In a flap

日期:2019-03-06 02:11:03 作者:褚脉橼 阅读:

By Paul Marks TRADITIONAL helicopters have a vertical tail rotor to stop the main rotor from spinning the craft endlessly round and round. But running that second rotor wastes around 8 per cent of the chopper’s fuel, says Vladimir Savov, an expert in aerodynamics at the Bulgarian Air Force Academy in Sofia. So to save that fuel, Savov has invented the “rotopter”,