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In a gentle breeze, if the user action increases the air speed around the kite 10 times, the generated force increases 100 times, since the wind force acting on a kite is proportional to the square of the wind speed acting on it. [53] Thus the relevant notion of apparent wind, which is the actual wind acting on the moving kite, sail or wing.
Crosswind kite power is power derived from airborne wind-energy conversion systems (AWECS, also AWES) or crosswind kite power systems (CWKPS). The kite system is characterized by energy-harvesting parts flying transversely to the direction of the ambient wind, i.e., to crosswind mode; sometimes the entire wing set and tether set are flown in crosswind mode.
In common usage, wind gradient, more specifically wind speed gradient [1] or wind velocity gradient, [2] or alternatively shear wind, [3] is the vertical component of the gradient of the mean horizontal wind speed in the lower atmosphere. [4] It is the rate of increase of wind strength with unit increase in height above ground level.
For example, a 10 knot wind coming at 45 degrees from either side will have a crosswind component of 10 knots × sin(45°) and a head/tailwind component of 10 knots × cos(45°), both equals to 7.07 knots. Pilots can use a use a crosswind component chart to calculate the headwind component and the crosswind component.
The tug kite line is very elastic; when tensed, the line is long; during use for launch, the kite line shortens. Controlling the kite's wing attitudes is up to the pilot who frequently is hung from a short kite line while controlling a triangle control frame or other airframe part or even aerodynamic surface controls. Professional instruction ...
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. [9] 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.
Wind speeds can vary considerably across a wind farm site if the terrain is complex (hilly) or there are changes in roughness (the height of vegetation or buildings). Wind flow modeling software, based on either the traditional WAsP linear approach or the newer CFD approach, is used to calculate these variations in wind speed. Energy production ...
The outright sailing speed record has since been claimed by the French trimaran Hydroptère which, on 4 September 2009, reached a speed of 51.36 knots over 500 meters and 50.17 over a nautical mile in open ocean and only 25 to 30 knots of wind.