Sound of electric motors, thoughts and ?

[trillian]

Recently it occurred to me as to what actually gives these brushless motors the sound we're so used to now. My theory is that what we hear as the high pitched turbine-like whine is the cycling of the three phases off and on from the ESC which makes the motor can into a crude speaker, the principle of which is used deliberately for the ESC startup and programming tones.

So the construction of the motors will make them a little louder or softer and give them their own distinctive tone (to a degree anyway).

Feel free to correct me if I'm wrong on this.

I also started thinking about it more lately due to one of the clubs I belong to having to get fairly serious about controlling the noise levels. Which then leads me to wonder; what motors are the loudest and the quietest? In my experience the loudest motors I have owned are Scorpions and the quietest are Hackers. It's not a scientific thing because in different airframes you have the variables of straight or slant gears, the resonance of the airframe and coverage of the canopy etc.

I noticed yesterday how much of a distinctive ringing sound the Scorpion 4035 makes in my Faifa. I'm sure it's the loudest 700 size electric I own (partly due to straight cut main gear as well and very little sound damping from the canopy). And I like the sound BTW, in fact I'd like it louder, more turbine-esque, but not everyone shares my sonic tastes.

[electricsceadu]

it'd interesting to read that your hacker motor are the quietest
as the one i had in the sceadu made a right din
an os 50 with a large volume zimmerman at 1500 rpm wasn't that much louder than it

[trillian]

it'd interesting to read that your hacker motor are the quietest
as the one i had in the sceadu made a right din
an os 50 with a large volume zimmerman at 1500 rpm wasn't that much louder than it

I have only run two Hackers, a 6s ET (electric turbine) that I had in an Outrage 550 and most recently an A50 'Turnado' that has been in the Triabolo and both were very quiet and smooth. I have just swapped out the Turnado for a bigger motor as it was running very hot and I want to see if a different motor will run cooler in that heli without having to cut lots of holes in the canopy.

[ghost2212]

I think it's more likely the sound of them moving the air through there cooling mechanism's that's what creates the most noise. Thinking about the motor noise in relation to noise control IMO though, The main factors there will always be drive train noise and the sound of the blades.

[highlightshadow]

For me the drive train makes a massive influence into the heli noise overall..
I ran a Fusion 50 with the CNC gears and umbrellas and they're noisy as hell
Whereas the MSH Protos 500 makes a lovely deep resonance, same as gobbler
Logos are quiet too .... all with scorpion motors

Slant cut, cnc'd thick delrin gears are much more grindy and clattering than belts