There's something that bothers me inherently, and just like the Hueys from Vietnam, 'only' having two blades. Doesn't seem enough, I mean, if despite your best planning, engineering -- whatever -- you lose one, you're like a twisty brick plummeting to the ground; and on the way down, it won't be any value shouting "That shouldn't have happened!!"
OK, first up, I accept the higher centre of gravity thing, if I have 4 blades, f'instance, but that's an engineering problem that can be fixed, ie. that's no reason.
There must be some other reason I can't have -- if in fact I actually can't -- have 4 or 6 or... isn't there an Aerospatiale chopper with 9??
Please tell me what I don't understand....