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Trex 450 se tail shakes

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Trex 450 se tail shakes

Old 01-01-2007, 01:27 PM
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Default Trex 450 se tail shakes

With or with out main blades on my heli the tail shakes violently in yaw when spooled up to 60%. I have balanced the tail and made sure the grips were not too tight. Any ideas how to fix this?

Trex 450se
Gy 401 / futaba 3145 digital
futaba 9c radio
Old 01-01-2007, 01:37 PM
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Default RE: Trex 450 se tail shakes

Try taking the tail belt off and spooling it up to see if it is a problem with the tail or the main shaft. If it doesn't shake with the tail belt off, have a look at your tail gear set, does it run true? Sounds like it might be a bent tail gear shaft.

murp
Old 01-01-2007, 01:43 PM
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Default RE: Trex 450 se tail shakes

That would suck, its never left the ground yet. bran spanking new. The blue main gear does seem to oscillate up and down about 1mm thru its rotation. Could that be causing it?
Old 01-01-2007, 01:53 PM
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Default RE: Trex 450 se tail shakes

Just my 2 cents with very little information given. The blue gear running not perfectly true is very common. The tail shake mite be caused by the gyro gain being way too high. Turn down the gain to around 50% and see if that helps. The gyro will actually fight itself if it is too high and cause the tail to go back and forth violently. Also check the tail pushrod to make sure it moves without ANY binding. These are the 2 number one things I see wrong with heli setups.
Old 01-01-2007, 02:06 PM
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Default RE: Trex 450 se tail shakes

Could it be the pushrod is connected to the middle hole of the control horn? Do i need to connect it to the closest hole to the servo horn screw? It does seem like the servo is causing the shake.
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Old 01-01-2007, 02:15 PM
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Default RE: Trex 450 se tail shakes

You could connect it too the closest hole. The tail rotor does not take much movement to just fly and normal aerobatics. I would say the problems are in this area, and are not something out of balance.
Old 01-01-2007, 02:38 PM
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Default RE: Trex 450 se tail shakes

seems to be working. I have moved it to the closest hole and lowered the acv to 30%. Hovering in bedroom now. Thanks for your help. Time for some exponential for hovering now!!
Old 01-01-2007, 04:17 PM
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Default RE: Trex 450 se tail shakes

Yea, Alot of guys use EXPO on the T-Rex's to smooth out hover. They are kinda jumpy.
Old 01-01-2007, 04:46 PM
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Default RE: Trex 450 se tail shakes

Is it normal for the tail to shake while hovering after a rudder movement left is given. It holds fine, but after a quick tail movement it starts shaking in the hover. I have lowered the avc to about 30%
Old 01-01-2007, 05:46 PM
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Default RE: Trex 450 se tail shakes

No, it shouldn't do that. It should be rock solid no matter what input. You have to remember the 401 Gyro is slightly differant. From 0 to 50% is in normal gyro mode, from 60 to 100% it is in heading hold mold. Heading hold is smoother. Make sure you have the dip switch on the gyro set to digital for the digital servo you have. It is very hard to locate the problem without being there in person. Double check the tail linkage for any sticky spots or sloppy linkage.
Old 01-01-2007, 07:22 PM
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Default RE: Trex 450 se tail shakes

Thanks for the help. In my futaba gyro sensitivity menu it has 0-100 acv and 0-100 for normal mode. I have it set to 30%acv mode. The shake starts when i give it Left rudder stick. only when i do it abruptly not when i give it smooth stick movement.
Old 01-01-2007, 07:52 PM
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Default RE: Trex 450 se tail shakes

I would say go down some more then. You sound close now but still to high. You will notice if you fly outside that the wind will cause this same condition to happen. You want to get to the point were it holds the tail but doesn't cause the tail wag inssue.

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