Limiting Servo Movement?

[mapes12]

I'm trying to get the THR channel on my Taranis X9D Plus to sync with the amount of movement I need on the throttle arm of an IC installation. Ground testing the engine has determined that the throttle arm on the carb only needs to move through an arc of about 8mm from idle to full throttle. But I need the THR stick on the TX to transition through its full movement across this arc. I've tried changing settings in the Limits menu but all I've achieved is a dead band area on the stick. Any ideas on how I can achieve this please? Mark

[jhsa]

You should not have a dead band by adjusting the limits, unless you have nixes with values over 100% on the throttle channel..
What do you have in the mixer for that channel??

Also for an IC engine you want to use the "Throttle trim" option somewhere in the Model Settings..
I use ersky9x, not openTX, but I think in this case they are identical.

João

[mapes12]

Like you João, I'm using Ersky9x. Thanks for the heads up on the Throttle Trim setting. I'll have a look at it and see how I get on.

[jhsa]

Oh,yes you are, sorry.. You mentioned the Taranis radio and I assumed you had openTX installed. I didn't see that this thread is on the Ersky9x forums

Then the setting is in "Model Setup / General". Then look for "Thr-Trim"

With this setting ON, the trim only changes the bottom of the stick travel, leaving the max throttle unchanged..

João

[mapes12]

Thanks for the reply João. I've just got round to looking at this again. Engaging THr-Trim gives me some adjustment on the THR channell but it isn't as much as I need. So, I've been playing around with Weight and Offset. The mechanical set up of the servo arm and the throttle linkage on the carb is such that the throttle is fully open when the stick is fully forward. I need to get to a position where the throttle is approx 25% open when the THR stick is in its full down position. In other words through the full transition of the THR stick the servo arm is going through +25% to 100%. In the eePeSKY simulator changing weight to +75 with offset +25 appears to achieve this. Have I got the logic to this correct and are weight and offset the correct variables to achieve what I'm after please?

[jhsa]

Do you need such high idle setting??
It can be done, of course.. Will have a look later.

João

Sent from my thor using Tapatalk

[mapes12]

Do you need such high idle setting??

Getting the servo arm in this position is at the point where the barrel in the carb is just starting to open i.e. tick over.

[jhsa]

Then you probably need to set the lower limit a bit higher, just at the point where the engine stops, with the trim all down?

João

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[mapes12]

Then you probably need to set the lower limit a bit higher, just at the point where the engine stops, with the trim all down?

This ones a petrol installation with a CDI kill switch on the Tx. Is my thinking about weight and offset looking correct?

[jhsa]

Depends on what approach is needed.. It is difficult to suggest something without seeing what is happening.. Your description earlier tells me that you need to adjust the limits on the throttle Channel.. Isn't the ignition switch on another channel?? So, that shouldn't have nothing to do with the throttle servo itself?
Please go to

viewtopic.php?f=5&t=6473

and download the er9x manual. Er9x is a lighter version of Ersky9x. Now go to the end of the manual where the examples are, and see example 12 ( Adjusting Throttle Idle with a Pot)..
This might give you some ideas.

João

[jhsa]

Or, I copy it here..

12. Adjusting Throttle Idle with a Pot
This example works exactly like the “Throttle trim” feature in Er9x, except that it uses the pot P1
instead of a trim switch. It adjusts the idle setting without affecting the full throttle setting.
Assuming CH3 is the throttle channel, the required lines are as follows:
CH03 -50% Thr Offset (50%) (defines half throttle range)
* +40% P1 Offset (40%) (multiply mix introduces P1)
+100% Thr (adds on the basic throttle stick mix)

João

EDIT: I also have an engine that is quite a pain to adjust the throttle.
It's a Zenoah 62.

[mapes12]

Thanks for the reply again João. I'm going to have to have a play with this. I did read the manual example but some of it went over my head. For example, what is the "*" on the second line? You're correct about the CDI kill switch being on an indendent channel. The power for the CDI and corresponding kill management is with one of these: http://www.tech-aero.net/ultra-ibec

[jhsa]

The "*" means that the mix is a multiply mix.. Check the "Mixer" chapter on the manual..
I use a dedicated ignition battery..
João