Genghis
Having re-read your original post I see you mentioned THREE methods, the Gray one is the general case of the equilateral triangle.
Shawn
The NTPS method written by your colleague Lewis is an enhancement of the Gray one and the Gray paper is available on the NTPS website. Could somebody there point me towards a derivation of the spreadsheet equations ? I assume you are the Shawn Coyle of 'The Art & Science of Flying Helicopters' so thank you for a very good book.
Dave
It looks like the into wind/downwind reverse course method is the most favoured in practice.
Thanks all, Alan
Genghis, we posted at the same time, yes it is that trigonometry that is causing me a pain.