Sprocket,
thanks for that. Yup! I think we're talking about the same thing.
Dave Jackson,
I must admit on first reading your post to not having a clue what you were talking about (through my own ignorance, not yours, I hasten to add!). Upon connecting to your link, I realised that I had walked into the mouth of the veritible Lion's Den
and after stumbling around ineptly for an hour or so like a blind man in the dark, I can honestly say that I have come away a slightly more enlightened man. On re-reading your post however I have realised the value (for the umpteenth time) of clear and concise terminology. I mentioned in my original question 'advance angle' which according to Wagtendonk's book is defined as "...the angular difference between the attachment point of the pitch link on the swashplate and the blade to which it refers." So for a given helicopter helicopter I assume that the advance angle is a fixed mechanical angle (for example 72 degrees on the R22 according to Sprocket). You refer in your post to 'phase angle' and on your web-page it states at the end that "The phase angle of a specific helicopter can vary depending on the forward velocity and other aerodynamic events at a specific time." So I can only assume that phase angle and advance angle are totally different concepts and that there has therefore been a slight misunderstanding between my question and your well-intentioned response.
Either that or this is even more confusing than I thought!
You have nevertheless opened up whole new horizons to me on the issue. Thanks!
Irlandés