Aileron differential on Taranis

[Geoff S]

I thought I'd sussed Taranis programing (at least all I've tried so far) but this has beaten me so far. I'm trying to set up aileron differential and having huge problems even though I know it's got to be possible (and probably simple!)

I have aileron servos on channel 1 and 5. I've set up Ch5 in the Mixer section and named it ail2 (CH1 is named ail1) and added as its source Ail. I've set up Curve on both Ch1 and 5 as Diff with CH1 +30 and CH5 as -30. This works fine and I get the aileron differential as I'd expect.

However when I select the rates I set up on the Inputs section it only works on Ch1! If I change the source on CH5 in the mixer to Ch1 ail1, the rates work OK but CH5 now only moves in both directions to the reduced throw setting intended to be the down deflection.

I'm obviously doing something silly - but what?

Help appreciated.

Geoff

Edited By Geoff Sleath on 24/10/2015 11:23:13

[Andy48]

Hi Geoff

I've just fiddled around with this, and the problem may be that you've used the curve function on the input section. Put the rates on the input section and put the curve on the mixer section for each aileron and everything should work, ..... well it did on the simulator.

[Geoff S]

Thanks Andy but it wasn't that. I only use Curve on the Input section to set exponential. Not sure how you would use Diff there on ailerons because it means there is less movement on (say) right than left (or vice versa).

However I have found my error though I'm still a little confused. The Input sources are named IAil, IEle, IThr and IRud which I don't entirely understand but that just happens with no choice. In the Mixer section when choosing the source I usually just wiggle the appropriate stick and it's selected automatically (works for switches too where appropriate). If you do that it chooses Ail (in trhis case) as the source and that's the root of my problem. The source actually needs to be IAil which can only be selected by stepping through the options. That's the only way the rates will work and I guess any exponential you've set up in the Inputs though I haven't checked that.

Not sure of the reason forthe difference between IAil and Ail. Why would you not want the Input settings to relate to the Mixer settings?

Anyway, both rates and expo work now. All I have to do now is finish the model

Geoff

[Bob Cotsford]

As you've discovered IAil gives you the Aileron stick out output AFTER any input processing whereas Ail is just the raw aileron stick position without diff, expo or curves applied.

[Geoff S]

Yes, that's true, Bob. As this is the first time I've ever felt the need to set up aileron differential on the Taranis it's only just cropped up. I wonder how many models I have that don't have Ixxx as the source in the Mixer and I haven't noticed! I'll have to check because it's not an obvious thing to do when moving a stick is suggested as a quick way of selection.

You live and learn and, with the Taranis, I suspect I have a lot yet to learn

Geoff

[Bob Cotsford]

I've just checked as what I posted previously didn't sound right, and I think it's the other way round with AIL or ELE etc.giving the control value AFTER modification by expo, curves, rates et al, and iAIL, iELE giving the raw control movement - or that's the way it's working in Open TX 2.0.16. For example, all my model setups have rates and expo set up on the Inputs tab. Mixers then use (I2)ELE, (I4)AIL, (I3)RUD for their inputs, with diff and curves applied on the mixer lines.

[Geoff S]

I think you were right the first time, Bob. I've done my set up on my Taranis and the only way it works as intended is if the source in the Mixer is IAil. If I just use Ail (as set just be moving the control as a quick select) then the differential works OK but the rate switch doesn't (and, presumably neither does the expo but I haven't checked that as I don't have the model completed and it's harder to observe on the transmitter itself using the Channels Monitor page).

I notice your simulator printouts don't show the source in the Mixer for each channel so they could be either IAil or Ail.

Geoff

[Andy48]

It sounds like you are setting up using the tranny. Its far easier to use the companion to set things up, and use the inbuilt simulator to see what is happening. I get exactly the same input and mixer screens as Bob.Notice that instead of just IAil on the tranny screen you get I4Ail, which can be a bit clearer.

Yes Bob was right first time. Ail is raw aileron stick input, and IAil is modified input.

His printout does show the source in the mixer, for the aileron it is I4, which on going back to the Input screen is aileron, with various rate settings, but no expo.

[Bob Cotsford]

You're right Andy, if I look at the same setup on the transmitter it does show them as IAil, IRudd, IEle etc. This is where you wish you could edit earlier posts

[Geoff S]

I do tend to use the transmitter itself for setting up a model, usually because I'm watching the actual effects on the control surfaces in RL. I suppose it's a throwback from setting up models using my Mux3030 when no simulator was available. I use Companion primarily as a back up and updating source though I haven't used it for a while. Plus, as Bob mentioned, the transmitter display shows more detail.

Actually I was playing with the transmitter as a bit of a rest from working on my Tiggie as I was fairly sure I'd need differential to avoid the effects of aileron drag which seems to bedevil older biplanes. I'll no doubt be cheating a bit too by adding a little coupled rudder/aileron but I think that mix should be straight forward.

I checked other model Mixer pages and the Source for most of them is of the Ixxx variety but I can't remember making an effort to do it. Perhaps I did but, as I often set up a new model by copying an older one and tweaking it to suit I probably just forgot. I've looked through what documentation I have but there's no mention of the difference between IAil and Ail etc. But then, Taranis documentation leaves a lot to be desired and relies on fora like this to diseminate knowledge.

Geoff

[Bob Cotsford]

Are you aware of the OpenTx University Geoff? It used to be THE reference for OpenTx. Alongside Scott Page's Youtube tutorials of course.

[Geoff S]

Yes I was aware of the OpenTX University, Bob but I admit that I'd forgotten about it. I prefer written manuals because they're quicker to shift back and forth and easier to reference when, for example, using OpenTX Companion on the same machine. I have print outs of what Taranis manuals there are. Even when I was writing software I found a printed listing essential in the debugging process.

Print is not yet dead

[Bob Cotsford]

I've spent many days spread over many years with fanfold COBOL listings a couple of inches thick spattered liberally with post-its sticking out on every side. These days I cut and paste into Notepad any bits I need to keep going back to - or use an editor that allows bookmarks

[Geoff S]

I've been retired for 20 years and most of my software was assembler but I was moving on to 'C' when I decided an early bath after an offer I couldn't refuse was the way to go Never regretted it.

[Tony Richardson]

Hi all, I am a Taranis newby and just getting my head around the differences between this radio and my JR 9303, I had the same issue as Geoff but solved it in a different manner not sure now if it is correct!! but I have been told there is more than one way to achieve the same result with this radio.

My solution for aileron differential was to access servos and set the min travel at the required -% on both channels in the min column and leave the travel at 100% in the max column it works on the sim and on the model but is there a reason or difference between this approach and using the mixer program? Just asking as it is all so new to me.

Tony.........................

[Denis Watkins]

Exactly Tony, that is the correct way to do it, leaving all the other mixes and switches free

[Mike Blandford]

For plain ailerons both methods work, however if you have ELEVONS, then the limit method doesn't work and you need to use the diff method in the mixers.

Mike.

[kevin lane]

Geoff, search you tube for painless360 gives a good explanation of the ! function plus lots of other Taranis tips. Unfortunately RCMEs text box won't let me insert the URL. Kevin

[Bob Cotsford]

Posted by Mike Blandford on 16/02/2016 09:42:58:

For plain ailerons both methods work, however if you have ELEVONS, then the limit method doesn't work and you need to use the diff method in the mixers.

 

Mike.

 

Same with flapperons or crow brakes, setting servo limits can mean you limit the aileron function when you switch in crow or flapperons. Using the diff function is often the better way. I'm not sure 'correct' can be used very often when using OpenTx.

Edited By Bob Cotsford on 16/02/2016 10:11:40

[Tony Richardson]

Thanks for the info guys, it was exactly what I was looking for, for the Balsa USA Citabria Pro I programed this way it is perfect but for other models a mix or curve would be appropriate, now here I am going to show my ignorance of aerodynamics and ask Mike why would you need aileron differential with elevons? are delta wings ( which I assume are the main employment of elevons ) prone to adverse yaw? That said I could see the need on a model of the Granger brothers Archaeopterix which I suppose uses elevons or is it ailevators, one interesting looking aircraft what ever they are, once again thanks for the info being a newbie I am sure there will be a lot more questions.

Tony.......