Rotors up or down?

[Alex El Caballo]

Hey fellas,
While i wait longingly for my Mavic i look at magazines and read incessantly forums and UAV stuff...
So here is a question...
What is the benefit of having rotors mounted top as most drones have as in compared to some out there that have the motors and props facing down?

 

[Kilrah]

Ground clearance/less risk for dirt to damage the props?

Beyond that it basically doesn't matter. Those who put them down do it to "be different".

 

[The Editor]

Hey fellas,
While i wait longingly for my Mavic i look at magazines and read incessantly forums and UAV stuff...
So here is a question...
What is the benefit of having rotors mounted top as most drones have as in compared to some out there that have the motors and props facing down?

Aside from the things mentioned above, mounting motors below the arms means that thrust washers become pretty redundant since the thrust pushes the shaft upwards and this puts the stress on the upper bearing.
Additionally, you can loose a small percentage of efficiency due to air mass blowing over the arm on top mounted motors.
Bottom mounted motors also alter COG and can make an aircraft slightly less stable.

 

[Mako79]

Ground clearance/less risk for dirt to damage the props?

Beyond that it basically doesn't matter. Those who put them down do it to "be different".

They point them down to make the drone more water resistant. There are some drones that can be flown in light rain.