Glider (aircraft)
This article includes a list of general references, but it lacks sufficient corresponding inline citations. (November 2009) |
A glider is a
There are a wide variety of types differing in the construction of their wings, aerodynamic efficiency, location of the pilot, controls and intended purpose. Most exploit
Etymology
Glider is the agent noun form of the verb to glide. It derives from Middle English gliden, which in turn derived from Old English glīdan. The oldest meaning of glide may have denoted a precipitous running or jumping, as opposed to a smooth motion. Scholars are uncertain as to its original derivation, with possible connections to "slide", and "light" having been advanced..[2]
History
Early pre-modern accounts of flight are in most cases difficult to verify and it is unclear whether each craft was a glider, kite or parachute and to what degree they were truly controllable. Often the event is only recorded a long time after it allegedly took place. A 17th-century account reports an attempt at flight by the 9th-century poet
19th century
The first heavier-than-air (i.e. non-balloon) man-carrying aircraft that were based on published scientific principles were Sir
The
as they worked towards achieving powered flight. They returned to glider testing in 1911 by removing the motor from one of their later designs.Development
In the inter-war years, recreational gliding flourished in Germany under the auspices of Rhön-Rossitten. In the United States, the Schweizer brothers of Elmira, New York, manufactured sport sailplanes to meet the new demand. Sailplanes continued to evolve in the 1930s, and sport gliding has become the main application of gliders. As their performance improved, gliders began to be used to fly cross-country and now regularly fly hundreds or even over a thousand of kilometers in a day,[10] if the weather is suitable.
Development of flexible-wing hang gliders
Foot-launched aircraft had been flown by Lilienthal and at the meetings at Wasserkuppe in the 1920s. However the innovation that led to modern hang gliders was in 1951 when Francis Rogallo and Gertrude Rogallo applied for a patent for a fully flexible wing with a stiffening structure. The American space agency NASA began testing in various flexible and semi-rigid configurations of this Rogallo wing in 1957 in order to use it as a recovery system for the Gemini space capsules. Charles Richards and Paul Bikle developed the concept producing a wing that was simple to build which was capable of slow flight and as gentle landing. Between 1960 and 1962 Barry Hill Palmer used this concept to make foot-launched hang gliders, followed in 1963 by Mike Burns who built a kite-hang glider called Skiplane. In 1963, John W. Dickenson began commercial production.[11]
Development of paragliders
January 10, 1963 American
Recreational types
The main application today of glider aircraft is sport and recreation.
Sailplane
Gliders were developed from the 1920s for recreational purposes. As pilots began to understand how to use rising air, gliders were developed with a high lift-to-drag ratio. These allowed longer glides to the next source of 'lift', and so increase their chances of flying long distances. This gave rise to the popular sport known as gliding although the term can also be used to refer to merely descending flight. Such gliders designed for soaring are sometimes called sailplanes.
Gliders were mainly built of wood and metal but the majority now have composite materials using glass, carbon fibre and
Initially training was done by short 'hops' in
A class of ultralight sailplanes, including some known as microlift gliders and some as 'airchairs', has been defined by the FAI based on a maximum weight. They are light enough to be transported easily, and can be flown without licensing in some countries. Ultralight gliders have performance similar to hang gliders, but offer some additional crash safety as the pilot can be strapped in an upright seat within a deformable structure. Landing is usually on one or two wheels which distinguishes these craft from hang gliders. Several commercial ultralight gliders have come and gone, but most current development is done by individual designers and home builders.
Hang gliders
Unlike a sailplane, a hang glider is capable of being carried, foot launched and landed solely by the use of the pilot's legs.[17]
- In the original and still most common designs, Class 1, the pilot is suspended from the center of the flexible wing and controls the aircraft by shifting their weight.
- Class 2 (designated by the FAI as Sub-Class O-2) have a rigid primary structure with movable aerodynamic surfaces, such as spoilers, as the primary method of control. The pilot is often enclosed by means of a fairing. These offer the best performance and are the most expensive.
- Class 4 hang gliders are unable to demonstrate consistent ability to safely take-off and/or land in nil-wind conditions, but otherwise are capable of being launched and landed by the use of the pilot's legs.
- Class 5 hang gliders have a rigid primary structure with movable aerodynamic surfaces as the primary method of control and can safely take-off and land in nil-wind conditions. No pilot fairings are permitted.
In a hang glider the shape of the wing is determined by a structure, and it is this that distinguishes them from the other main type of foot-launched aircraft,
Paragliders
A paraglider is a free-flying, foot-launched aircraft. The pilot sits in a harness suspended below a fabric wing. Unlike a hang glider whose wings have frames, the form of a paraglider wing is formed by the pressure of air entering vents or cells in the front of the wing. This is known as a ram-air wing (similar to the smaller parachute design). The paraglider's light and simple design allows them to be packed and carried in large backpacks, and make them one of the simplest and economical modes of flight. Competition level wings can achieve glide ratios up to 1:10 and fly around speeds of 45 km/h (28 mph).
Like sailplanes and hang gliders, paragliders use rising air (thermals or ridge lift) to gain height. This process is the basis for most recreational flights and competitions, though aerobatics and 'spot landing competitions' also occur. Launching is often done by jogging down a slope, but winch launches behind a towing vehicle are also used. A
Comparison of gliders, hang gliders and paragliders
There can be confusion between gliders, hang gliders, and paragliders. Paragliders and hang gliders are both foot-launched glider aircraft and in both cases the pilot is suspended ("hangs") below the lift surface. "Hang glider" is the term for those where the airframe contains rigid structures, whereas the primary structure of paragliders is supple, consisting mainly of woven material.
Paragliders
|
Hang gliders
|
Gliders/Sailplanes | |
---|---|---|---|
Undercarriage | pilot's legs used for take-off and landing | pilot's legs used for take-off and landing | aircraft takes off and lands using a wheeled undercarriage or skids |
Wing structure | entirely flexible, with shape maintained purely by the pressure of air flowing into and over the wing in flight and the tension of the lines | generally flexible but supported on a rigid frame which determines its shape (note that rigid-wing hang gliders also exist) | rigid wing surface which totally encases wing structure |
Pilot position | sitting in a harness | usually lying prone in a cocoon-like harness suspended from the wing; seated and supine are also possible | sitting in a seat with a harness, surrounded by a crash-resistant structure |
Speed range (stall speed – max speed) |
slowest – typically 25 to 60 km/h for recreational gliders (over 50 km/h requires use of speed bar),[18] hence easier to launch and fly in light winds; least wind penetration; pitch variation can be achieved with the controls | faster than paragliders, slower than gliders/sailplaines | maximum speed up to about 280 km/h (170 mph);[19] stall speed typically 65 km/h (40 mph);[19] able to fly in windier turbulent conditions and can outrun bad weather; good penetration into a headwind |
Maximum glide ratio | about 10, relatively poor glide performance makes long distance flights more difficult; current (as of May 2017[update]) world record is 564 kilometres (350 mi)[20] | about 17, with up to 20 for rigid wings | open class sailplanes – typically around 60:1, but in more common 15–18 meter span aircraft, glide ratios are between 38:1 and 52:1;[21] high glide performance enabling long distance flight, with 3,000 kilometres (1,900 mi) being current (as of November 2010[update]) record[22] |
Turn radius | tightest turn radius[citation needed] | somewhat larger turn radius than paragliders, tigher than gliders/sailplanes[citation needed] | widest turn radius but still able to circle tightly in thermals[23] |
Landing | smallest space needed to land, offering more landing options from cross-country flights; also easiest to pack up and carry like a bag to the nearest road | 15 m to 60 m length flat area required; can be derigged by one person and carried to the nearest road | landings can be performed in ~250 m length field. Aerial retrieve may be possible but if not, specialized trailer needed to retrieve by road. Some sailplanes have engines that remove the need for an out-landing, if successfully started on time |
Learning | simplest and quickest to learn | teaching is done in single and two-seat hang gliders | teaching is done in a two-seat glider with dual controls |
Convenience | packs smaller (easier to transport and store) | more awkward to transport and store; longer to rig and de-rig; often transported on the roof of a car | often stored and transported in purpose-built trailers about 9 metres long, from which they are rigged. Although rigging aids allow a single person to rig a glider, usually the rigging involves 2 or 3 people. Some frequently used sailplanes are stored already rigged in hangars. |
Cost | cost of new is €1500 and up,[24] cheapest but shortest lasting (around 500 hours flying time, depending on treatment), active second-hand market[25] | cost of new glider very high (top of the range 18 m turbo with instruments and trailer €200,000) but it is long lasting (up to several decades), so active second-hand market; typical cost is from €2,000 to €145,000[26] |
Military gliders
Military gliders were used mainly during the
Research aircraft
Even after the development of powered aircraft, gliders have been built for research, where the lack of powerplant reduces complexity and construction costs and speeds development, particularly where new and poorly understood aerodynamic ideas are being tested that might require significant airframe changes. Examples have included delta wings, flying wings, lifting bodies and other unconventional lifting surfaces where existing theories were not sufficiently developed to estimate full scale characteristics.
Unpowered flying wings built for aerodynamic research include the Horten flying wings, the scaled glider version of the Armstrong Whitworth A.W.52 jet powered flying wing.
The NASA Paresev Rogallo flexible wing glider was built to investigate alternative methods of recovering spacecraft. Although this application was abandoned, publicity inspired hobbyists to adapt the flexible wing airfoil for modern hang gliders.
Rocket gliders
Rocket-powered aircraft consume their fuel quickly and so most must land unpowered unless there is another power source. The first rocket plane was the
Rotary wing
Most unpowered rotary-wing aircraft are kites rather than gliders, i.e. they are usually towed behind a car or boat rather than being capable of free flight. These are known as rotor kites. However rotary-winged gliders, 'gyrogliders', were investigated that could descend like an autogyro, using the lift from rotors to reduce the vertical speed. These were evaluated as a method of dropping people or equipment from other aircraft.
Unmanned gliders
Paper airplane
A paper plane, paper aeroplane (UK), paper airplane (US), paper glider, paper dart or dart is a toy aircraft (usually a glider) made out of paper or paperboard; the practice of constructing paper planes is sometimes referred to as aerogami (Japanese: kamihikōki), after origami, the Japanese art of paper folding.[28]
Model gliders
Model glider aircraft are flying or non-flying models of existing or imaginary gliders, often scaled-down versions of full size planes, using lightweight materials such as
Larger outdoor models are usually
Glide bombs
A
See also
References
- ^ FAA Glider handbook Archived 2009-02-06 at the Wayback Machine
- ^ Liberman, Anatoly. "An Addendum to “Ten Scandinavian and North English Etymologies”", from alvíssmál 7. 1997. 101–104.
- ^ Lynn Townsend White Jr. (Spring, 1961) "Eilmer of Malmesbury, an Eleventh Century Aviator: A Case Study of Technological Innovation, Its Context and Tradition", Technology and Culture 2 (2), pp. 97–111 [100–101].
- ^ White, L. Jr., Eilmer of Malmesbury, an Eleventh Century Aviator. Medieval Religion and Technology. Los Angeles: University of California Press, 1978, Chapter 4.
- ^ Lynn Townsend White Jr. (Spring, 1961). "Eilmer of Malmesbury, an Eleventh Century Aviator: A Case Study of Technological Innovation, Its Context and Tradition", Technology and Culture 2 (2), pp. 97–111 [98 & 101].
- ^ Who is Hezarfen Ahmet Çelebi? Archived 2016-01-21 at the Wayback Machine
- ^ Hezârfen Ahmed Çelebi "The First Man to Fly" Archived 2016-01-21 at the Wayback Machine
- ^ Çelebi, Evliya (2003). Seyahatname. Istanbul: Yapı Kredi Kültür Sanat Yayıncılık, p. 318.
- ^ Harwood, Craig S. and Fogel, Gary B. Quest for Flight: John J. Montgomery and the Dawn of Aviation in the West, University of Oklahoma Press 2012.
- ^ "FAI list of people with 1000km diplomas". 5 October 2017. Retrieved 24 May 2019.
- ^ The Fédération Aéronautique Internationale Hang Gliding Diploma (2006) for the invention of the modern hang glider: FAI Award: The FAI Hang Gliding Diploma Archived 2011-05-18 at the Wayback Machine
- ^ "History of Paragliding". Archived from the original on 2009-09-13. Retrieved 2009-02-15.
- ^ "Pilot Profile: David Barish, the Probable Inventor of the Paraglider". Archived from the original on 2010-06-08. Retrieved 2009-03-10.
- ^ David Barish, The Forgotten Father of Paragliding Archived 2010-10-29 at the Wayback Machine
- ISBN 0-87474-828-3
- ^ "Definition of gliders used for sporting purposes in FAI Sporting Code". Archived from the original on 2014-01-06. Retrieved 2013-01-01.
- ^ "FAI Sporting Code Section 7" (PDF). Archived from the original (PDF) on 2009-03-19. Retrieved 2009-03-13.
- ^ "Technical data for Advance Omega 8". Advance AG. Archived from the original on 2013-05-30. Retrieved 2011-10-22.
- ^ a b Flight Manual of Scheicher ASW27b. Alexander Schleicher GmbH & Co. 2003.
- ^ "FAI Paragliding record". Fédération Aéronautique Internationale. Archived from the original on 2011-05-09. Retrieved 2010-11-30.
- ^ "Handicap list 2008" (PDF). Deutsche Meisterschaft im Streckensegelflug. Deutscher Aero Club. Archived from the original (PDF) on 2009-02-24. Retrieved 2008-08-07.
- ^ "FAI records". Fédération Aéronautique Internationale. Archived from the original on 2011-09-11. Retrieved 2010-11-30.
- ISBN 1-85310-504-X.
- ^ "Brochures Ozone". Ozone France. Archived from the original on 2013-10-27. Retrieved 2011-10-21.
- ^ "Typical set of classified ads for paragliders". Archived from the original on 2012-03-30. Retrieved 2011-10-22.
- ^ "Typical set of classified ads for gliders". Archived from the original on 2010-12-06. Retrieved 2011-01-18.
- ^ The Me 163 was powered by an unstable fuel mix and landing with fuel left caused several accidents
- ^ "Aerogami – Event Description". Pragyan. Retrieved 21 March 2019.