The Sigma is an experimental glider developed in Britain from 1966 by a team led by Nicholas Goodhart. Its unusual feature is its ability to vary its wing area using Fowler flaps. It had been tried before by the Hannover Akaflieg in 1938 with their AFH-4 in the South African Beatty-Johl BJ-2 and in the LET L-13 Blaník. A company was set up which attracted sponsorship from Hawker Siddeley and assistance from eminent aerodynamicists.
Made by Operation Sigma Ltd.