Thankyou ladies and gentlemen for your insights. I guess I hadn’t really thought about it too much but I understand the role of the gear box on helicopters now.
So a tail rotor should keep spinning with the main rotor even in the result of an engine(s) failure allowing auto rotation. I guess both sets of blades will keep spinning on the Chinook allowing for the same.
A TR failure or blade collision on a Chinook are both clearly dramatic emergencies. One more so than the other depending on circumstances (apart from being on the ground I can’t really imagine a blade collision ever being surviveable).
So really cost is the main reason we don’t see more twin blade (I apologise if this is not the correct term) designs.
Again, thanks for your inputs. I think I’ll still avoid helicopters whenever possible though. They’re just not right.
BV😁