Y6-Hexacopter configuration

[coptop]

Hello everybody

Im currently planning to build a Y6 copter. I noticed that in every project I read about they used the following configuration -->

Or similar. At least there are never all rotors in the upper level spinnig in the same directon. Same for the lower level. My question is; why isn't it common to use for example all cw's in the upper level and all ccw's in the lower level? I mean the problem with the turning moment would be solved as well.

 

[Cyberdactyl]

I've never built any over-under multirotor, but I suspect, as you suggest, the torque would be balanced in the yaw, but having them all spin in the same direction on top and opposite underneath, would introduce a pitch/roll torque imbalance along the z-axis CG. The imbalance would probably be more extreme the more separation between the bottom and top props

 

[coptop]

I've never built any over-under multirotor, but I suspect, as you suggest, the torque would be balanced in the yaw, but having them all spin in the same direction on top and opposite underneath, would introduce a pitch/roll torque imbalance along the z-axis CG. The imbalance would probably be more extreme the more separation between the bottom and top props

Thank you very much! I think I have a basic understanding now, but can you explain in more detail what do you mean with this pitch/roll torque imbalance and how it is created?

 

[jamieFL]

I don't know this for a fact, but a Y6 can fly with only 3 motors. If all are spinning in the same direction, the copter will spin.

 

[coptop]

I don't know this for a fact, but a Y6 can fly with only 3 motors. If all are spinning in the same direction, the copter will spin.

that makes sense... but I'm not sure if a hex is actually abel to fly with only three rotors. And it's also not very common that three motors stop at the same time or am I wrong ? I never heard about flying a Y6 with only three motors is it a thing?