A wind harnessing
system using a plurality of self supporting airfoil kites 50 for production of useful power. The
system comprising multiple airfoil kites 50 in tandem attached to a pivotal control housing 32 by control lines 58L and 58R and support lines 60L and 60R. Control lines 58L and 58R can change length with respect to the length of support lines 60L and 60R to control the airfoil kites' 50 angle-of-
attack,
pitch angle, direction of flight, and
flight speed. The length of control lines 58L and 58R are controlled from
ground station 30 by a movable
pulley system in control housing 32 to adjust the airfoils' direction to follow a specific flight path 140. Control lines 58R and 58L and support lines 60R and 60L are also wound on a power shaft and
pulley system in control housing 32. As the airfoil kites are propelled by the wind at very-high speed, the airfoils generate a powerful
AXIAL force. The control lines 58L and 58R and support lines 60L and 60R are then reeled-out under this AXIAL tension causing the power shaft and
pulley system in control housing 32 to turn a generator to generate
electricity. After airfoil kites 50 have finished their reel-out
power stroke 140a, the airfoil's
pitch angle is made negative so they can be reeled-in by their control and support lines using a minimum of force along path 140b. Once the airfoils have been rewound to the proper distance, the airfoils are again angled for high-speed operation to generate powerful
AXIAL force and reeled-out along 140c to provide another
power stroke. The airfoil kites are then reeled-in again along path 140d and the entire process repeats starting with
power stroke 140a. Since the force to rewind the airfoils is much less than the force generated during reel-out, there is net power generated.