Foil kite

Foil kites are soft kites based on the design of the parafoil. 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 section. Due to the amount of power that these kites can generate, they can be used for a variety of different activities including kitesurfing, kite landboarding, snowkiting, kite buggying, kite-energy systems or airborne wind energy, 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)

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 kites. The aerofoil section means that they can still provide significant lift when parked overhead, unlike leading edge inflatable 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 company). Merry and Jones also experimented with kite pulled vehicles, a concept which was further developed by Peter Lynn and popular today in its current form as kite buggying.

The Flexifoil 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.”

...
Wikipedia