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By the end of the sixth century A.D., the Chinese had managed to build kites large and aerodynamic

enough to sustain the weight of an average-sized person. It was only a matter of time before someone

decided to simply remove the kite strings and see what happened. Most early glider designs did not

ensure safe flight; the problem was that early flight pioneers did not sufficiently understand the

underlying principles that made a bird’s wing work. Starting in the 1880s technical and scientific

advancements were made that led to the first truly practical gliders, such as those developed in the

United States by John Joseph Montgomery. Otto Lilienthal built controllable gliders in the 1890s, with

which he could ridge soar. His rigorously documented work influenced later designers, making Lilienthal one of the

most influential early aviation pioneers.

Hang gliding saw a stiffened flexible wing hang glider

in 1904, when Jan Lavezzari flew a double lateen sail

hang glider off Berck Beach, France. In 1910 in

Breslau, the triangle control frame with hang glider

pilot hung behind the triangle in a hang glider, was

evident in a gliding club’s activity. Volmer Jensen with

a biplane hang glider in 1940 called VJ-11 allowed

safe three-axis control of a foot-launched hang glider

The biplane hang glider was very widely publicized in

public magazines with plans for building; such biplane

hang gliders were constructed and flown in several

nations since Octave Chanute and his tailed biplane

hang gliders were demonstrated. In April 1909, a how–

to article by Carl S. Bates proved to be a seminal hang

glider article that seemingly affected builders even of

contemporary times, as several builders would have

their first hang glider made by following the plan in his

article.

Components

Flyer pilots can stay airborne for hours by flying through air that is ascending as fast or faster than the glider itself is

descending, thus gaining potential energy. The most commonly used sources of rising air are described in the

following.

Sail

There are basically two types of sail materials used in hang glider sails: woven polyester fabrics, and composite

laminated fabrics made of some combinations.

Woven polyester sailcloth is a very tight weave of small diameter polyester fibers that has been stabilized by the hot-

press impregnation of a polyester resin. The resin impregnation is required to provide resistance to distortion and

stretch. This resistance is important in maintaining the aerodynamic shape of the sail. Woven polyester provides the

best combination of light weight and durability in a sail with the best overall handling qualities.

Laminated sail materials using polyester film achieve superior performance by using a lower stretch material that is

better at maintaining sail shape but is still relatively light in weight. The disadvantages of polyester film fabrics is that

the reduced elasticity under load generally results in stiffer and less responsive handling, and polyester laminated

fabrics are generally not as durable or long lasting as the woven fabrics.

Control frame

In most hang gliders, the pilot is ensconced in a harness suspended from the airframe, and exercises control by

shifting body weight in opposition to a stationary control frame, also known as triangle control frame, control bar or

base bar. This bar is usually pulled to allow for greater speed. Either end of the control bar is attached to an upright

pipe, where both extend and are connected to the main body of the glider. This creates the shape of a triangle or ‘A–

frame’. In many of these configurations additional wheels or other equipment can be suspended from the bottom bar

or rod ends.

Home Builders of the Future.

Lift

The powerfully rising and sinking air in mountain waves was discovered by glider pilot, Wolf Hirth, in 1933. Gliders can

sometimes climb in these waves to great altitudes, although pilots must use supplementary oxygen to avoid hypoxia.

This lift is often marked by long, stationary lenticular (lens-shaped) clouds lying perpendicular to the wind. Mountain

wave was used to set the current altitude record of 15,453 metres (50,699 ft) on 29 August 2006 over El Calafate,

Argentina. The pilots, Steve Fossett and Einar Enevoldson, wore pressure suits. The current world distance record of

3,008 kilometres (1,869 mi) by Klaus Ohlmann (set on 21 January 2003) was also flown using mountain waves in

South America.