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Belt cp vibrate in a certain RPM


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edenwhw
Hopping Maniac
Hopping Maniac


Joined: 12 Jan 2009
Posts: 27
Location: Malaysia

PostPosted: Thu Jan 15, 2009 6:48 pm
PostPost subject: Belt cp vibrate in a certain RPM
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hey fella here, just wanna ask here see izzit normal for my belt cp to vibrate (seriuos) when the rotor start to rotate to a certain RPM n when i decrease the throttle then the rotation drop to a certain RPM. have anyone here been facing the same problem??
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silhouette015
Site Admin
Site Admin


Joined: 06 Jul 2007
Posts: 581
Location: Thailand

PostPosted: Thu Jan 15, 2009 10:26 pm
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I don't have a belt-CP but I do have a T-REX and I can tell you that the vibration is not normal.

I used to have that problem on two occasion, on of them was when the belt that drives the tail rotor had one too many turns in it. The other time was when I forgot to insert one of the rubber o-rings into the rotor head.

Those two are just a few of the many things that could cause a vibration but hopefully that will help you with the diagnostics somewhat.

Please keep us updated..
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edenwhw
Hopping Maniac
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Joined: 12 Jan 2009
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Location: Malaysia

PostPosted: Thu Jan 15, 2009 10:53 pm
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hey thanks for the info.
but its not constantly vibrate, it just vibrate when it start to rotate o when its power down to a certain RPM, so do u think it might b sumthing to do with the motor?
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jordy
Hover Master
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Joined: 24 Apr 2007
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PostPosted: Fri Jan 16, 2009 10:25 pm
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I don't think it's the motor. It sounds more like something mechanical around the rotor. You know how if you spin a top and it spins slowly and it wobble and if it spins fast it'll be steady? It's the same thing with the rotors of a helicopter. Basically the symptom you're describing is probably caused by the main shaft or something like that wobbling when the RPM is low and it stops when the RPM is high enough.

Perhaps the main shaft is not hold strongly enough.
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edenwhw
Hopping Maniac
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Joined: 12 Jan 2009
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Location: Malaysia

PostPosted: Sat Jan 17, 2009 7:24 pm
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had change the feathering shaft, but doesnt seems help much. blade tracking becoming too much diff in a case which the same blade went higher than the other blade while low RPM but lower while the rotor spining with high RPM.
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midnite
Flying Inverted
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Joined: 11 Apr 2007
Posts: 60

PostPosted: Sat Jan 17, 2009 8:12 pm
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edenwhw,

Ok now that you've changed replaced your feathering shaft don't forget to also check the main shaft. Sometimes those are bent as well. For the main shaft, it's harder to see with with plain sight weather it's bent or not. What you want to do is take it out and roll it on the table or floor or flat surface... The you'll know immediately if the shaft is bent.

Also, you need to track your blades. It sounds like your blades are really out of track and as a result it can make your heli vibrate at low RPM (it vibrates at low RPM on the ground but in the air it vibrates all the time, you just can't see it)...

Here is one article that's pretty about blade tracking on eZine articles.:

Quote:

RC helicopter blade tracking has been a mystery to many new RC helicopter owners, but I'm going to demystify the whole concept for you right now so that you'll have a complete understanding of blade tracking by the time you finish reading this article.

First, we need to answer this important question: What is blade tracking?

Essentially, blade tracking is when one rotor blade rotates in a circular motion and the following blade follows exactly behind it. Both rotor blades spin on the same plane without one blade being higher or lower than the blade it's following. Another way to look at it is that both blades travel through the same airspace created by their spinning. If the rear blade is following the front blade on a higher or lower plane, then it can cause a lot of unwanted vibrations for the RC helicopter.

How To Track Your Blades

If you're flying your RC helicopter for the first time, you need to see if the blades are tracking properly and you may need some help from an experienced RC helicopter pilot. You can check the blade tracking by simply hovering the helicopter in place at eye level and looking at the blades as it hovers. If you see a lot of shaking and vibrating, your RC helicopter is more than likely not tracking properly. If you're not sure if it's tracking properly, do this:

Get two different colors of tape and apply a small strip of one color to one blade. Put a red strip on one blade and a blue strip on the other blade. By using a different color on each blade, it makes it a lot easier to see which blade might be out of track.

Now that you've applied the colored tape, have an experienced RC helicopter pilot hover the helicopter in place so that you can see the blades as they spin. As you watch the blades spin, you'll know if they're in track if you only see a single circle or both blades spinning on one line. If you see two circles or two lines, (red above blue or vice versa) then you'll know that one of the blades are off and needs to be aligned.

To properly track your rotor blades, you need to land the hovering RC helicopter first. After the blades have stopped spinning, you can adjust the blade that is out of alignment. You'll need to have your RC helicopter manual handy so that you can look up the proper blade tracking information in it. Be sure that you adjust the correct linkages in what the manual says and not what someone says. This is the best way to be sure that you've done it correctly.

Once you've tightened or loosened the correct linkage or linkages, you need to have someone fly the helicopter again so that you can look at the blades. You'll repeat this process as often as needed until your blades are tracked properly and they spin on the same plane. Once you've completed proper blade tracking, your RC helicopter will handle a lot smoother than it did before and be much easier to fly.

This article is provided by Justin Smith and may be used only in it's entirety with all links included.

For more detailed information on How To Track Your Blades, RC Helicopter Tips or for some more RC Helicopter How To Articles please visit http://www.RCHeliSite.com.

Article Source: http://EzineArticles.com/?expert=Justin_R._Smith
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edenwhw
Hopping Maniac
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Joined: 12 Jan 2009
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Location: Malaysia

PostPosted: Sat Jan 17, 2009 9:51 pm
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had changed the main shaft either, still the same, the blade tracking is extremely hard to adjust. still working on it.
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edenwhw
Hopping Maniac
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PostPosted: Mon Jan 19, 2009 4:11 pm
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after i'd take out my heli n let some experienced flyer to try it, they told me its a normal issue for belt cp to vibrate like that with its stock blade. thanks to all who response to this thread and provided such informative tips.
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ANAMALS14
Charging
Charging


Joined: 24 Aug 2009
Posts: 2
Location: Mt Holly, NC. USA

PostPosted: Tue Aug 25, 2009 6:43 am
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Idea I just went through the same with my belt, the main shaft was bent from the factory. Replaced it and still couldn't get the tracking right, went to 325 align pro woods. Got to reshape them to fit the blade holders, best to bolt a stock esky on top and dremel to match. Wow tracking achieved!!( also a 1mm shim is needed). But mid stick vibes, belt too tight,loosened it still vibrating. Checked the head again, 1/4 turn fly bar bolt tighter, little less. Then I noticed one paddle a hair off level. Set that and much better. Now all I have is a bit of resonance at mid stick, probably from the hard surface of the lazy susan work station. U got to check everything.
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