Just wondering what it would take to make a aerial drone (planes, helicopters, quads, etc.) be able to go underwater?
Granted, all of the electronics must be waterproofed, but what about the motors and propellors?
BLDC motors have the advantage over brushed motors in that they don't have brushes... this means potentially that a BLDC can be completely submerged in a conductive fluid (water or otherwise) and could still work...
Propellors for designed for air probably won't have the same performance in water, in fact they might not be strong enough for water. The RPM will probably have to be much lower, too...
Would it still be aerial under water?
If it's submerged, then it's no longer aerial... :P
What I was proposing is making a drone amphibous, so that it could be in air or water and still work.
There's obviously many details to be worked out on making one work well... which I unfortunately neither have the time or background knowledge of submarines.
our company is producing totally waterproof frames, so you are right about the RPM and that BLmotors works under water. The salt might damage the ball bearings if they are not adapte and the copper wire varnish of the coil might get erased with time. It will creat a short circuit and the motor won't want to run. We are here with my friends thinking of doing such a quadricopter . So far we got the frame ready, soon we will work on the motor waterproof. We already have a water proof Tourette stabilized on two Axes. We now need to work on the electronique and the propeller's. We came up with few solutions. You have to be careful about the link two. The robot can be programed to do certain task under water like go not to deep 50cm max, I guess, and wait for a signal to deploy. If you want to get him to navigate under water like a quad to go forward the quad front should be facing down or up . So the propeller have to be perpendicular to the ground and you still have to solve the link issue.
I hope that helped see you body
I've come across a few RC boats that had isolated the motor from the water, and used a bushing instead of bearings where the drive shaft. I've also come across some mentionings of using a non-conductive fluid like mineral oil to help ward off any water from entering the electronics cases, but this adds a bit of mass to the quad which would reduce its aerial capabilities.
I've wondered about flying in rain. Would an outrunner motor work if it was wet? If you taped over your servos and cut little slits in the tape for the horns to poke through, and generally taped over any air holes in the fuselage, could you fly a plane while it was raining?
the brushless will just fine in the rain. The bearings dont do so well and need extra care. Look at OpenRov they are using brushless motors as thrusters in salt water!