Filling the Gap

TWENTY years ago the phenomenon of ground‐effect was known and to some extent understood but at the same time regarded generally with some misgivings. An aircraft in close proximity to the ground was often found to have lift capabilities far in excess of those evident at higher altitudes and this was attributed to the air ‘trapped’ between the aircraft and the ground. To the student pilot attempting a three‐point landing at a predetermined spot on the runway the tendency for the aeroplane with flap down to float on interminably was all too easily attributed to ground‐effect. This feature, embodied in the ram wing, was one portent of a number of air‐riding vehicles that certain far‐sighted men recognized as having tremendous potential. More recently it has become increasingly apparent that the ground‐effect phenomenon has a definite application to transportation and many countries are actively pursuing research and development investigations regarding the choice of the most suitable system.