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HomeAircraftHelicopterAlignT-REX 600N › Need help tracking down a tail vibration.
03-14-2010 11:09 PM  8 years agoPost 1
flyride

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Salt Lake City UT

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Ok I have a 600nsp heli with os 50 hyper that has always had a tail vibration and I cant get rid of it and I am out of ideas as to what else to do. The tail has an accasional pulse to it and it looks like a slight up and down motion and the vertical fin has a vibration and also the tail boom supports look like a guitar string being plucked strait to vibrating to strait ect and there is a low harmonics sound from the tail boom or supports or something, most of this seems would point to the engine out of tune but I have got new gas and plug and tuned it as good as I could low needle is at about 1 oclock position and when I pinch fuel line I get about 4-5 seconds before it leans out and I have the high end needle at about 7/8 out from closed position this is the best position for everything to run strong and consistant without getting too hot. Here is what else I have done to check for the vibration,I dial indicated the main shaft, tail shaft, and feathering shaft all 100% true then I rebalanced the tail to perfection and also the head with just the flybar to perfection and then added blades and balanced to perfection( blades will hold in any position I put them on the rotation scale thing i dont remember the name) then took it out and ran it up and tracked blades until both were tracking as one and the bearings seem to be good and smooth throughout. I also ran the heli without head or tail and still got the vibration in the boom supports so I think the engine is part to blame for the harmonic vibration noise and the tail pulsing but still dont know why the tail has a vibration in it up and down. What have I overlooked and what can I try to fix the problem I am worried the tail will rip apart in flight or something. I have the stock plastic tail on it and it has alot of play side to side on the grips but not any outward, has anyone had a problem with the stock plastic tail causing vibration issues? What about the engine what can I do to make it run smoother and get rid of the vibration it is causing? it is running strong and has plenty of smoke and gets about perfect as far as temp goes. Please help it is driving me crazy,the heli has very little time on it (mostly test hovers) because of the issue and I just want to go have fun with it.

and the blonde said "RECTUM, Hell damn near killed em!!"

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03-15-2010 02:27 AM  8 years agoPost 2
2LTime

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Walworth,NY

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I had a similar bad shake that took me a while to fix. It ended up being the bearing in the clutch bell. The bearing right above the clutch itself, mounted in the clutch bell was loose in the bell. The hole it mounts in was oversize fro some reason. I could hover and it be perfect than shake like crazy, than be smooth again.

Jeff

If you can't learn to do it well, learn to enjoy doing it badly.

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03-16-2010 02:44 AM  8 years agoPost 3
flyride

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Salt Lake City UT

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Ok just pulled out the engine and balanced the metal fan and then added the clutch and balanced as close as I could then I checked the run out again and it was within .005 so I put it back together and this seemed to help a little of the vibration but I still have a tail wag and a little up and down type vibration and my header tank has vibration.I also swapped out my k&b orange dampers for the stock ones to see if it was just too stiff and it didnt make any difference. So my next step is to upgrade to the quick uk tail (I am running stock plastic tail and it has alot of slop)and also a new tt as mine doesnt seem to be 100% true and maybe an extra bearing on it.any suggestions as to what I have missed?

and the blonde said "RECTUM, Hell damn near killed em!!"

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03-16-2010 07:23 PM  8 years agoPost 4
basmntdweller

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Indianapolis IN

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You can balance in the shop all you want but you have to spin it up to get it perfect. That goes for both main and tail blades. I have electrical tape on the blades for most of my balance adjustments. I have also used extra nuts on the tail blade bolts to help get one balanced.
I'd start with one wrap of tape on one blade. Fly it and see if it is worse or better. If worse, take it off that blade and put it on the other. I always put the tape about the spanwise cg of the blade. You mentioned that the tail was bouncing up and down. That is almost always the main blades out of balance. The guitar string boom supports can be either main ot tail but more often is the tail.

Matt


Stupid people have no idea how stupid they are!!!

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03-17-2010 01:00 AM  8 years agoPost 5
flyride

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Salt Lake City UT

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I have never had a problem with the way I balance before. I put the head on the roll balancer without blades and balance the paddles and then add the blades and balance them (after I weigh them on a gram scale and also find the blade cg) with the blades on I could rotate the head in any direction and it would stay without falling to one side. I tried your Idea of putting on tape then running it up, I tried each blade and it didnt help it seemed to get worse then I took the balance tape off the tail that I had on there and ran it up and it was worse so I added tape to one blade and it was worse then I added it to the one that originally had the balance tape on it and it balanced back to where I had it in the first place (did not help anything). The higher the head speed it seems to be worse, it is definatly a fast side to side action and it is hard to tell if it is a slight up and down also or if it just looks that way from the side vibration. The engine is running pretty good but I do get a little spurt here and there that doesnt help the tail(nnnnnnnnnnnnnn-grr-nnnnnnnnnnnnnnnnn-grr-nnnnnnnnnnn sound) but if I lean it anymore it will just start to run hot.I have the quick uk tail and a new TT on the way maybe this will help my stock tail has alot of slop. I tried changing my gyro gain and it didnt do much of anything I even went to 100% and it didnt help it. Has anyone had to shim the head of the hyper to make it run smoother or any other ideas as to what to look for?

and the blonde said "RECTUM, Hell damn near killed em!!"

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03-17-2010 01:41 AM  8 years agoPost 6
basmntdweller

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Indianapolis IN

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Okay, my only other thought is torque tube. I had a Fury once that one of the torque tube bearings slid to one end so the tube would run eccentric and vibrate like crazy. Just a few seconds in idle up sounded like the heli was about to self destruct!

Good luck and post what you find to be the cure.
Matt


Stupid people have no idea how stupid they are!!!

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03-17-2010 03:11 AM  8 years agoPost 7
fastflyer20

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N. Tonawanda, NY

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I am chasing a vibration on my 600 for the second time. I bought it used and found the following problems the first time:

Bent TT shaft
Bad main bearings
Bad large diameter clutch bearing
Too high gyro gain
(dx7, travel adj, JR770 gain turned down to 18)

2nd time- I just had a minor wreck, replaced the usual stuff, and the tail shake is back. I am on the hunt to find the gremlin this time too.

While I don't think it is your issue, you should be able to dial indicate the clutch hub down to .002" max. I have been able to get a few down to .0015", but never lower.

I would say it is not your engine, I tried leaning the engine, the vibes would get better, but the engine was way to lean.

Suggestions:
Check the tail and TT very closely
Try turning the gain down lower than you think.

It will be interesting to hear what you finally find.

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03-17-2010 03:24 AM  8 years agoPost 8
flyride

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Salt Lake City UT

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I tried turning the gain down and it wouldnt hold the tail very well and it was still doing it. I realy hope the new quick tail will take care of the problem. I have had the heli for about 1 1/2 years and it has always had this stupid tail issue and I have not been able to realy fly it. Maybe I will just fly it until it blows and then throw the whole d@mn thing in the trash (sorry just frusterated). Never had these problems with my Rappy. You spend $1000 on a heli and then have to dump $500 more into new everything just to fly it because on the first test flight everything sh!t the bed!!!

and the blonde said "RECTUM, Hell damn near killed em!!"

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03-17-2010 03:28 AM  8 years agoPost 9
flyride

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Salt Lake City UT

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I was dial indicating the clutch to within .005 not the clutch hub or is this what you are talking about and how do you get it better? I can only turn it 2 times to match up with the bolts and then pick the best runout.

and the blonde said "RECTUM, Hell damn near killed em!!"

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03-17-2010 03:42 AM  8 years agoPost 10
stadanco

rrNovice

San Diego

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I had the same issue after rebuilding mine last week. I loosened every thing in the frame within reason, took off the main blades fired it up and ran it at low rpm's. tightened everything back up from the center out, main bearing blocks out, and it runs smooth now.

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