Kite rig

Kite rigs are wind-assisted propulsion systems for propelling a vehicle. They differ from conventional sails in that they are flown from kite control lines, not supported by masts. Vehicles driven by kites include boats, buggies, and vehicles with snow and ice runners. They may be as simple as a person flying a kite while standing on a specialized skateboard, or be large, complex systems fixed to the vehicle, with powered and automated controls. They have recreational and commercial uses. Current kite rigs can be sailed within 50 degrees of the wind. This allows them to sail upwind by tacking. A power kite is held at an angle to the wind using control lines. Like any other sail, the kite develops lift and drag, pulling the vessel. The vector of the kite's pull is added to the forces produced by the vessel (water resistance against the hull, force of wheels against the ground, etc.) to move the vessel in the desired direction. Windspeed increases with height, allowing kites to develop substantially more thrust per unit area than a conventional sail. Winds are also steadier and less turbulent higher up. Kites may be adjusted with respect to the wind, manually or by an automated system. A kite cannot stay aloft when there is no wind, and must be re-launched. Kite rigs power a variety of recreational conveyances on water and land. On water, kites are used to power surf-board-like boards in the sport of kitesurfing. Kiteboating is done in boats with kite rigs. On land, kite landboarding derives the same mode of power for skate-board-like boards. Over snow, kites power snowboards or skis in the sport of snowkiting. Traction kites for solosports generally have an area of 1-16 square meters, with anything over ~5 square meters being a big kite that requires expertise. Ship-pulling kites run to hundreds of square meters of area and require a special attachment points, a launch and recovery system, and fly-by-wire controls. The SkySails propulsion system consists of a large foil kite, an electronic control system for the kite, and an automatic system to retract the kite.