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.