Trex 600 E - GY401 - Tail Wag

[Rotorworks]

Hello all.... Hoping to find some help here! We finally got the new Trex 600E going. We've got a GY401 with a S9254 for the tail servo. We are using the Castle BEC Pro feeding 6.0 volts to everything. We have the 5.1volt stepdown regulator between the gyro and the tail servo. The gyro is mounted on the one foam pad. Here is the problem, the tail is wagging on us. It is not the consistent wag of a too high gain setting. We are using the DX7 TX and the AR7000 RX. Should we have a metal plate in there like the GY611 mounts? The tail servo linkage works freely. We do have some vibration, so I'm thinking we should balance the main blades...they are the stock align carbons I believe. ...............any thoughts??

Thanks in advance for your time!! Rob

[solaris]

On that gyro the sweet spot is 85%-90% servo limit throw.

So set the Gyro limits to 85% then work the linkages and servo location to get the tails centered on MECHANICAL 0 pitch.

do not center in rate mode. The Gy401 likes a Physical rudder neutral center

[dingfangle]

Are you flying in normal mode or in idle up? If your head speed is too low it can affect performance as the tail will also be slow when manuvers are added and the head boggs down a bit, if in normal mode try increasing the mid point of you throttle curve some to help bring the speed up but not have to fly in idle up. Definitely balance your blades if you think they are causing any noticeable vibration and make sure your batteries are strapped down very tight. Any wiggle in the batteries can cause the wagging affect as the gyro tries to compensate for it. Also check that your main and tail blades are bolt fairly tight, you should be able to move them by hand but there should be some resistance (on my 600 I keep them quite tight). Also look at the flybar paddles and see that the are running flat and true. Looking down the trailing edge of the paddle the tips should be dead center to the center of the bolt for the end cap of the flybar cage.

Also Make sure that the gyro is set up for the type of servo you are using on the tail. That servo is a digital so make sure the tiny switch on the top of the 401 is set to "on" for the DS (digital servo) switch.
You could also try turning the delay dial up ever so slightly. Do this with the power off make your small adjustment and then power back up. you may have to do this a few times.

Adam

[Rotorworks]

Thanks for the replies! I did find one problem that seemed to help. The person that built this heli had installed a big flat washer between the case and the tail pitch control arm (the L shaped one your tail pushrod hooks onto) I found the best washer I could and made that operate more freely. Yes, I have switch the DS switch to ON. It seemed to hover better, but I could turn my gail up over 100 in the travel adjust section on the gear channel and I don't seem to get the hunt I should with high gain. The head speed seems to be quite nice, but I want to tach it to be sure. 1600 to 1900 should be good, right? How far out from the screw should my ball be on the tail servo control horn? Also, how important is it to find the neutral......by the following procedure..... This is maybe a silly question, but I have never done it before and generally my 401 setup works good. I make sure my tail servo horn is 90 degrees to the servo in rate mode, set my limits with the little pot on the gyro and away I go. My HH mode on my trex 450 is at 35 I think and it works well, tail holds well!
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Next step is adjusting the tail linkage length in normal mode until the tail holds without you needing to compensate with rudder input. Spool up the heli and bring it into a low hover. You might need to hold the tail steady by using a little left or right rudder. Just make a mental note of which way you are having to push the rudder to hold it steady and land. If the heli wanted to turn left and you had to give it a little right rudder then shorten the linkage rod one full turn and try again. conversly if it went right and you had to hold left then lengthen the linkage one full turn. Continue to adjust this until the helicopter will hover steady without any rudder input. If the servo pushrod length is massively out then you may need to move the servo clamps along boom in order to compensate instead of adjusting the pushrod length.
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What numbers should I start with for the Trex 600 on the gear channel in the travel adjust section. 49% for rate mode and 75% for HH mode? I balanced the main blades so the heli is much smoother. I shouldn't have to turn up the delay should I , seeing that I am using the S9254 Futaba digital servo?

Thanks
Rob

[beensoko]

If your head speed is to low your tail will bob up and down.

[Rotorworks]

Thanks for all your answers. I think I found the problem. When I would spool up to speed the tail would sieze up and the servo couldn't seem to move the tail pitch slider, slow the heli down and it would move fine. This must be an older 600E kit with no thrust bearings in the tail blade grips...........and I discovered that both of the outside bearings in the tail grips are very "notchy", one worse than the other. Going to put on the new tail hub/grip/bearing assembly H60109 on the heli, it comes with thrust bearings. We were taching the head around 1700 rpm. Thanks for now.

[Rotorworks]

Hello all. Ok, replaced the two outer radial tail blade grip bearings on the Trex 600. I wanted to see if that really was the problem. It was......!! Two tiny little bearings was shutting that tail down. Works well now! Trex 600 is sure a pleasure to fly !!! Thanks ...