In quadcopters (or in any other drones), must the propellers/motors all be at the same height, or can there be symmetric height differences (like for eg, two of the motors at the "back" are elevated just a little like by say 5cm or even less... Is that going to make a significant trouble in the drone performance?

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    $\begingroup$ Questions like these are the exact reason for SE.Drone $\endgroup$
    – ifconfig
    Nov 13, 2018 at 2:30

1 Answer 1


Tandem rotor helicopters have the aft rotor elevated to keep it clear of the front rotor's downwash and improve performance in forward flight (at the cost of reduced performance in rearward flight).

Most small quadcopters achieve substantial pitch angles in forward flight, often in excess of 30 degrees, which keeps the aft rotors out of the downwash anyway. Therefore, your proposal changes nothing in hover and fast forward flight, improves performance somewhat in slow forward flight and reduces performance in rearward flight.

  • $\begingroup$ what if opposite propellers are at the same levels, but the diagonal pairs are at different levels? $\endgroup$
    – space
    Feb 13, 2020 at 2:50
  • $\begingroup$ @space - If one rotor is downstream (aft and below) of another, that rotor will have reduced performance. $\endgroup$
    – Rainer P.
    Feb 13, 2020 at 12:40

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