This past weekend I attempted to maiden my new Twister. It had a Scorpion Commander 45A ESC, KR timer and a generic IFly 2820 850kv motor spinning an APC 11x5.5 pusher prop. I had the esc all set up and had everything set on the KR timer except the rpm. I was using my tach to set it with the programming stick. I noticed the rpm wasn’t real steady. I figured maybe the gain setting needed adjustment. I reached for the battery to disconnect and the motor screeched for a half second or so and both the motor and esc rolled smoke.
I admit, I forgot to bring my watt meter so no idea how many amps I was pulling at that moment. I’ve ran that motor and prop before maxing out at 41A.
I now have a ZTW 50A esc and a Cobra 2826 930kv motor on it ready to test. I ran it up from an RC receiver and everything seemed good to go. My only concern at this point is the gain setting on the KR governor. I think I set it to 3 which was the middle of the range. There was nothing in the instructions as to a starting point for the gov. I’m wondering if too much gain is why it was varying rpm and possibly caused the smoke release.

Suggestions?
I know both the Cobra and the ZTW are overkill on a Twister but I really needed a little nose weight. I might still be a touch tail heavy but it’s definitely in a flyable range.


Thanks, Matt

I’m surprised the KR timer didn’t shut down due to the RPM variances. I believe that’s how it senses a prop strike.
Did you have the governor turned off in the ESC? If not, maybe the timer and ESC were both trying to “govern” the RPM and it was a toxic mix.

For anything on the ground, use an undersized prop - around 2" smaller on diameter works well.  The system will strive to get to that RPM - or die trying - when you reinstall the flight prop, but in the air the load is somewhere around 15% to 20% lower.

FWIW, I did the same thing a long time ago while checking watts vs RPM on a set-up using the intended flight prop. Never did find a way to get the smoke back in...   

I'd be pointing the finger at a loose motor connection, that got worse as the motor was running, the engine lost timing and then just fried - or a dead short.