Turnigy HeliDrive SK3 - 4249-1600kv misfire?

[mole hunter]

Hi folks,

I've had this motor installed on my 500 for a few months now and I'm still trying to get it to run smooth. Initially I though it was a mechanical issue making vibes and giving the gyro and tail servo a hard time because there is a persistent fine tail wag. I've replaced the main gear, belt, tail shaft, slider and blades and the tail box is earthed to the motor mount. Adjusting the gain makes little difference.

At certain mid range RPM it sounds rough like the timing is out or a bad solder joint on the motor or esc. I've replaced the original Hobbywing 80amp esc for a Yep 60amp and have tried various timing / pwm settings, currently 30*/16kHz but still not managed to find the sweet spot. Using new and older packs produces different results. The motor only ever gets hand warm as does the esc and pack.

It's described as having 14 poles but I'm peeking into the can and counting 8 magnets. Anyone else using this motor and at what settings?

Running out of ideas, Marty

[woodsta888]

Looking at in the discussions section on the Hobbyking page on their website Radio Control Planes, Helicopters, Cars, Boats, FPV and Quadcopters - Hobbyking 

Someone mentions using 8Khz for PWM as timing and as he has counted 6 magnets and deduced 6 poles, though his calculation makes 10.66khz. He says turnigy recommend 8Khz. Have a look in the files section on the page for that motor at the bottom and see if there is some data that recommends timing & pwm. Won't open for me currently.

[mole hunter]

Hi woodsta,

There's a lot of conflicting advice there but the photo of the inside of the can shows 6 magnets / poles Using the accepted formula that gives me a PWM of 10kHz. I'll just have to play with the timing and see if I can get it to run smoother.

Many thanks, Marty