My general intention of this thread is to give factual and anecdotal info on Sigma hopefully without upsetting anyone.Here are some useful links on Flight Global Archive.
http://www.flightglobal.com/pdfarchi...a super-glider
http://www.flightglobal.com/pdfarchi...a super glider
Operation Sigma Ltd was formed in Feb 1966 by G E Burton,H C N Goodhart,F G Irving,B S Shenstone,W N Slater,C O Vernon,L Welch and
K G Wilkinson to manufacture a glider for the 1969 World Champs incorporating the principle of an area and camber changing wing.The flap gave an area extension of 35%.
Sigma is the Greek mathematical letter for " the sum of"
The final result was this.