This very expensive aircraft has up to now not had outstanding success in competition, but it for a while seemed to impact the cost of remaining competitive in the class. The 'eta biter' and its successor, the Concordia single-seater, as well as Walter Binder's EB28/EB29 until 2012 were being presented as challengers to eta, but the appearance and performance of shorter wingspan competitors in World Gliding Championships of 2012 may change established views on the design trends. In July 2007, the IGC increased the maximum weight allowed in the Open Class to 850 kg provided the aircraft has a valid certificate of airworthiness at that weight, i.e. the manufacturers must re-certify the glider. 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, flight-disposable ballast, radios and lift-enhancing devices such as flaps. 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. Retractable wheels were allowed by 1970 and water ballast by 1972. Manufacturers were fitting these as production items, and they had to be disabled to fly in competitions. In 1965 the American Richard Schreder flew a variant of his HP-11, which in normal form had simple flaps as airbrakes. To comply with the rules, the ship was modified for the World Championships so that the outer half of the flaps hinged upwards to comply with the rules. Schreder pointed out that this made the glider more expensive and less safe (higher landing speed, less effective brakes).