Hang glider
A hang glider , also known as a kite , delta glider or slope glider , is a motorless aerial sports device that can be carried by the pilot during take-off and landing. The pilot depends in flight in a special harness prone or sitting under the wing. Classic kites with flexible wings are mainly controlled by shifting weight . Since the mid-1990s, more and more hang-gliders with rigid wing surfaces have been built. These fixed-wing aircraft can only be controlled around the longitudinal axis by means of aerodynamic systems ( airbrakesor ailerons ), while steering around the transverse axis continues by shifting your weight.
A typical hang glider consists of a fabric-covered wing with a wingspan of around 11 meters and an area between 11 and 18 square meters, which is held in shape by a stable main frame made of aluminum tubes or carbon fiber reinforced plastic . In addition, flexible battens (consisting of a front part made of thin aluminum tube and an end piece made of flexible glass fiber ) are pushed into the sail. Since this construction dispenses with many of the components common in aircraft such as the fuselage, landing gear and tail unit ( flying wing ), a low weight of 25 to 50 kg is achieved. For transport on the ground, the wing can be folded up and packed in a long bag.
classification
Technically, hang gliders to the aircraft of the categories flying wing and glider .
In Germany, hang gliders and fall paragliders air law within the aircraft into the category of air sports equipment . Motorized hang-gliders are also aircraft , but they are classified as microlight aircraft .
According to Austrian and Swiss aviation law, a hang glider is “an aircraft suitable for foot launching for gliding”. Paragliders and speed flyers also fall into this category . Colloquially and in flying practice, hang gliders are only understood to mean kites (delta gliders).
Range and glide performance
For flights that go beyond simply sliding from the take-off to the landing site, hang-gliders, like paragliders and gliders , use dynamic slope updrafts and thermals . In this way, altitudes of over 5000 m and distances of more than 700 km were reached. Cross-country flights by good pilots range from 25 to 300 km, depending on the external conditions. Flights range from a few minutes to several hours, depending on the flight site and weather conditions.
The glide ratio of hang-gliders is between about 10 and 15 for the flexible version and 16 and 19 for the fixed-wing aircraft. This means that a hang glider can glide about 1 to 2 km for every 100 m height in still air. Thus, compared to paragliders in similar pilot requirement classes, such a piece of sports equipment has about twice as high a glide performance, which is however clearly below that of gliders.
story
Aerodynamicist Francis Rogallo developed a collapsible wing for NASA for the return of spaceships to Earth. A flexible sail was held in place by rod-shaped girders. The wind gave the loose cloth an aerodynamically effective profile. Although only two preliminary studies were carried out with this wing, the project inspired the construction of the first more modern hang gliders years later. Using photos published in magazines, the American Barry Hill Palmer constructed a grand piano made from bamboo and cellophane based on the Rogallo design . This made him the first hang-glider. In the coastal regions of the USA there were other fans of this air sport. In these early hang-gliders, the pilot hung with his upper arms between parallel bars, similar to the parallel bars in apparatus gymnastics. By shifting his legs he could influence the flight direction. He determined the speed by moving forwards or backwards.
The Australian John W. Dickenson introduced the control system used to this day with a central suspension for the pilot and the triangular control bar . His friends Bill Moyes and Bill Bennett brought hang gliding to many countries with air shows. With the realization of the dream of flying with the simplest technical means, hang gliders met the zeitgeist determined by the hippie movement in the USA . In Europe, media coverage was initially low.
At the same time, the brothers Reinhold and Werner Schmidt from Upper Hesse wanted to revive the tradition of Otto Lilienthal's normal sailing apparatus and, in 1965, dared the first hops with self-made rogallo kites made of bamboo. Wolfgang Schwarzbauer sailed from the mountains around the Schliersee in Bavaria from 1971 . They did this lack of flight legal approval far from the public. When the Californian Mike Harker flew from the Zugspitze with a spectacular action on April 11, 1973 , interest in the media awoke and there were also new followers here. Shortly afterwards, Mike Harker founded the first hang-gliding schools in Switzerland and Germany and Sepp Himberger in Kössen , Austria, and thus became the nucleus of hang-gliding in Europe .
In 1974 the “1. Austrian Kiting Club Kössen "was founded as the first hang-glider club in the world, (also in the same year the German Hang-glider Club Stuttgart). In 1975 the" 1. World Championships in Alpine Hang Gliding ”. This was the dress rehearsal for the official recognition of the young hang-glider flight sport by the world aviation association FAI; In 1976 the first official world championship in hang gliding took place (also in Kössen).
Like every swept flying wing, the kite also achieves its flight stability by twisting the wing, also known as twisting, which results automatically from the upward curvature of the sail. In the case of falling winds or in high-speed flight, however, the kite sail could be flown against from above and lose its twist with the not uncommon result of fluttering or flapping forward, also known as "tuck". To prevent this loss of setting, the aeronautical engineer Michael Schönherr invented the "setting stop" and presented it in 1976 in the "Drachenfliegermagazin". To this day, all hang gliders in the world use this component in various designs. With this, the flutter fall could be completely averted. The risk of a forward rollover has also been largely reduced.
The aerodynamic measurement vehicles developed in Germany also played a major role in the safety and performance gains of the hang glider.
The devices gradually became more powerful thanks to more sophisticated technology. Soon some of them were equipped with a motor so that they could gain altitude independently of thermal conditions. This resulted in the first weight-controlled ultralight aircraft .
Aircraft
A distinction is essentially made between classic kites (also called flexis because of the flexible surface ) and fixed-wing aircraft .
Classic kites
These flexible aircraft are made of polyester fabric and tubes made of aluminum . The sails consist either of a single top sail (so-called single sail, as an entry-level class for beginners and occasional flyers) or of top and bottom sail (so-called double sail: better glide angle and more weight). The upper sails are brought into a buoyancy-generating shape by means of curved sail battens;
With some devices, the pilot can change the nose angle in flight using a pulley system (variable geometry, VG) in order to achieve optimal flight characteristics for flying in thermals and when gliding (change in sail tension and profile).
For transport, the kite is folded up like an umbrella, whereby the battens must be removed before folding. The sail remains on the frame, and a 5-6 m long roll is created, which is usually transported on the car roof. If necessary, you can pull off a two-meter-long piece of the wing tube on most kites and thus shorten the length to about 4 m. On some models specially built for mountaineers, the frame could be dismantled to a length of 2 meters (pack size); the kites could be carried like a rucksack when climbing a mountain.
Towerless dragons
The towerless dragons are a further development of the classic dragons . The difference between these flying devices and the classic kites is that there is no bracing above the wing with the associated tower. The resulting reduced air resistance has a positive effect on gliding performance and forward speed. The function of the missing bracing is taken over by a self-supporting construction made of aluminum or carbon . Safety in the sense of self-intercepting flight properties is guaranteed by internal or internal bracing stops.
Fixed wing aircraft
In the case of fixed-wing aircraft, the wing is not held in shape by the fabric tension between the wing tubes, but is inherently stable. The stiff spar required for this is often made of fiber composite materials . This design principle allows a higher aspect ratio of the wing. These aircraft are controlled by spoilers on the upper side of the wing, which brake on one side if necessary. Some fixed-wing aircraft also have ailerons , which, similar to gliders, influence the lift on the respective wing side. In contrast to gliders, spoilers and ailerons are not moved with a control stick , but rather with cables from the control bar to the wing, which are tensioned when the pilot pushes himself to the side. In this way, the movements required to initiate a turn are very similar to controlling the weight of flexible hang gliders. Fixed-wing aircraft also equipped with flaps (are flaps ) equipped, which are used at the start, in thermaling and landing.
In terms of gliding performance and handling on the ground, fixed-wing aircraft are somewhere between classic kites and gliders. Compared to flexible hang gliders, they have the advantage of a significantly better gliding performance, but are more difficult to handle when transporting them to the starting point.
begin
Since hanggliders do not have their own propulsion system, they cannot take off from a level runway under their own power like airplanes do. Different techniques are used to get into the air anyway.
Slope start
When starting a slope, the pilot runs down a slope with the device and accelerates until the wing carries him and lifts him off the ground. Then he goes into the lying position that is characteristic of hang gliders. For a successful start, the pilot must exceed the stall speed of around 30 km / h in relation to the air . The slope helps so that the necessary take-off speed can be achieved without any problems. A moderate headwind is accordingly helpful, while a tailwind makes the start impossible. In order to facilitate the take-off run on uneven terrain, launch ramps have been set up in many airfields.
UL tow
This take-off variant is similar to the aircraft tow commonly used in gliding . The hang glider is pulled up on a comparatively short rope (60 m for single-seaters, 80 m for double-seaters) behind a motorized aircraft. At the desired altitude, the hang glider separates the connection to the rope, as with winch towing, and flies on freely. The towing aircraft must not be faster than the permitted speed of the hang glider. Therefore, particularly slow ultralight aircraft, from which the name of this type of take-off is derived, are used. When the team takes off, the pilot usually lies in a three-wheeled launch vehicle, which remains on the ground after taking off. With this somewhat more complex take-off, heights of 1000 to 2000 m above ground can be reached without any problems. In addition, an experienced tow pilot can pull the hang glider directly into a thermal updraft .
Winch launch
When wind start of the hang glider as one is Kite pulled up on a leash. At the highest point, the pilot releases himself from the line with a tow release and flies on freely. The height at which the pilot disengages and begins his gliding flight is a few hundred meters above the launch site. In this way you can also start in the flatlands.
There are two ways to start the winch . With the first, the rope is completely rolled out at the beginning and is then hauled in with a stationary reeling winch . An alternative is to start with an unwinding winch mounted in the rear of a car . The car driving a straight stretch tows the hang glider on an initially short rope. With a suitable mechanism, the rope gives way when there is enough tension and the hang glider can climb higher. In an emergency, when there is a risk that the rope will pull the hang glider to the ground, the rope can be cut. In a special form that is widespread in Australia, the tow vehicle has a large platform on which the pilot initially stands and rides. It takes off as soon as the tow vehicle is fast enough.
Balloon launch
To begin a flight at high altitude, the hang glider can be pulled vertically upwards under a balloon when it is set up. After the hang glider is released, it quickly turns the fall into a forward flight and can then start a long glide flight. This complex and therefore expensive take-off was chosen for spectacular course records such as the flight over the English Channel .
Electric start
Especially for the newly introduced “electric ascent aid” (foot start) take-off type, an ultralight aircraft pilot license is no longer required. According to the guidelines of the German Hang Glider Association (DHV), a one-time training or instruction of the pilot is required for this type of take-off. After successful instruction, the additional take-off type will be entered by the DHV in the pilot's license upon request. In addition, the area must be approved for this type of take-off by the responsible aviation authority. In some cases, the task of off-road approval for the “electrical ascent aid” start type was delegated to the DHV. The electric ascent aid is to be seen as an uncomplicated thermal entry. The battery capacity must not exceed 3.0 kWh. When starting, the motors have an output of 12.5 kW or 16 kW, which is limited to 10 kW or 13.5 kW continuous output after about 10 minutes. Without thermal influence, you can reach a height above the launch site of up to 1800 m.
The components of an electric drive are usually:
- Control unit or "throttle" with display of the engine parameters and the remaining range
- brushless three-phase synchronous electric motor
- directly driven foldable propeller
- Power electronics for generating the rotating electrical field
- Lithium-ion or lithium-polymer batteries with 48 V nominal voltage and a usable capacity of 1.2 to 3.0 kWh
- Motor controller for monitoring and controlling the power unit
In flight
In contrast to the airplane with its multitude of flaps, a classic hang glider is controlled by shifting weight, in that the pilot pushes himself on the trapeze bar in one direction or the other relative to the wing. So you don't hold onto the trapeze bar, you use it like a steering wheel.
speed
The pilot is significantly heavier than the wing. Its position therefore determines the center of gravity . Due to the movable suspension, it can influence the trimming of the aircraft and thus the speed. The speed of the kite is increased if you pull yourself forward on the trapeze bar. As a result, the kite not only moves faster, but it also sinks faster. At higher speeds it even drops disproportionately faster and the glide angle becomes worse. Conversely, the speed decreases if you push yourself backwards on the trapeze bar. Below a minimum speed (v min ) that is typical for the respective device , the flow is stalled and the wing only generates very little lift. He begins to fall, tips his nose down and picks up speed again. The device is then back to normal flight status.
direction
To fly a left turn, the pilot pushes his body to the left, taking care not only to twist the body, but also to shift it completely with his legs to the left. The trapezoid base is pushed to the right from the pilot's point of view. As a result, the pilot shifts his center of gravity to the left. As a result, the profiles of the left and right wings change because of the flexible sail. The right wing creates more aerodynamic lift than the left, and this is what gives the actual momentum for the kite's rolling motion. The rolling movement is ultimately caused aerodynamically, and not by the pilot's weight pulling the left side of the kite down. A steep turn is carried out in that the pilot first pulls the base towards him and accelerates with it, then shifts his weight to the side and then pushes the trapeze away from him (corresponds to the elevator deflection). In the case of a fixed-wing aircraft , a lateral shift in weight of the pilot therefore does not cause the kite to roll, and the pilot can only initiate the roll movement by means of aerodynamic control aids in the form of one-sided or mutual actuation of airbrakes or ailerons .
Stay up
A typical, classic hang glider has a minimum sink rate of around 1 m / s. That means, from a height of 300 m, he is back on the ground in calm air after five minutes. If the weather is unstable, it is possible to extend the flight time. To do this, go to the updrafts. If the updraft is stronger than the rate of descent, you gain height above ground. Thermal and so-called "dynamic updraft" can mix with one another. For example, there is a constant updraft on coastal dunes that are swept across by the sea wind . Directly in front of the dune, the air flows diagonally upwards. In a narrow area in front of a sufficiently high dune with a sufficiently strong wind, a hang glider even climbs. With elongated figure-eight flight movements (curves always "away from the slope") it can stay in the air as long as the wind is blowing. This technique, known as soaring , was used early on on the coasts of Hawaii and California .
Another updraft that can be used for hang gliders occurs when the sun heats the ground and it releases its heat into the air. The rising, heated air has the tendency to collect like a river and to flow upwards in larger quantities at certain points. In addition, it tends to first form a warm "bubble" on the ground and only detach itself from it when there is a certain temperature difference to the surrounding air. The challenge for the pilot is to find these thermal updraft areas and let them carry him upwards in tight circles.
Updrafts as such are invisible. If you get into a slight updraft and climb, this is not easily noticeable and also difficult to see at a height of a few hundred meters. Therefore, many pilots use an instrument (" variometer ") that shows the current rate of climb or descent and usually also the altitude - calculated from the air pressure. It has a visual display and can also display the current measured value by means of the pitch of a beep. Kite pilots can therefore fly 'by ear' in order to stay in the regions with the best lift. A good pilot can stay in the air for hours in good weather conditions. Cross-country flights are also possible.
landing
Similar to take-off, the landing is carried out against the wind in order to keep the speed as low as possible compared to the ground. So that the hang-glider neither shoots out over the landing area nor reaches the ground too early, it is necessary that the height is reduced and divided accordingly. The following procedure is standardized for this: The pilot willing to land approaches the landing site at any height and moves to a position that is to the side of the selected landing point. Significantly, this introductory phase is called “position”. Here only circles are flown (not in updrafts!) In order to reduce the altitude so far that it is just enough for the so-called landing volte . This consists of three rectangularly arranged short straight flights (counter approach, transverse approach, final approach, each connected by 90 ° curves). This procedure allows the pilot the best possible approach to the targeted landing point and is a requirement for an orderly landing.
An ideal landing with a hang glider is standing, similar to a bird. For this purpose, shortly before reaching the ground at the lowest possible speed, a flow stall (stall) is brought about by pushing the trapezoid forward as much as possible. If this pushing out does not succeed optimally at the right time, you have to run along more or less. Bad landings (crash) can damage the kite and injure the pilot. A rather frowned upon alternative or one that is only used in tandem flights is the horizontal landing , which is comparable to airplane landings . The kite rolls out on two wheels attached to the trapeze bar.
A suggestive variant of the landing is the slope segment , in which the slope angle is used for the reduction of speed. To do this, the pilot flies towards a steep meadow at high speed and possibly even with the wind. Only shortly before the slope does he push the control bar forward. In response, it rises parallel to the slope and slows down. If the kite falls below its minimum speed, the wing would tip forward in the open air and accelerate downwards. Instead, the pilot sits down standing on the meadow. Because of the abrupt stop on a steep stretch of meadow, this technique is also called fly on the wall .
Rigid hang gliders usually have landing flaps that reduce the minimum speed at which the device can fly and thus simplify landing. Another aid that is used by some pilots is a braking parachute a few square meters in size , which makes the approach angle steeper.
Landing is generally considered to be the most demanding part of hang-gliding, which even licensed pilots often do not know how to do one hundred percent.
Tandem flight
Depending on the design, a hang glider can carry an additional passenger. A flight with a passenger is called a tandem flight . The passenger hangs next to or above the pilot under the wing. He automatically makes the same steering movements as the pilot. Because of the additional responsibility for the passenger, a special tandem flight license is required for the pilot. The hang glider must be approved for the higher take-off weight. Many flight schools and some amateur pilots offer tandem flights for a fee.
Tandem flights have been approved for training in Germany since 2003. The student is hung in the lower position, the teacher above. In this way, the situation for the student is similar to that of a solo flight, except for the higher weight to be moved. The teacher can intervene at any time from his elevated position and take control of the kite. For example, he controls the kite during take-off and landing on the first few flights. In addition, he can communicate directly with the student, as in the training for powered or glider flight. This variant of the training is quite complex, but leads to rapid progress for the students, who can experience and fly all relevant phases of a flight from the very beginning.
Experiential aspects
Hang gliding is an adventure sport. It requires a courageous personality who is willing to take the risk of giving up the safe ground underfoot and entrusting himself to the airspace. Thanks to the advanced technology and sophisticated training methods of the pilots, the risk potential is now limited and manageable with a good level of training, well-maintained aircraft and relevant knowledge of weather events, air traffic rules and emergency behavior. The high experience value as an extraordinary sport, the aspect of health gain as an open-air activity, the possibility of meaningful leisure time activities and the challenge of the personality in relation to the acquisition of skills, care and a sense of responsibility make hang-gliding a sport that is also educationally valuable and worth promoting. Above all, it can give young people essential impulses for character formation in the phase of self-discovery.
When dealing with the element of air, air currents, updrafts and downdrafts, as well as becoming familiar with the aircraft, on whose function and control life and health depend, courage, knowledge, ability and self-confidence are required. You reward with the happy use of a new space for movement and experience, which is not naturally available to people, but has to be worked out.
The venture researcher Siegbert A. Warwitz sees five "facets of world expansion" in aviation:
Gaining space: The pilot uses the airspace to develop a new space for living, experiencing and designing. It is a space that is naturally only available to birds and is only available to humans using a technical aircraft. This represents an “elementary experience” in the original sense of the word (p. 94).
Gaining perspective: kite flying helps to see the earth with its landscapes, cities and people from a different perspective, creates a new, distant perception. According to Warwitz, the “frog's eye view” changes to the “bird's eye view”. This can also unsettle fearful people, especially because they have to leave safe ground, lose the familiar view of things and the height above ground harbors dangers. Cross-country pilots need a different orientation in order to be able to feel comfortable in this unusual living space.
Body and movement gain: The aircraft gives the human body extended freedom of movement that is not possible on the ground. The closer the pilot becomes familiar with his aircraft, the more the aircraft is "incorporated" into the motor activities, the more he thinks in terms of flying, the more freely he can move in the newly won element of air.
Intellectual gain : Through the intelligent use of technology, with flying knowledge and skills, the pilot can outsmart and use nature, which he actually did not intend to be a flying creature. Flying, the independent active movement through the air, is a creative achievement for humans, which can also degenerate into arrogance towards non-flyers.
Emotional gain: The much-cited “exhilaration of flight” arises from the ability to lift off the ground and to be able to escape the gravity of the earth. The release from gravity and the attachment to the earth, the view that expands with the ascent, the floating over forests and people, playing with the winds, being carried up creates that happy feeling of freedom that is sought again and again and creates a high spirits among the pilots, the often expresses himself in shouts of joy. The educator Wolfram Schleske calls this the " kick " when flying.
Terrifying effect on wildlife
In Thuringia , four cases have become known in which breeding females of the owl left their breeding site after a hang-glider had flown over them and only returned to it after hours. Two of these broods were completely abandoned. It remained unclear whether the hang glider or the shadow cast triggered the escape.
There are now a number of studies and reports on the nature conservation aspects of hang- gliding and paragliding . In heavily flown areas they confirm that most of the animals have got used to aviation.
literature
- Claus Gerhard: The limited sky - hang gliding and paragliding in the GDR . Metropol Verlag , Berlin 2011, ISBN 978-3-86331-008-0 .
- Martin Scholz: Adventure-Risk-Adventure - Orientation of meaning in sport . Hofmann, Schorndorf 2005, ISBN 3-7780-0151-5 .
- Burkhard Martens: The thermal book . 2nd Edition. Thermal cloud, Gaißach 2007, ISBN 978-3-00-023282-4 .
- Burkhard Martens: The route book . 1st edition. Thermal cloud, Gaißach 2007, ISBN 978-3-00-020067-0 .
Web links
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Associations :
- German Hang Glider Association (DHV) [1]
- Austrian Aero Club (ÖAeC) [2]
- Swiss Hang Glider Association (SHV) [3]
Individual evidence
- ↑ Graeme Henderson: With the Australian John Dickenson, Rogallos dragon became an aircraft. In: Website of the Otto Lilienthal Museum . Retrieved March 29, 2020 .
- ↑ Text on Mike Harker's homepage about the flight from the Zugspitze ( memento of the original from October 5, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ^ German hang-glider club Stuttgart eV
- ↑ Drachenfliegermagazin February 1976 issue
- ↑ Aerodynamic measuring vehicles
- ↑ Chronology of a company known in the 1970s and 1980s with a focus on mountaineering kites
- ↑ Martin Scholz: Adventure-Risk-Adventure. Orientations of meaning in sport . Hofmann, Schorndorf 2005
- ↑ Siegbert A. Warwitz: Is it worth taking a risk - Or do we prefer to let ourselves be adventurous? In: Outdoor-Welten 1 (2014) pages 68 ff
- ↑ Siegbert A. Warwitz: Phenomenon and fascination of flying and its possibilities of expanding the world, In: Ders .: Search for meaning in risk. Life in growing rings. 2., ext. Edition, Verlag Schneider, Baltmannsweiler 2016, ISBN 978-3-8340-1620-1 . Pp. 92-97
- ^ Siegbert A. Warwitz: Faszinosum Deltaflug - 100 years of hang gliding . In: Sport Practice. 3 (1992), pp. 43-47
- ↑ Wolfram Schleske: The kick when flying . In: Zeitschrift für Erlebnispädagogik 1-2 (1995) pages 3–8
- ↑ Martin Görner 2015: On the ecology of the eagle owl (Bubo bubo) in Thuringia: A long-term study. Acta ornithoecologica Vol. 8, H. 3-4, p. 162.
- ↑ Studies and reports. In: German Hang Glider Association DHV. Retrieved January 15, 2020 .
