Using coaxial compared to single?


Using coaxial motor setup on a multicopter is known to be less efficient regarding for example flight time. I have seen some use one inch bigger props on the lower motors. Same motors. What is the theories? Should I use bigger props on the lower motors on the octacopter?

Best regards

Have no one used this different sized propeller-idea on coaxial?
I am building a X8 with lifted arms, the 15" lower props almost touches the frame, 2mm from it, when off. Thats not gonna work when revving up.

There’s mixed information, and it’s difficult to separate opinion from fact.
A slightly higher pitch on the lower motors makes some theoretical sense but in practice I think the consensus is that it doesn’t really matter.

Ok, we are moving out the motor attachments and are gonna use Tiger 15" CFs on all eight motors. Coaxial propeller-setup is special…

There are a lot of Y6 and X8 out there.
Any one who have tested coaxial versus standard setup?
And with different propellers?