My point is that the above VG diagram is a direct image from the Illustrated Guide To Aerodynamics. I have made this point over and over again when people like "Weedwhacker" and "TWCobra" claim I made up my own VG diagram. But the fact remains, Vd is the end of the flight envelope and the start of the structural failure zone as determined by wind tunnel and flight testing... and as depicted in the above VG Diagram. This is why they have avoided the question. So, Mick, it is up to you who you wish to support. Objective and real world analysis... or some guys who dodge and weave when presented with the facts.