http://makezine.com/projects/wavecopter-a-waterproof-quadcopter/

exposed brushless motors can run while immersed? won't it get spoilt?

Don't think he intended to create a submersible quad

Just minimizing damage and number of parts replaced if it crashed into water.

A wet Brushless motors would run fine.
It's the ESC and FCB which is more likely going to create problems if wet.

Does water and live electricity mix that well ?

Water and (Medium/High Voltage) AC Current doesn't go well.
But no major problem with (Small/Medium voltage) DC current or (small voltage) AC current. So a regular Brushless Motor will work just fine.
Plain water just don't have enough conductivity to create an effective short circuit in such case. Like in case of regular Brushless motors on an average size quad.

Various small electronic components, specially IC's do get crazy with water though.
Since Brushless motors don't have such components, Water have no effect on them.

One has to consider the impact of salt water also, if flying over beaches.

BTW, I hadn't really thought of brushless motors being so forgiving about water... learnt something today.

Yep, Sea water is most likely going to create some impact on the Motor as well on the ESC since it would be like short circuiting motor leads which will directly affect the components inside the ESC.

Although sea water is still not as conductive as a copper wire. So it will more be more like a short circuit with a resistance (Sea water) in between.
Also, since only 1 or 2 Pole out of the 3 poles in a brushless motor carry current at a time it may further lighten up the effect of the sea water.

Only a formal test can provide a better insights on the result.

Even if we dipped in the motor in sea water it will not get damaged...
I have tested the brushless motor characteristics when dipped in normal water and sea water as well..
The only problem is that is , when flying in seaside and a drop in to the sea will fill the motor with sand and which will create a friction and the motor will stop working coz of that..
In case of normal water the motor is going to work fine for sure...
Also you may need to cleat it of when back to home after a cool aquaquad mission...

BL motors will only run a short while under water - before the bearings seize (I'm talking cheapo chinese ones)


Bushed ,brushed motors on the other hand will run much longer .

I agree. I run brushed motors under water all the time. I can safely overvoltage them under water,over twice the voltage with no issues , except perhaps corrosion at the connectors. But brushless motors tend to be not as forgiving. Prolonged usage under water will result in seized bearings and also potentially damage the esc. Usually the brushless motors we use need higher current. High current under water will corrode the connection points (solder pints, or any naked conductor surface) fast.

One thing to note while using BRUSHED motors under water: Some brushed motors wear out their brushes within minutes under water. If you plan on running your motors under water, first test them in a mug or glass. Run them for a few minutes and then check the brushes.

A thread I had gone through sometime ago

http://www.rcindia.org/boats/submarine-and-amphibian-lovers-brushless-works-under-water-!!!/

Thanks for the share Anwar, def trying that the next time im bored! But I think we'd be better off using something a little lighter, atleast for the center, say an airtight container can you drills holes into and then seal.

Watch "RFTC: RQCX-3 "Raven" FPV Hexacopter Technical Report" on YouTube -