The idea of using an air-cushion as a means or aid to acceleration and reduction in (hydrodynamic) drag was first explored by Sir John Thornycroft, a British engineer, who, in the 1870's built some experimental models on the basis of an air cushion system that would reduce the drag of water on boats and ships.
In 1877 he successfully patented the idea and his theory was that if a ship's hull was given a concave bottom, which could be filled - and replenished - with air, it would create significant additional lift. And so the air cushion effect was born.
Decades later scientists and inventors were still busy with his ideas but without any practical applications. With the coming of the airplane however, it was noticed that additional lift was obtained if the plane flew closer to land or water, creating a "funnel effect", a cushion of air.
The air lift that this funnel effect created differed with the type of wing and its height above ground. The effect was strongest if this height was between one half and one third of the (average) front-to-rear breadth of the wing. Also known as "chord".
The next two decades saw little interest in air cushion development.
The successful use of the air cushion effect was not lost on engineers after World War 2 was over and in the early 1950's British, American and Swiss engineers started to rethink Sir John Thornycroft's problem.
The Englishman Christopher Cockerell, commonly seen as the father of the hovercraft, being retired from the army, settled into boat building where he soon got captivated by Thornycroft's problem of reducing the hydrodynamic drag on the hull of a boat by using some kind of air cushion.