On Saturday, February 10, 2018 at 12:18:30 PM UTC-5, john firth wrote:
The link below produces Nick Goodhart's essay on the marvels of
Sigma, a Britsh effort to make a world beater; this was before it flew!
It failed probably due to excessive mechanical complexity and the high

Here is the link to Goodhart's Sigma presentation at the 1970 Soaring Symposia:

http://www.betsybyars.com/guy/soarin.../70-sigma.html