Gliders have several advantages over aeroplanes. They are relatively cheap, simple, quiet, efficient, safe and low maintenance.
Gliders are currently used almost exclusively as recreational vehicles. There are several reasons for this:
-They need to be towed into the air by an aircraft, so the
obvious question is why not just use the aircraft itself as the transport means. There are other launch methods such as a bungee fling, cliffs and hot air balloons but these have their own disadvantages.
-They are at the mercy of the weather, and it takes skill to navigate the thermals and waves.
-They have limited range.
Some improvements to gliders to make them more practical as a transport means:
-Gaining altitude is the energy consuming aspect of flying. Gliders could be launched from tethered blimps. The glider would be hooked onto a blimp which rises due to buoyancy. When it reaches a sufficient altitude (eg 800 m) the glider is released, first diving to gain speed, then flattening to glide. The blimp would then be reeled in by a motor on the ground.
-A head-up display for showing information such as thermals and maps. Information from weather stations and instruments on the glider (such as radar) would be used to calculate optimal paths.
-Solar chimneys could be placed strategically around the country (on popular routes). The chimneys could have a valve mechanism which is operated remotely by the glider pilot. On approach, the pilot would open the chimney valve, releasing the trapped hot air, hence creating an artifical thermal.
-The gliders could also be motorised to increase range.