Author Topic: Ground Needed to be Lower (Read 3074 times)

Motorman · « **on:** June 05, 2015, 06:37:23 PM »

I said pilot error my wife said not your fault ground needed to be lower after I bellied in from a vertical 8. No damage but the prop came loose and the motor screamed out then quit. It won't restart and feels tight to turn over. I get motor error message from the esc. I checked the system with a known good motor and everything else works. I also did continuity checks and it tests the same as the good motor. I took it apart and the bearings and shaft are ok. What do you think is wrong, did the barrel get warped? If I can loosen it up do you think it will run?

Thanks,
MM

Tim Wescott · « **Reply #1 on:** June 05, 2015, 07:00:14 PM »

Mention the motor brand and model. I don't know enough to tell you which is which, but some are assembled more stoutly than others.

It wouldn't take much bend in the shaft to make the bearings bind up.

One other thing I know to check for is that all the magnets are in place -- they can come loose, and getting thumped on the ground followed by a high-speed (and possibly high-vibration) run may have shaken one or more loose. Do a visual inspection, then poke at each one with a stick to make sure they don't shift around.

If that doesn't find anything, I'd reassemble it and see if I could figure out what's rubbing. As part of that I'd look at the bell to see if there's any visible runout at the unsupported end.

John Cralley · « **Reply #2 on:** June 05, 2015, 07:02:27 PM »

What Tim said! Since the continuity checked out it sounds mechanical. May not take much of a blend to bind the bearings or cause the bell to rub. Are you absolutely sure the shaft is true and the bearings are ok?

Crist Rigotti · « **Reply #3 on:** June 05, 2015, 07:21:27 PM »

I would think that if you were in governor mode, the rpm would have stayed the same and not screamed out.

Motorman · « **Reply #4 on:** June 05, 2015, 07:32:55 PM »

E Flight Power 15. It hit then kept going for a 1/4 lap before the shaft run. It might not have screamed out real fast but it sounded weird for 2 seconds without the prop moving. Actually don't know why it quit unless it hit the high amp limit or something.

Motorman · « **Reply #5 on:** June 06, 2015, 10:52:39 PM »

Ok, took the motor apart again. Before I took it apart I checked the run out on the barrel and got .004". The shaft is straight, couldn't get a .001" feeler gauge under it as I rolled it on a surface plate. Both bearings turn free with the shaft through them. The only thing I found was some rub marks on the edge of the stator and also some marks on the magnets. They don't seem to favor one side or the other. So I'm thinking to file down the shinny areas to give it more clearance. It's funny though after some rough measuring the parts have about .017" clearance so I don't know how they could be rubbing.

MM

Russell Bond · « **Reply #6 on:** June 07, 2015, 01:09:25 AM »

The "can" was probably flexing in normal flight.
This is a major problem with one of the Arrowinds if it is rear mounted.

Motorman · « **Reply #7 on:** June 07, 2015, 07:18:29 AM »

Mine is rear mounted so I can believe the spots are from flexing but why does it turn so stiff, does it have more magnetism? My other eflight 15 turns fairly free.

I noticed some of the wires have a small amount of what looks like bubbly yellow glue. I hope that's not melted insulation.

MM

Curare · « **Reply #8 on:** June 08, 2015, 05:03:44 PM »

Sounds to me like you've cooked the motor.

Both of mine did exactly the same thing, and afterwards felt weird to turn over.

Take a look at the windings with a magnifying glass, if you see bubbles everywhere, then you've probaly cooked it and created a short in the windings.

Tim Wescott · « **Reply #9 on:** June 09, 2015, 03:37:14 PM »

If it feels stiff when you turn it quickly but OK when you turn it very slow, then you've shorted out at least one set of windings (if you have a good motor you can feel what this is like by unplugging it from the ESC, holding the wires together, then giving it a spin). If it feels just as stiff at dead slow as it does when you turn it rapidly, then it's not a winding issue.

Motorman · « **Reply #10 on:** June 09, 2015, 10:19:52 PM »

You're saying that even though the motor's not hooked up to anything it will turn over harder if there's a short? That would explain it because the wires are all bubbled up.

MM

Curare · « **Reply #11 on:** June 09, 2015, 11:10:56 PM »

If the wires are all bubbled up, it's toast.

Tim Wescott · « **Reply #12 on:** June 10, 2015, 12:08:22 AM »

Quote from: Motorman on June 09, 2015, 10:19:52 PM

You're saying that even though the motor's not hooked up to anything it will turn over harder if there's a short? That would explain it because the wires are all bubbled up.

Yes and no. It'll turn over harder if you're going any appreciable speed, but not if you're going slowly. With a short it'll feel like you're trying to stir molasses, and the faster you try to turn the more it'll resist. If it's a grindy, sticky sort of "hard to turn" that doesn't change with speed then it's not from a short circuit.

But there's a big clue in those bubbled-up wires...

Author Topic: Ground Needed to be Lower (Read 3074 times)

Motorman

Ground Needed to be Lower

Tim Wescott

Re: Ground Needed to be Lower

John Cralley

Re: Ground Needed to be Lower

Crist Rigotti

Re: Ground Needed to be Lower

Motorman

Re: Ground Needed to be Lower

Motorman

Re: Ground Needed to be Lower

Russell Bond

Re: Ground Needed to be Lower

Motorman

Re: Ground Needed to be Lower

Curare

Re: Ground Needed to be Lower

Tim Wescott

Re: Ground Needed to be Lower

Motorman

Re: Ground Needed to be Lower

Curare

Re: Ground Needed to be Lower

Tim Wescott

Re: Ground Needed to be Lower