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Power kite

A power kite or traction kite is a large kite designed to provide significant pull to the user.

Kitesurfing in strong onshore winds off the north shore of Oʻahu in Hawaii.

Types Edit

The two most common forms are the foil, and the leading edge inflatable. There are also other less common types of power kite including rigid-framed kites and soft single skin kites. There are several different control systems used with these kites which have two to five lines and a bar or handles.

Foil kites consist of a number of cells with cloth ribs in each cell. It is the profile of these ribs that gives the kite its aerofoil shape and enable it to generate lift. The most common type is the ram-air foil, where each cell has a gauze-covered opening at the front, meaning air is forced in during flight, giving the kite its stiffness and enabling it to hold its profile. Some ram-air foils are closed-cell, where a one-way valve locks the air inside the cells, giving some increased water relaunch capability.

Leading edge inflatable kites (LEIs) are made of a single skin of fabric with, as the name suggests, an inflated tubular leading edge and inflated ribs. The leading edge and ribs are inflated by the user with a pump prior to launching the kite. The profile of an LEI type kite comes from the inflatable edge and ribs. LEI kites are primarily used for kitesurfing, as they retain their structure when wet and can be easily relaunched from the water after sitting on the surface for an extended period. Conversely, an open-celled foil kite crashed into the sea immediately becomes saturated with water and unflyable.

Uses Edit

Power kites are generally used in conjunction with a vehicle or board, such as in:

Power kites can also be used recreationally without a vehicle or board, as in kite jumping or kite man lifting, where a harnessed kite flier is moored to the ground or one or more people to provide tension and lift

Research is also under way in the use of kites to generate electric power to be fed into a power grid.[1][2][3][4] Laddermills[5] are a type of airborne wind turbine. Kites are used to reach high altitude winds such as a jet stream, which are always present, even if ground level winds available to wind turbines are absent.

Kites of related design are used for sailing, including speed sailing. Jacob's Ladder, a kite-powered boat, set the C-Class world sailing speed record with a speed of 25 knots (46 km/h) in 1982, a record that stood for six years.[6] A kiteboard was the first sailing craft to exceed a speed of 50 knots (93 km/h) in October 2008.[6]

Power kites range in size from 1.2 to 50 m2 (13 to 538 sq ft). All kites are made for specific purposes: some for water, land, power or maneuverability.

Bridle configuration Edit

The lift generated by the kite and other flying characteristics are affected by the kite's angle of attack, which is set by the bridle; the arrangement of lines which terminate the main kite lines and attach to a number of points across the kite's surface. Power kites having 4 or 5 lines come in two variants, fixed bridle and depowerable.

Fixed bridle Edit

Fixed bridle kites have a fixed angle of attack which is set by the bridle. Small adjustments may be possible by adjusting the bridle with the kite on the ground, however the angle of attack is not adjustable whilst the kite is airborne. A high angle of attack setting results in more power from the kite, but at the expense of speed and ability to fly close to the wind. A low angle of attack results in less power, but speed is increased and the kite can fly a lot closer to the edge of the wind window.[7] Fixed bridle kites may be used with handles or a bar, with handles typically being preferable for activities such as kite jumping and kite buggying, and a bar being preferable for kite landboarding.

Depowerable Edit

Depowerable kites are used with a control bar and harness system, with the kite's primary power lines attached to the user's harness through a hole in the centre of the bar. The bar has a few inches of travel along the lines, and the lines are configured such that the user may pull the bar towards themselves to increase the kite's angle of attack, increasing the lift and thus the power delivered through the harness whilst the kite is in flight. Kites used for kitesurfing are almost invariably depowerable, and some modern kites such as bow kites allow power to be reduced by almost 100% for increased safety and versatility.

 
Illustration of LEI (R), bow (L) and foil (T) power kites
Power kite video

Safety Edit

Kite safety systems have become more prevalent in recent years, and today almost all 4 and 5 line kites are used with a safety system designed to remove power from the kite in the event that the user becomes overpowered or loses control of the kite. When flying a fixed bridle kite, one or more straps known as 'kite killers' are attached to the user's wrist(s) by bungee cords. When the handles or bar are released, these straps pull on the kite's brake lines at the trailing edge of the kite, allowing the kite to flap in the wind with no structure.

Depowerable kites have safety systems that work in a similar way, but since the kite is semi-permanently attached to the user's harness, a toggle or handle is used to activate the safety system which releases the bar and power lines from the harness.

Some depowerable kites have a 5th line safety system, the 5th line being redundant during normal use until the safety mechanism is activated. Here, all of the usual four lines are slackened, causing the kite to either fold or roll backwards, and lose its profile to the wind and therefore its power. The kite is left attached to the user by the 5th line to allow retrieval.

History Edit

19th century Edit

In the 1800s, George Pocock used kites of increased size to propel carts on land and ships on the water, using a four-line control system—the same system in common use today. Both carts and boats were able to turn and sail upwind. The kites could be flown for sustained periods.[8] The intention was to establish kitepower as an alternative to horsepower, partly to avoid the hated "horse tax" that was levied at that time.[9] Aviation pioneer Samuel Cody developed several "man-lifting kites" and in 1903 succeeded in crossing the English Channel in a small collapsible canvas boat powered by a kite.[10]

20th century Edit

 
1984 patent of the Legaignoux brothers[11]
 
Peter Lynn lifting a kite in Dieppe, September 1988

In the late 1970s, the development of Kevlar then Spectra flying lines and more controllable kites with improved efficiency contributed to practical kite traction. In 1978, Ian Day's "FlexiFoil" kite-powered Tornado catamaran exceeded 40 km/h.

In October 1977 Gijsbertus Adrianus Panhuise (Netherlands) received the first patent[12] for KiteSurfing. The patent covers, specifically, a water sport using a floating board of a surf board type where a pilot standing up on it is pulled by a wind catching device of a parachute type tied to his harness on a trapeze type belt. Although this patent did not result in any commercial interest, Gijsbertus Adrianus Panhuise could be considered as the originator of KiteSurfing.

On 28 August 1982 Greg Locke and Simon Carter, from Brighton UK, set the world record for kite traction at sea, travelling nearly 26 miles under wind power alone along the English channel.[13] This followed a successful crossing of the English Channel from Sussex to France by Locke & Carter the previous year.

Through the 1980s, there were occasionally successful attempts to combine kites with canoes, ice skates, snow skis,[14] water skis and roller skates.

Throughout the 1970s and early 1980s, Dieter Strasilla from Germany developed parachute-skiing and later perfected a kite-skiing system using self-made paragliders and a ball-socket swivel allowing the pilot to sail upwind and uphill but also to take off into the air at will.[15] Strasilla and his Swiss friend Andrea Kuhn used this invention also in combination with surfboards and snowboards, grasskies and self-made buggies.[16] One of his patents describes in 1979 the first use of an inflatable kite design for kitesurfing.[17]

Two brothers, Bruno Legaignoux and Dominique Legaignoux, from the Atlantic coast of France, developed kites for kitesurfing in the late 1970s and early 1980s and patented an inflatable kite design in November 1984, a design that has been used by companies to develop their own products.

In 1990, practical kite buggying was pioneered by Peter Lynn at Argyle Park in Ashburton, New Zealand. Lynn coupled a three-wheeled buggy with a forerunner of the modern parafoil kite. Kite buggying proved to be popular worldwide, with over 14,000 buggies sold up to 1999.

See also Edit

References Edit

  1. ^ Jha, Alok (2008-08-03). "Giant kites to tap power of the high wind". The Observer.
  2. ^ Martinelli, Nicole (2006-10-10). "Generating Power From Kites". Wired.com. Condé Nast Digital. Retrieved 2009-12-28.
  3. ^ "Competitors for kite generated wind power". Next Big Future. 2008-08-04. Retrieved 2009-12-28.
  4. ^ . Optimisation in Engineering Center (OPTEC) Katholieke Universiteit Leuven. 2010-01-19. Archived from the original on 2011-05-20. Retrieved 2010-01-19.
  5. ^ Jha, Alok (2008-08-03). "Giant kites to tap power of the high wind". The Observer.
  6. ^ a b "500 Metre Records". WSSRC Records. World Sailing Speed Records Committee. Retrieved 2009-12-28.
  7. ^ "The Triple A Bridle Adjustment System" (PDF).
  8. ^ Jakob Jelling History of kitesurfing 29 November 2006 at the Wayback Machine Kitesurfingnow
  9. ^ Peter Lynn A brief history of kitesurfing 19 August 2006 at the Wayback Machine, Aquilandia.com, 2006
  10. ^ Samuel Franklin Cody and his man-lifting kite, www.design-technology.org, 2005
  11. ^ US 4708078, Bruno T. Legaignoux, Dominique M. Legaignoux, "Propulsive wing with inflatable armature" 
  12. ^ [1], Patent NL7603691 (A) ― 11 October 1977
  13. ^ [2], Kitelines Vol 4, No. 3, p60
  14. ^ Mark Harris Sea kayaking and kites 3 July 2006 at the Wayback Machine, July 2002
  15. ^ "Dieter Strasilla".
  16. ^ Dieter Strasilla (1987). History of paragliding: Andrea with surfboard and skywing. Archived from the original on 2021-12-12.
  17. ^ Patent DE2933050

External links Edit

  • Current traction kites are aerodynamically far from optimal A more efficient traction kite would beat all skate sails, at least in light wind.
  • Kiteboarding Links - Guide All about Kite Surfing.
  • Powerkiter (France) - How to use a powerkite (language : French)

power, kite, power, kite, traction, kite, large, kite, designed, provide, significant, pull, user, kitesurfing, strong, onshore, winds, north, shore, oʻahu, hawaii, contents, types, uses, bridle, configuration, fixed, bridle, depowerable, safety, history, 19th. A power kite or traction kite is a large kite designed to provide significant pull to the user Kitesurfing in strong onshore winds off the north shore of Oʻahu in Hawaii Contents 1 Types 2 Uses 3 Bridle configuration 3 1 Fixed bridle 3 2 Depowerable 4 Safety 5 History 5 1 19th century 5 2 20th century 6 See also 7 References 8 External linksTypes EditThe two most common forms are the foil and the leading edge inflatable There are also other less common types of power kite including rigid framed kites and soft single skin kites There are several different control systems used with these kites which have two to five lines and a bar or handles Foil kites consist of a number of cells with cloth ribs in each cell It is the profile of these ribs that gives the kite its aerofoil shape and enable it to generate lift The most common type is the ram air foil where each cell has a gauze covered opening at the front meaning air is forced in during flight giving the kite its stiffness and enabling it to hold its profile Some ram air foils are closed cell where a one way valve locks the air inside the cells giving some increased water relaunch capability Leading edge inflatable kites LEIs are made of a single skin of fabric with as the name suggests an inflated tubular leading edge and inflated ribs The leading edge and ribs are inflated by the user with a pump prior to launching the kite The profile of an LEI type kite comes from the inflatable edge and ribs LEI kites are primarily used for kitesurfing as they retain their structure when wet and can be easily relaunched from the water after sitting on the surface for an extended period Conversely an open celled foil kite crashed into the sea immediately becomes saturated with water and unflyable Uses EditPower kites are generally used in conjunction with a vehicle or board such as in kitesurfing on a kiteboard kite buggying on a purpose built 3 wheeled cart kite landboarding on an all terrain mountain land board kite skating on all terrain roller skates kiteboating on a boat snowkiting on skis or snowboardsPower kites can also be used recreationally without a vehicle or board as in kite jumping or kite man lifting where a harnessed kite flier is moored to the ground or one or more people to provide tension and liftResearch is also under way in the use of kites to generate electric power to be fed into a power grid 1 2 3 4 Laddermills 5 are a type of airborne wind turbine Kites are used to reach high altitude winds such as a jet stream which are always present even if ground level winds available to wind turbines are absent Kites of related design are used for sailing including speed sailing Jacob s Ladder a kite powered boat set the C Class world sailing speed record with a speed of 25 knots 46 km h in 1982 a record that stood for six years 6 A kiteboard was the first sailing craft to exceed a speed of 50 knots 93 km h in October 2008 6 Power kites range in size from 1 2 to 50 m2 13 to 538 sq ft All kites are made for specific purposes some for water land power or maneuverability Bridle configuration EditThe lift generated by the kite and other flying characteristics are affected by the kite s angle of attack which is set by the bridle the arrangement of lines which terminate the main kite lines and attach to a number of points across the kite s surface Power kites having 4 or 5 lines come in two variants fixed bridle and depowerable Fixed bridle Edit Fixed bridle kites have a fixed angle of attack which is set by the bridle Small adjustments may be possible by adjusting the bridle with the kite on the ground however the angle of attack is not adjustable whilst the kite is airborne A high angle of attack setting results in more power from the kite but at the expense of speed and ability to fly close to the wind A low angle of attack results in less power but speed is increased and the kite can fly a lot closer to the edge of the wind window 7 Fixed bridle kites may be used with handles or a bar with handles typically being preferable for activities such as kite jumping and kite buggying and a bar being preferable for kite landboarding Depowerable Edit Depowerable kites are used with a control bar and harness system with the kite s primary power lines attached to the user s harness through a hole in the centre of the bar The bar has a few inches of travel along the lines and the lines are configured such that the user may pull the bar towards themselves to increase the kite s angle of attack increasing the lift and thus the power delivered through the harness whilst the kite is in flight Kites used for kitesurfing are almost invariably depowerable and some modern kites such as bow kites allow power to be reduced by almost 100 for increased safety and versatility nbsp Illustration of LEI R bow L and foil T power kites source source Power kite videoSafety EditKite safety systems have become more prevalent in recent years and today almost all 4 and 5 line kites are used with a safety system designed to remove power from the kite in the event that the user becomes overpowered or loses control of the kite When flying a fixed bridle kite one or more straps known as kite killers are attached to the user s wrist s by bungee cords When the handles or bar are released these straps pull on the kite s brake lines at the trailing edge of the kite allowing the kite to flap in the wind with no structure Depowerable kites have safety systems that work in a similar way but since the kite is semi permanently attached to the user s harness a toggle or handle is used to activate the safety system which releases the bar and power lines from the harness Some depowerable kites have a 5th line safety system the 5th line being redundant during normal use until the safety mechanism is activated Here all of the usual four lines are slackened causing the kite to either fold or roll backwards and lose its profile to the wind and therefore its power The kite is left attached to the user by the 5th line to allow retrieval History Edit19th century Edit In the 1800s George Pocock used kites of increased size to propel carts on land and ships on the water using a four line control system the same system in common use today Both carts and boats were able to turn and sail upwind The kites could be flown for sustained periods 8 The intention was to establish kitepower as an alternative to horsepower partly to avoid the hated horse tax that was levied at that time 9 Aviation pioneer Samuel Cody developed several man lifting kites and in 1903 succeeded in crossing the English Channel in a small collapsible canvas boat powered by a kite 10 20th century Edit nbsp 1984 patent of the Legaignoux brothers 11 nbsp Peter Lynn lifting a kite in Dieppe September 1988In the late 1970s the development of Kevlar then Spectra flying lines and more controllable kites with improved efficiency contributed to practical kite traction In 1978 Ian Day s FlexiFoil kite powered Tornado catamaran exceeded 40 km h In October 1977 Gijsbertus Adrianus Panhuise Netherlands received the first patent 12 for KiteSurfing The patent covers specifically a water sport using a floating board of a surf board type where a pilot standing up on it is pulled by a wind catching device of a parachute type tied to his harness on a trapeze type belt Although this patent did not result in any commercial interest Gijsbertus Adrianus Panhuise could be considered as the originator of KiteSurfing On 28 August 1982 Greg Locke and Simon Carter from Brighton UK set the world record for kite traction at sea travelling nearly 26 miles under wind power alone along the English channel 13 This followed a successful crossing of the English Channel from Sussex to France by Locke amp Carter the previous year Through the 1980s there were occasionally successful attempts to combine kites with canoes ice skates snow skis 14 water skis and roller skates Throughout the 1970s and early 1980s Dieter Strasilla from Germany developed parachute skiing and later perfected a kite skiing system using self made paragliders and a ball socket swivel allowing the pilot to sail upwind and uphill but also to take off into the air at will 15 Strasilla and his Swiss friend Andrea Kuhn used this invention also in combination with surfboards and snowboards grasskies and self made buggies 16 One of his patents describes in 1979 the first use of an inflatable kite design for kitesurfing 17 Two brothers Bruno Legaignoux and Dominique Legaignoux from the Atlantic coast of France developed kites for kitesurfing in the late 1970s and early 1980s and patented an inflatable kite design in November 1984 a design that has been used by companies to develop their own products In 1990 practical kite buggying was pioneered by Peter Lynn at Argyle Park in Ashburton New Zealand Lynn coupled a three wheeled buggy with a forerunner of the modern parafoil kite Kite buggying proved to be popular worldwide with over 14 000 buggies sold up to 1999 See also EditKite types Kite applications Kite mooring SkySails industrial scale power kites for pulling shipsReferences Edit Jha Alok 2008 08 03 Giant kites to tap power of the high wind The Observer Martinelli Nicole 2006 10 10 Generating Power From Kites Wired com Conde Nast Digital Retrieved 2009 12 28 Competitors for kite generated wind power Next Big Future 2008 08 04 Retrieved 2009 12 28 Kite Power Optimisation in Engineering Center OPTEC Katholieke Universiteit Leuven 2010 01 19 Archived from the original on 2011 05 20 Retrieved 2010 01 19 Jha Alok 2008 08 03 Giant kites to tap power of the high wind The Observer a b 500 Metre Records WSSRC Records World Sailing Speed Records Committee Retrieved 2009 12 28 The Triple A Bridle Adjustment System PDF Jakob Jelling History of kitesurfing Archived 29 November 2006 at the Wayback Machine Kitesurfingnow Peter Lynn A brief history of kitesurfing Archived 19 August 2006 at the Wayback Machine Aquilandia com 2006 Samuel Franklin Cody and his man lifting kite www design technology org 2005 US 4708078 Bruno T Legaignoux Dominique M Legaignoux Propulsive wing with inflatable armature 1 Patent NL7603691 A 11 October 1977 2 Kitelines Vol 4 No 3 p60 Mark Harris Sea kayaking and kites Archived 3 July 2006 at the Wayback Machine July 2002 Dieter Strasilla Dieter Strasilla 1987 History of paragliding Andrea with surfboard and skywing Archived from the original on 2021 12 12 Patent DE2933050External links EditCurrent traction kites are aerodynamically far from optimal A more efficient traction kite would beat all skate sails at least in light wind Kiteboarding Links Guide All about Kite Surfing Powerkiter France How to use a powerkite language French Retrieved from https en wikipedia org w index php title Power kite amp oldid 1066315953, wikipedia, wiki, book, books, library,

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