Unpowered aircraft

Unpowered aircraft can remain airborne for a significant period of time without onboard propulsion.

Gliding aircraft include sailplanes, hang gliders, and paragliders that have full directional control in free flight.

The first manned free flight was in a hot-air balloon built by the brothers Joseph-Michel and Jacques-Etienne Montgolfier in Annonay, France in 1783.

The first practical, controllable glider was designed and built by the British scientist and pioneer George Cayley who many recognise as the first aeronautical engineer.

Free-flying ballooning using coal gas (which has about half the lifting effect of hydrogen) became a popular sport.

Military assault gliders were also developed during World War II, while the rotor kite was used by the German Navy for seaborne observation.

If the air is rising faster than the aircraft is descending through it, the glider will gain height and additional potential energy.