Hovercraft project design & construction

Abstract

Hovercraft or Air Cushion Vehicle (A.C.V.) is the name given to vehicles which are dependent for their support on the deliberate generation of a cushion of air between their bottom surfaces and the land or water over which they may operate. In machines of this type, a more or less static region of air, at slightly more than atmospheric pressure, is formed and maintained below the craft. The difference between the pressure of the air on the lower side and the atmospheric pressure on the upper side, produces a force tending to lift the craft. The trapped mass of air under the craft. is formed by the effect of an annular jet of air, directed inwards and downwards from near the periphery of the underside. The downwards ejection of the annular jet produces an upward reaction on the craft, tending to lift it. In steady hovering, the weight is balanced by the jet thrust and the force due to the 'cushion' of air below the craft. The difference between the hovercraft and normal direct jet lift machines lies in the air cushion effect which amplifies the vertical force available, permitting the direct jet thrust to be only a small fraction of the weight of the craft. Forward motion of the craft can be achieved in either of several ways: 1. An aft-mounted engine driving an airscrew. 2. An integrated air lift propulsion system in which air is bled from the lift supply and ejected through ducts at the rear of the craft. 3. By the use of ducted propellers [...].