Hang gliding is an air sport. It is both recreational and competitive. Although it started out as simply gliding down small hills on low performance kites, hang gliding has evolved the ability to soar for hours with hawks and eagles, gain thousands of feet of altitude in thermal updrafts, and fly cross country over distances of hundreds of miles. 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

In one perspective there are three classes of hang glider:

1. The 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.
2. The 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.
3. Class 2 (designated by the FAI as Sub-Class O-2) where the pilot is integrated into the wing by means of a fairing. These offer the best performance and are the most expensive.

All types of hang gliders can be foot-launched, but landing some class-2 hang gliders is only possible on wheels.

In another perspective there are more than three classes of hang glider. Consider a multi-plane rigid-winged hang glider that does not "shape change" in virtue of shifted pilot weight; Otto Lilienthal introduced this class of hang glider. Further, the rotary-wing hang gliders, though not popular, are in a class by themselves. Paragliders can be seen simply as one class of hang glider in alternative perspectives.

Training & Safety

Certified hang gliding schools in the USA:

Hang gliding has traditionally been considered an unsafe sport, ever since its inception. Otto Lilienthal himself died of a fractured 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 in the harness. In case of serious problems the parachute is deployed and carries both pilot and glider down to earth. 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.

Launch

Launch techniques include foot-launching from a hill, tow-launching from a ground-based tow system, aerotowing (behind a 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. Flights in non-soarable conditions are referred to as "sled runs".

Soaring Flight

Glider pilots can stay airborne for hours. This is possible because they seek out rising air masses (lift) from the following sources:

Thermals

The most commonly used source of lift is created by the sun's energy heating the ground which in turn heats the air above it. This warm air rises in columns known as thermals. Soaring pilots quickly become aware of visual indications of thermals such as: cumulus clouds, cloud streets, dust devils and haze domes. Also, nearly every glider contains an instrument known as a variometer (a very sensitive vertical speed indicator) which shows visually (and often audibly) the presence of lift and sink. Having located a thermal, a glider pilot will circle within the area of rising air to gain height. In the case of a cloud street thermals can line up with the wind creating rows of thermals and sinking air. A pilot can use a cloud street to fly long straightline distances by remaining in the row of rising air.

Ridge lift

Another form of lift occurs when the wind meets a mountain, cliff or hill. The air is deflected up the windward face of the mountain forming lift. Gliders can climb in this rising air by flying along the feature. Another name for flying with ridge lift is slope soaring.

Mountain wave

The third main type of lift used by glider pilots are the lee waves that occur near mountains. The obstruction to the airflow can generate standing waves with alternating areas of lift and sink. The top of each wave peak is often marked by lenticular cloud formations.

Convergence

Another form of lift results from the convergence of air masses, as with a sea-breeze front.

More exotic forms of lift are the polar vortexes which the Perlan Project hopes to use to soar to great altitudes. A rare phenomenon known as Morning Glory has also been used by glider pilots in Australia.

Performance (2006)

With each generation of materials and with the improvements in aerodynamics, the performance of hang gliders has increased. One measure of performance is the glide ratio. For example, a ratio of 12:1 means that in smooth air a glider can travel forward 12 meters while only losing 1 meter of altitude.

Topless gliders: glide ratio ~17:1, speed range ~30 to >145 km/h, best glide at ~45 to 60 km/h Rigid wings: glide ratio ~20:1, speed range ~ 35 to > 130 km/h, best glide at ~50 to 60 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.

Balast The extra weight provided by ballast is advantageous if the lift is likely to be strong. Although heavier gliders have a slight disadvantage when climbing in rising air, they achieve a higher speed at any given glide angle. This is an advantage in strong conditions when the gliders spend only little time climbing in thermals.

Costs (2003)

• Rigid wings: ~10000 Euro (approx. $13400US)
• Topless gliders: 5-6000 Euro (approx. $8100US)
• Intermediates: ~4000 Euro (approx. $5400US)
• Beginner gliders: < 3000 Euro (approx. $4000US)
• 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) 800-1000 Euro

Instruments

In order to maximise a pilots understanding of how the hang glider is flying, most pilots carry a series of instruments. The most basic being a variometer and altimeter- often combined. Some more advanced pilots also carry airspeed indicators and radios. When flying in competition or "Cross country" pilots often also carry maps and/or GPS units. Hang gliders do not have instrument panels as such, so all the instruments are mounted to the control frame of the glider.

Vario

People can sense the acceleration when they first hit a thermal, but they cannot detect the difference between constant rising air and constant sinking air, so they turn to technology for help. A variometer is a very sensitive vertical speed indicator; in other words, indicates climb or sink rate with audio signals (beeps) and/or a visual display. These units are generally electronic, vary in sophistication and often include, an altimeter and airspeed indicator. More advanced units often incorporate a barograph for recording flight data and/or a built in GPS. The main purpose of a variometer is in helping a pilot find and stay in the ‘core’ of a thermal to maximise height gain, and conversely indicating when he or she is in sinking air, and needs to find rising air. Variometers are sometimes capable of electronic calculations based on the 'MacCready Ring' to indicate the optimal speed to fly for given conditions. The MacCready theory solves the problem of how fast a pilot should cruise between thermals, given both the average lift the pilot expects in the next thermal climb, as well as the amount of lift or sink he encounters in cruise mode. Some electronic variometers make the calculations automatically, after allowing for factors such as the glider's theoretical performance (glide ratio), altitude, hook in weight and wind direction.

Radio

Pilots use radio for training purposes, and for communicating with other pilots in the air – particularly when travelling together on cross-country flights.

Radios used are PTT (push-to-talk) transceivers, normally operating in or around the FM VHF 2-metre band (144–148 MHz). Usually a microphone is incorporated in the helmet, and the PTT switch is either fixed to the outside of the helmet, or strapped to a finger.

GPS

GPS (global positioning system) is a necessary accessory when flying competitions, where it has to be demonstrated that way-points have been correctly passed.

It can also be interesting to view a GPS track of a flight when back on the ground, to analyse flying technique. Computer software is available which allows various different analyses of GPS tracks (e.g. CompeGPS).

Other uses include being able to determine drift due to the prevailing wind when flying at altitude, providing position information to allow restricted airspace to be avoided, and identifying one’s location for retrieval teams after landing-out in unfamiliar territory.

More recently, the use of GPS data, linked to a computer, has enabled pilots to share 3D tracks of their flights on Google Earth. This fascinating insight allows comparisons between competing pilots to be made in a detailed 'post-flight' analysis.

Records

Records fall into nearly the same categories as those for sailplanes and are sanctioned by the FAI. The current world record(s) (as of 2005) for "free distance" is held by Manfred Ruhmer with 700.6 km (435.3 miles) in 2001, but Mike Barber has flown an uncertified distance of 704 km (437 miles) on June 19 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 was hosted by Quest Air in Florida. Big Spring, Texas is hosting the 2007 World Championship. Hang gliding is also one of the competition categories in World Air Games organized by Fédération Aéronautique Internationale (World Air Sports Federation - FAI). The FAI also has a chronology of the FAI World Hang Gliding Championships.

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

United States Hang Gliding and Paragliding Association
Hang Gliding Org hang gliding forums and community, videos, pics, news
Hang Glider History Timeline
Hang glider bible
Current hang gliding records
DMOZ Open Directory category: Hang Gliding
Hang Gliding Photo Gallery
The Oz Report - Worldwide Hang Gliding eZine and blog
Hang Gliding Faq
Hang Glider History group
The Scottish Hang-gliding & Paragliding Federation
The Longest Running Hang Gliding Competition in the World
Info about Hang Gliding
The British Hang Gliding and Paragliding association

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