Belvedere
Many thanks for the info, FED and BEagle for the link, just the kind of stuff I was looking for. I flew the commercial Chinook for three years and it was an excellent aircraft in just about every area. The twin-rotor system had several advantages and Boeing had ironed out just about all the problems. Everything about it seems to have been thought through so much better than was the Belvedere. The Brits have built some turkeys in their time.