Originally Posted by
horlick97
I understand the larger the separation, the larger will be drag. But, it can't be worse off than Chinook (i.e. adjusted for similar size of the aircraft) which tendem rotors also need to be similarly separately vertically, can it?
Tandems don't have to be vertically separated. In certain (most) flight regimes the Chinook blades will be intermeshing. Due to axis Offset the tips will be moving in the same direction where they intermesh. In a Co-ax they will only intermesh once and that only very briefly...
Plus the Chinook wasn't designed primarily for all out speed.
So no comparison here.