Paraglider | |||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Paragliding 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 its suspension lines and the pressure of air entering vents in the front of the wing.
Contents |
In 1952 Domina Jalbert advanced governable gliding parachutes with multi-cells and controls for lateral glide.[1]
In 1954, Walter Neumark predicted (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”.[2]
In 1961, the French engineer Pierre Lemoigne produced improved parachute designs which led to the Para-Commander. The ‘PC’, had cut-outs at the rear and sides that 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 the 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 ram-air design. He filed US Patent 3131894 on January 10, 1963.[3]
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”.[4] 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).[5] NASA originated the term ‘paraglider’ in the early 1960s, and ‘paragliding’ was first used in the early 1970s to describe foot-launching of gliding parachutes.
In 1971, Steve Snyder marketing the first wing : Paraplane.
Author Walter Neumark wrote 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. Authors Patrick Gilligan (Canada) and Betrand Dubuis (Switzerland) wrote the first flight manual "The Paragliding Manual" in 1985, officially coining the word Paragliding.
These threads were pulled together in June 1978 by three friends Jean-Claude Bétemps, André Bohn and Gérard Bosson from Mieussy Haute-Savoie, France. After inspiration from an article on ‘slope soaring’ in the Parachute Manual magazine by parachutist & publisher Dan Poynter,[5] 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.[6] ‘Parapente’ (pente being French for slope) was born.
From the 1980s equipment has continued to improve and the number of paragliding pilots has continued to increase. The first World Championship was held in Kössen, Austria in 1989.
The paraglider wing or canopy is known in aeronautical engineering as a ram-air airfoil, or parafoil. Such wings comprise two layers of fabric which are connected to internal supporting material in such a way as to form a row of cells. By leaving most of the cells open only at the leading edge, incoming air (ram-air pressure) keeps the wing inflated, thus maintaining its shape. When inflated, the wing's cross-section has the typical teardrop aerofoil shape.
In some modern paragliders (from the 1990s onwards), especially higher performance wings, some of the cells of the leading edge are closed to form a cleaner aerodynamic airfoil. Like the wingtips, these cells are kept inflated by the internal pressure of the wing Wings Infos.
The pilot is supported underneath the wing by a network of lines. The lines are gathered into two sets as left and right risers. The risers collect the lines in rows from front to back in either 3 or 4 rows, distributing load as in a whippletree. The risers are connected to the pilot's harness by two carabiners.
Paraglider wings typically have an area of 20–35 square metres (220–380 sq ft) with a span of 8–12 metres (26–39 ft), and weigh 3–7 kilograms (6.6–15 lb). Combined weight of wing, harness, reserve, instruments, helmet, etc. is around 12–18 kilograms (26–40 lb).
The glide ratio of paragliders ranges from 8:1 for recreational wings, to about 11:1 for modern competition models. For comparison, a typical skydiving parachute will achieve about 3:1 glide. A hang glider will achieve about 15:1 glide. An idling (gliding) Cessna 152 will achieve 9:1. Some sailplanes can achieve a glide ratio of up to 72:1.
The speed range of paragliders is typically 20–60 kilometres per hour (12–37 mph), from stall speed to maximum speed. Beginner wings will be in the lower part of this range, high-performance wings in the upper part of the range. The range for safe flying will be somewhat smaller.
Modern paraglider wings are made of high-performance non-porous fabrics such as OLKS from Gelvenor, with Dyneema/Spectra or Kevlar/Aramid lines.
For storage and carrying, the wing is usually folded into a stuffsack (bag), which can then be stowed in a large backpack along with the harness. For pilots who may not want the added weight or fuss of a backpack, some modern harnesses include the ability to turn the harness inside out such that it becomes a backpack.
Tandem paragliders, designed to carry the pilot and one passenger, are larger but otherwise similar. They usually fly faster with higher trim speeds, are more resistant to collapse, and have a slightly higher sink rate compared to solo paragliders.
Since 2000 Juan Salvadori in Argentina has been exploring a variant wing termed Paramontante that involves some firm beams. In April 2009 Pere Casellas has joined in a collaboration with Juan Salvadori for polishing the paramontante. Laboratori d'envol Paramontante
The pilot is loosely and comfortably buckled into a harness which offers support in both the standing and sitting positions. Modern harnesses are designed to be as comfortable as a lounge chair in the sitting position. Many harnesses even have an adjustable 'lumbar support'. A reserve parachute is also typically connected to a paragliding harness.
The primary purpose of parachutes (including skydiving canopies) is for descending, as when jumping out of an aircraft or dropping cargo. In contrast, the primary purpose of paragliders is for ascending. Paragliders are categorized as "ascending parachutes" by canopy manufacturers worldwide, and are designed for "free flying" meaning flight without a tether (for an example of tethered flight, see parasailing). However, in areas without high launch points, paragliders may be towed aloft by a ground vehicle or a stationary winch, after which they are released, creating much the same effect as a mountain launch. Such tethered launches can give a paraglider pilot a higher starting point than many mountains do, offering similar opportunities to catch thermals and to remain airborne by "thermaling" and other forms of lift. As with other forms of free flight, paragliding requires the significant skill and training required for aircraft control, including aeronautical theory, meteorological knowledge and forecasting, personal/emotional safety considerations, adherence to applicable Federal Aviation Regulations (US), and knowledge of equipment care and maintenance.
Most pilots use variometers, radios, and, increasingly, GPS units when flying.
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 turn to technology to help. Modern variometers are capable of detecting rates of climb or sink of 1 cm per second, such is the case of the Flymaster B1 which uses extremely low noise electronics and complex algorithms to detect such minute changes in air pressure.
A variometer indicates climb-rate (or sink-rate) with short audio signals (beeps, which increase in pitch and tempo during ascent, and a droning sound, which gets deeper as the rate of descent increases) 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 variometer is in helping a pilot find and stay in the "core" of a thermal to maximise height gain and, conversely, to indicate when a pilot is in sinking air and needs to find rising air.
The more advanced variometers have an integrated GPS. This is not only more convenient, but also allows one to record the flight in three dimensions. The track of the flight is digitally signed and stored and can be downloaded after the landing. Digitally signed tracks can be used as proof for record claims, replacing the 'old' method of photo documentation.
Pilots use radio for training purposes, for communicating with other pilots in the air, particularly when travelling together on cross-country flights, and for reporting the location of landing.
Radios used are PTT (push-to-talk) transceivers, normally operating in or around the FM VHF 2-metre band (144–148 MHz). The "2 Meter" band is an amateur radio band, sometimes used for interpersonal communications, and Aviation Frequencies are usually 108 MHz to 136 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 (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 analyze flying technique. Computer software is available which allows various different analyses of GPS tracks (e.g. CompeGPS, See You).
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.
Brakes: Controls held in each of the pilot’s hands connect to the trailing edge of the left and right sides of the wing. These controls are called 'brakes' and provide the primary and most general means of control in a paraglider. The brakes are used to adjust speed, to steer (in addition to weight-shift), and flare (during landing).
Weight Shift: In addition to manipulating the brakes, a paraglider pilot must also lean in order to steer properly. Such 'weight-shifting' can also be used for more limited steering when brake use is unavailable, such as when under 'big ears' (see below). More advanced control techniques may also involve weight-shifting.
Speed Bar: A kind of foot control called the 'speed bar' (also 'accelerator') attaches to the paragliding harness and connects to the leading edge of the paraglider wing, usually through a system of at least two pulleys (see animation in margin). This control is used to increase speed, and does so by decreasing the wing's angle of attack. This control is necessary because the brakes can only slow the wing from what is called 'trim speed' (no brakes applied). The accelerator is needed to go faster than this.
More advanced means of control can be obtained by manipulating the paraglider's risers or lines directly:
Problems with “getting down” can occur when the lift situation is very good or when the weather changes unexpectedly. There are three possibilities of rapidly reducing altitude in such situations, each of which has benefits and issues to be aware of:
By pulling on the outer A-lines the wing tips of the glider can be folded in. This method drastically deteriorates the glide angle with only a small decrease in forward speed. The effectiveness of this technique can be increased by using the speed system at the same time.
To reinflate on a low performance glider (e.g. DHV1 rated) it is simply necessary to release the lines. On higher performance gliders (e.g. DHV1/2 and above) it may be necessary to help the reinflation with brief, deep pumps of the brakes.
Whilst big ears are in use, the loading on the remaining flying surface of the glider is increased and it is therefore more stable and less prone to collapse. However there is an increased risk of stalling because 'pulling the ears' increases the angle of attack and reduces the speed of the wing. So while 'ears' and speed bar is a good combination, 'ears' and brake is not - it is best not to use the brakes when the ears are 'in'.
In a 'B-line stall', the second set of risers from the leading-edge/front (the B-lines) are pulled down independently of the other risers; with the specific lines used to initiate the condition being responsible for its name. This puts a crease in the upper surface of the wing, thereby destroying the laminar flow of air over the aerofoil. This dramatically reduces the lift produced by the canopy and thus induces a higher rate of descent.
The B-line stall should be initiated with the wing in normal flight (no speed bar; not accelerated). Grasp the B-lines on both sides above the line links and pull them down. There is no need to release the brake toggles while B-stalling. DHV 1/2 wings are very resistant to creasing; the pilot may have to pull on the B-lines with sufficient force to almost lift themselves out of the seat to get the wing to crease. Once the crease is in, it requires less effort to keep it in that it does to initiate it.
The sensation for the pilot when the B-line stall is induced is that the breeze is upwards rather than in your face. Pulling the B-lines even further down will not enhance the sink rate, but can lead to a more unstable flight position.
To recover from the B-line stall, release the B-risers so that the aerofoil shape of the wing is resumed. This will normally be sufficient to resume normal flight, but if the canopy remains in a stall push forward gently on the A-risers to lower the leading edge of the wing and reattach the laminar airflow to the upper surface of the wing.
The spiral dive is the most rapid form of controlled fast descent. With a little bit of practice you will achieve a sink rate of 15 m/s and more.
However, spiral dives put strong G-forces on the wing and glider and must be done carefully and skilfully. The G-forces involved can induce blackouts, and the rotation can produce disorientation. Spiral dives, as with all paragliding techniques, are best learned under expert supervision. Paragliding 'SIV' courses offer a chance to practice spiral dives over water with a rescue boat standing by.
The spiral dive is initiated by pulling the brake on one side and holding it down. Constant pulling on one brake narrows the radius of the turn and forms a spiral rotation in which high sink rates can be reached. As soon as the glider is in a spiral dive (clear increase of sink rate and turn bank), the outside wing should always be stabilised with the outside brake and the desired sink rate should be controlled with great delicacy.
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 complete the launch.
Reverse launches have a number of advantages over a forward launch. It is more straight forward to inspect the wing and check the lines are free as it leaves the ground. In the presence of wind, the pilot can be tugged toward the wing and facing the wing makes it easier to resist this force, and safer in case the pilot slips (as opposed to being dragged backwards). These launches are normally attempted with a reasonable wind speed making the ground speed required to pressurise the wing much lower - the pilot is initially launching while walking forwards as opposed to running backward.
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. There are two major ways to tow: Pay-in and pay-out towing. Pay-in towing involves a stationary winch that pays in the towline and thereby pulls the pilot in the air. The distance between winch and pilot at the start is around 500 meters or more. Pay-out towing involves a moving object, like a car or a boat, that pays out line slower than the speed of the object thereby pulling the pilot up in the air. In both cases it is very important to have a gauge indicating daN to avoid pulling the pilot out of the air. There is one other form of towing; ‘static’ towing. This involves a moving object, like a car or a boat, attached to a paraglider or hanglider with a fixed length line. This is very dangerous because now the forces on the line have to be controlled by the moving object itself, which is almost impossible to do. With static line towing a lockout is bound to happen sooner or later. Static line towing is forbidden in most countries and if not, should be avoided at all cost.
Landing involves lining up for an approach into wind, and just before touching down, ‘flaring’ the wing to minimise horizontal speed. In light winds, some minor running is common. In moderate to medium headwinds, the landings can be without forward speed.
The slope can be a Dune or Ridge. In slope soaring, pilots fly along the length of a slope feature in the landscape, relying on the lift provided by the air which is forced up as it passes over the slope. Slope 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 slope, but too much wind, and there is a risk of being ‘blown back’ over the slope.
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 (the "core"), 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.
Coring: The technique to "core" a thermal is simple: turn tighter as lift decreases, and turn less as lift increases. This ensures you are always flying around the core.
Often there is strong sink surrounding thermals, and there is often also strong turbulence resulting in wing collapses as a pilot tries to enter a strong thermal. Once inside a thermal, shear forces reduce somewhat and the lift tends to become smoother.
Good thermal flying is a skill which takes time to learn, but a good pilot can often "core" a thermal all the way to cloud base.
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.
Since the shape of the wing (airfoil) is formed by the moving air entering and inflating the wing, in turbulent air, part or all of the wing (airfoil) can deflate (collapse). Piloting techniques referred to as "active flying" will greatly reduce the frequency and severity of deflations or collapses. On modern recreational wings, such deflations will normally recover without pilot intervention. In the event of a severe deflation, correct pilot input will speed recovery from a deflation, but incorrect pilot input may slow the return of the glider to normal flight, so pilot training and practice in correct response to deflations is necessary. For the rare occasions when it is not possible to recover from a deflation (or from other threatening situations such as a spin), most pilots carry a reserve (rescue, emergency) parachute. Most pilots never have cause to ‘throw’ their reserve. Should a wing deflation occur at low altitude, i.e. shortly after takeoff or just before landing, the wing (paraglider) may not recover its correct structure rapidly enough to prevent an accident, with the pilot often not having enough altitude remaining to successfully deploy a reserve parachute (with the minimum altitude for this being approximately 200 ft, but typical deployment to stabilization periods using up 400 – 600 ft of altitude). Different packing methods of the reserve parachute affect its deploying time. It is also important to note that, should the wing collapse have been due to turbulence, this 'bad air' can cause the reserve parachute to take significantly longer to inflate and stabilise. In this example, it may be of greater benefit to the paraglider to purposefully lose altitude to 'clear' this turbulent air before deploying their reserve; should they have spare altitude to use on this process. Low altitude wing failure can result in serious injury or death due to the subsequent velocity of a ground impact where, ironically, a higher altitude failure may allow more time to regain some degree of control in the descent rate and, critically, deploy the reserve if needed. In-flight wing deflation and other hazards are minimized by flying a suitable glider and choosing appropriate weather conditions and locations for the pilot's skill and experience level.
Some pilots like to stretch themselves beyond recreational flying. For such pilots, there are multiple disciplines available:
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.
The current world champion is Andy Aebi of Switzerland; he won the title in February 2009 at Valle de Bravo in Mexico.[7] His predecessor was Bruce Goldsmith.
There is great potential for injury for the unlucky, the reckless or ill-prepared.
Safety is directly influenced by the pilot's experience, skill, reaction time, active nature of the air and whether or not the paraglider is flying at an altitude where the emergency reserve parachute might possibly have time to open in the event of an unrecoverable collapse or spiral dive. Incidents of any nature that happen in an altitude that does not allow to recover or deploy the reserve parachute (as while start and landing) are the most likely situtations to cause severe or fatal injuries.
Given that equipment failure of properly certified paragliding equipment can be considered a non-issue, it is accurate to say that paragliding can be a very safe sport. The individual pilot is the ultimate indicator of his or her personal safety level.
In general:
The following weather is to be avoided:
General safety precautions include pre-flight checks, helmets, harnesses with back protection (foam or air-bag), reserve parachutes, 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 en vol, or simulation of flying incidents) courses are available to teach pilots how to cope with hazardous situations which can arise in flight. Through instruction 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).
As always, fatalities and freak accidents can occur, but most properly-trained, responsible pilots risk only minor injuries, such as twisted ankles.
Most popular paragliding regions have a number of schools, generally registered with and/or organized by national associations. Certification systems vary widely between countries, though around 10 days instruction to basic certification is standard.
There are several key components to a paragliding pilot certification instruction program. Initial training for beginning pilots usually begins with some amount of ground school to discuss the basics, including elementary theories of flight as well as basic structure and operation of the paraglider.
Students then learn how to control the glider on the ground, practicing take-offs and controlling the wing 'overhead'. Low, gentle hills are next where students get their first short flights, flying at very low altitudes, to get used to the handling of the wing over varied terrain. Special winches can be used to tow the glider to low altitude in areas that have no hills readily available.
As their skills progress, students move on to steeper/higher hills (or higher winch tows), making longer flights, and learning to turn the glider, control the glider's speed, then moving on to 360° turns, spot landings, ‘big ears’ (used to increase the rate of descent for the paraglider), and other more advanced techniques. Training instructions are often provided to the student via radio, particularly during the first flights.
A third key component to a complete paragliding instructional program provides substantial background in the key areas of meteorology, aviation law, and general flight area etiquette.
To give prospective pilots a chance to determine if they would like to proceed with a full pilot training program, most schools offer tandem flights, in which an experienced instructor pilots the paraglider with the prospective pilot as a passenger. Schools often offer pilot's families and friends the opportunity to fly tandem, and sometimes sell tandem pleasure flights at holiday resorts.
Most recognised courses lead to a national licence and an internationally recognised International Pilot Proficiency Information/Identification card. The IPPI specifies five stages of paragliding proficiency, from the entry level ParaPro 1 to the most advance stage 5.
FAI (Fédération Aéronautique Internationale) world records:[8]
Other records (distance/speed for out-and-return and triangular course) can be seen on the FAI site
Recently a flight of over 500 km was made by Nevil Hulett in excellent conditions in South Africa; Flight record
Numbers of actively flying pilots can only be a rough estimate, but France is believed to have the largest number, at around 25,000. Next most active flying countries are Germany, Austria, Switzerland, Japan, and Korea, at around 10,000 – 20,000, followed by Italy, the UK, and Spain with around 5,000 – 10,000. The USA has around 4,500. (All as of 2004).[9]
|