DX6i Sub Trim Query

[Bernie the Bolt]

I am trying to set up the Align HH gyro on my Trex 450 by reducing the rudder servo arm from creeping back to neutral in HH mode as described in the Finless Bob's Video ie by using Rudder Sub Trim. The problem is that I can only adjust the trim in one direction only.

In my Dx6i the sub trim program only appears to allow you to stop the creep in one direction only ie I can stop the creep by holding left stick and adjusting the sub trim values for that side but when I hold the stick in the opposite direction and adjust the other set of values, they cancel out the previous entries. In other words, I can stop the creep in one direction but not both.

Is this a limitation of the DX6i or am I doing it all wrong. Any advice on how I can reduce creep in both directions would be much appreciated.:confused:

[Danal Estes]

Creep in HH mode when sitting on the ground is normal. Don't adjust it out.

[Bernie the Bolt]

Thanks Danal Estes.

I appreciate what you are saying but my gyro setup is exactly how it should be but I am getting none or very little response in HH mode and I put it down to the fact that I cannot reduce the creep. Its not only Finlay Bobs videos that tell you to reduce creep in HH mode ' on the ground' but in other gyro setup guides too and as it would be impossible to do it in flight, why mention it in the guides if there is no need for it to be done or are you saying it is just not possible with the DX6i ?

[BarracudaHockey]

You're doing the right thing, only you're treating sub trim like end points where you have to move the stick.

There is no left/right subtrim per se. It adjusts the center point of the servo so there's only one value.

[Danal Estes]

Well, I certainly don't want to cross Bob's setup guide... so I'll be quiet.

Sort of quiet anyway; I have to ask why the sheet that comes with the 401 says some very specific things about "return to center" and trim in AVCS (HH) mode. See the "Rudder Neutral Check Method" and "AVCS mode usage precatutions" sections of this sheet.

Again, I trust Bob... I'm just confused as to why this seems to be in conflict with the sheet and with statements I've heard that say "never trim (or subtrim) a 401... start at the middle of the slider, then set it up via pushrod adjustments for no tail movement in rate mode, set the gain, and fly it" or similar).

Anyway, not important that I understand. Barracuda's correct, subtrim sets the CENTER POINT of the channel, can be a positive or negative number, and it is a single number. Therefore, no right/left (or up/down) like the pair of endpoints on a channel.

[Pinecone]

You don't need to move the stick, you need to just adjust subtrim to stop the drift. ANd yes, when you adjust subtrim the other way, you cancel out the other setting, as it moves the center point.

So leave the stick in the middle and adjust the subtrim, then move the stick and wait to see any drift, it it drifts, repeat. If it drifts the other way, you overshot the setting. So go back a click or two.

[Bernie the Bolt]

Many thanks all of you for responding so quickly. BarracudalHockey was right in that I was treating Sub Trim as though it were ATV and I am grateful to you all for putting me straight.

Ain't this just a brill' forum !!

Bernie :cheers

[BarracudaHockey]

Danal...
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I am trying to set up the Align HH gyro on my Trex 450

He's not talking about a 401. A 401, indeed all Futaba gyros, memorize the width of the rudder pulse at start up. Lets say thats 1500us. (1000 being full left, 2000 being full right)

That becomes center, if you try to play with the trim after that it flashes thinking its getting a rudder input.

Other gyros aren't as smart. They assume 1500us (usually 1520 i think) but that might only be correct for a certain reciever, another reciever might be off just a hair and the center pulse is 1510us so the gyro drifts in heading hold mode. The way to get rid of it with these gyros that aren't as bright (all the jr gyros are this way) is to turn the gain all the way up and tweak the subtrim till it stays put. Now what the gyro expects as the center pulse, and the transmitted center pulse are the same.

[Danal Estes]

AHHHHHHRRRRGGGHHHHH!

Am I embarrassed. I did not read closely enough.... Align gyro, not GYxxx

Never mind, never mind, just ignore me, I was never here... :oops::oops::oops::oops:

(Danal runs out the nearest door)