Kites

The idea of flying with a pair of wings alone seemed to have been forgotten after the deaths of lilienthal and other pioneer gliders around 1900. Then in the 1940s, an American called Francis Rogallo created a new kite plane using fabric delta (triangular) wing  at first,it was developed simply, as a steerable parachute for bringing equipment back to earth from space. But some people began to fly Rogallo wings by hanging beneath the wing and steering it by shifting weight. The idea caught on. Soon "hang-gliders" were running off hills all over the world. Hang-gliding is now one of the most popular aerial sports.

Modern Glider
 

Although gliders played a prominent part in the pioneering days of aviation, interest in them waned after powered flight was achieved. The problem was that, without power, gliders can only fly, in effect, "downhill" and, for a long time, no glider could stay up for than a few seconds. Then, in the early 1920s, it was found that gliders could ride up on the wind rising over ridge or hill, so that skilled pilots could stay aloft for hours at a time. Germans and allied used Gliders for transportation troops during World War II. In invasion to Belgium and Crete Island German used many of them and allied used for D-Day too.