How Do Hang Gliders Fly?
The sport of hang gliding developed in the 1950s as aerospace engineers constructed "parawings," made of lightweight bamboo frames and polythelene sails. Modern hang gliders allow skilled pilots to ride currents of air aboard a simple, lightweight aircraft. There is no propulsion system or engine; the flight depends on the pilot's skill in keeping the craft stable, steady and aloft. The basic science behind hang gliding is simple, and the sport can be learned in a short series of lessons.
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Takeoff
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Hang gliders are constructed of a flexible single wing mounted on aluminum tubes, a harness for the pilot, and a control bar, used by the pilot to control the direction and pitch of the aircraft. The pilot launches the craft from a hillside, along which he or she runs to gain initial speed and lift. The forward movement of the craft keeps air moving over and across the wing, which overcomes the force of gravity.
Thermals
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The pilot's task is to locate air currents known as thermals that continuously rise from the ground and can keep the hang glider aloft. The pilot searches for thermals by watching for rising dust, or birds that are stationary or gaining altitude with little effort. By circling the area of rising air, he or she can gain altitude and extend the flight.
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Updrafts and Turbulence
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Lift is also created when wind blowing horizontally meets land features such as slopes or mountain sides. The wind is pushed upward, creating a thermal updraft which the pilot can ride for some distance or use to gain altitude. Normally thermal updrafts cause a rough ride, but the flexible wing allows the hang glider to absorb more turbulence and remain relatively stable, in comparison to an aircraft with a rigid wing.
Control
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The pilot controls the hang glider by pushing and pulling on a control bar, which shifts his weight forward and backward and causes the craft to rise or fall, as desired. The pilot can also use body movement to shift weight on the glider to the right or left, which helps to steer the craft.
Instruments
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Instruments mounted on the control bar may include an altimeter, a variometer to measure vertical wind speed, airspeed indicator and sometimes a GPS unit for long-distance flying. Safety-conscious pilots also wear helmets and carry parachutes and radios aboard.
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References
- Photo Credit hang-glider image by maya from Fotolia.com
