An excerpt from the patent abstract:
"The combustion engine is also geared to vertically oriented ducted fans (40) and a horizontally oriented ducted fan or propeller (76) for providing the vehicle with the capability of travel through the air. Pressure jets (62), supplied with compressed air from a compressor (66) driven by the combustion engine, augment the lift of the ducted fans and provide steering for the vehicle."

You can see United States patent 5,141,173 here.

See also:
The Future World of Transportation 13 Feb 2007