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Old Mar 18, 2007, 05:01 PM
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How do you know when your main motor is going on a HBFP?

Is it possible to tell if the main motor on the HBFP is on its way out. I think I must be getting close to the 10-20 hours that is quoted for its lifespan, and this could have been reduced by upgrading to a lipo (even tho I have a heat sink)..

One of the reasons I ask this is a started to get quite a bit of vibrations going through the heli whilst hovering at about waist height in the garage.

I haven't had any crashes that could have moved/broke anything that could cause these vibrations so was wondering if a motor on the way out could do this?

Thanks
Mark
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Old Mar 18, 2007, 05:46 PM
Sussex, UK
RobinBennett's Avatar
Crawley, West Sussex, UK
Joined Jun 2004
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I think I've heard people say you get main motor glitches, and the tail can suddenly swing out 45 degrees or more as the main motor torque changes.

I'd suggest listening to FM radio to see if you can hear more interference than usual, or checking to see if you can see the brushes are worn out.

I don't think an old main motor is likely to cause vibes, as the brushes wear out long before the bearings.
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Old Mar 18, 2007, 06:27 PM
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Monroe, CT
Joined Mar 2005
724 Posts
I just went through the "worn out motor trouble" scenario with my HB CP2 for the first time. Started having trouble after about 25 packs, which comes to around 6-7 flight hours. The heli started glitching, the motor started running very hot, the run times went way down, and things just didn't feel right, particularly with the tail. That makes sense, since if I needed more left stick to hover as the motor got overheated, it would push things futher up the revo-mix curve, and make the tail feel off.

Just changed the motor out yesterday, and it feels like a new machine again. It was shocking how much of a difference it made, returning the feel "back to normal."

Regards,
Chris
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Old Mar 18, 2007, 10:42 PM
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NE Florida
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Changed out my main motor after well over 110 flights. Tail motor at 80 or better. No vibration associated to either of them.

A few thing to look at that have caused me problems with vibration:

Check Rotor blade balance and tightness should be loose enough to allow then to swing into Center when spinning up!
Check Flybar balance.
Check Rotor head for wear in the area that the Center Hub bearings seat.
Check for an out of round or cracked Center Hub.
Check the collar on the bootom of the Main Shaft. Mine was a little loose and allowed a lot of vertical movement on the Main gear and shaft. This made any vibration seem worse than normal.
Check that the ESC is mounted to both the botom and rear of the holder. Mine came loose and would cause an exagerated shaking and possibly some glitching.

Good Luck with it!
Dobsonly
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Old Mar 19, 2007, 04:34 AM
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Quote:
Originally Posted by DobsOnly
Changed out my main motor after well over 110 flights. Tail motor at 80 or better. No vibration associated to either of them.

A few thing to look at that have caused me problems with vibration:

Check Rotor blade balance and tightness should be loose enough to allow then to swing into Center when spinning up!
Check Flybar balance.
Check Rotor head for wear in the area that the Center Hub bearings seat.
Check for an out of round or cracked Center Hub.
Check the collar on the bootom of the Main Shaft. Mine was a little loose and allowed a lot of vertical movement on the Main gear and shaft. This made any vibration seem worse than normal.
Check that the ESC is mounted to both the botom and rear of the holder. Mine came loose and would cause an exagerated shaking and possibly some glitching.

Good Luck with it!
Dobsonly
Thanks for info, will check it out.

On the point of the ESC mounting, that L shaped bracket snapped on the joint after a heavy landing. The ESC is still stuck to the bottom bit but the rear of the holder is loose. I tried to overcome this by cable tieing around the ESC and the rear bit of the holder and whilst it is tight, it could be the cause of the vibration i guess.

Can this section be repalced on its own or does it connect to the main shaft that runs through the heli?

Thanks
Mark
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Old Mar 19, 2007, 05:27 AM
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Manila, Philippines
Joined Oct 2006
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You can shine a flashlight on the endbell. Motors with less than 1mm brush (thickest part of brush) is near death.

If you are just hovering, it will be difficult to tell without visual inspection. If you can punch out already, you will notice that with a worn motor, the ehli is bogged down.
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Old Mar 19, 2007, 05:40 AM
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Huntsville, TX.
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When my motor went, I had to tap the blades to get them to spin.


Brian
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Old Mar 19, 2007, 05:57 AM
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Manila, Philippines
Joined Oct 2006
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Don't allow your motors to reach that point. The motors can still run even if the brushes are gone. And when the arms wear through, they swing to the other side shorting your 4-in-1. A 7.5a fuse protects you from this.
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Old Mar 19, 2007, 06:10 AM
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Huntsville, TX.
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This happened within a matter of minutes (between batteries) on a heli that was 3 weeks old.

Brian
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