Hang gliding

Hang gliding is an air sport. It is both recreational and competitive. The sport is closely related to paragliding and gliding (flying sailplanes) but using a much simpler and less expensive craft consisting of an aluminum- or composite-framed fabric wing, with the pilot mounted on a harness hanging from the wing frame and exercising control by shifting body weight.

Classes

There are three classes of hang glider. A flexible wing hang glider, having flight controlled by a wing whose shape changes in virtue of the shifted weight of the pilot. This is not a paraglider. The second class is a rigid wing hang glider, having flight controlled by spoilers, typically on top of the wing.

In both flexible and rigid wings the pilot hangs below the wing without any additional fairing. A third class of hang gliders exists (officially called Sub-Class O-2 by the FAI) where the pilot is integrated into the wing by means of a fairing. This offers the best performance and is the most expensive. All types of hang gliders can be foot-launched, while landing some class-2 hang gliders is only possible on wheels.

History

Overview

The early experiments with gliding flight were made throughout the late 19th century by pioneers such as Otto Lilienthal. These early craft would now be considered hang gliders.

Modern hang gliding was invented, or at least strongly influenced, by the NASA technician Francis Rogallo in 1948 with the invention of the Flexkite. This device was considered as a possible landing system for the astronauts return to earth. From there, much of the development of hang gliders occurred in Australia, where the first hang glider manufacturing firms were established. Hang gliding then became popular world-wide, with the peak in the 1980s. An alternative to hang gliding is Paragliding since the gear is more easily transported although it offers lower performance.

The Rogallo wing was subseqently improved in the mid-1970s with the invention of the Swallowtail design, several of which were used to impressive effect in the 1976 film Sky Riders. Other improvements in leading edge and materials design soon followed, improving the handling and efficiency of flexible-wing hang gliders.

History of Rigid Wing Hang Gliding

The first notable hang gliders to abandon the Rogallo wing were Icarus I and Icarus II, built in 1971 and 1972 respectively ^*. These were rigid biplane flying wing designs by Taras Kiceniuk, Jr.. Icarus V was the precursor to the modern hang glider. It was essentially a monoplane version of the previous Icarus designs. All of the hang gliders in the Icarus series had hand-controlled rudders and the pilot flew in a reclining position (rather than a prone position as with other hang gliders). Although many Icarus II and Icarus V gliders were built from plans sold by Kiceniuk, they were never commercially produced.

In the late 1990's the first commercially successful rigid wing hang glider came on the market (the "Exxtacy") with a leading edge of carbon fiber, which does not deform. The nose angle and wing span is a little higher, and the sail is rather stiff.

Flying

Launch techniques include foot-launching from a hill, tow-launching from a ground-based tow system, aerotowing (behind another powered aircraft), and powered harnesses. Other, more exotic launch techniques have also been used successfully, such as hot-air balloon drops for very high altitude launches. In flight, conditions can be either soarable or not soarable (flights in non-soarable conditions are referred to as "sled runs"). Soaring flight can be sustained generally through thermals (caused by solar heating of surface air) or ridge lift (caused by wind rising over geographical features), or both. Flights powered by ridge lift are generally confined to the vicinity of the ridge (which can be very high and long in mountainous regions) or coastal cliff, while thermal flights can extend over great distances and reach thousands of feet in altitude over mountains and flatlands.

Safety

Hang gliding has traditionally been considered an unsafe sport, ever since its inception. Otto Lilienthal himself died of a cracked spine from a glider crash after a gliding career lasting only five years. Modern hang gliders are fairly sturdy when constructed by HGMA, BHPA or DHV*-certified manufacturers using modern materials, though they remain lightweight craft that can be easily damaged, either through misuse or by continued operation in unsafe wind/weather conditions. All modern gliders have built-in stall recovery mechanisms (such as luff lines in kingposted gliders) and are designed and tested for as much stability as possible, depending on the performance characteristics desired. Pilot safety is, as in all other forms of aviation, a matter of training (through certified instructors) and perhaps most importantly, self-discipline. Nevertheless, the inherent danger of gliding at the mercy of unpredictable thermal and wind currents, often in proximity to dangerous terrain, has resulted in numerous fatal accidents and many serious injuries over the years, even to experienced pilots, and the resultant adverse publicity has affected the popularity of hang gliding.

As a backup, pilots carry a parachute with them in the harness. In case of serious problems the parachute is deployed (thrown by hand) and carries both pilot and glider down to earth. The size is typically 30 m² and the related sink rate should not exceed 6 to 7 m/s (but can be less, depending on the state of the glider). This is still sufficient to break some bones, so pilots are encouraged to climb into their control frame after a parachute deployment to allow the frame to absorb some of the impact energy. Some pilots have used rocket-assisted (pyrotechnic or compressed air) parachutes to increase the chances of a successful parachute deployment, but these systems proved unreliable enough that carrying a hand-deployed backup parachute was deemed necessary, so most just carry a single, hand-deployed system. Many hang gliding clubs hold parachute deployment clinics to practice this emergency technique on the ground and to encourage regular inspection and re-packing of parachutes.

Pilots also wear helmets and generally carry other safety items such as hook knives (for cutting their parachute bridle after impact or cutting their harness lines and straps in case of a tree or water landing), light ropes (for lowering from trees to haul up tools or climbing ropes), radios (for calling for help), and first aid equipment.

Another issue that has dramatically improved the safety of the modern hang glider pilot is training. Early hang glider pilots learned their sport through trial and error. Many of those errors have led to effective training techniques and programs developed for today's pilot, with emphasis on flight well within safe limits, as well as the discipline to cease flying when conditions are unfavorable. While the pitch and roll stability built into modern hang gliders can help prevent high altitude problems in flight, these features require altitude to take effect. If a stall or slipping turn happens while close to the ground or other obstacle then the glider will not have the time to self correct. This has placed the prevention of accidents during launch and landing as the main priority of early training.

Performance (2003)

Topless gliders: glide ratio ~15:1, speed range ~30 to >100 km/h, best glide at ~45 to 50 km/h
Rigid wings: glide ratio ~19:1, speed range ~ 35 to > 100 km/h, best glide at ~50 to 55 km/h

Note: Glide ratio is typically not provided by the manufacturers as it is nearly impossible to measure reliably and because the pilot is in the airstream (unlike in a sailplane) depends on many factors like pilot weight, pilot position, harness design, helmet, placement of instruments and so on.

Costs (2003)

Rigid wings: ~10000 Euro
Topless gliders: 5-6000 Euro
Intermediates: ~4000 Euro
Beginner gliders: < 3000 Euro
Harness: 500 - 1500 Euro
Parachute: ~ 500 Euro
Instruments: 200 - 1000 Euro
School: 2-3 lessons (introductory package) 3-400 Euro
School: 10 lessons (full course) 8-1000 Euro

Records

Records fall into nearly the same categories as those for sailplanes and are authorized by the FAI. The current world record(s) (as of 2005) for "free distance" is held by Manfred Ruhmer with 700,6 km in 2001, but Mike Barber has flown an uncertified distance of 704 km (437 miles) on June 19th 2002 in Zapata Texas.

Competition

Competitions started with "flying as long as possible" and spot landings. With increasing performance cross-country flying replaced them. Usually two to four waypoints have to be passed with a landing at a goal. In the late 90s low-power GPS units were introduced and have completely replaced photographs of the goal. Every two years there is a world championship. The Rigid and Women's World Championship in 2006 is being hosted by Quest Air in FloridaBig Spring, Texas is hosting the 2007 World Championship.

Related sports

The related sports are gliding, in which the gliders have full control surfaces and an enclosed cockpit, and paragliding, where the pilot is sitting on a harness suspended below a fabric wing.

External links

Hang gliding FAQ ^*

International Organisation

Hang Gliding and Paragliding Commission of FAI

National Organisations

Hang glider manufacturers

Other