12-02-2016, 04:29 PM
Introduction:
Two major jet streams, the Sub-Tropical Jet and the Polar Front Jet exist in both Earth hemispheres. These enormous energy streams are formed by the combination of tropical region sunlight falling and Earth rotation. This wind resource is invariably available wherever the sun shines and the Earth rotates. These jet stream winds offer an energy benefit between one and two orders of magnitude greater than equalrotor- area, ground mounted wind turbines operating in the lowest regions of the Earth’s boundary layer. In the USA,Caldeira and O’Doherty and Roberts have shown that average power densities of around 17 kW/m2 are available. In Australia, Atkinson et al show that 19 kW/m2 is achievable.These winds are available in northern India, China, Japan,Africa, the Mediterranean, and elsewhere.Various systems have been examined to capture this energy, and these include tethered balloons, tethered fixed-winged craft, tether climbing and descending kites, and rotorcraft.Our preferred option is a tethered rotorcraft, a variant of the gyroplane, where conventional rotors generate power and simultaneously produce sufficient lift to keep the system aloft. This arrangement, using a twin-rotor configuration, has been described and flown at low altitude by Roberts and Blackler