Campgems

First, I'm not an electric flyer, so for me this is just a curious issue. One of our guys was out to day with his electric converted twin star. I don't know the motors or ESCs that he has, but he has two identical motors and ESCs With no power, one motor almost free turns with minimual "feel" of the magnets going over the humps. The other motor has a very strong feel of the magnets. Both crank the prop at 10400. The plane flys well and has maybe a little to much power, but it does fly well. Now, on landing, when he cut the throttle back, one motor quits turning way before the other.Our first thought was the the motor with the lesser amount of magnet feel was just freewheeling. It turns out that the motor with the stronger magnet feel is the one to keep turning a bit at throttle is cut. About four of us today all came up with ideas and on closer examination, none made much sense.

Back in the early 70's when I was a field rep for a computer comany, our console printers were just starting to use stepper motors and wire print heads. I found that there was a huge difference in the "feel" of turning those motors depending on wheather the leads were all shorted together or if they were open.

This brings up my question, is is possible that the two ESC's are acting differntly in clamping down the windings at throttle down?

Just a though, but it was the only thing that I could come up with that would explain the different motor response to throttle off.

Again, it is the motor with the stronger magnet hump feel that keeps running, up to about 2 seconds longer thant the other motor.

Any ideas ??????

Don

speedy72vega

He needs to check his ESC programming. It sounds like the brake is programmed on one of the controllers. The one that is hard to turn would be the one with the brake on. Try this, have him unplug the batteries and see if there's still a difference in feel. If not, it's the ESC brake most likely. If there's still a difference with no power, then it's more likely a motor or bearing problem.

Campgems

Speedy, that is kind of my take also. My suggestion to him was to swap ESC's and see how the motors responded.

I'm Curious, how does the braking work? Besides my early stepper motor experieence, I've put together a CNC mill and learned a lot aboutabout acceleration and deceleration of the motors and the need to blead off reverse EMF from thecoasting motors to prevent damage to the motor controler, ESC in comparable terms.

All of this is quite interesting. Guess I'llsitck toglow fuel for a while yet.

Don