Designing Purpose-Built Drones for Ardupilot Pixhawk 2.1

Too many freakin' wires!

That thing looks like a mess, doesn't it? It's not. Cable management is the key. You don't want any wires in danger of obstructing (or even breaking) propellers. That spells instant crash. The following image shows how the wires to the ESCs and motors are routed under the airframe and bundled:

Not only that, but electromagnetic (EM) interference is your enemy in the air. It can completely disrupt your video, telemetry, GPS, or even control signals. So never wrap your cables in circles. Instead, notice that they're wrapped up in figure-eights (especially power leads).

Since we're on this angle—don't leave out any screws! ...