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Unpowered aircraft
Hang glider launching from Mount Tamalpais
Part of a series on
Categories of Aircraft
Supported by Lighter-Than-Air Gases (aerostats)
Unpowered Powered
Balloon Airship
Supported by LTA Gases + Aerodynamic Lift
Unpowered Powered
Hybrid airship
Supported by Aerodynamic Lift (aerodynes)
Unpowered Powered
Unpowered fixed-wing Powered fixed-wing
Glider
hang gliders
Paraglider
Kite
• Powered airplane (aeroplane)
powered hang gliders
Powered paraglider
Flettner airplane
Ground-effect vehicle
Powered hybrid fixed/rotary wing
Tiltwing
Tiltrotor
Mono Tiltrotor
Mono-tilt-rotor rotary-ring
Coleopter
Unpowered rotary-wing Powered rotary-wing
Rotor kite Autogyro
Gyrodyne ("Heliplane")
Helicopter
Powered aircraft driven by flapping
Ornithopter
Other Means of Lift
Unpowered Powered
Hovercraft
Flying Bedstead
Avrocar

Unpowered aircraft are a group of aerial vehicles that can fly without propulsion. They can be classified as gliders, balloons and kites. In this instance, 'flight' means a trajectory that is not merely a vertical descent such as a parachute. In the case of kites, the flight is not free, but tethered. In the case of balloons, the flight is free but there is little directional control. The remainder of this group are the heavier-than-air craft such as gliders, hang gliders and paragliders that have complete directional control and so can fly freely.

Contents

History

The first manned aircraft were kites, balloons and gliders. Kites are recorded in ancient Chinese history as being used for lifting men. Unmanned hot air balloons are also recorded in Chinese history. However the first free flight (ie untethered) by manned craft was by 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.[1] It flew in 1849. Thereafter gliders were used for aerodynamic research, until their sporting use was developed in the 1920s.

Glider aircraft

Gliders (sailplanes), hang gliders and paragliders can gain some initial energy from a launch process, but then can then gain additional potential energy from rising air such as thermals. The launch may be by pulling the aircraft into the air with a tow-line, with a ground-based winch or vehicle, or with a powered "tug" aircraft. For foot-launched aircraft, there is also the option of merely stepping off a high location.

For glider aircraft to generate lift, they must maintain sufficient forward air speed. This is achieved by a gradual descent, though if the air is rising faster than the aircraft is descending, it will also ascend. Today, the majority of the use of all types of glider aircraft is recreational.

Balloons

Balloons drift with the wind, though normally the pilot can control the altitude either by heating the air or by releasing ballast, giving some directional control (since the wind direction changes with altitude). A tethered wing-shaped balloon has been tested [2] which has greater directional control. Today, the majority of the use of manned balloons is recreational, whereas unmanned balloons are widely used for meteorological measurement.

Kites

Kites are aircraft[3] that are tethered to the ground or other object (fixed or mobile) or other means that maintains tension in the kite line; and rely on virtual or real wind blowing over and under them to generate lift and drag. Kytoons are balloon kites that are shaped and tethered to obtain kiting deflections, and can be lighter-than-air, neutrally buoyant, or heavier-than air.

See also

References

  1. ^ Dee, Richard (2007). The Man who Discovered Flight: George Cayley and the First Airplane. Toronto: McClelland and Stewart. ISBN 978-0771029714.  
  2. ^ Winged balloon
  3. ^ "Kites". NASA. http://www.grc.nasa.gov/WWW/K-12/airplane/kite1.html. Retrieved 2009-03-18.  

External links

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