FAI Two-Seater Class

Competition classes in gliding, as in other sports, mainly exist to ensure fairness in competition. However the classes have not been targeted at fostering technological development as in other sports. Instead classes have arisen because of:

The FAI Gliding Commission (IGC) is the sporting body overseeing air sports at the international level so that essentially the same classes and class definitions are followed in all countries.

Seven glider classes are currently recognised by the FAI and are eligible for European and World Championships:

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:

Glider classes not recognised by the FAI have been used in some regional and national competitions. The most significant of these are:

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 1950s.

This unrestricted class has been a favourite testing ground for technological innovation. Many research prototypes fall under this class definition, e.g. 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 as far as 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.

Until the 1960s, a fair number of gliders were 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 for a while became the exclusive preserve of only two manufacturers. The World Gliding Championships of 2012 brought into competition new designs, some of significantly lower wingspan, which flew successfully against "traditional" (wingspan 28 m+) machines of this class.

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Wikipedia