3GX Did You Know...!!!

[tourerjim]

Some good news so worth a read
v2 parameters are much easier to work with then previous V's so is very user friendly & I have now spent many hours now with v2 parameter adjustments so defo best yet, last couple days I have been doing various tests with 3GX & now know contrary to what you may of read on not recommending sub trim use with 3GX is quite the opposite because I now its the only trim that can be used as 3GX as its own settings memory.
Weather has still not been that great but have manage to do few adjustment tests to now find the reason so many of us with various size heli's have a tail-ward drift, like the days of the flybared heli's although swash would be completely level you would still get a degree of drift & you would need to put in same cyclic trim in compensate but Align don't recommend you use any form of trim.
Align's design behind the 3GX is to maintain the flybar feel so if you have any drift then you can only use sub trim to compensate but because 3GX has its own setting memory it can only be adjust in DIR mode.
If your heli has a drift i.e my 450 has the tail-ward drift so the only way this can be sorted is with the following action, put 3GX into dir mode with swash level (if sub trim is already used make a note of the numbers used in case you need to revert back) then I applied few degrees of elev sub trim so swash had slight forward tilt then you have to go through the dir settup including the 8 degree setup then 3GX will save your latest settings, once you know there's no drift I advise to recheck your mid stick zero pitch.
Once I worked it all out with the 3GX it took me about an hour to correct the drift with sub trim as it was my first attempt didn't think that was to bad & now she's flying perfect but that was only on two packs so need more time to be sure but I'm more than happy with the setup so far.

[helimadness]

Hi.
Very interesting indeed. Would be nice if Align actually had information on how these things work so we don't have to try and reverse engineer them to troubleshoot. Would be interesting to know why they say not to use sub trim.

If the 3GX is having to make correction to keep the heli from drifting then surely tweaking the swash level so the heli is balanced when in hover is ok. That way the 3gx is not having to work to keep from drifting. Who is to say Align don't have the main shaft mounted and a very slight angle back. You set the swash up square to the main shaft but if the whole thing is leaning back them maybe a cause. Also have been wondering about the levelness of the 3gx unit. Has anyone tried running DIR mode with it tilted to see if the 3GX stores a level point?

I am going to leave as is and watch for now. Mine doesn't seem to be consistent. Sometime I have it some times not. Last weekend there was actually a point it had forward drift. Will be interesting to see whats happens to your 450 after some more flights.

How many pips of sub trim did you have to move from a "square" swash to get it to stop drifting? I notice it is almost impossible to see maybe 2 or 3 pips change even with the level tool.

Nice job on the fault finding.

Cheers.

[coolice]

Hey all.

Just to clarify I don't specifically advise using subtrim out of DIR to make trim changes for flight, however normal transmitter trims can be used without problems on the cyclics.
Same principle applys to keep it to a minimum, mind you if you have to add a lot of trim the swashplate can't be level, so you'd then have to adjust linkages to fix.

I did read a piece on another forum reference 3GX and subtrim. It's not in the manual, but it was said to level the servo arms in DIR with the aid of subtrim if need be, but then when finished and out of DIR mode return subtrims to zero. This falls inline with what Tourerjim accidentally tried already, as the 3GX remembers the zero position (explains the need to leave throttle/collective at mid stick for remainder of setup) which then tells us once DIR is finished we must remove any subtrim or the 3GX will treat it as a control command to move.
However, this trick is not documented by Align and so is just a theory and not recommended.

I still advocate minimal, if any, use of subtrim if at all possible. On my own models and those I've setup, none have had a drift problem that can be linked to the FBL unit, only a helis natural tendancy to not stay still for long. So it begs the question, have I not had problems because I am so fussy about not wanting to use subtrim?
Something I can't answer, but maybe you guys can. Remove all and any subtrim then fly, if you are experiencing drift.

Actually, a good question would be does your model drift in the direction of any subtrim used? For example, if you've had to add back cyclic to level the swashplate, does the model drift backwards.
.

[bikerflier]

I have +31 points elevator trim and +62 points aileron trim but my 500 only drifts backwards with slow tail drop. If it was subtrim causing the problem then I should get twice the effect on aileron but I don't, it's stable on aileron.
The tail drop is progressive, at the start it is stable, then gradually gets worse until 5 mins into the flight it is difficult to hover because of the pronounced tail drop.
All of the problems I have seen on at least 5 helis with 3GX are due to tail drop.

Nice if 'tourerjim' does nail the way to correct the tail drop but there is more to this problem than at first sight.

Has there ever been any comment from Align on this, seems to be enough reports of a problem for them to know and act on it?

Actually, a good question would be does your model drift in the direction of any subtrim used? For example, if you've had to add back cyclic to level the swashplate, does the model drift backwards.
.

[helimadness]

I have a trex 500 elf pro with the blue alloy single arm servo horns. I now have 2 spare as broke a link off in one so had to buy another set. I assumed they would all be the same but if I swap them around am I likely to find a closer fit. Have about 30% sub trim on some to get square now. Will have to check later which servos.

[coolice]

I have +31 points elevator trim and +62 points aileron trim but my 500 only drifts backwards with slow tail drop. If it was subtrim causing the problem then I should get twice the effect on aileron but I don't, it's stable on aileroon.
The tail drop is progressive, at the start it is stable, then gradually gets worse until 5 mins into the flight it is difficult to hover because of the pronounced tail drop.
All of the problems I have seen on at least 5 helis with 3GX are due to tail drop.

Nice if 'tourerjim' does nail the way to correct the tail drop but there is more to this problem than at first sight.

Has there ever been any comment from Align on this, seems to be enough reports of a problem for them to know and act on it?

Hey buddy.

What's your centre of gravity like out of interest?

As this is fitted to a T500 are you using the stock ESC BEC? This has been another question, could the voltage drop be causing an issue perhaps? It shouldn't do, as dropping 6s to 5-6 volts leaves a lot of head room, but its possible.
.

[coolice]

I have a trex 500 elf pro with the blue alloy single arm servo horns. I now have 2 spare as broke a link off in one so had to buy another set. I assumed they would all be the same but if I swap them around am I likely to find a closer fit. Have about 30% sub trim on some to get square now. Will have to check later which servos.

Hey.

They are the same in theory, however swapping the arms around does show there is a better suited servo position for each individual arm. I've seen it myself on 600EFL's, I keep swapping and changing arms until I find the best position for each one. This normally means only one servo needs any subtrim to line up.
.

[bikerflier]

Using standard Align Esc and Motor that came with 500esp combo about 2 years old.
Checked the C of G only yesterday, very slightly nose heavy but only just.
Now using DFC head. When I first flew it with new head and v2 firmware in a howling gale it held on the spot hands off for 20-25 seconds. Those first two flights in the wind didn't seem to show any tail drop, but yesterday in calmer conditions the tail drop was there as bad it was on v1.2 and standard flybarless head.

If it is due to voltage drop, why does almost everyone report only tail drop?
Wouldn't it be affecting any of the servos?
Baffling.

Hey buddy.

What's your centre of gravity like out of interest?

As this is fitted to a T500 are you using the stock ESC BEC? This has been another question, could the voltage drop be causing an issue perhaps? It shouldn't do, as dropping 6s to 5-6 volts leaves a lot of head room, but its possible.
.

[Made2Fade]

I thought it was common knowledge to go through the whole setup (which takes seconds BTW) if you have altered any settings in the transmitter (mainly Travel Adjust/Subtrim/Expo/DR) and before you fly the machine again. You always use linear pitch curves and set your Expo/DRs back to default before going through the setup again. So whats the problem here? I must be missing something or im having trouble understanding whats been wrote here.

[coolice]

I thought it was common knowledge to go through the whole setup (which takes seconds BTW) if you have altered any settings in the transmitter (mainly Travel Adjust/Subtrim/Expo/DR) and before you fly the machine again. You always use linear pitch curves and set your Expo/DRs back to default before going through the setup again. So whats the problem here? I must be missing something or im having trouble understanding whats been wrote here.

Hi Lee.

Going through the setup isnt the problem mate, what's happening is there is a persistant backward (up elevator) drift creeping in during a flight. The baffling part is that it's not there within the first minute or two of flight, but develops part way through. However not everyone gets it, it seems more of a problem on the smaller machines.
.

[Made2Fade]

Hi Lee.

Going through the setup isnt the problem mate, what's happening is there is a persistant backward (up elevator) drift creeping in during a flight. The baffling part is that it's not there within the first minute or two of flight, but develops part way through. However not everyone gets it, it seems more of a problem on the smaller machines.
.

Interesting, will look out for this when i setup mine on the 500EFL this evening. So whats the logic for this then Ian? Couldnt really understand Jims first post, was a bit confusing for me... lol sorry Jim no offence mate

[Made2Fade]

So i take it that this is happening on electric machines? Has anyone got these results on a larger or nitro machine?

[helimadness]

For the record my sub trims are . Ail=34, ELE=22, PIT=22. My new XG7 tx has receiver voltage feedback. I have only glanced at it a few times during flight but always says 6v. Think I have seen 5.9 one time. After landing always 6v. It does seem to have a fairly big delay. Maybe a few seconds so might be missing the spikes but nothing obvious.
COG is fairly good. Maybe slightly tail heavy but not a lot in it. I get the tail aft drift about half of my flights. rest seem fine. Certainly not consistent.

Mark

[tourerjim]

Interesting, will look out for this when i setup mine on the 500EFL this evening. So whats the logic for this then Ian? Couldnt really understand Jims first post, was a bit confusing for me... lol sorry Jim no offence mate

I'm confused myself Lee, I know what im doing but very hard to put into words, my 500efl is perfect throughout each lipo but 450 as soon as i start the hover i get tail-ward drift that does get more progressive as flight goes on but after my final setup yesterday I think i've cured it but will need few more flights to be extra sure.

[tourerjim]

Hey all.

Just to clarify I don't specifically advise using subtrim out of DIR to make trim changes for flight, however normal transmitter trims can be used without problems on the cyclics.
Same principle applys to keep it to a minimum, mind you if you have to add a lot of trim the swashplate can't be level, so you'd then have to adjust linkages to fix.

I did read a piece on another forum reference 3GX and subtrim. It's not in the manual, but it was said to level the servo arms in DIR with the aid of subtrim if need be, but then when finished and out of DIR mode return subtrims to zero. This falls inline with what Tourerjim accidentally tried already, as the 3GX remembers the zero position (explains the need to leave throttle/collective at mid stick for remainder of setup) which then tells us once DIR is finished we must remove any subtrim or the 3GX will treat it as a control command to move.
However, this trick is not documented by Align and so is just a theory and not recommended.

I still advocate minimal, if any, use of subtrim if at all possible. On my own models and those I've setup, none have had a drift problem that can be linked to the FBL unit, only a helis natural tendancy to not stay still for long. So it begs the question, have I not had problems because I am so fussy about not wanting to use subtrim?
Something I can't answer, but maybe you guys can. Remove all and any subtrim then fly, if you are experiencing drift.

Actually, a good question would be does your model drift in the direction of any subtrim used? For example, if you've had to add back cyclic to level the swashplate, does the model drift backwards.
.

Ian, the subject of sub trim has been mentioned on other forums HF for one that no sub trim must be used but the problem is using transmitter trims with 3GX on my heli's does not work well its hard to explain why but its abit like links tightening the more you put in.
The only way I can find around at the moment is to use sub trim so its stored in 3GX dir mode, I even tried to adjust the links at first but found she drifts to much one way or other but I think I may have an idea of the fault so i'll just go & test it now & post back in a bit