Aerotechnik WGM 21 was a single-seater helicopter, developed by the the German company “Aerotechnik, Entwicklung und Apparatebau GmbH” in Frankfurt. It has been a rare quadrocopter type. The engineers wanted to develop a simple VTOL aircraft, easier to fly than a conventional helicopter that should cost not more than a medium-class car. Furthermore it had to require little place in a hangar.
The WGM 21 had four diametral arranged rotors, each with two rotor blades. It didn’t need neither a tail rotor nor any control surface. The steering around its yaw axis was similar to the steering of a plane with pedals. The rotor arms moved around their own axis.
The four rotors were connected with the airframe by aluminium tubes. A two cylinder BMW flat engine with a power of 54 hp drove the rotors. The power transmission had been performed by V-belts. The pilot sat in an open seat. Controls were a V-shaped stick and pedals.
Text from Wikipedia, the free encyclopedia