blown down by the aerodynamic drag applied on the wide and unavoidable Reynolds surface excluding them de facto from the HAWP category. W. R. Benoit US Patent 4350897 Lighter than air wind energy conversion system by William R. Benoit, filed Oct 24,1980, and issued: Sep 21, 1982. The TWIND system ( International patent application PCT/W02010/015720) is based on the use of a sail surface elevated by the climbing force of an aerostatic balloon connected to the ground by a cable used also for energy transmission. The wind present at high altitudes creates a horizontal push on the sail which in its movement transmits this energy to the ground via the connecting cable. At the end of its movement forward, the sail surface is reduced allowing it to move upwind with reduced energy waste. The Magenn aerostat is a vertical-axis wind turbine held with its axis horizontal by bridling the axis traverse to the wind so that Magnus-effect lift obtains during autorotation; the electricity is generated with end-hub generators. The LTA Windpower PowerShip uses lift from both an aerostat and wings. It operates close to neutral buoyancy and doesn't require a winch. Power is generated by turbines with the propellers on the trailing edge of the wings. The system is designed to be able to take off and land unattended. Airbine proposes to lift wind turbines into the air by use of aerostats; the electricity would return to ground loads by way of conductive tether. Airship power turbine by William J. Mouton, Jr., and David F. Thompson: Their system integrated the turbine within the central portion of a near-toroidal aerostat, like putting a turbine in the hole of an aerostat donut. The HAWE system is developed from Tiago Pardal's idea. This system consists of a pumping cycle similar to that of kite systems. In the generation phase, the pulling force increases 5–10 times due to the Magnus effect of a spinning cylinder (aerial platform). Like a kite, the pulling force produced by the aerial platform will unwind the cable and generate electricity on the ground. In the recovery phase it rewinds the cable with no Magnus effect in the aerial platform. Wind Fisher is developing cross-wind capable Magnus effect balloons which generate electricity with ground based generators operating a pumping cycle with a pair of helium inflated, lighter-than-air cylindrical wings. The company, based near Grenoble, is currently testing a 1.7m span