Foil kite - AbsoluteAstronomy.com

Foil kites are soft kites based on the design of the parafoil

Parafoil

A parafoil is a nonrigid airfoil with an aerodynamic cell structure which is inflated by the wind. Ram-air inflation forces the parafoil into a classic wing cross-section. Parafoils are most commonly constructed out of ripstop nylon....

. They consist of a number of cells running fore to aft, some or all of which are open at the front to allow air to inflate the kite so it takes on an aerofoil

Airfoil

An airfoil or aerofoil is the shape of a wing or blade or sail as seen in cross-section....

section. Due to the amount of power that these kites can generate, they can be used for a variety of different activities including kitesurfing

Kitesurfing

Kitesurfing or Kiteboarding is an adventure surface water sport that has been described as combining wakeboarding, windsurfing, surfing, paragliding, and gymnastics into one extreme sport. Kitesurfing harnesses the power of the wind to propel a rider across the water on a small surfboard or a...

, kiteboarding on land, snowkiting

Snowkiting

Snowkiting is an outdoor winter sport where people use kite power to glide on snow or ice. The sport is similar to kitesurfing, but with the footwear used in snowboarding or skiing. In the early days of snowkiting, foil kites were the most common type; nowadays some kitesurfers use their water gear...

, kite buggying and recreational kiting.

Foil kites are flown with various line set-ups that includes 2-, 3- and 4-line systems; 2-line systems consisting of rings, wrist bands or bar compared to depowerable 4-line systems using a bar or handles. (See also: kite control systems

Kite control systems

Kite types, kite mooring, and kite applications result in a wide variety of kite control systems. Contemporary manufacturers, kite athletes, kite pilots, scientists, and engineers are expanding the possibilities....

)

In order to make them suitable for use on water some foils have limited air inlets in the centre of the leading edge, with valves to keep the air in and (hopefully) the water out. Internal holes in the cell sides allow the whole kite to inflate. These kites are naturally slower to inflate than an open-fronted foil.

Foils are the most efficient of the power kite

Power kite

A power kite or traction kite is a large kite designed to provide significant pull to the user.They come in three main forms: foils, leading edge inflatables and supported leading edge. There are also rigid-framed kites and soft single skin kites. There are several different control systems used...

s. The aerofoil section means that they can still provide significant lift when parked overhead, unlike leading edge inflatable kite

Leading edge inflatable kite

A leading edge inflatable kite or LEI is a single skin kite with inflatable bladders providing structure. It is useful as a power or traction kite. These kites are flown using 2, 4 or 5 control lines and a bar. A LEI is a great kite for water use because the inflated bladders cause it to float on...

Development and History of Foil Kites

One of the first popular foil-based kites was the development of a two-line power kite by Ray Merry and Andrew Jones in the early 1970s in England which became known as the Flexifoil (and later the Flexifoil

Flexifoil

Flexifoil International is a designer and manufacturer of kite products. Started in 1972 by Ray Merry and Andrew Jones in Cambridgeshire, England, Flexifoil has become known for its power kiting products. Flexifoil owes its early success to its original Stacker 6 kite, which became the first...

company). Merry and Jones also experimented with kite pulled vehicles, a concept which was further developed by Peter Lynn

Peter Lynn

Peter Lynn is a New Zealand kitemaker, engineer and inventor. He is notable for his construction of the world's largest kites , giant inflatable display kites , the popularisation of kite buggying and contributions to the development of power kiting and kitesurfing...

and popular today in its current form as kite buggying.

The Flexfoil kite, still sold today as a 'Stacker' has a solid carbon spar in its leading edge to maintain its shape as it flies.

The second-generation two-line parafoil was called the Sparless Stunter, designed by Ted Dougherty. Development began mid-1985 and was available for sale in mid-1988. These parafoil kites were square in shape and had 6 cells. In September 1988 a 460-square-foot (43 m²) version was flown at the Ocean City Sunfest breaking the record for the World's Largest Stunt kite. In January 1989 the Sparless Stunter was introduced at the KTA show as the first totally sparless parafoil stunt kite. The Sparless Stunter saw a very brief history as kite technology evolved by May 1990 the first version of the original Quadrifoil was flown in competition at Wildwood, NJ. The first Quadrifoil was essentially two Sparless Stunters sewn together with a swept back shape. Later generations were refined into the widely known “classic.”

Peter Lynn introduced a similar foil-based kite in 1991 for kite traction with the Peter Lynn 'Peel' - this was a completely soft foil kite without any spars. The Peel was a popular kite traction kite in the early to mid-90s and continued to sell into the late 90s and was sold in sizes up to 10m^(2). The Peel was also a two-line kite flown in the same style as the Flexifoil.

The next evolution on the foil kites for traction activities was the development of the 4-line foil kite. While 2-line kites require sometimes significant push and pull arm movement to fly (especially true the larger the kite), the development of the 4-line kite required less arm movement. 4-line kites are flown with two lines on each handle: a top line (or power line), and a bottom line (or brake line). 4-line kites can still be flown with push and pull arm movement, but if the bottom brake line is pulled in the bottom edge of the kite stalls and will cause the kite to turn on that bottom edge. This results in tighter turns with less arm movement - this is important if sitting in a kite buggy

Kite buggy

A kite buggy is a light, purpose-built vehicle powered by a traction kite . It is single-seated and has one steerable front wheel and two fixed rear wheels. The driver sits in the seat located in the middle of the vehicle and accelerates and slows down by applying steering manoeuvres in...

.

One of the first available 4-line kites was the Quadrifoil, designed by Ted Dougherty, popular as a buggy kite in the mid-90s. The Quadrifoil in its original design became known as the 'Classic' - the kite was rectangular in shape in contrast to today's more elliptical designs. Later evolutions of the kite were sold as the Competition (more elliptical in design - C1, C3), Q2000 range, and lastly the Competition X range (XXS, XS, XM, XL and the XXL). Although these were sold under the Quadrifoil brand-name by Active People, none of these were designed by Dougherty himself.

Dougherty's next kite after the Quadrifoil was the 'QuadTrac' build and sold in by Skynasaur in the US in the mid-90s.

Following the success of the Quadrifoil, Ray Merry (of Flexifoil fame) designed the Skytiger range of 4-line kites that was the dominant 4-line traction kite of the mid to late 90s. This too was a rectangular design and a very solid and stable flying kite. The design was refined for more pull with the introduction of the 'Hi' series with an increased aspect ratio (wing)

Aspect ratio (wing)

In aerodynamics, the aspect ratio of a wing is essentially the ratio of its length to its breadth . A high aspect ratio indicates long, narrow wings, whereas a low aspect ratio indicates short, stubby wings....

. Commonly available were the Hi-22, Hi-40 (3.7 metre) and the Hi-60 (5.6 metre). A Hi-80 and Hi-100 were also available although not commonly seen. The 'Hi' series was available in regular ripstop nylon, or also available made from 'Icarex', a lightweight polyester material that allowed the kites to fly in much lower winds.

In Europe in the late 90s the kite buggy scene was becoming popular and there were a large number of traction kite designs from a large number of European companies. The designs took two different directions - those that were steady and reliable in most winds and typically resistant to 'luffing

Luffing

In sailing, luffing refers to when a sailing vessel is steered far enough toward the direction of the wind , or the sheet controlling a sail is eased so far past optimal trim, that airflow over the surfaces of the sail is disrupted and the sail begins to "flap" or "luff"...

' in gusty or unreliable winds, and those that were tuned to produce maximum pull at the cost of stability (known as 'race kites'). In the UK in the late 90s, the 'Predator' kite designed by Peter Mirkovic of Sky Kites was the most popular and successful traction kite amongst people competing in buggy races, winning the majority of races at this time. Kites are very popular now. Many people have paid the kite makers a lot of money to make kites.

By late 90s/early 00s a number of new companies entered the traction kite market that had prior experience with development of paragliders, and used this knowledge and experience for the developmment of traction kites. These companies included Airea (no longer in business?), Libre powersails in Germany, Paracontrol and their kite business Paracontrol Kite Division (PKD) in Germany, and Ozone in France.

External links

Nautikites Blog (http://www.nautikites.net/blog/index.php?entry=entry091117-182426) - The compared evolution of kitesurfing and other great air & water sports.
Extreme Kites (www.ExtremeKites.com.au) - Leading Power Kite Information Portal, Forums, Videos, Reviews, News and Galleries.

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.