Hang gliding is an air sport employing foot-launchable aircraft known as a hang gliders. Typically, hang gliders are composed of an aluminium or composite framed fabric wing. The pilot is ensconced in a harness depending from the airframe, and exercises control by shifting body weight in opposition to a control frame.
Early hang glider designs did not reliably achieve safe flight, their builders lacking a comprehensive understanding of the underlying principles of flight. The first recorded controlled flights were by German engineer Otto Lilienthal, whose research, published in 1889, strongly influenced later designers. The type of aircraft employed by Lilienthal is now referred to as a hang glider. Further hang glider research was undertaken during the 1920s in Europe, Australia and the U.S.A, where designers tested several wing concepts and the 'pendulum weight-shift control system'.
In 1957 the American space agency NASA began testing various formats of a new wing called the Rogallo wing with the intent of possibly implementing the design as a recovery system for the Gemini space capsules. The wing's simplicity of design and ease of construction, in combination with its slow flight characteristics, did not go unnoticed by hang glider enthusiasts; Rogallo's flexible wing airfoil was soon adapted to the purpose of recreational flight, launching a hang glider Renaissance.
The sleek high performance jets, sailplanes and hang gliders of today have a heritage that dates back to man’s first attempts at flight.
The Chinese Daoist writer Ge Hong (284–364 AD) wrote that kite vehicles with frames made of wood from the jujube tree had ox-leather straps "fastened to returning blades" that could allow the device to soar high into the air. As a form of execution, the notoriously cruel Emperor Wenxuan of Northern Qi (r. 550–559) had members of the rival Yuan and Tuoba clans attached to kites and launched from the top of the Tower of the Golden Phoenix in the capital, Ye, China, as test pilots; Yuan Huangtou (d. 559) glided for a while and survived the landing, but he was executed shortly after. The Venetian traveler Marco Polo (1254–1324) wrote that "some fool or drunkard" of the crew of a Chinese ship was the standard candidate to be strapped into a man-flying kite (which he called a "hurdle" made of willow stems attached to eight cords), which served the purpose of fortune-telling (i.e. they believed that if the man strapped to the kite rose fine, a prosperous voyage was ahead, if not, no foreign merchant would make deals with them).
There are accounts of two attempts at flight by a Abbas Ibn Firnas near Cordoba, Spain in the 9th century. His first, in 852 CE, was a parachute jump using a huge wing-like cloak to break his fall; the second, in 875 CE, at the age of 70, employed a rudimentary glider. Both efforts ended in crashes and injury. It is possible that word of Ibn Firnas' wing-like parachute reached the monk Eilmer of Malmesbury of England, a scholar of mathematics and astrology. A fellow monk and historian, William of Malmesbury, reported that Eilmer flew off the roof of an Abbey in Malmesbury, England sometime between 1000 and 1010 AD, gliding about 200 metres (220 yd) before crashing, breaking a leg.
The Kraków Museum of Ethnography in Poland claims that in 1866, painter and carpenter Jan Wnęk completed construction of an ash wood glider frame which he covered with linen impregnated with varnish and that Wnęk was firmly strapped to the glider by the chest and hips. It is claimed but not verified, that Jan Wnęk made several public flights from the local church tower during 1866-1869.
Starting in the 1880s advancements were made in aerodynamics and construction that led to the first truly practical gliders; this information was often shared and published by early aviators and inventors, building a long series of incremental achievements. Through the 1880’s several aviation pioneers emerged in different countries around the world all perusing glider designs with varying degrees of success. Chief among these were Otto Lilienthal in Berlin, Germany, Lawrence Hargrave in Sydney, Australia, Percy Pilcher in the United Kingdom, John Joseph Montgomery at Otay Mesa near San Diego, California (1880s) as well as at Santa Clara, California (1905) Octave Chanute and his team in Gary, Indiana in the U.S.A., just to name a few.
Otto Lilienthal duplicated some of his contemporaries' work and greatly expanded on it from 1874, publishing all of his research in 1889.He also produced a series of gliders, and in 1891 was able to make flights of 25 metres (82 ft) or more routinely, as well as some soaring flights. He rigorously documented his work, influencing later designers; for this reason he is one of the best known and influential of the early aviation pioneers. His type of aircraft is now known as a hang glider. By 1896 he had made about 2000 flights on a number of his designs when he crashed from a height of roughly 17 metres (56 ft) fracturing his spine. Percy Pilcher took a growing interest in aviation and built a glider called The Bat which he flew for the first time in 1895. Later that year Pilcher met and consulted with Otto Lilienthal, who was the leading expert in gliding; these discussions led to Pilcher building two more hang gliders, The Beetle and The Gull. Based on the work of his mentor Otto Lilienthal, in 1897 Pilcher built a third hang glider called The Hawk with which he broke the world distance record when he flew 250 metres (820 ft).
The hang glider lost some importance through the introduction of wing warping in 1902 by the Wright brothers and subsequently of aileron control by the French. When the World War I ended in 1918, the Treaty of Versailles practically ended engine driven flights in Germany, thus, in the 1920s and 1930s, while aviators and aircraft makers in the rest of the world were working to improve the performance of powered aircraft, the Germans were designing, developing and flying ever more efficient gliders and discovering ways of using the natural forces in the atmosphere to make them fly farther and faster. These activities on Wasserkuppe promoted a renaissance of gliding aviation. Many of these gliders flown in 1920 were hang gliders in that they were controlled by the pilot's weight shift alone. The first Wasserkuppe glider competition was held in 1920 and from 1924 they were organised by Rhön-Rossitten Gesellschaft. Over the next decade, the contest grew in popularity. As many as 70 glider clubs from Europe sent their best gliders and pilots to compete for duration, altitude and distance prizes, the most coveted prize was that donated by President von Hindenburg. As many as 60,000 spectators dotted the mountain slopes to watch these events. Virtually every European aeronautical engineer of the time tested and modified their aircraft there and reports were generated. Some competing hang glider designers were Alfried Gymnich, Gottlob Espenlaub, Alexander Lippisch, Heinz Schneider, Francis Chardon, Willi Pelzner, Hans Richterand Segelflieger Peltzner, while engineer Henri Mignet was busy in France and Czesław Tański was busy in Turkey.
Invention of the flexible wing
On 1948, aeronautical engineer Francis Rogallo invented a self-inflating wing which he patented on March 20, 1951 as the Flexible Wing, also known as the flexwing and Rogallo wing. Francis Rogallo had first proposed his flexible wing concept to the Langley Research Center in the late 1940s as a simple, inexpensive approach to recreational flying, but the idea was not accepted as a project.
It was on October 4, 1957 when the Russian satellite Sputnik became a concern to the United States and marked the beginning of the 'space race' and the creation of NASA. Rogallo was in position to seize the opportunity and with his help at the wind tunnels, NASA began a series of experiments testing Rogallo's flexible wing, which got renamed Parawing, in order to evaluate it as a recovery system for the project Gemini space capsules. Rogallo designed his flexible wing to allow the astronauts to deploy it like a parachute at subsonic speeds during reentry, then glide their capsule to a specified touchdown point. F. Rogallo's team collaborated with at least two American aircraft companies, Ryan Aeronautical Company and North American Aviation, as there was potential for gliders, dirigible parachutes, and other new types of manned aircraft; this mainly involved stabilizing the leading edges with compressed air beams or rigid structures like aluminium tubes. By 1961 NASA had already made test flights of an experimental STOL 'aerial utility aircraft' called Ryan XV-8 (the Flying Jeep or Fleep) and by March 1962, of a weight-shift glider called Paresev.
Round parachutes were selected over the Rogallo wing to be used on the Gemini spacecraft and on 1965, funding on flexible wings stopped.
Flexible wing hang gliders
The simplicity of the Rogallo wing, ease of construction, capability of slow flight and its gentle landing characteristics did not go unnoticed by some hang glider and ultralight glider enthusiasts. The publicity on the Fleep and the Paresev tests sparked interest in independent builders like Barry Palmer and John Dickenson, who separately explored distinct airframes and control systems to be adapted to a Rogallo wing and be flown as a hang glider.
On August 1961, American engineer Barry Palmer developed and flew the first foot-launched Rogallo wing hang glider. This took place near Latrobe, east of Sacramento, California. Palmer used aluminium tubing and no wires for construction, fearing kinking during assembly. Most flights were performed with just a set of inclined parallel bars that split his weight between his underarms and hands and he demonstrated that the Rogallo wing, when used as a hang glider, could also be controlled by weight-shift alone. The last of Palmer's foot-launched hang gliders flew in the summer of 1962 and it had a ski-lift type of seat mounted to the keel with a universal joint for pendulum weight-shift control; a single control stick was projected down from the wing. During the period from 1961 to 1963 Barry Palmer made tens of flights using this concept. His longest flight ranged in length up to 180 metres (590 ft), at altitudes up to 24 metres (79 ft), and had an overall glide ratio of 4.5 to 1.
In April 1963 Mike Burns first flew the Skiplane, a flexible wing glider on pontoons. In Septermber 1963, Australian John Dickenson set out to build a water ski wing that could be released at altitude and glide to a safe landing. After seeing a Rogallo airfoil in a magazine, Dickenson designed the ski kite he called the Ski Wing. Dickenson fashioned an airframe that incorporated a triangle control frame and utilized wire bracing to distributed the load to the Rogallo airfoil; the pilot sat on a swinging seat. Dickenson's Ski Wing was stable and controllable compared to the flat manned kites used at water ski shows at the time. The Ski Wing was first flown in public at the Grafton Jacaranda Festival, Australia, in September 1963 by Rod Fuller while towed behind a motorboat. The Ski Wing was light and portable so Dickenson decided to file for a patent; however, lacking resources, Dickenson procured a provisional patent - which would later lapse. By 1972, australian builders Bill Bennett and Bill Moyes developed the Dickenson format of water ski kite into a foot-launched hang glider.
Rigid wing hang gliders
There have been several rigid wing hang gliders flown since Otto Lilienthal took his first flights in the 1890s. Jack Lambie from California, designed in 1971 the popular Hang Loose Chanute hang glider, and the first two high performing modern hang gliders were the Mitchell Wing and the Icarus.
On 1971 and 1972 the Icarus I and Icarus II were built, respectively. These were rigid biplane flying wing designs by Taras Kiceniuk, Jr. The Icarus V 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 early 1940s Don Mitchell, an aeronautical engineer, first became involved with flying wing glider design and construction. WWII interrupted his research until 1974, with the advent of hang glider mania, adventurers were experimenting with design and exploring records worldwide. It was then that Mitchell's flying wing resurfaced. Dr. Howard Long took an interest and asked Don Mitchell to make him a refined 'flying wing' hang glider. The result was the foot-launched Mitchell Wing. When the foot-launched Mitchell Wing B-10 flew in the 1977 U.S.A. Nationals, the hang gliding world was completely astounded. The Mitchell Wing then went on to set and hold every world record in its class. In 1980, George Worthington soared to 17,000 feet (5,200 m) high and glided 105 miles (169 km), setting two new rigid wing records. The Mitchell Wing had a single "D" spar with aircraft birch plywood torsion proof leading edge and 3-axes control. Foam ribs placed every 4.5 inches (110 mm) hold the D shape. The built-up truss ribs aft of the spar are covered with fabric. This structural design is simple, extremely strong and light (under 80 Lbs).
The Exxtacy, designed by Felix Ruehle In the early 1990s, followed by the IXBO, became the first two rigid wing hang gliders on the market with a leading edge of carbon fiber. Ruehle then produced the ATOS in 1999. The nose angle and wing span of modern rigid wings are a little larger than flexible wings and the sail is rather stiff.
The research by NASA as well as government reports and photographs of the flexible wing, were published and became available to the general public and soon, the Rogallo wing was turned into an easily constructed, inexpensive, foot-launchable glider. Barry Palmer corresponded Richard Miller, who in 1964 developed the Bamboo Butterfly, followed by Tara Kiceniuk's Batso. Dave Kilbourne published his plan for a Rogallo wing Kilbo Kite hang glider in the early 1970s. Jim Foreman produced the Bat-Glider plans for a Rogallo wing hang glider and sold copies for $5 USD throughout the world; later, Taras Kiceniuk, Tom Dickinson and two other team members made a similar hang glider called Batso and sold copies of its plans. The plans of these hang gliders circulated in some magazines in the mid 1960s.
Eventually, word of John Dickenson's success got out and more portable flexible wing gliders were built; the sudden commercial availability of his improved water ski hang gliders in 1969 by manufacturers like Bill Bennett (Delta Wing) and Bill Moyes (Moyes Gliders) added signinicantly to the flexible wing's popularity, which began to rise world wide as a full fledged sport.
The extreme nature of foot-launched hang gliding appealed to the freewheeling culture of the early 1970s across America more as an expression of freedom than an air sport. Popularity was further fueled by the distribution of specialized international publications such as the Low & Slow magazine founded in 1971, Hang Glider Weekly and Ground Skimmer in 1972 and Glider Rider in 1975. Hang gliding was simultaneously promoted by major international publications such as Popular Mechanics, Popular Science and the Life magazine, all three magazines distributed world-wide in 1971; the Sky Raiders hang gliding movie was released in 1976 with a powerful effect. The British SkyWings magazine has been published monthly since 1975 and Cross Country, the first truly international hang gliding magazine began publication in 1988.
Free hang gliding took longer to catch on in Australia, where hang gliding was a water skiing sport and part of the New South Wales Water Skiing Association. In fact, Dickenson's Ski Wing was competing in the NSWWSA kite-flying section against the polygonal Japanese style flat kites. The first recorded foot-launched flight in Australia occurred in 1972 and the Australian Self Soaring Association was formed by foot-launched pilots in 1974. The first foot-launched Australian Championships were held in 1976.
First flights in the early 1970s from Mt. Kilimanjaro by Moyes, and Caril Ridley’s flights in India met with headlines. On 1973 the ZDF German Television produced a 30 min documentary on Mike Harker's world record hang glider flight from Mt. Zugspitze in Germany, this TV documentary helped promote the development of hang gliding in Europe. Harker also produced other hang gliding documentaries in the mid 1970s which were presented in TV by 16 countries.
Although by the early 1970s many rigid wings were developed, none sold terribly well, while dozens of flexible wing hang glider companies were springing up all over the world. The mid 1970s underwent significant improvements in hang glider design as manufacturers were bringing out new and improved models at a fast rate. From the simple structures of the early 1970s, the aspect ratio of the gliders increased dramatically, sails became tighter, battens became the rule, and the gliders became safer. In the late 1970s preformed aluminium battens became common and in 1980, the Comettook the industry by storm and popularized the free-floating internalized crossbar and double-surface sail construction that has since become the standard.
As usual, essentially parallel developments can be difficult to sort out and serialize, but in fact, the flexible wing hang glider popularity started with the publicized Paresev and Fleep concept, followed by John Dickenson's adaptation and the aggressive entrepreneurial energies of Bill Bennett, Bill Moyes, Joe Faust, Dick Eipper, Mike Riggs, the Wills brothers and the massive enthusiasm of thousands of people wanting to glide, and began what is now an estimated $50 million USD annual industry. Ironically, Dickenson never made any money and Francis Rogallo never claimed the rights to the patent he held, thus allowing his flexible wing airfoil to be used royalty free.
It is certain that many people from many countries, made contributions to the development of the flexible wing hang glider. In the aviation context of 'first flights' and recreational vs. commercial developments, it must be noted that new and old inventions often complement in synergy; it is in this evolutionary and social context that the crucial developments put together by Francis Rogallo and John Dickenson, were the ones that were most successful and influential on the evolution of hang gliders.
The following generations follow the classification from the British Hang Gliding Museum's Hang Gliding History: Development in Britain of the Flexwing hang glider. 
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Published in July 2009.
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