Sikorsky Cypher

The Sikorsky Cypher is an unmanned aerial vehicle developed by Sikorsky Aircraft, a vertical take-off and landing craft that uses two opposing rotors enclosed in a circular shroud. Work began in the late 1980s on a small machine with coaxial rotors inside a torus-shaped duct that added lift and made handling safer. The first proof-of-concept aircraft measured 1.75 metres across and flew in the summer of 1988; a larger prototype with a 40 kilowatt Wankel engine made its first flight in April 1992 and, over the 1990s, more than 550 demonstration flights for United States government agencies. The Cypher could carry a sensor payload or external loads of up to 23 kilograms, and it led to the larger Cypher II.