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T-REX 500 › Trex 500 bad tail Vibration - Help needed
02-21-2011 01:26 AM  6 years agoPost 1
JC Aguilar

rrNovice

Panama, Panama

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Hi I am posting this because i have already tried everything i know and still can not figure it out.

I have replaced most of the rotating parts and the tail continues to vibrate badly (Fluttering sound and Tail control rod oscillating) in one of the tests the vibration broke a tail rod guide. Latest tests have been done with servos unplugged and without the head and even removing the swash plate trying to isolate the root cause -Vibration is still there.

The heli is a Trex 500 ESP never crashed with about 20 flights, Scorpion hk-3026 1600kv, 13T, CC ice75, apart from removing the head I have replaced already the following: Main gear/Tail gears (all of them), main shaft, all main shaft/tail TT bearings, an TT. We have tested the heli with a second Trex500 tailcase/grips and blades and continues to vibrate.

I already replaced the motor for a new scorpion. Also placed a second bearing to the TT. I think the only component i have not replaced is the speed controller but not sure if that could create the vibration in a heli (I tried it in fixed pitch and governor modes, same results).

The heli flew perfect until in the mddleof a flight during a spool up after adjusting the expo in my radio, it started to make a fluttering noise and took it down.

I would apprecite any help

Thanks,

JC

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02-21-2011 02:01 AM  6 years agoPost 2
JOLT

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Baltimore, MD

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The only thing that comes to mind when you say "fluttering" are the main blades (balance/tracking) and possibly the torque tube + tt bearing. I had more problems with vibration/resonance coming from a tt that was not true and the crappy bearing that guides it, then anything else.

I would also check the gear mesh of the motor pinion to main gear and front TT bearings as well.

I prefer a decent amount of backlash in the mesh of the main gear to motor.

Any video by chance?

edit--I failed to mention that I got rid of just about all the vibration in the Trex 500ESP when I switched from the TT to the belt.

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02-21-2011 02:11 AM  6 years agoPost 3
Steff Giguere

rrProfessor

St-Eustache, Quebec,​Canada

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If you hear fluttering then it has something to do with the main blades getting out of track. Check if the blades are solid, no cracks, check that the main blade ball links are still straight, you could have hit it some where, also check that the main blade screws are straight (too high head speed could slightly bend these). Also make sure that the blades are not too tight.

Team Synergy, Rail blades, Team Scorpion, V-Team

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02-21-2011 02:34 AM  6 years agoPost 4
JC Aguilar

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Panama, Panama

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Hi thanks for the reaplies,

The flutter/resonance sound comes from the tail...no head or main blades are installed in the heli at this point, over 75% throttle the tail starts to make a resonance sound and the tail rod starts to oscillated badly.

Jolt, I might try the belt change.
JC

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02-21-2011 02:49 AM  6 years agoPost 5
Safe_Cracker

rrKey Veteran

Chicago, IL

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Did you remove the tail blades and try spooling it up? If it still does then remove the tail rotor.. Check the tail shaft for trueness?

Polo

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02-21-2011 03:07 AM  6 years agoPost 6
JC Aguilar

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Panama, Panama

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Yes, when i remove the tail blades it is ok, no major vibration can be detected. As soon as I install them vibration is there. I tried 3 different pair of tail blades and nothing. I already replaced all shafts/pinions and bearings with no luck.

JC

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02-21-2011 07:06 AM  6 years agoPost 7
Safe_Cracker

rrKey Veteran

Chicago, IL

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Ok, then the problem is in the tail rotor somewhere... Did you look down while it is spooled up to see if the blades are in track, tail blades that is. Could be a bent blade grip, or bad bearing. Try grabbing a grip and see if there any excessive play also check the grip screws...

Polo

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02-21-2011 09:46 PM  6 years agoPost 8
JOLT

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Baltimore, MD

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Something comes to mind here--you remove the tail blades and the resonance goes away? Might be the radial play in the tail blade grips acting up when you put the blades on and spool up.

I have had 3 Trex 500's and there is some variance in the tail blade grips. There are several fixes for this, one of which is using a dremel to file down the tail blade grip spindle and another is a whole new aftermarket tail grip assembly.

The reason you still had the same problem when you replaced the tail assembly from another Trex 500 is just that--because you replaced the tail assembly from another Trex 500 with the same problem.

I know exactly what you're talking about now.

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02-22-2011 03:09 AM  6 years agoPost 9
JC Aguilar

rrNovice

Panama, Panama

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Jolt,

We installed a complete new belt system and vibration/resonance continous there. Also tested a new speed controller, new boom braces with no success.

After seeing your post, I tried tonight the tail grips milling with the dremel and removed all radial play in them without bidding and it really delayed the resonance to the very end of the throttle curve, but not fully cured.

I think i am going to give it a try with an aftermarket grips, but honestly i am about to give up, there is nothing left to change appart from that.

Thanks,

JC

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02-22-2011 05:11 PM  6 years agoPost 10
swsc

rrNovice

Alamogordo, NM

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Tail blades

I just went through this myself. It ended up being the tail blades themselves. I went from the plastic to the carbon's and problem solved.

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02-23-2011 04:07 AM  6 years agoPost 11
JOLT

rrVeteran

Baltimore, MD

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Well, at this point if the problem has showed an improvement you might want to try shims between the grips and center hub. It sounds like your almost there and it would really stink to throw more money at the problem in the form of a whole new tail assembly.

This hobby can be so frustrating at times. This sounds like one of those times.

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07-21-2011 05:09 AM  6 years agoPost 12
flyride

rrKey Veteran

Salt Lake City UT

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JC Aguilar

Did you ever solve the problem with the vibration? I have been fighting the same thing and have tried everything to get it right and I still can not get the vib to go away. It seems to be fine until I hit a certain speed them it vibrates like crazy and feels like it is going to blow apart. If I take the tail blades off and just run it up with the hub the vibrations are minimal but with the tail blades on it crazy...

I have replaced all plastic gears and bearings shafts etc. This thing is driving me crazy.

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

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07-21-2011 04:10 PM  6 years agoPost 13
JC Aguilar

rrNovice

Panama, Panama

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Flyride,

I was never able to find the source. I replaced all moving parts and including motor and ESC and nothing. I finally gave the frame to a friend of mine and he has not flown it yet.

But i am very happy i never solved it, because I took all the electronics (Servos, motor, ESC, batteries, blades, etc) and put it on a Logo 400 and I am very happy with it. Very light, precise,durable and nice helicopter.
That was my first Logo and now a have the L500 which is a even better machine.

Sorry for not being able to help you.

JC

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07-21-2011 06:01 PM  6 years agoPost 14
hpilotrc

rrVeteran

NY--->>Mooresville,​NC USA 8/2005

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Trex 500 Tail Vibration as seen on my Mikado​Mini V-bar

Yes I too have discovered vibration from my tail rotor - to the point where my heli has gone off course several times during the last two flights! My Mikado Mini V-bar V5.1 Pro analyzer software shows a problem with the tail once the blades are attached.

I decided to go with carbon tail blades and am waiting for my favorite dealer to get them in. Looking at the Align H50087's. The Align stock plastics seem to introduce too much vibration when using the V-bar. Haven't had this problem up to now but do not want to risk a crash! I also will try another layer of double sided mounting tape for isolation. Right now I am just using one piece of the white foam tape but can feel the vibration reaching the mini-v's case. What I really need is some of the thinner vibration mounting gel. The stuff I have now is too thick at 1/4".

Anyone else have a recommendation for fiberglass or carbon tail blades for the 500? Would try CY's but they are way too expensive!

Thanks,

Michael

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07-21-2011 11:15 PM  6 years agoPost 15
rotornoggin

rrNovice

Florida

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Be careful. I was dealing with this tail vibration issue and "flying around it" by switching down to a lower throttle curve whenever it would start vibrating. Then one time I before I could switch out of it one of the tail grips flew off, followed by the canopy shaking loose and into the rotor disk (inverted at the time), followed by the main blades hitting the boom, followed by a twisted mass of parts plummeting back to earth--all in about a second.

Most of the failed tail bolt was still in the hub.

T-Rex 550, E-Sky D550

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T-REX 500 › Trex 500 bad tail Vibration - Help needed
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