JF and Bellerophon - many thanks for your replies! My memory of the SR71 figures was indeed incorrect - gleaned from an article 25 years ago. The figures I now have state that at M3.2, over 80% comes from the inlet - consistent with JF's figures. I vaguely remember that you have to 'integrate the total pressure envelope around the intake, engine and nozzle' to come up with that result. However, it still seems like black magic!
Amazing to think that aircraft such as the SR, Concorde (and who knows what else) have been doing this sort of thing for well over a quarter of a century now!
[This message has been edited by BEagle (edited 26 May 2001).]