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Old May 11, 2011, 09:56 PM
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arc motor bent shaft

powered up my ARC 28mm MOTOR ARC-28-58-1 3180Kv
with 4.75 4.75 prop with amp meter 70 amps shaft bentalmost 90 degrees how can this do this
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Old May 12, 2011, 07:42 AM
Jack
USA, ME, Ellsworth
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What happened? You powered up a motor and it bent the shaft 90 degrees? It is not clear what happened.

Jack
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Old May 12, 2011, 09:25 AM
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Did you balance your prop?
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Old May 12, 2011, 09:59 AM
Jack
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OK, I think I get it now. That must have been pretty exciting until you got it shut down.

What was the battery voltage or RPM? Any idea?

Jack
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Old May 12, 2011, 04:52 PM
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United States, MN, St Paul
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arc motor bent shaft

i was flying my fun jet on 4 cell 26.50 i decided to try 5 cell 3.000 i put amp and wat meter to check amp draw i got to 80 amps and it bent and stop scary and yes prop balance had 10 flight s on it i hope this help i hoping this was a fluke i wood like to stay with the same motor as it performed well but i dont no if shaft are weak not harden thanks for the help chris
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Old May 12, 2011, 05:00 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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Could you tell if the prop had lost a blade under power? That could throw it badly out of balance.

The prop should have been mounted as close to the motor as possible, if there was quite a bit of distance between the back of the prop and the motor, that also makes the shaft easier for it to get bent.

And the bend happened during a run up? Not in flight.

Tell us the motor you were using and we can tell if you were exceeding the RPM limits for the prop.

Jack
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Old May 12, 2011, 05:10 PM
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I experience this same thing once with a 28mm Ammo and a balanced edf rotor. It was primarily due to the flat cut halfway through the shaft; poor engineering.

I only have one Arc (36mm, love it) and it doesn't have a flat cut into the shaft, so I assume yours doesn't either?

Jack has a good point about how far out on the shaft the prop is sitting; closer is stronger.
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Old May 12, 2011, 05:13 PM
Jack
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I looked at the Multiplex Fun Jet to see what it is, it is a pusher with a small prop in the back. So I am assuming he has an inrunner with a small prop on it.

Jack
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Old May 12, 2011, 06:03 PM
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motor

prop is still fine happened during a run up
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Old May 12, 2011, 06:05 PM
Jack
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And how far away from motor is it when mounted and how is it mounted?

I ask that because if there is just a little imbalance and prop is mounted some distance from the motor it can do what happened to you.

Jack
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Old May 12, 2011, 06:11 PM
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about

1/4 inch
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Old May 12, 2011, 06:12 PM
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thanks for all the help

jackerbes
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