Sinclair C5 of Liverpool, which planned to sell 1,000 of them to an Egyptian businessman for use on a university campus while another 1,500 were intended to be sold in the UK. Many reasons have been suggested for the failure of Sinclair Vehicles and what Dale calls "the jigsaw of the C5's disappointment". One of the receivers of Sinclair Vehicles, John Sapte, suggested that Sinclair had taken the wrong tack with its marketing of the C5: "It was presented as a serious transport, when perhaps it should have been presented as a luxury product, an up-market plaything." Ellar's director Maurice Levensohn took
Personal air vehicle breakthroughs. A ground transport alternative is enabled by unmanned aircraft technologies: Autonomous Systems and electric propulsion. Barriers include aviation safety, airworthiness, operating costs, usability, airspace integration, aircraft noise and emissions, tackled first by small UAS certification then experience. Other names discussed include PIVITOLs (Personal Vertical TakeOff vehicles), Air-cars, PACs (Personal AirCraft), AVs (Air Vehicles). The first technical paper to explain the difference in vehicle characteristics between PAVs and existing General Aviation single engine piston aircraft was "Personal Air Vehicles: A Rural/Regional and Intra-Urban On-Demand Transportation System" by Mark D. Moore (the NASA PAV Sector Manager) from NASA Langley Research Center.