1891. Derwitz / Krielow in Brandenburg, Germany. Otto Lilienthal uses weight shift to control his gliders, with his weight suspended from his arms and his upper body protruding through the wing. Control is achieved by swinging his body from the waist down. This method allows Lilienthal to achieve the first heavier-than-air flights by man. The control system works but its inefficiencies ultimately lead to his death, after he has completed over 2000 flights 1903.
Plage De Berck, France. Lavezzari flies a double lateen wing using a weight shift design similar to Lilienthal’s, with the pilot’s upper body protruding through the wing so that his centre of mass is close to the level of the wing.
1960. California, USA. Barry Hill Palmer uses a bamboo-pole frame with a bi-conical sail to achieve low-level hang gliding flights. This machine is controlled by a weight shift system somewhat similar to Lilienthal’s, with the pilot swinging his legs and lower body to achieve control. However, because the pilot’s centre of mass hangs well below the wing’s centre of lift on a solid structure, there is a considerable self-stabilizing effect.
1961. Raleigh-Durham Airport, USA. Thomas Purcell flies a Delta Wing glider inspired by the work by NASA, and uses a mechanical weight shift system. This aircraft starts out using wheels over land but the last version used floats over water. It creates much interest at NASA.
1962. USA. NASA flies its first Paresev. The Paresev uses a double conical sail and mechanical weight shift control system. About a hundred flights are made with the various models of the Paresev, but they all have control problems and the project is abandoned. The Paresev was designed to be a teaching aid for Astronauts intending to use Para Wings for re-entry from space. This Para Wing project never happened as the Para Wing proved too unreliable in deployment and a satisfactory control system was still not developed.
1963. April, Sydney, Australia. Mike Burns and Dick Swinbourne of Aerostructures, an aero-engineering company, first fly the Skiplane. This is a Delta Wing on floats that uses a mechanical weight shift system. The Skiplane is so easy to handle that members of the public are able to fly them while being towed behind boats at water-ski parks. Some are exported, including one to Cape Canaveral in the USA. Aerostructures had obtained their information of Conical sailed wings from an accident report (Mike Burns recalls that it was a fatal accident but no evidence of such a fatality has been found,)that described these wings as being quite dangerous. Aerostructures designed and built the Skiplane as a project for Bill McLaughlin, an entrepreneur involved in water-ski shows which were popular in that era.
1963. September 8, Grafton, Australia. Rod Fuller completes the first successful flight of a Dickenson Wing. Without knowledge of any but Lilienthal’s efforts at a weight shift control system, John Dickenson creates the Dickenson Wing, which he later sells commercially as the Ski Wing. This wing uses the Pendulum Weight Shift Control System that is found on modern hang gliders and ultralight aircraft. It is this aircraft that is copied in the thousands around the world, leading not just to the boom in hang gliding in the early 1970s, but the entire era of modern ultra-light aviation.
1963. October 8. John Dickenson files a patent application for a Gliding Apparatus with the Australian Patents Office. This was modified to "An Improved Gliding Apparatus" for the final application. John Dickenson was granted a “patent pending” on his invention but could not afford the cost involved in securing the final patent.
1966. Aerostructures becomes the first company to commercially manufacture and sell the Dickenson Wings, marketed as the Ski Wing, in a licensing deal with John Dickenson. This was the Mark V version of the glider. John Revelle sells Bill Moyes what may be the first unauthorised copy of the Dickenson Wing.
Development of the Dickenson Wing and the Pendulum Wight Shift Control System
Early in 1963 John Dickenson was asked by members of the Grafton Water-ski Club if he would build a water-ski kite and fly it at the annual Grafton Jacaranda Festival to be held at the end of October. He was approached because he was a member of the club, and his experience flying auto gyros was known about within the club. John agreed to give it a go and set out to design a suitable kite, but he identified three problems.
When he hung a weight under the model kites that he built, the kites became unstable. John had never actually seen a water-ski kite and he was working somewhat blind on the project.
Kites require a constant force to be applied to the tow-line to stay airborne. They fly in a stalled configuration, are total drag devices like parachutes, and simply fall from the sky when tow boats run out of fuel, stop because of water in the fuel, or stop when they hit a sandbar. All of these problems were common enough during water-ski sessions to require consideration. John realized that it would be better to have a ‘wing’ that would glide back to the water in a safer, more controlled manner. In his estimation a 45-degree, 1:1, glide angle would be ideal.
All previous water-ski kite displays at Grafton had reportedly resulted in spectacular crashes, mostly without serious injury, and the event was a crowd-puller for this very reason.
With these things in mind John began looking for a ‘wing’ design that he could use, rather than a ‘kite’ design. He had spent a lot of time in his youth building flying models so he had a reasonable knowledge of aerodynamics. John was especially interested in models with minimum structures.
He began studying flying foxes, the large fruit bats that were common in the area. He then built model gliders based on a bat wing design. They had a very good glide angle that exceeded his requirements. This meant that if there were an emergency, the wing would be able to glide back to earth. However, the drawback was that it could glide too far, landing on hard ground or crashing into a crowd of onlookers. This was no safer than the kites falling into the river and he realized that he would need a way of controlling this glider if it was to be made safe to use.
The Bat wing was going to be very involved and expensive to build, and it would end up looking similar to the elaborate Lilienthal gliders. At this point a member of the club showed John an article about the work NASA was undertaking with Paragliders. The simplicity of the bi-conical sail design of NASA's gliding parachute appealed to John, and given the financial and time constraints he was under, he abandoned the Batwing design.
John saw that for foot-launching behind a ski-boat the wing would require a solid frame to keep it out of the water, and so he created on using his limited engineering facilities and skills, and the materials available in Grafton in 1963.
While he was building models of this wing, John discovered to his surprise that it achieved a similar glide performance to the Batwing. This was good, but it meant that this wing would also require a control system to be flown safely.
The solution came to him while he was pushing his daughter on a swing at a local park. When she asked him to swing her sideways, John had a Eureka moment. He realised that if he suspended the pilot from the centre of lift, the pilot would be able to swing his or her weight beneath the wing to achieve control.
John then built a half-scale glider to test his control system. This was towed behind a boat and John discovered that it would easily pull him sideways when he banked the wing by moving the control-bar.
The next step in developing his Pendulum Weight Shift Control System was to calculate at what distance below the wing the pilot should hang, and the distance between the wing and the control bar to allow adequate control but not over-control. John’s experience flying autogyros meant that he was well aware of control sensitivity issues. It is important to note that the control bar is the base-bar of the A-frame. The A-frame is a structural component that incorporates the control bar and it came into existence only to increase the structural integrity of the airframe during the ongoing development of the Mark I Dickenson Wing.
With these calculations done, John set out to build a full-scale wing. Although his calculations indicated that the crossbar should be positioned at the centre of pressure on the wing, the fact that he could not obtain a long enough piece of aluminium meant that on the prototype, the Mark I, the crossbar was placed forward of this point. This was after all only an experimental design, and it was expected that it would fly only a few practice runs and then be flown at the Jacaranda Festival before being thrown away.
The next stage was to determine where the pilot should hang from the keel. John made some calculations and decided to make three attachment points on the glider to allow him to change the attachment point easily.
John made the first attempt to fly the glider on September 8, 1963, but he failed to get into the air because he had the harness attached to the most forward point and he was unable to get the wing to lift. Norm Stanford, a member of the water-ski club, had the next go and encountered the same problem. The next attempt was by Bob Clements, another club member. The harness had been moved to the rear-most setting and Bob took off, shot up into the air and promptly came straight back to crash heavily into the river. He was not injured and the wing survived.
For the next attempt the harness was moved to the centre point, and Rod Fuller, the club water-ski champion, successfully flew the glider across the Clarence River and turned 180 degrees before touching down in a tailwind landing that was perfect until the tailwind upended him into the river as the boat slowed down. Rod reported difficulty getting the wing to descend and so the harness attachment was moved a little forward again.
John Dickenson then flew his wing for the first time. This was when he realized the true enormity of his invention. The wing flew exactly as planned and the control system was excellent. It not only allowed control to be effected, it also provided the pilot with instant feedback, meaning that the glider was a dream to fly. Inspired by this John quickly set about applying for a patent for his Gliding Apparatus.
The Delta Wing design has undergone considerable development in the past 43 years, but the control system, and the ultra-light airframe developed by John Dickenson, is still evident in today’s hang gliders.
It should be noted that although the Pendulum Weight Shift System developed by John Dickenson is associated mainly with Delta Wings, designs such as the Tweetie hang glider (Australia) and the Quicksilver hang glider (USA), both monoplane designs, used John’s Pendulum Weight Shift System for all, or partial control, as did the Manta Fledgling.
Many modern fixed-wing gliders also use this system, or a hybrid version of it. John’s later wing design, the Frigate, built experimentally by Bill Moyes in 1980, also used the same control system on a ‘flying wing’ platform.
The ultra-light air-frame system, the Pendulum Weight Shift Control System, and the good flying qualities of the Dickenson Wing, combined with its easy set-up, and its portability, lead directly to the boom in hang gliding in the early 1970s. Power systems for his wing were quickly developed, and John himself worked on a Trike system in the late 1960s until financial and family commitments meant he had to abandon these pursuits. The Tweetie eventually became the Skycraft Scout, a powered ultra-light, the first certified ultra-light aircraft in the world, and the Quicksilver was powered in many ways, and became a cornerstone design in the evolution of modern ultra-light aviation.
Bill Moyes and Bill Bennett bought their first gliders from Aerostructures, and copied them to form multi-million dollar businesses. As they took these gliders around the world, many others followed suit, creating a global industry building John’s glider. No significant changes were made to John’s design until the mid-1970s. John spent many hours over the years helping Bill Moyes to further develop the glider design. When Bill wanted to slow the glider down for foot launching, John gave him the dimensions of the Mark I wing, which at 16-foot had launched too slowly to allow the water-skier enough time to get comfortably into the seat.
From the Mark II onwards, the leading edges and the keel of the gliders had been shortened to 13-foot to allow take-offs and landings to happen at a speed more harmonious with water-skiing speeds. With the smaller Mark II, III, IV and V’s, the A-frame was attached to the crossbar at the centre of pressure, and the pilot’s harness was hung from the A-frame a few inches below the centre of pressure. This dampened the control to make it less easy to over-control the smaller wing, and it also introduced a natural tendency for the wing to return to level flight if the pilot released the control bar.
The intervening years have seen no major changes to the Pendulum Weight Shift Control System developed by John Dickenson. In the 1980s there was the French Connection, a mechanical system designed to lighten the forces required to control the wing. This has fallen into disuse, and in a reverse of the early requirements to hang the pilot lower on the A-frame to dampen control, various gliders have appeared on the market with the pilot suspended from above the keel, or from the kingpost, to overcome handling difficulties inherent in their design. By hanging the pilot from above the keel, the pilot’s movements are enhanced rather than dampened.
The History of the bi-conical wing before 1963.
In Japan the Tosa Dako kite, which is a square or diamond shaped kite that uses a bi-conical sail, has been popular for centuries.
The square fighting kites flown across much of Asia utilize an adjustable bi-conical design sail that is essentially flat under normal line pressure, and that is tuned to turn when flat. When pressure is increased on the line it bends the cross-bar and so reduces the nose angle, increases the billow, and causes the kite to stop turning and to fly straight! As the flier attempts to cut his opponent's line.
The wing appears in many patents dating back to the 1800s.
Patents of particular significance are:
1910. US 989786. Lee & Darrah. Flying Machine.
1926. US 1632822. Dahl C.. Self Balancing Kite.
1947. US 2463135. Bach R. F.. Flying Wing Kite.
1948. US 2537560. Wanner G. D.. Kite.
1953. US 2785870. Green W. Kite.
The wing was used by Jan Lavezzari in 1904.
The wing used as a water-ski kite in Indonesia by 1955.
1959, NASA begins examining the wing for use in the space race.
1961, Barry Hill-Palmer builds and flies a hang glider using a bi-conical wing. Robert Purcell builds and flies a glider with a bi-conical wing.
1962. Mike Burns and Dick Swinbourne begin work on their bi-conical glider.
1963. John Dickenson builds and flies the bi-conical Mark I.
The great interest shown in the wing since 1963 has seen the wing evolve to a point almost beyond recognition.
First written; Graeme R. Henderson July 2007.
Revised and updated: Graeme R. Henderson November 2011
Copyright©2011 Graeme R. Henderson. All rights reserved