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Competition classes in gliding, as in other sports, are created as a means to promote the development of the sport. Classes may be created to further a sporting policy or as an answer to popularity, market and technology trends.
Class policy in gliding mostly seeks to promote fairness in competition, contain the cost of access to the sport and establish a stable environment for investment decisions by both manufacturers and competitors. Gliding enjoys a well integrated institutional framework at the international level which ensures that essentially the same classes and class definitions are followed in all countries.
As gliding is by its very nature performance-oriented, classes have not been targeted at fostering technological development, which has been stimulated mostly by market dynamics and by a strong cross-feeding between research and industry.
FAI Competition Classes
The Fédération Aéronautique Internationale (FAI) is the sporting body overseeing air sports at the international level. Seven glider classes are currently recognised by the FAI and are eligible for European and World Championships:
- Open Class, places no restrictions except a limit of 850 kg to the maximum all-up mass, eg. eta, Nimbus-4, ASH 25.
- Standard Class, restricted to a maximum wing-span of 15 metres and fixed wing sections (flaps or other lift-enhancing devices not allowed), eg. ASW 28, LS8, Discus-2.
- Two Seater Class, restricted to a maximum wing-span of 20 metres, eg. Duo Discus, DG-1000.
- Club Class, allows a wide range of older small gliders within a specified range of performances, eg. Libelle, Standard Cirrus, LS1, Pilatus PC-11, with the scores being adjusted by handicapping. Disposable (i.e. water) ballast may be installed but must not be used in this class.
- World Class, a monotype class comprising only the Warsaw Polytechnic PW-5.
Gliding World Records are classified by the FAI under sub-classes that do not have a one-to-one correspondence with the above competition classes:
- DO - Open Class, accepts sporting performances achieved with any glider type. Sporting performances by Open, 18 metre and Two Seaters are eligible only for this sub-class.
- D15 - 15 metre Class, accepts sporting performances achieved with gliders whose wing-span is smaller than or equal to 15 metres.
- DW - World Class, for sporting performances by World Class gliders only.
- DU - Ultralight Class, for sporting performances by gliders having maximum mass below 220 kg, eg. the SparrowHawk, Apis WR, Silent.
A microlift class with an upper limit of 18 kg/m² wing loading to encompass types such as the Carbon Dragon is currently under discussion.
Non-FAI Classes
Glider classes not recognised by the FAI have been used in some regional and national competitions. The most significant of these are:
- Sports Class, a handicapped class similar in concept to the Club Class but allowing a wider range of gliders, usually both flapped and unflapped and with spans not limited to 15 metres. This class is often used in competitions where the number of entries is too small to warrant subdivision of the participants into separate classes.
- 1-26 Class, a monotype class very popular in the western United States, based on the Schweizer SGS 1-26 glider and managed by the 1-26 Association, a division of the Soaring Society of America.
History
Open Class
The Open Class is the oldest competition class, although it only came into formal existence with the creation of the two seater class in the early 1950's.This unrestricted class has been a favourite testing ground for technological innovation. Many research prototypes fall under this class definition, eg. the Akaflieg Darmstadt D-30 of 1938, which had variable-dihedral wings and spars built of light alloys, the extremely large-span SB-10 of 1972, the telescoping-wing Akaflieg Stuttgart FS 29 of 1975 and the solar-powered Icare.
In contests, the Open Class usually delivers the top performances, with daily tasks above 1000 km being possible in favourable weather. To be successful, however, an Open class glider must blend high performance with practicality. "Extreme" designs tend to be failures, of which the Austria of 1931, the Sigma of 1971 and the BJ series are but the most conspicuous examples. Arguably the only 'extreme' glider that ever won a World Championships was the Nimbus I.
The Open class is, notwithstanding its name, rather exclusive. Until the 1960's a fair number of gliders was able to do well in open competition, with smaller-span types occasionally beating larger but more cumbersome types. The composite revolution caused a shake-down, further aggravated when the ASW 22 and Nimbus-3 were introduced in 1981, after which the Open Class became the preserve of only two manufacturers.
Following a couple of decades of small, incremental performance gains, the appearance in 2000 of the eta brought a sudden jump in performance and a further price escalation. This very expensive aircraft has up to now not found outstandingly success in competition, but it will unavoidably impact the cost of remaining competitive in the class. The 'eta biter' (a highly modified ASW 22 first seen at the 2006 World Gliding Championships) and the 'Concordia' single-seater project are both being presented as challengers to eta.
Standard Class
The Standard Class was introduced in the late fifties as an alternative to the increasingly heavy, difficult to fly and costly Open Class ships of that time. Striving for affordability and simplicity, the original standard class rules restricted the span to 15 metres and ruled out retractable undercarriages, lift-enhancing devices such as flaps and flight-disposable ballast. The archetypal embodiment of these rules is the Ka 6.Technological change was fast paced in the years following the introduction of the Standard Class. The transition to fibreglass construction made the existing rules increasingly awkward. The stronger composite structures allowed higher wing loadings, and competitors resorted to fixed ballast to exploit this competitive advantage, which of course increased landing speeds and the risk of damage when alighting in unprepared fields. The fixed undercarriages caused a major fraction of the drag of sleek fibreglass airframes. Designers reacted by recessing the wheels into the fuselage, which further increased the risk of ground-related damage. Manufacturers took to arguing that the single cheapest way to increase performance was to retract the wheel.
In view of these safety and cost-related arguments, the Standard Class rules were updated to allow disposable water ballast and retractable undercarriages. The requirement for large airbrakes able to limit speed in a vertical dive was dropped, and trailing-edge airbrakes, championed especially by the American Richard Schreder as a cheaper glidepath control device, were for the first time allowed.
The later concession would bring difficulties in that the demarcation line between airbrake/landing flaps and performance enhancing flaps is vague. The reluctance within the IGC to allow the later in the Standard Class led to an unsuccessful attempt to codify what constitutes a landing flap. After the LS2 and the PIK-20 exploited this loophole to win the 1974 and 1976 World Championships in the Standard Class, the IGC banned all camber-changing devices from the class and created a parallel 15 metre Class to accommodate them. This decision was polemic as it was the second rule change in a few years and it orphaned several gliders types that did not fit well within either class definition (especially the PIK-20 and the Libelle that had been built in large numbers). Notwithstanding, the decision was vindicated by the great success subsequently enjoyed by both the Standard and 15 metre classes.
Some significant Standard Class types are the Ka-6 and Mucha (1958), the LS1 (1967), the Standard Cirrus (1969), the LS4 (1980) and the Discus (1984).
15 metre Class
This class was created specifically to end the trailing-edge airbrake controversy in the Standard Class . The class has been very successful, being since its inception a feature of all World and European Championships. Technological development has eroded the performance gap that once existed between the Standard and 15-metre classes, which today is perceptible only in strong gliding weather. Some observers argue that the difference is not meaningful enough, that the 18 metre class is the natural successor to the 15 metre class and that the later should be removed from World Championships to give space to new classes. Notwithstanding, the class has a sizeable following and official support for the foreseeable future.Significant 15 metre types include the ASW 20 (1977), Ventus (1980), LS6 (1983) and Ventus-2 (1994).
18 metre Class
The availability of carbon fibre at affordable prices has allowed the manufacture of light and economical spans exceeding 15 metres. Manufacturers started to exploit this potential by offering tip extensions for their flapped sailplanes. Spans increased gradually from 16.6 metres in the first implementations (ASW 20L and Ventus b 16.6) to 17 metres (DG-200/17, DG-600, Glasflügel 403), 17.5 metres (LS6-c), finally settling on 18 metres. The trend towards turbo and self-launching sailplanes also favours the 18 metre span, which is large enough to carry the additional weight of the power unit without impairing the ability to climb in weak lift.Following a decade of contests at regional level, which permitted the resolution of issues such as mixed glider/motorglider competition, this class came to feature for the first time in a World Championships in 2001.
Two Seater Class
A two seater class appeared for the first time in a World Championships in 1952. The reason for having a separate class was that the drag of the larger fuselage put two seaters at a significant disadvantage vis-à-vis singe seaters. This class was discontinued after the 1956 World Championships, although two seater World records were retained until 1996.The very large spans made possible by modern materials have obliterated the performance gap that once existed between single and two seaters in Open Class competition. Today double seaters are increasingly common and often win in this class.
The IGC voted in 2005 to reinstate a Two Seater Class with a span limitation of 20 metres. This class has no relationship to the 'old' two seater class, as it targets the high performance trainers that have been steadily gaining in popularity. Their smaller size sets them apart from the Open Class two seaters which are very expensive and require highly experienced crews. The 20 metre double seaters handle and fly very much like Standard Class single seaters and cost little more than half the price of an Open Class "ship".
The contenders in this class are principally the Duo Discus and DG-1000, with the older Janus and DG-500 and a smattering of other types also being eligible.
Club Class
Handicapped contests have been a long standing feature of many regional and national level events. These 'Club' or 'sports' contests allow the use of gliders of widely differing levels of performance. They are thus popular in places where mostly older types are available, or where the number of entrants is not large enough to warrant their separation into the usual classes.The formal recognition by the FAI of a handicapped class is however quite recent, with the first Club Class World Championships having taken place only in 2001. It is intended by the FAI as an affordable entry-level class. It has been extremely successful, attracting some of the most talented and experienced pilots in addition to the young or impecunious it was supposed to target. Among the reasons for this are the long lifespans of gliders that invite their continued use, the relative simplicity of the class rules where e.g. water ballast is not allowed and the typically more relaxed "atmosphere" of Club Class competitions.
The glider types allowed are not explicitly defined. The criterion for admission is given by an interval of performance handicaps, which may be adjusted by the organisers of each event but that is understood to exclude the current state-of-the-art gliders. It is further understood to comprise only standard class types (unflapped, 15 meter span).
The class is perceived as being fair in spite of the diferences in glider performance. This may become compromised by the trend towards modification/customisation of club class gliders in ways that distort the handicapping and are difficult to control by the sporting bodies.
The emergence of the Club Class is a significant factor in the decline of the World Class, as it is equally affordable, yields higher performances and allows a degree of personal choise in equipment that does not exist in the World Class.
World Class
The International Gliding Commission (IGC/CIVV) which is part of the FAI and an associated body called Organisation Scientifique et Technique du Vol à Voile (OSTIV) announced a competition in 1989 for a low-cost sailplane, which should have moderate performance, be easy to assemble and to handle, and safe for low hours pilots to fly. The winning design was announced in 1993 as the Warsaw Polytechnic PW-5. The first World Class World Championship took place in 1997 in Inonu, Turkey. A further three World Championships have been held in this class, but participation and interest have been falling and the future of the class is uncertain beyond the 15-year period during which the FAI is pledged to lend its support.Ultralight Class
to be developedSources
"Glider Competition Classes"