Within a decade or so of their introduction the fifth generation gliders had reached a plateau of performance and possibly could not gain much by way of detail redesign. However it was to be some nineteen years before a new innovation and step up in performance was to challenge their supremacy. It was by the removal of the king post, top rigging and associated luff lines that an increase in performance was sought. The engineering solutions to this design requirement had to be quite sophisticated as it entailed the manufacture of carbon fibre spars and the introduction of internal ribs to support the necessary reflex at the trailing edge of the sail. The first 'topless' gliders produced were heavy and therefore not popular with club pilots. Naturally competitive pilots had to accept this penalty in order to gain the extra performance. As the design was refined the machines became lighter but of course at ever escalating cost and it became obvious that for relatively little extra outlay pilots could purchase a rigid wing of significantly higher performance.
General Specification of sixth generation gliders
Aspect ratio 8.5 or higher.
Nose angle 120 degrees or higher.
Sail planform Full flying wing.
Sail shaping Double surface airfoil that is entirely cut and sewn to match the frame exactly. Keel contained in small horizontal pocket.
Keel and leading edges Constructed from extra stiff 6080-T6 and 7075-T6 tubing.
Cross tubes Manufactured from carbon fibre.
Sail slackness So tight on frame to give minus quantities of billow.
Top rigging None. Battens Preformed metal battens under tension top and bottom of sail.
Pitch stability From planform stability, reflex retained by internal sprogs and spare ribs.
Duration of type 1997 to present.
Examples Airwave Concept FR and Xtreme, Solar Wings Scandal XK, and Avian Cheetah.