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.
The Future World of Transportation 13 Feb 2007