Finally - cross trims and "idle only" to be fixed!

[sande005]

Version 2.3.10 is getting very close to being released. Preliminary release notes have been written up.
Here's the note:

• Instant trim now only applies to default trims
• Support "trim idle only" with crossed trims

I have not downloaded the "nightly" beta version, but my understanding is that there will be a new option, to designate the alternative trim lever to be used for throttle and "idle only".

For those wondering - what are "crossed trims"? - Generally it is the swapping of the trim levers. So the conventional ele trim now trims throttle, throttle trims elevator, rud trims ail, ail trims rudder. (or whatever variation you prefer). Why? - so one does not have to take their hands off of the ele/ail stick to make trim adjustments, or reach across to do the same. This has been a configuration option in OpenTX for a very long time.

But, this resulted in problems if the "idle trim only" checkbox was selected. That normally allows trim to only be applied to throttle when it is in the lower end of the stick range. Trim has no effect on the top end. The radio didn't "know" that an alternative trim lever was being used, so bad things happened to the elevator (!). There were other ways to implement this feature with cross trims, but needed custom mixes or curves to be added. This has been an identified problem for several years.

Note that using cross trims also had an undesired effect when using the Instant Trim feature. So that has now been set to only work with conventional trims.

This was fix was confirmed to also play nicely when using different trim values in flight modes, or when using the trim→subtrim option.

 

[davemcddd]

I waited awhile before updating my two X9D+ to see if any bug reports showed up about the trim idle only with crossed trims. I didn't see any, so yesterday I went ahead and updated from 2.2.4 to 2.3.10 on both of my transmitters. So far on the bench, the TIO issue with crossed trims seems to be solved with the new "Trim Switch" selection box, but I haven't flown them yet. Still checking out that the new update didn't mess anything else up.

 

[Wayne]

Good to hear..

 

[sande005]

Back from my road trip, and able to actually download and test.

FYI - a gotcha when using the new capability for "idle trim only" and cross trims in ver 2.3.10
If you define an alternate trim in Setup, but forget to also define the same alternative switch in Inputs, not only will the intended cross trim switch not work for throttle, but the conventional idle trim will now be reversed - it only affects the high end, not the idle side of stick movement.

Or, if you define an alternative trim in Inputs, but don't also define it the same in Setup, you get reversed functionality out of whatever is defined in Inputs.

Best order of business - set up your cross trims on the Inputs page as desired. THEN go to Setup and confirm the trim switch to be used for throttle.
Of course, if you don't care about cross trims, don't change the default on the setup page, or don't use the "idle trim only" check box.....

 

[davemcddd]

I've now flown several planes on each of the X9D+ transmitters that were updated to 2.3.10 and haven't noticed any issues with the new TIO/crossed trim solution. It seems to work just fine. I truly don't understand why it took 7 years to fix it, but I'm REALLY glad that it's finally fixed! And as sande005 mentioned above, be sure the assigned throttle trim button matches in both the new Throttle Trim Switch selection box and also in the Inputs screens.

 

[sande005]

Careful using this new fix....I was converting my models that used a work-around, and stumbled across....

If using the TTrim lever to control Elevator trim, and pick the option in Outputs to apply Trim→Subtrim, the subtrim does change correctly. But, the TTrm lever is not reset to 0, like it is for all the other trims when using the option. You have to move it back to center manually, otherwise you have double the amount of trim you intended.
Trim→Subtrim does work correctly with cross trims in older versions...but then, of course, Trim Idle Only and Instatrim doesn't.

Haven't yet tried using TTrm for some other variation of cross trims, but would assume it has the same issue with Trim→Subtrim.

(BTW - with the new fix, Instatrim is deliberately disabled if you have cross trims set up, so at least you can't get deep into trouble that way!)

Case opened over on Github.

--Yep, I'm cross posting this, just so people that are interested are aware!