The principle

A kite turbine produces energy 90% of the time; remaining 10% of the time pulling the kite back.

The kite flies in a circle like the tip of  the wind turbine blades. To produce energy the kite is reeled out with a speed 1/3 of the wind speed. The kite flies then in a helical path, extract the energy from the wind that passes the area it sweeps.

When the kite being retracted the angle of attack being changed and the area exposed to the wind are reduced. The kite being retrieved several times faster than the reel out speed. 

Basis in principle

Energy = power x time

Power = traction force x reel out speed

The speed we pull out the cord with 1/3 of wind speed up to 12 m / s wind, that we pull out the line with a variable speed from 0 to 4 m / s. Highest effect being dimensioned for plant and achieved 12 m / s wind where we reels out 4 m / s.

The tether being pulled out from the reel drum by 1/3 of the wind speed, up to 12 m / s wind, causing a variable reel out speed from 0 to 4 m/s as the wind increases to 12 m/s. For wind speeds above 12 m/s the reel out speed stays constant at 4 m/s.

Example:

To produce 30kW must kite pull 7500 N with force in 12 m / s wind.

We find pull force by dividing the power 30,000 W by 4 (m / s) which is the reel out speed at 12 m / s wind.