all RC-copters/cars that i've seen have noisy motors. i posted on this topic before and the answer i got was basically that those motors are cost efficient. but what's inside these motors that make them so noisy and where can i find a quiet one?
Or less succintly they are open, so the churning air inside radiates high intensity
sound waves out through the cooling holes. Close the cooling holes and the motor
fries fast - these disspate lots of power being the highest power-per-volume of any
electric motors made.
all RC-copters/cars that i've seen have noisy motors.
Do you mean the drive motors (ie - on a quadcopter for instance, the ones that spin the propellers) - or do you mean the servo motors?
If the former - a lot of the noise is actually from the blades and/or the gearing mechanism (depending on what is being driven) - though a fair amount is from the motor itself, depending on how fast it is moving and the technology (brushed vs brushless) being used - plus the size of the motor.
If the latter - then yes, it is due mainly to cost - and the fact that low noise isn't needed for the intended application of R/C servos (where other noises will be much louder, and/or the vehicle will be far away from anyone to worry about servo noise). If you want quiet servos - you'll need to spend the money (or develop them yourself).