9257/ GY401 Drift

[Dizzyflyer]

Hello all,
I decided to get the 9257 tail servo and GY401 for my B400. I a little over 50 flights and am still learning (no crashes to date...knock on wood). I feel like I was fighting the tail a bit too much in nose-in flight on the stock setup so I figured I would take the plunge. Everything is installed. I flew it this evening with the new servo and I still have an ever so slight drift to the left. MUCH better than the stock....but in hover it will inch over to the left. Is this normal? If not, any advice?

I installed the Gyro on the frame (where the stock one was....I heard that this is a no-no, so I am looking for a boom mount so I can invert it. For now it will have to do. The servo is mounted completely on the boom tilted about 45 deg and the pushrod is centered down the boom. (in other words...everything moves smoothly with no binding). I centered the trim on the rudder and plugged the servo into the RUDDER channel first to find center. I then mounted the control horn 90deg to the servo. Next I attached the rudder pushrod to the servo control horn and slid the servo on the boom till the tail rotor was centered. Tightened the servo on the boom and plugged it into the Gyro. I checked the control limits and adjusted them down slightly on the gyro so the servo would not bind. Delay is set to ZERO and the gyro is in digital mode.

I plug the battery in and do not move the heli or controls till the gyro is armed. The Gyro in HH mode is set to 72%. Spool up and it feels locked in, but it still has an ever so slight drift..........

What did I miss?
Thank you for your assistance!!!
Dizzyflyer

[LockMD]

I know this makes no sense, didnt to me anyhow. But, try it!

re-bind your tx to rx and all will be perfect, somehow the tx remembers centers and if you do ANY adjustments to the tail you need to re-bind.

I know it sounds weird but it works!

[JASON671]

i had the same problem too. what lockmd said will work. but what i did was put zip-tie around the gyro to hold it snug to the frame, it will read the tail better, then i bumped up my throttle curve for more head speed. now the tail holds like my trex 450. goodluck

[LockMD]

i had the same problem too. what lockmd said will work. but what i did was put zip-tie around the gyro to hold it snug to the frame, it will read the tail better, then i bumped up my throttle curve for more head speed. now the tail holds like my trex 450. goodluck


I came from honey bee fp and cp pro (tail motor helis) took me for ever to get this threw my thick skull, the higher the head speed the more tail authority (with a belt tail) the tail spins as fast as the main and changes directions with pitch.

Sorry, guys most of you are like DUH! but coming from motor tails slowing to go left and speeding up to go right made alot of sense and now learning about tail rotor pitch I was dumb founded. But now I am grasping the concept and the motor tail birds sit on the shelf. Belt tail GOOD. :YeaBaby:

[JASON671]

lol i been there too

[SeaComms]

If that doesnt work, try Finless's version. Set it all up, then with it sitting stationary on the bench, move lever to the left and then release slowly and see if it creeps. If not, then move it right then gently release and see if it then creeps. If it does, then use a little subtrim at a time til it no longer creeps after release from either direction.

This should get it to hold good.

I am using the stock gyro and a Futaba 3154. If I set it to digital mode I can not stop the creep and jitters, but in analogue it holds fine.

[philiusm]

The gyro needs to sit freely on its mounting pad. If you have anything touching the case of the gyro or the wires to the gyro don't have enough slack in them you can get high frequency vibration transmitted into the gyro.

On the Swift this manifests itself as a slow anticlockwise drift of the tail. I normally put a little loop in the cables going to the gyro to stop this happening.

I notice in your picture you have a cable running between the frame and the gyro which may be causing the issue.

Here is a picture of my Swift gyro setup.

[Dizzyflyer]

..

[Dizzyflyer]

Thank you everyone! I will definitely give these a shot today. The re-bind deal is pretty easy so I'll try that first. Philiusm, that is EXACTLY what I am seeing....a slight creep counterclockwise. Another easy fix. Now I just hope the rain will stop so I can give it a try outdoors. I'll let you know how it goes.

I read somewhere where someone suggested flying the gyro in rate mode and centering it there first...then flipping to HH mode. Then it said something about toggling between rate and HH 3 or 4 times. Any truth to that? I don't know if I am good enough yet to fly in rate mode......had enough trouble with the Blade stock gyro drifting hard. Can't imagine flying basically with little gyro input.

Thanks!
Dizzyflyer

[philiusm]

Re-read the datasheet on the 401. That's how they tell you to set it up.

I adjusted mine mechanically so that I had equal throw on the tail pitch slider and around 100% on the limit adjustment. You have to change which hole you use on the servo arm to influence the limit setting.

Once you have the mechanics correct you need to trim it on the radio to couteract the torque of the rotor. You do this in rate mode. Then when you swap to HH mode for normal use.

I found that I didn't need to adjust the trim in practise, as the gyro seems to cope with the offset. BUT it's not how the datasheet tells you to do it. Just RTFM.

Again check you have nothing touching the gyro case and use the supplied tape and it should be fine.

[Dizzyflyer]

Well I set the bind again and adjusted the wiring so nothing touched the Gyro. Seems to work just fine now. Thanks for everyone's help!!
Dizzyflyer

[carlo_the_wonder_frog]

just FYI, you don't use ANY trim or subtrim with a GY401 gyro, if it drifts that is because it has not had its neutral setting commited to memory, thats why you rebind it on the radio. You can also reset the neutral by switching from HH mode to rate mode 3 times fast, but everytime you unplug the battery you will have to reset the neutral, hence it is easier to rebind it permanently.