The Avrocar saucer shaped aircraft which was a conceptual vertical take off and landing (VTOL) aircraft built by Canadian company Avro in 1958 for the US Air Force. It was able to hover a few feet off the ground from the thrust generated by a centrally located 'turborotor'. When flown without tethers the Avrocar was unstable and could only reach a top speed of only 35 mph. The engines created excessive heat and noise. The project was cancelled in 1961.