AILE DE KITESURF
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Le kitesurf (planche volante) est un sport nautique de traction consistant à glisser avec une planche sur une étendue d'eau tracté par un cerf-volant de traction. Le kitesurfeur pilote à l'aide d'une barre une aile souvent gonflable reliée généralement par quatre lignes d'une vingtaine de mètres. La planche peut être un twintip inspirée du wakeboard dont l'avant et l'arrière sont symétriques, ou un surf de taille réduite. Souvent appelé flysurf à l'origine, il peut l'être par son appellation anglaise kiteboard, voire abrégé kite pour l'aile en anglais. Les termes préconisés par la Commission générale de terminologie et de néologie au lieu de ces anglicismes sont planche volante ou la planche aérotractée. De même, le pratiquant est appelé aéroplanchiste, le mountainboard Planche terrestre aérotractée et le snowkite Planche à neige aérotractée.
Aile
L'aile, comparable à une voile, fournit la traction nécessaire au déplacement. Les ailes habituelles ont surface à plat de généralement 10 m², entre 5 m² pour les conditions de vent fort et jusqu'à 20 m² pour les vents légers - leur surface projetée est plus faible. Deux grands types d'ailes sont utilisés :
Aile
L'aile, comparable à une voile, fournit la traction nécessaire au déplacement. Les ailes habituelles ont surface à plat de généralement 10 m², entre 5 m² pour les conditions de vent fort et jusqu'à 20 m² pour les vents légers - leur surface projetée est plus faible. Deux grands types d'ailes sont utilisés :
- les ailes à boudins gonflables issues du brevet déposé par les frères Legaignoux en 1984 : une structure est gonflée à l'aide d'une pompe, qui maintient le profil de l'aile et lui permet de redécoller de l'eau ; il en existe deux principaux types avec des hybrides entre elles :
- en forme d'arche (ou C-shape) : le bord d'attaque en demi-cercle est tenu à ses deux extrémités par les lignes avant. Elles sont surtout utilisées pour le wakestyle par des pratiquants expérimentés , elles conservent de la puissance même barre choquée.
- les ailes dont leur bord d'attaque est maintenu par un bridage (SLE, supported leading edge) (ailes plates, delta). Il est possible de plus varier leur angle d'attaque, et elles offrent donc une plage de vent plus importante, en plus de bénéficier d'un redécollage facilité : elles sont plus accessibles pour les débutants mais restent performantes pour la plupart des pratiques et sont les plus utilisées.
- aile à caissons, profils souples issus du parapente : les caissons de l'aile sont gonflés par le vent relatif. Sans gonflage, elles sont plus rapides à gréer et ayant une surface projetée plus importante, elles sont plus petites à traction équivalente. Davantage utilisées pour la traction terrestre, il y a des ailes à caissons marines permettant le redécollage sur l'eau avec des clapets (caissons fermés) ou sont des twin skin qui se gonflent grâce à une fermeture qui laisse entrer l'air.
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Kitesurfing or kiteboarding is a surface water sport combining aspects of wakeboarding, windsurfing, surfing, paragliding, and gymnastics into one extreme sport. A kitesurfer or kiteboarder harnesses the power of the wind with a large controllable power kite to be propelled across the water on a kiteboard similar to a wakeboard or a small surfboard, with or without foot-straps or bindings. The terms kiteboarding and kitesurfing are interchangeable, although kiteboarding may also refer to kite landboarding or kite snowboarding. There are different styles of kiteboarding, including freestyle, freeride, downwinders, speed, course racing, wakestyle, jumping and wave-riding. In 2012, the number of kitesurfers has been estimated by the ISAF and IKA at 1.5 million persons worldwide (pending review). The global market is worth US$250 million.
Power kites
A power kite is available in two major forms: leading edge inflatables and foil kites.
Leading edge inflatables
Leading edge inflatable kites, known also as inflatables, LEI kites or C-kites, are typically made from ripstop polyester with an inflatable plastic bladder that spans the front edge of the kite with separate smaller bladders that are perpendicular to the main bladder to form the chord or foil of the kite. The inflated bladders give the kite its shape and also keep the kite floating once dropped in the water. LEIs are the most popular choice among kitesurfers thanks to their quicker and more direct response to the rider's inputs, easy relaunchability once crashed into the water, and resilient nature. If an LEI kite hits the water or ground too hard or is subjected to substantial wave activity, bladders can burst or it can be torn apart. In 2005, Bow kites (also known as flat LEI kites) were developed with features including a concave trailing edge, a shallower arc in planform, and frequently a bridle along the leading edge. These features allow the kite's angle of attack to be altered more and thus adjust the amount of power being generated to a much greater degree than previous LEIs. These kites can be fully depowered, which is a significant safety feature. They can also cover a wider wind range than a comparable C-shaped kite. The ability to adjust the angle of attack also makes them easier to re-launch when lying front first on the water. Bow kites are popular with riders from beginner to advanced levels. Most LEI kite manufacturers developed a variation of the bow kite by 2006. Early bow kites had some disadvantages compared to classic LEI kites:
They can become inverted and then not fly properly
They can be twitchy and not as stable
Heavier bar pressure makes them more tiring to fly
Lack of "sled boosting" effect when jumping
In 2006, second generation flat LEI kites were developed which combine near total depower and easy, safe relaunch with higher performance, no performance penalties and reduced bar pressure. Called Hybrid or SLE kites (Supported Leading Edge), these kites are suitable for both beginners and experts. In 2008, Naish introduced another kite design, with their "Sigma Series" of kites. These kites are a SLE design and feature a unique "bird in flight" shape with the center of the kite swept back to put much of the sail area behind the tow point, which Naish claims has multiple benefits. In 2009, the performance revolution shows no sign of slowing. Bridled designs feel more like C kites, and five-line hybrids have better depower capability than ever before. There are more than thirty companies manufacturing Leading edge inflatable kites. The delta-kites are growing in popularity since 2008 with around 12 companies offering delta-kites since 2008/2009. Between 2009 and 2013 kite technology has continued to grow. Kites have become lighter, more durable, much easier to launch and safer. Manufacturers have continued to add new safety features. This has resulted in a growing number of new riders, both younger and older. In 2013, there are at least 20 "major" kite manufacturers, each with multiple models available. Many of the manufacturers are on their third or fourth generation of kites.
Power kites
A power kite is available in two major forms: leading edge inflatables and foil kites.
Leading edge inflatables
Leading edge inflatable kites, known also as inflatables, LEI kites or C-kites, are typically made from ripstop polyester with an inflatable plastic bladder that spans the front edge of the kite with separate smaller bladders that are perpendicular to the main bladder to form the chord or foil of the kite. The inflated bladders give the kite its shape and also keep the kite floating once dropped in the water. LEIs are the most popular choice among kitesurfers thanks to their quicker and more direct response to the rider's inputs, easy relaunchability once crashed into the water, and resilient nature. If an LEI kite hits the water or ground too hard or is subjected to substantial wave activity, bladders can burst or it can be torn apart. In 2005, Bow kites (also known as flat LEI kites) were developed with features including a concave trailing edge, a shallower arc in planform, and frequently a bridle along the leading edge. These features allow the kite's angle of attack to be altered more and thus adjust the amount of power being generated to a much greater degree than previous LEIs. These kites can be fully depowered, which is a significant safety feature. They can also cover a wider wind range than a comparable C-shaped kite. The ability to adjust the angle of attack also makes them easier to re-launch when lying front first on the water. Bow kites are popular with riders from beginner to advanced levels. Most LEI kite manufacturers developed a variation of the bow kite by 2006. Early bow kites had some disadvantages compared to classic LEI kites:
They can become inverted and then not fly properly
They can be twitchy and not as stable
Heavier bar pressure makes them more tiring to fly
Lack of "sled boosting" effect when jumping
In 2006, second generation flat LEI kites were developed which combine near total depower and easy, safe relaunch with higher performance, no performance penalties and reduced bar pressure. Called Hybrid or SLE kites (Supported Leading Edge), these kites are suitable for both beginners and experts. In 2008, Naish introduced another kite design, with their "Sigma Series" of kites. These kites are a SLE design and feature a unique "bird in flight" shape with the center of the kite swept back to put much of the sail area behind the tow point, which Naish claims has multiple benefits. In 2009, the performance revolution shows no sign of slowing. Bridled designs feel more like C kites, and five-line hybrids have better depower capability than ever before. There are more than thirty companies manufacturing Leading edge inflatable kites. The delta-kites are growing in popularity since 2008 with around 12 companies offering delta-kites since 2008/2009. Between 2009 and 2013 kite technology has continued to grow. Kites have become lighter, more durable, much easier to launch and safer. Manufacturers have continued to add new safety features. This has resulted in a growing number of new riders, both younger and older. In 2013, there are at least 20 "major" kite manufacturers, each with multiple models available. Many of the manufacturers are on their third or fourth generation of kites.
Foil kites
Foil kites are also mostly fabric (ripstop nylon) with air pockets (air cells) to provide it with lift and a fixed bridle to maintain the kite's arc-shape, similar to a paraglider. A depowerable foil kite can cover about the same wind range as two traditional C-shape LEI kite sizes, so the rider can use a smaller kite, giving a wider depower range, although the new LEI "bow" kites have a comparable wide range. Foil kites have the advantage of not needing to have bladders manually inflated, a process which, with an LEI, can take up to ten minutes. Foil kites are designed with either an open or closed cell configuration.
Open Cell
Open cell foils rely on a constant airflow against the inlet valves to stay inflated, but are generally impossible to relaunch if they hit the water, because they have no means of avoiding deflation, and quickly become soaked.
Closed Cell
Closed cell foils are almost identical to open cell foils except they are equipped with inlet valves to hold air in the chambers, thus keeping the kite inflated (or, at least, making the deflation extremely slow) even once in the water. Water relaunches with closed cell foil kites are simpler; a steady tug on the power lines typically allows them to take off again. An example for a closed cell kite is the Arc Kite.
Kite sizes
Kites come in sizes ranging from 0.7 square meters to 21 square meters, or even larger. In general, the larger the surface area, the more power the kite has. Kite power is also directly linked to speed, and smaller kites can be flown faster in stronger winds. The kite size—wind speed curve tapers off, so going to a larger kite to reach lower wind ranges becomes futile at a wind speed of around eight knots. Kites come in a variety of designs. Some kites are more rectangular in shape; others have more tapered ends; each design determines the kite's flying characteristics. 'Aspect ratio' is the ratio of span to length. High aspect ratios (ribbon-like kites) develop more power in lower wind speeds. Seasoned kiteboarders will likely have three or more kite sizes which are needed to accommodate various wind levels, although bow kites may change this, as they present an enormous wind range; some advanced kiters use only one bow kite. Smaller kites are used by light riders, or in strong wind conditions; larger kites are used by heavier riders or in light wind conditions. Larger and smaller kiteboards have the same effect: with more available power a given rider can ride a smaller board. In general, however, most kiteboarders only need one board and one to three kites (7-12 sq m in size).
Foil kites are also mostly fabric (ripstop nylon) with air pockets (air cells) to provide it with lift and a fixed bridle to maintain the kite's arc-shape, similar to a paraglider. A depowerable foil kite can cover about the same wind range as two traditional C-shape LEI kite sizes, so the rider can use a smaller kite, giving a wider depower range, although the new LEI "bow" kites have a comparable wide range. Foil kites have the advantage of not needing to have bladders manually inflated, a process which, with an LEI, can take up to ten minutes. Foil kites are designed with either an open or closed cell configuration.
Open Cell
Open cell foils rely on a constant airflow against the inlet valves to stay inflated, but are generally impossible to relaunch if they hit the water, because they have no means of avoiding deflation, and quickly become soaked.
Closed Cell
Closed cell foils are almost identical to open cell foils except they are equipped with inlet valves to hold air in the chambers, thus keeping the kite inflated (or, at least, making the deflation extremely slow) even once in the water. Water relaunches with closed cell foil kites are simpler; a steady tug on the power lines typically allows them to take off again. An example for a closed cell kite is the Arc Kite.
Kite sizes
Kites come in sizes ranging from 0.7 square meters to 21 square meters, or even larger. In general, the larger the surface area, the more power the kite has. Kite power is also directly linked to speed, and smaller kites can be flown faster in stronger winds. The kite size—wind speed curve tapers off, so going to a larger kite to reach lower wind ranges becomes futile at a wind speed of around eight knots. Kites come in a variety of designs. Some kites are more rectangular in shape; others have more tapered ends; each design determines the kite's flying characteristics. 'Aspect ratio' is the ratio of span to length. High aspect ratios (ribbon-like kites) develop more power in lower wind speeds. Seasoned kiteboarders will likely have three or more kite sizes which are needed to accommodate various wind levels, although bow kites may change this, as they present an enormous wind range; some advanced kiters use only one bow kite. Smaller kites are used by light riders, or in strong wind conditions; larger kites are used by heavier riders or in light wind conditions. Larger and smaller kiteboards have the same effect: with more available power a given rider can ride a smaller board. In general, however, most kiteboarders only need one board and one to three kites (7-12 sq m in size).