Electric motor Idle Up

There is a suggestion that keeping the motor spinning , at minimum revs, when the throttle stick is fully down speeds up throttle response and lessens stress on the motor. A TX control would need to be be assigned to enable idle up on take off and disable it after landing.

Before I dive into my TX programming manual has anyone done this and have anything good or bad to say about it?

Hi Alan
The startup mode of a sensorless brushless motor, (the type we use for E flying), is different to the normal high rev running mode. It is not as efficient because the phase switching points at low revs can only be guessed at by the electronics. What I do not know is what speed a motor starts to run in normal mode. If your tickover RPM is below this threshold, then the motor and ECU could be stressed and it would be better to stop the motor completely.

I think the idea is to get the motor to 'tickover' at just above its start up phase but still running at very low rpm. I've only played with a small motor so far and one click of throttle trim gets the motor from 0 rpm through it's start up phase to smooth but low rpm. From there on the throttle does seem crisper than when starting from 0 but I'm not sure what benefit this will have with a bigger motor in flight.

Hi Alan,

I do it with a throttle curve, and just lift the low end until the motor starts to run and add a faction more. I also drop the top of the curve until I can hear the max RPM start to decrease, and then up it again until I don't here the RPM increasing any more. This is after setting up the ESC, on some you can tell it where the end points are by moving your throttle stick.

I have one switch which overrides the throttle channel with a -100 value.

On the Atlas I felt the throttle response was better with a curve as seen in the attachment, but on the Mythos (different ESC) when I tried a similar curve it didn't feel right at all so I went back to the straight line.

At start-up, a brushless controller sends a pulse to the motor and the motor will either spin clockwise or anticlockwise. The controller senses the back emf and determines if the motor is spinning the correct way. It will then send another pulse to keep it spinning the same way or the opposite pulse as necessary. In flight, a windmilling prop can confuse this sequence and the controller/motor combination squeals and shuts down. This is more evident with some controllers and the cheaper ones seems to suffer more. Keeping the motor ticking over at low rpm avoids this problem.

Also, a motor at tickover will keep air moving over the control surfaces at low speed. This gives better control on landing.