Even so, Leonardo grasped the essential differences between the flexible, sail-like wings of hang-gliders and the more rigid structures that were to become the staple of sailplanes and powered aircraft.
Sailplanes insulate the pilot too much from the passage of air.
These include hang gliders, gliders, and sailplanes.
Gliders are usually used for flight training and have the capability to fly reasonable distances when they are catapulted or towed into the air, but they lack the dynamic sophistication of sailplanes.
The second are sailplanes, which have reached new levels in structural and aerodynamic refinement.
An early example of the latter is the U.S. AeroVironment FQM-151 Pointer, a UAV weighing less than 10 pounds (4.5 kg) and resembling a powered model sailplane.
Most sailplanes are towed to launch altitude, although some employ small, retractable auxiliary engines.
Also encompassed are specialized aircraft such as agricultural sprayers, acrobatic craft, sailplanes, motor gliders, air ambulances, fire-control aircraft, pipeline-patrol aircraft, and others with a broad variety of civil applications.
In a sailplane, height attained by mechanical, orographic, or thermal techniques is translated into speed by means of gravity.
They, and sailplanes in particular, have become increasingly popular for recreational purposes and as vehicles for sports competition.
Gliding for sport originated in Germany in 1910; the sailplane was first developed there after World War I, during the time when the Treaty of Versailles prevented the Germans from constructing powered aircraft.
