Robert D Hunt, chairman and co-founder of Nevada based Hunt Aviation, Corp, invented a new flight technology called “gravity powered hybrid aircraft”. The aircraft is a rigid glider made of lightweight composite materials, and this allows it to manupulate compressed air for landing and departure, i.e. taking in new compressed air for landing and discharging compressed air for departure; the theory behind it is similar to submarine’s.
Here’s the interesting part quoted from their website which also explains how does the aircraft generate the power:
Power is generated by wind turbines aboard the hybrid aerostat glider during both upward and downward gliding. A portion of the wind turbine generated power can be stored and brought back to earth for later use and may be used for propulsion during take-off and landing for example. In the alternative, power may be used while flying to produce hydrogen via electrolysis or to produce other valuable chemicals or goods. These products can be manufactured while traveling enroute to deliver the products to a purchaser. The GravityPlane can become a flying factory that can generate the power to run a manufacturing process from the atmosphere!
Link: Fuel-less Gravity Powered Flight | Via: toxicle.org