I want to create lift of an object about the size of 36 in by 8 in. the lift would be provided by compressed air and the object would have an air dam and skirt (like hovercraft) and lift approx 250 lb mass on it to floatation level of .05 in (where skirt would not reach above lift surface. What type of psi would it take to constant hover. Assume Skirted area is approx. the area of the underside of the object. If air pressure underneath equals mass of object doesnt buoyancy occur?