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Old Oct 02, 2009, 11:23 PM
Doing it in the Lateral Axis
modfly's Avatar
USA, OH, Akron
Joined Dec 2006
15,360 Posts
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Parkzone Ultra Micro P-51 LVC pulses the motor before it should

Well I got about 12 flights out of mine before I noticed a problem. Something is wrong with the motor\gearbox is what I'm thinking as it does not seem to rotate smoothly and its making a rattling noise. I noticed on the 8th flight that something was up as the flight times were getting shorter each flight before hitting the LVC pulsing. I thought I would see what happened if I kept flying it after the pulsing...after another minute, the motor hit hard LVC and shut off and could not be restarted. I blew the dead stick landing and flopped it hard on the bottom of the nose. Some damage to the foam there and the spinner came loose. You can tell if you hit hard LVC because the LED is flashing slowly and the motor will not restart.

So now looks like I need to take it apart to see whats up.


Sukhoi motor replacement with Motor clocking .. http://www.rcgroups.com/forums/showp...19&postcount=5

Videos showing a problem GB.. http://www.rcgroups.com/forums/showp...2&postcount=13

GWS Prop and rubber spinner.. http://www.rcgroups.com/forums/showp...5&postcount=28

20c 240mah lipo mod.. http://www.rcgroups.com/forums/showp...&postcount=289

Latest video with 240mah lipo. Using a Vapor TX here..
PZ UM Mustang with 240mah lipo (2 min 16 sec)
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Last edited by modfly; Nov 02, 2009 at 06:04 PM.
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Old Oct 02, 2009, 11:31 PM
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Butters's Avatar
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Joined Mar 2005
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WOW that sucks dude. My nose cone came off too.

I hope get her fixed and document everything. You never know this might be a problem others get.
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Old Oct 02, 2009, 11:36 PM
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Chompers's Avatar
USA
Joined Feb 2007
665 Posts
allright modfly let us know what you find.

Thanks
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Old Oct 03, 2009, 12:17 AM
Off we go.............
SabreHawk's Avatar
Seattle, WA. USA
Joined Jan 2006
3,325 Posts
Mmmm, good you brought this out Modfly I'll be keeping an eye.

From the sound of it, it seems we all might be well to open it up and inspect the motor/gear unit and even lube it some. My Citabria when I frst bought it it got lubed before it's first flight and worked like a charm. Then after replacing the unit, I forgot to lube it before running it under load and it ran like crap, squalling and lacking power. Then after lubing it it was fine.

This too may well be a situation where a lube job is in order before putting it in the air.
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Old Oct 03, 2009, 12:35 AM
Doing it in the Lateral Axis
modfly's Avatar
USA, OH, Akron
Joined Dec 2006
15,360 Posts
Sukhoi motor replacement with clocking

Before I did anything I measured 1.60 amp draw WOT. Thats a bit high, about 300-500ma too high I reckon. I will be back in a bit with some video and pics..you can tell your plane has the problem by its flight time or lack there of.

edit..I swapped in a Suki motor and no more gear binding, however, the motor may have to be timed or "clocked" to the gearbox to get the proper gear lash. I put a red dot on each motor and I found at a certain spot the motor from the Suki would not bind and worked perfect. I could not find that spot with the stock motor making me suspect either the pinion gear or motor shaft centering in the case.

Still testing the P-51 motor. I'm not convinced its bad. It seems to have stronger magnets and does not spin as easy as the Suki motor.

I did not remove the GB from the P-51 but rather the motor was removed from the GB and the Suki motor installed in its place. The wires on the P-51 motor(white\black) are a bit longer than the Suki wires(red\black). The Suki motor has a white end cap where as the P-51 has a black end cap.

edit. I will be getting a new Mustang motor\Gearbox from HH and I will report my findings with it.
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Last edited by modfly; Oct 15, 2009 at 06:30 PM.
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Old Oct 03, 2009, 08:00 AM
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Steve McBride's Avatar
Agra, Oklahoma
Joined Feb 2000
5,390 Posts
Wow, that's very interesting. So it's not that the pinion is out of spec, it's that the motor shaft does not exit in the middle of the can. I can see that happening with these motors as they were probably originally designed to do something less precise that mesh two gears.

Thanks for that info.
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Old Oct 03, 2009, 09:09 AM
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Butters's Avatar
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Modfly,

Do ya think all or most or some planes will develop this issue?
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Old Oct 03, 2009, 11:32 AM
Doing it in the Lateral Axis
modfly's Avatar
USA, OH, Akron
Joined Dec 2006
15,360 Posts
Quote:
Originally Posted by Steve McBride
Wow, that's very interesting. So it's not that the pinion is out of spec, it's that the motor shaft does not exit in the middle of the can. I can see that happening with these motors as they were probably originally designed to do something less precise that mesh two gears.

Thanks for that info.
Thats a possibility but I think its something else.
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Last edited by modfly; Oct 04, 2009 at 08:56 PM.
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Old Oct 03, 2009, 11:33 AM
Doing it in the Lateral Axis
modfly's Avatar
USA, OH, Akron
Joined Dec 2006
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Quote:
Originally Posted by Butters
Modfly,

Do ya think all or most or some planes will develop this issue?

At this point I'm gonna say "some".
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Old Oct 03, 2009, 11:35 AM
Doing it in the Lateral Axis
modfly's Avatar
USA, OH, Akron
Joined Dec 2006
15,360 Posts
Quote:
Originally Posted by SabreHawk
Mmmm, good you brought this out Modfly I'll be keeping an eye.

From the sound of it, it seems we all might be well to open it up and inspect the motor/gear unit and even lube it some. My Citabria when I frst bought it it got lubed before it's first flight and worked like a charm. Then after replacing the unit, I forgot to lube it before running it under load and it ran like crap, squalling and lacking power. Then after lubing it it was fine.

This too may well be a situation where a lube job is in order before putting it in the air.
Not this time. The GB had plenty of lube on it. The problem is the gear mesh is too tight.
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Old Oct 03, 2009, 11:52 AM
Registered User
Columbus Ohio
Joined Aug 2009
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I just picked up my P-51 and right out of the box the gear is very noisy. Is this normal or should I be worried?
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Old Oct 03, 2009, 12:04 PM
Doing it in the Lateral Axis
modfly's Avatar
USA, OH, Akron
Joined Dec 2006
15,360 Posts
Noisy Gearbox..not exactly

Quote:
Originally Posted by jsbaugh
I just picked up my P-51 and right out of the box the gear is very noisy. Is this normal or should I be worried?
Noisy is nothing to worry about. Flight time will be an indicator if there is a problem or not. I will post some videos here in a bit but it looks like the "knocking" sound is nothing to worry about as its just a combination of electronic\acoustic motor sound that is audible resonate in the foam and is nothing to worry about.

My plane with the stock motor was drawing 1.6 amp and had a 3 minute or less flight time and now with the Sukhoi motor it draws 1 amp and should have a flight time of near 8 minutes.
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Last edited by modfly; Oct 04, 2009 at 09:08 PM.
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Old Oct 03, 2009, 12:20 PM
Doing it in the Lateral Axis
modfly's Avatar
USA, OH, Akron
Joined Dec 2006
15,360 Posts
Here is a video showing how tight the gear mesh is on my P-51 GB as compared to the Sukhoi GB..
Gear mesh too tight (0 min 19 sec)


Here is one with the noisy gearbox..
Micro P-51 noisy GB (0 min 12 sec)


Its not actually the gearbox that is causing the "knocking" sound. This is a normal sound for the P-51 by the way.

Here is the motor Pulsing..
Micro P-51 Pulsing LVC (0 min 24 sec)


Here is a video of the Suk hoi replacement motor with current draw and voltage shown under load..
Replacment motor current draw (0 min 14 sec)


Current and voltage under load with the Sukhoi replacement motor...
Replacement Sukhoii motor (0 min 38 sec)
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Last edited by modfly; Oct 03, 2009 at 02:26 PM.
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Old Oct 03, 2009, 12:36 PM
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Chompers's Avatar
USA
Joined Feb 2007
665 Posts
i think modfly figured it out. my plane is showing the same symptoms.
i have three movies uploading to compare with.
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Old Oct 03, 2009, 05:52 PM
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Chompers's Avatar
USA
Joined Feb 2007
665 Posts
Ok I went out and changed out my motors, it spins a lot freer now. but i have two questions for you if you will.

1, the motor wires are not long enough, did you turn the board 180* or just solder a lengh of wire to the leads.

2, all though it spins freely now, my gearbox grinds no mater where the sukhoi motor is "timed". how to stop the grinding.


one final observation, although the pkz 120 works ok "no pulsing" (don't know about flight times) the tenergy cells are totally useless for this application, it still pulses.

any thoughts if you will
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Last edited by Chompers; Oct 03, 2009 at 06:31 PM.
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