Not to distract from the original thread, but the neccesity for a 3 engine helicopter was driven by a lack of adequate powerplants in the 1960's, the advent of turbine helicopters.
The AZ-101G would probably have been as succesful as the other tri-motored abortion, the Super-Frelon. The 101 was Gnome powered; the original Frelon, Turmo IV powered; and the Israeli monstrosity Frelon was powered by T-58's.
That the three engine design survived through the mid-1980's EH-101 design phase is again a difficult technological challenge to understand. As the machine now competes with other twins, it is a little hard to justify the expense of three motors, when perhaps there might be two available today, with an adequate power margin?
Three engines doesn't just stop with installing the engine, there's a 3rd MGB input, installation, controls and instrumentation, accessories, fuel system, etc, all adding to the basic D.O.C and weight of the finished product.
One thing is for sure, the original 101 was equally as ugly as a Super Frelon (maybe more so), and I have to wonder if they didn't sell the design to the Russians in some money-making espionage double dealing - looks awful like the Mil-8 to me! <img src="wink.gif" border="0">
To divert it one step more, does anyone know what a Frelon is? <img src="confused.gif" border="0">