(made in 1980)
The Sigma is the first offering from Southdown Sailwings, it follows the basic concept of the Chargus Cyclone by appealing to the more experienced pilot for use in competition and cross country flying. The Sigma is a crosstube-less bowsprit design. The machine has a high aspect ratio with a tight sail and drooped tips which lock up at the minimum desired angle of attack to aid pitch stability. The airframe is very simple with little weighty hardware and no non-functional parts. Rigging is straightforward and quick, the longest operation being fitting the flexible battens. The Sigma comes in two sizes, 11 sq m and 12 sq m.
Sigma 12 m. Span 38 ft, sail area 188 sq ft, aspect ratio 7.5, nose angle 140 deg.