Theory of an Air Cushion Landing System for Aircraft
Technical rept. Aug 1968-Jun 1971
AIR FORCE FLIGHT DYNAMICS LAB WRIGHT-PATTERSON AFB OH
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The Air Cushion Landing System is a scheme to replace the wheeled landing gear on aircraft by a peripheral jet air cushion. The concept employs a flexible elastic membrane or trunk which is attached to the bottom of the aircraft fuselage. During flight, the trunk shrinks elastically and hugs the bottom of the fuselage like a de-icing boot. When a flow of air is applied to the inside of the trunk, the elastic material stretches and forms an elongated doughnut-shaped protrusion on the underside of the aircraft. The air flow is ducted by the trunk to the fuselage periphery and exhausted through a large number of holes or slots. As a result, a pressure builds up under the aircraft when the ground is approached. The pressure is sufficient to support the aircraft and absorb its vertical landing velocity. The study develops analytical relationships between the variables associated with the Air Cushion Landing System. Included are the following The derivation of a theory which predicts the static characteristics of the system Analytical methods for predicting flow, jet height and power requirements Curves which illustrate the interrelationships among the design variables Computer programs for predicting the cross-sectional area and shape of the elastic trunk The development and test of an analytical model which predicts the dynamic response of the system to landing impact A discussion of the design considerations for the system.