days, with a mixture of winch and aerotow launches. It may take ab initios at least 50 training flights before they are deemed to have the skill and the airmanship necessary to fly solo. Ab Initio Software Corporation was founded in the mid 1990's by the former CEO of Thinking Machines Corporation Sheryl Handler, and several other former employees Airmanship is skill and knowledge applied to aerial navigation, similar to Seamanship in maritime navigation ^[59]

If winches are used, the cost of learning to glide is much less than that of learning to fly powered aircraft. Training using aerotow costs more than using winches, though fewer launches (as few as 25) might be needed. Simulators are also beginning to be used in training, especially during poor weather. A flight simulator is a system that tries to copy or simulate, the experience of flying an aircraft

After the first solo flight, further training with an instructor continues until the pupil is capable of taking a glider cross-country. In most countries pilots must sit examinations on the regulations, navigation, use of the radio, weather, principles of flight and human factors.

Related air sports

Hang gliding uses a simpler and cheaper aircraft in which pilots exercise control by shifting body weight, whereas glider pilots use conventional flight controls. History See also History of hang gliding Summary: Hang gliding existed in China perhaps by the 4th century AD according to the writing of the Hang gliders typically use fabric wings, shaped over a framework. WING "ESPN 1410" is a commercial AM radio station in Dayton Ohio operating with 5000 watts at 1410 kHz with studios offices and transmitter located on David The lower aerodynamic efficiency of these wings means that shorter cross-country distances are flown than in gliders. Unlike the hang gliders' wings, paragliders' wings have no frames and their shape is entirely formed by the pressure of the air. Paragliding is a recreational and competitive flying sport A paraglider is a free-flying foot-launched Aircraft. The aerodynamic efficiency of paragliders is lower still and so cross-country flights are even shorter. Radio-controlled gliding uses scale-models of gliders mainly for ridge soaring. A radio-controlled glider is a type of Radio-controlled airplane that normally does not have any form of propulsion

See also

• Glider
• Hang gliding
• Wingsuit flying
• Motor glider
• Powered hang glider
• Gliding competitions
• List of notable glider pilots
• National gliding associations
• Flying and gliding animals

References

Further reading

• Longland, Steve (2001). Gliding: From Passenger to Pilot. The Crowood Press Ltd. ISBN 1-86126-414-3.  
• Piggott, Derek (2002). Gliding: A handbook on soaring flight. A & C Black. ISBN 0-7136-6148-8.  
• Stewart, Ken (2003). The Glider Pilot's Manual. Air Pilot Publisher Ltd. ISBN 1-84336-078-0.  

External links

• Links to all national gliding federations
• International Gliding Commission
• Video of gliding on You Tube

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