Cierva C.17

The Cierva C.17 was a British experimental autogyro built by the Cierva Autogiro Company in England in 1928, in association with Avro, which designated it the Type 612. It tried to build on the successful Cierva C.8 by starting from the smaller, more streamlined fuselage of an Avro Avian IIIA. The first version was powered by a 90 horsepower A.D.C. Cirrus III piston engine, and a Mark II was fitted with an Avro Alpha radial piston engine. The type was found to be underpowered, and when the first attempt at fitting a more powerful engine still did not give acceptable performance the design was abandoned. It had a single crew seat, a main rotor about 33 feet across and a published maximum speed of 90 miles per hour.