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Paragliding

Flying in a free-flying, foot-launched aircraft.

Paragliding (known in some countries as "parapenting") is a recreational and competitive flying sport. A paraglider is a free-flying, foot-launched aircraft. The pilot sits in a harness suspended below a fabric wing, whose shape is formed by the pressure of air entering vents in the front of the wing.

It is closely related to hang gliding, but quite different from parasailing/parascending, which doesn't involve free flight. (Paramotoring uses the same equipment, with the addition of a propeller mounted behind the pilot, making it a form of ultra-light aviation as opposed to free flight).

Paragliding

Gliders

The paraglider wing (or 'canopy') is a self-inflating structure consisting of a row of cells, most of them open at the front and all of them closed at the back, joined together side by side. Moving through the air keeps them inflated because air goes in the front but can't get out the back. In cross-section, the cells form an aerofoil cross-section to produce lift, just like an airplane wing.

The pilot is supported underneath the wing from a web of lines (each with the strength to support the pilot). The lines are then attached to strap-like risers that are attached to the pilot's harness.

Controls held in the pilot's hands, which pull down the trailing edge of the wing, are used to control speed and to turn.

The pilot is strapped into the bucket-seat harness, which holds a reserve parachute, and includes a 'speed system' which pulls down the leading edge for maximum flying speed. All recreational harnesses have a foam or air-bag back protector.

Solo paraglider wings typically have an area of 20–30 m2 with a span of 8–12 m, and weigh 4–7 kg. Combined weight of wing, harness, reserve, instruments, etc is around 12–16 kg.

Glide ratio is typically around 8:1 (compared with 15:1 for hang gliders and 60:1 for sailplanes), and speed range is typically 20–50 km/h (stall speed – max speed): though safe flying range is smaller.

Modern paraglider wings are made of high-performance non-porous fabrics such as Porcher Marine & Gelvenor, with Dyneema/Spectra or Kevlar/Aramid lines.

For storage and carrying, the wing is folded into the harness seat, and the whole stored in a backpack (which is normally stowed in the harness in flight).

Tandem paragliders, designed to carry the pilot and one passenger, are larger but otherwise similar.

Flying

In unpowered flight, rising air is needed to keep a glider aloft. This rising air can comes from two sources:

*when the sun heats features on the ground, columns of rising air known as thermals are generated

*when wind encounters a ridge in the landscape, the air is forced upwards, providing ridge lift.

In mountainous environments, flying is mostly based around thermals, which can be used to stay aloft before heading for a landing field below the launch site. In hill environments, ridge lift is used for ridge soaring, and landing can be done either back at the launch site, or at a landing field at the bottom of the ridge. In either case, more experienced pilots can use thermals to go 'cross country'.

Ridge soaring

In ridge soaring, pilots fly along the length of a ridge feature in the landscape, relying on the lift provided by the air which is forced up as it passes over the ridge.

Ridge soaring is highly dependent on a steady wind within a defined range (the suitable range depends on the performance of the wing and the skill of the pilot). Too little wind, and insufficient lift is available to stay airborne (pilots end up 'scratching' along the slope). With more wind, gliders can fly well above and forward of the ridge, but too much wind, and there is a risk of being 'blown back' over the ridge.

When ridge soaring, it is usually possible to either 'top land' or 'slope land' close to the launch site, which saves time returning from a landing site back to the launch site.

Thermal flying

When the sun warms the ground, it will warm some features more than others (such as rock-faces or large buildings), and these set off thermals which rise through the air. Sometimes these may be a simple rising column of air; more often, they are blown sideways in the wind, and will break off from the source, with a new thermal forming later.

Once a pilot finds a thermal, he or she begins to fly in a circle, trying to center the circle on the strongest part of the thermal, where the air is rising the fastest. Most pilots use a 'vario' (vario-altimeter), which indicates climb rate with beeps and/or a visual display, to help 'core-in' on a thermal.

Good thermal flying is a skill which takes time to learn, but a good pilot can often follow a thermal up to cloud base.

Cross-country flying

Once the skills of using thermals to gain altitude have been mastered, pilots can glide from one thermal to the next to go 'cross-country' ('XC'). Having gained altitude in a thermal, a pilot glides down to the next available thermal. Potential thermals can be identified by land features which typically generate thermals, or by cumulus clouds which mark the top of a rising column of warm, humid air as it reaches the dew point and condenses to form a cloud. In many flying areas, cross-country pilots also need an intimate familiarity with air law, flying regulations, aviation maps indicating restricted airspace, etc.

Launching / landing

As with all aircraft, launching and landing are done into wind (though in mountain flying, it is possible to launch in nil wind and glide out to the first thermal).

In low winds, the wing is inflated with a 'forward launch', where the pilot runs forward so that the air pressure generated by the forward movement inflates the wing. In higher winds, particularly ridge soaring, a 'reverse launch' is used, with the pilot facing the wing to bring it up into a flying position, then turning under the wing to launch.

In flatter countryside, pilots can also be launched with a tow. Once at full height, the pilot pulls a release cord and the towline falls away. This requires separate training, as flying on a winch has quite different characteristics from free flying. In many countries, only towing from a stationary winch is permitted: 'static' towing, with a fixed length towline attached to a car, is far more dangerous.

Landing involves lining up for an approach into wind, and just before touching down, 'flaring' the wing to minimize forward speed. The angle of approach to the landing zone will depend on wind speed. Landing will typically be at a gentle forward run.

Control of the glider

The pilot holds controls in each hand which pull down the trailing edge of the wing. Pulling down the trailing edge increases the angle of attack of the wing from its 'trim' (hands-off) position, which slows it down (like flaps on an aircraft wing). Turning is achieved by a combination of pulling down the control on one side, and 'weight shift' within the harness. Faster than 'trim' speed can be achieved by pushing out a 'speedbar' with the feet, which pulls down the leading edge to reduce the angle of attack.

On occasions when it is necessary to lose height more rapidly, the outer part of the wing can be 'folded in', in what is known as 'big ears'. This reduces the flying area of the wing, effectively reducing the glide ratio.

In more extreme conditions, other manoeuvres such as 'b-line stalls' and spiral dives can be used, but most pilots avoid getting themselves into situations where these are required.

Collapses

In turbulent air, since the wing is not rigid, part or all of the wing can collapse. On modern recreational wings, such collapses will normally recover themselves without pilot intervention. For the rare case where it is not possible to recover from a collapse (or from other threatening situations such as a spin), most pilots carry a reserve parachute. Thankfully, most pilots never have cause to 'throw' their reserve.

In case the collapse happens near ground, i.e. shortly after take of or just before landing, the collapse may not recover even with pilot intervention, and there will not be enough time for throwing the reserve. In that case, serious injury or even fatal accidents occur.

Sports/competitive flying

Some pilots like to stretch themselves beyond recreational flying. For such pilots, there is a variety of disciplines available:

* cross-country leagues – annual leagues of the greatest distance 'XC' flying

* 'comps' – competitive flying based around completing a number of tasks such as flying around set waypoints

* accuracy – spot landing competitions where pilots land on targets the size of jam-jar lids

* 'acro' – aero-acrobatic manoeuvres and stunt flying; heart stopping tricks such as helicopters, wing-overs, synchro spirals, infinity tumbles, and so on: see the for some descriptions

* national/international records – despite continually improving gliders, these become ever more difficult to achieve; aside from longest distance and highest altitude, examples include distance to declared goal, distance over triangular course, speed over 100 km triangular course, etc.

Competitive flying is done on high performance wings which demand far more skill to fly than their recreational counterparts, but which are far more responsive and offer greater feedback to the pilot, as well as flying faster with better glide ratios.

Instruments

Most pilots use varios and radios when flying; some more advanced pilots also use GPS units.

Vario

Birds are highly sensitive to atmospheric pressure, and can tell when they are in rising or sinking air. People can sense the acceleration when they first hit a thermal, but cannot detect the difference between constant rising air and constant sinking air, so they turn to technology to help.

A vario-altimeter indicates climb-rate (or sink-rate) with audio signals (beeps) and/or a visual display. It also shows altitude: either above takeoff, above sea level, or (at higher altitudes) 'flight level'.

The main purpose of a vario 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.


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 PPT (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 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 analyze flying technique. Computer software is available which allows various different analyses of GPS tracks (e.g. ).

Other uses include being able to identify one's location to retrieval teams after landing-out in unfamiliar territory.

Safety

Paragliding is perhaps often viewed as a higher-risk sport than it actually is. Nonetheless, there is great potential for injury for the reckless or ill-prepared.

It is sometimes said that the factor which most affects safety is pilot attitude. A large proportion of accidents involve over-confident novices failing to heed advice, or pilots flying beyond their limits – often in a competitive context.

Most pilots will try to stay clear of:

* Overly 'active' thermic conditions – harsh thermals can induce collapses in the wing, which require skill and experience to manage.

* Excessively windy conditions – landing can become dangerous. If a glider is blown back behind a ridge where there is no longer rising air, it can encounter 'rotor' or turbulent air, which can collapse the wing – generally below the height at which a reserve parachute can be deployed.

* Cu-nimbs: Cumulo-nimbus clouds are fed by massive thermals which rise faster than a paraglider can lose height, and can push a pilot deep into enormously turbulent, blind cloud.

* Hazardous landing conditions – In the lee of large trees or buildings, there is 'rotor' which can collapse a wing; but among the greatest dangers are power lines.

* Reckless pilots – They are a danger to others, as well as themselves.

Safety precautions include pre-flight checks, flying helmets, harnesses with back protection (foam or air-bag), a reserve parachute, and careful pre-launch observation of other pilots in the air to evaluate conditions.

For pilots who want to stretch themselves into more challenging conditions, advanced 'SIV' ("simulation d'incidents de vol", or simulation of flying incidents) courses are available which teach pilots how to cope with hazardous situations which can arise in flight. Through tuition over radio (above a lake), pilots deliberately induce major collapses, stalls, spins, etc, in order to learn procedures for recovering from them. (As mentioned above, modern recreational wings will recover from minor collapses without intervention).

While fatalities do occur, most properly-trained, responsible pilots suffer nothing worse than possible minor injuries, particularly twisted ankles and back injuries, and an occasional pounding heart.

Learning to fly

Most popular paragliding regions have a range of schools that are generally registered with national associations. Certification systems vary widely between countries, though 10 days instruction to basic certification is standard.

Initial training is done on gentle slopes where students can glide just above the ground to get used to the handling of the wing. As their skills progress, students move on to steeper/higher hills, making longer flights, learning to turn the glider and control speed, and then going on to 360 degree turns, 'big ears', and so on. Training instruction is given over radio. An alternative approach is to learn on a winch, which tows the student up to increasingly greater heights above an airfield.

As well as teaching flying skills, schools teach air law, meteorology, flight theory, etc.

All schools offer tandem flights and day tasters to enable people to find whether they have an interest in the sport.

World records

The current (as of January 2006) world distance record was set by Canadian William Gadd on 21 June 2002 who flew 423.4 km (263 miles) in 10½ hours from the town of Zapata, Texas, United States.

The height gain record was set by Robbie Whittall from the UK who flew 4,526 m (14,850 ft) above takeoff on 6 January 1993 from Brandvlei, South Africa.

History

In 1954, the prescient Walter Neumark foresaw (in an article in "Flight" magazine) a time when a glider pilot would be "able to launch himself by running over the edge of a cliff or down a slope ... whether on a rock-climbing holiday in Skye or ski-ing in the Alps".

In 1961, the French engineer Pierre Lemoigne produced improved parachute designs which led to the Para-Commander ('PC'), which had cut-outs at the rear and sides which enabled it to be towed into the air and steered – leading to parasailing/parascending.

Sometimes credited with the greatest development in parachutes since Leonardo da Vinci, the American Domina Jalbert invented in 1964 a rectangular parafoil which had sectioned cells in an aerofoil shape; an open leading edge and a closed trailing edge, inflated by passage through the air – the so-called 'ram-air' design.

Walter Neumark shortly afterwards wrote the wonderfully entitled "Operating Procedures for Ascending Parachutes", and he and a group of enthusiasts with a passion for tow-launching 'PCs' and ram-air parachutes eventually broke away from the British Parachute Association to form the British Association of Parascending Clubs (BAPC) in 1973.

Meanwhile, David Barish was developing the 'Sail Wing' for recovery of NASA space capsules – "slope soaring was a way of testing out ... the Sail Wing". After tests on Hunter Mountain, New York in September 1965, he went on to promote 'slope soaring' as a summer activity for ski resorts (apparently without great success).

(NASA probably originated the term 'paraglider' in the early 1960's, and 'paragliding' was first used in the early 1970's to describe foot-launching of gliding parachutes).

These threads were pulled together in June 1978 by three friends Jean-Claude Bétemps, André Bohn and Gérard Bosson from Haute-Savoie, France. After inspiration from an article on 'slope soaring' in the "Parachute Manual" magazine by parachutist & publisher Dan Poynter, they calculated that on a suitable slope, a 'square' ram-air parachute could be inflated by running down the slope; Bétemps launched from Pointe du Pertuiset, Mieussy, and flew 100 m. Bohn followed him and glided down to the football pitch in the valley 1000 metres below. 'Parapente' was born.

Through the 1980's and since, it has been a story of constantly improving equipment and ever greater numbers of paragliding pilots. The first World Championship was held in Kössen, Austria in 1989.

Comparison with hang gliders

Paragliding and hang gliding are closely related sports – foot-launched gliders with flexible wings, with options for tow launching and for powered flight – and there is sometimes confusion about the differences.

The main differences between them are:

Paragliders:
*Wing structure: entirely flexible, with shape maintained purely by the pressure of air flowing into the wing in flight.
*Pilot position: sitting 'supine' in a seated harness.
*Speed range (stall speed – max speed): slower – hence easier to launch and fly in light winds
*Glide angle: poorer glide performance makes long-distances more difficult.
*Landing-out: smaller space needed to land, offering more landing options from cross-country flights
*Learning: quicker to get 'into the air' with most skills learned in the air.
*Convenience: pack smaller (easier to transport and store); lighter (easier to carry); quicker to rig & de-rig
*Cost: cheaper

Hang gliders:

*Wing structure: It is supported on a rigid frame which determines its shape.
*Pilot position: lying 'prone' in a cocoon-like harness suspended from the wing.
*Speed range (stall speed – max speed): faster – hence easier to launch and fly in stronger conditions.
*Glide angle: better glide performance enables longer-distance flying.
*Landing-out: longer approach & landing area required, limiting landing options.
*Learning: basic control skills are learned close to the ground prior to high flights.
*Convenience: more awkward to transport & store; difficult to carry single-handed; longer to rig & de-rig.
*Cost: more expensive


Source: Wikipedia


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