A kite turbine produces energy 80% of the time; remaining 20% of the time pulling the kite back.
The kite flies in a circle across the wind direction and builds up a lifting capacity of the line to the ground station. To produce energy be slowed line at a speed of 1/3 of the wind's velocity. The kite flies then in a spiral, slows winds that hit the area it sweeps.
When the kite being retracted the angle of attack being changed and the area exposed to the wind are reduced and close to insignificant. 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.
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.
The production starts as the wind velocity increases above 5 m/s. At 12 m/s wind, the kite turibine reaches 100% production.