Using trims on TX with 3GX?

[heli ed1]

I was wondering ,can you use the trims on the TX with the 3GX system

Grtz Ed

[Riff]

subtrim OK (for rudder additional binding is needed so don't use it)
end points NOK

[bad007]

Originally Posted by heli ed1

I was wondering ,can you use the trims on the TX with the 3GX system

Grtz Ed

On a three servo swash mixing like 3G and 3GX you can use a small amount, on one servo swash like BX and VBAR no. If you link up and look at the movement sreen what ever amount of trim you can add before it shows up is how much you can add, you'll see the swash roll when you see movement in the gui.

[squibcakes]

I was wondering why you would want to?

[bad007]

Originally Posted by squibcakes

I was wondering why you would want to?

Is there such a thing as a absolute perfect mechanical setup? No, that's why VBAR provides auto trim which 3G and GX doesn't need if you need to fine tune for a slight drift.

[wkma7six]

I guess I am one of the lucky ones? So far, no issues with the 3GX. No subtrim needed and no drift in hover. I thought you were not supposed to use subtrims with the FBL system. Just let the heli boot up and initialize on a horizontal plane. All this stuff I'm reading about the 3GX is really getting me worried about how reliable the unit is. I've ordered the new Spektrum AR7200BX FBL unit for my TREX 250. I'm going to see what it's like to set that thing up since my 3GX wasn't too difficult other than me assigning the wrong channel to the gyro gain and not having any gain control at first.

[stiganas]

You can use trim with 3g. If the mechanic setup is not perfect the heli will drift. You are not allowed to use subtrim, you can use subtrim only in the initial setup.

As far as I know 3g is the only FBL unit where you can use trim.

[squibcakes]

3GX Manual states:

The trim must be zero not adjusted at anytime. If helicopter hovering tend to one side, it means the swashplate doesn't keep horizontal when setting.

I read that as:

You have not setup up a perfectly level swashplate - go back and re-do it - don't fudge it with trims.



I don't care for what V-bar or 3G do or don't do (both of which I own and have owned and fly)

[bad007]

Here read for yourself right out of the 3GX manual. The 3G states the same. Got both.
If you do see a tilted swash go back threw setup but small amout of trim can be used for a slight drift.

[mcvaz79]

Some people state if you use subtrim the flybarless unit can understand as a command input from the tx. I'd prefer not to use it.

[bad007]

Originally Posted by mcvaz79

Some people state if you use subtrim the flybarless unit can understand as a command input from the tx. I'd prefer not to use it.

What? Sub trim is used during setup to level the horns with 3G and 3GX and trim is different than subtrim.
With one servo mixing like Vbar and BX trim is seen as input but not 3G and 3GX.

[DesJardins]

Trim & subtrim are 2 different options I see people posting about.
I wouldn't touch "trim" but subtrim is absolutely fine... I adjust in DIR mode only though

[bad007]

Originally Posted by DesJardins

Trim & subtrim are 2 different options I see people posting about.
I wouldn't touch "trim" but subtrim is absolutely fine... I adjust in DIR mode only though

Check out trim on the bench when you get around to it. The 3GX will take some trim but at a point it will roll the swash like it is seeing cyclic input. In the F@Qs it does state you may use trim but your limited on how much, too much and it will consider it as input and roll the swash.

[DesJardins]

Yup, I saw that when working on my DX8 set up's and decided I didn't want to mess with the trim at all after seeing it

[dcanon]

You can use subtrims to correct mechanical setup. But when you change subtrims you should do re-setup for 3GX that allows 3GX to remember new zero values.
You cannot use trims. Because subtrims are corrections for separate channels but trims are corrections for movements means for all channels in a swash mix.

[Coolice]

Hey.

As Bad007 has said using transmitter trim in small amounts is perfectly acceptable and is normal, as a level swashplate on the bench does not guarantee a level hover. The reason for this is that helicopters naturally lean to one side due to the thrust generated by the tail rotor, due to this side thrust a level swashplate could make the model be out of trim in the hover.

Sub trim must only be added while in DIR mode, do not add it out of DIR. This is one area where the Align units benefit and that is by keeping sub trim to a minimum, swap servo arms/horns around until you find the best combination which requires the least amount of sub trim.
.