FrSky Taranis - user chat

[Barry Cole 2]

Mike,

I am running OTX 2.2.0 on an X9D, and the throttle trim only works at the bottom end. As far as I know this has been the same on 2.0 and 2.1.

BC

[Bob Cotsford]

Barry, it's been an option for as long as I've used OpenTX, it's a tick box on the model settings tab.

[Martyn K]

Well, I have had my first genuine Taranis fail today

Flying my Meteor and a very unusual fault. Basically, I had a mix throttle to elevator.

It became obvious there was a problem at take off as on full throttle the model was severely over elevated. Of course when I throttled back to crusing velocity all appeared ok. Opening the throttle and a handful of down elevator needed to keep it level.

Not thinking this through, I then used my programmed throttle cut to kill the engine and attempt a dead stick landing. Big mistake. This resulted in copious amounts of down elevator being added and before I had worked out what I done the model had buried itself. Repairable but it will never be the same again as the glass fus was badly cracked.

Of course when I got to the model everything was working ok and no evidence of any interaction.

Any thoughts about this anyone?

Martyn

[trebor]

I'll watch out for that one . Only odd thing with mine is on electric motors my throttle is on a kill switch and if I put the transmitter too close to the model while testing on a flight table even though the throttle is switched off it fires into action at full throttle not sure what causes that !

[Denis Watkins]

Posted by trebor on 17/09/2017 21:13:16:

I'll watch out for that one . Only odd thing with mine is on electric motors my throttle is on a kill switch and if I put the transmitter too close to the model while testing on a flight table even though the throttle is switched off it fires into action at full throttle not sure what causes that !

Final bind on throttle down Trebor

 

Edited By Denis Watkins on 17/09/2017 21:26:21

[Nicky Strahan]

Having used several Fr-Sky "hack" modules in Fleet and Sanwa transmitters I obtained a Taranis X9D+. Spent some time getting my head round it, or so I thought! Set up a motor glider with switch sounds, throttle cut etc, felt really chuffed when it all worked ok. Decided to check the fail-safe, re-bound with everything where I wanted it, tested all and switched off the transmitter. At this point the motor started at mid speed (prop was off, phew). Re-checked all but could not stop it happening. Back to You-tube, 2 hours later found out that you have to set where your failsafe positions on the transmitter and that because in Opentx "low" throttle is -100 and "full" is +100 when the receiver goes to failsafe the throttle goes to an output of 0, so half throttle!!! Love the flexibility of Taranis and Opentx, but you have to be careful and double check everything.

[trebor]

I'm pretty sure I did the final bind with throttle in down position. Has to be related to the failsafe as I have had warnings when getting too close to the model with the transmitter.

Nicky, how did you sort the failsafe throttle out ?

[Ron Gray]

@Martyn. If your throttle was programmed to always apply elevator then you apply the kill switch to give throttle -100 then surely your elevator will also respond (as it is linked)? I'll have to try it on mine to see!

[Attilio Rausse]

Martyn

Looks like the mix applied was too a) much and b) reversed, ie as more throttle is applied elevator should have been made less sensitive so a negative value was needed in the weight box ie -10. Secondly looks like the source was the throttle output channel, probably better to use thr (stick) as source. Finally if you press page (on transmitter) three times you will see the channel monitor so you can check what effect your mixes have on the elevator (as you move throttle stick). Make sure the Multiplex is add.

Trebor

Make sure throttle fail safe is set -100 not 0. When your transmitter is too close to receiver, receiver signal is swamped and goes into failsafe. If you set failsafe by pressing f/s button on receiver make sure throttle stick is all the way down.

[Dave Bran]

Martyn, your post seems unclear if this was after previous successful flights with that same set up or not. If so, what had been changed. Or what you were actually intending to cure (or prevent). We might guess, but................

I have found over many years, way before FrSky existed, that its not a good idea to do any flying control surfaces mix that is not in flight controllable. For example, several of my multis have throttle/rudder mix, but ALL are switchable, in flight strength adjustable, and were never first time used from launch/take off.

Attilio's point on the Monitor is spot on, but even after that you can never be sure of the effectiveness of any mix till airborne, and a bail out means is essential.

[Martyn K]

Hi Dave

Apologies. The model has been in use for nearly 3 years I think. Up until yesterday, it was faultless. I haven't added any mixes of that nature, so I assume that there was some form of coupling between the throttle (ic) and the elevator.

Very strange, Rx was/is an X6R but I probably wont use it again unless I find a cause

Martyn

[Chris Bott - Moderator]

Hi Martyn.
I think I'd be clutching at straws like a loose battery changing the C/G or a flexing tailplane changing incidence, that sort of thing.


Could there be a possibility outside the radio?

or maybe a poor servo connection, wiring moving as attitude changed or with g forces.


Either that, or I'd be wary of using the Tx again, rather than the Rx.
Were all other controls working OK?

[Barry Cole 2]

I'll watch out for that one . Only odd thing with mine is on electric motors my throttle is on a kill switch and if I put the transmitter too close to the model while testing on a flight table even though the throttle is switched off it fires into action at full throttle not sure what causes that !

That is almost certainly your failsafe settings, or lack of. If you get the Tx too close to the Rx it WILL go into failsafe.

BC

 

Edited By Barry Cole 2 on 18/09/2017 08:54:17

Edited By Barry Cole 2 on 18/09/2017 08:54:35

[Martyn K]

Hi Chris

It was very strange. It took me a while to fathom out what was happening.

I flew 2 more models after this incident with no radio problems at all. I still think its a receiver issue but its not a short circuit, i.e altering the elevator didn't result in a corresponding throttle change.

There was nothing loose inside, the model was well assembled. However, there were a few loose bits after the arrival..

[Peter Christy]

Martyn, I had a strange one on my Taranis a while back, whilst programming a vintage helicopter. It might well be related. I quote from my post on the OpenTx forum and the replies I got:

"The helicopter in question is quite an old design, and doesn't need any of the special helicopter functions for swashplate mixing, so all these are ignored. However, like most helicopters, it does need a throttle curve to simplify starting, take-off and landing.

A typical "Normal" throttle curve will have five points. On a helicopter, it is important to get the rotor-head up to speed quite quickly, so the throttle curve rises quite quickly initially, then flattens off across the middle of the range, before rising quite steeply at the end again (the "get me out of here!" portion of the curve). For example, in my case, because I was using a modern engine in an older design and needed to reduce the power in the hover as well, I started off at 0, 35, 40, 50 and 100 as my five points. 0 represents a fully shut throttle that will kill the engine, but with the trim advanced from the bottom, this should give a reasonable tickover. I found that I needed to advance the trim up to about 75% to get a decent tickover.

The first test flight indicated that I had set the throttle curve a bit low across the middle, so I landed, shutdown, and then advanced the pitch curve to 0, 40, 45, 55 and 100.

When I restarted the engine, I had the fright of my life, as the throttle was now way too far open, the engine was revving very high and the clutch engaged!!!

Luckily, I had a firm grip on the rotor head, but there followed a frantic few seconds while I dis-engaged the starter (the wand flew off across the pits!) and pulled the fuel line off!

Moving the throttle curve had affected the idle setting, despite the trim being set to "idle-only" in the model setup page!

This is NOT expected behaviour, and completely different from every other helicopter radio out there. It is also potentially dangerous. A "hot start" is not a pleasant experience on a helicopter!

The issue appears to be that when a curve is applied, the trim acts to move the lower point of the throttle stick position - moving the "cursor" along the X axis of the curve. As a result, any alteration to the curve affects the idle."

The problem was caused by my application of the curves. One of the OpenTx devs pointed out to me that here is a difference in behavior whether you apply your curve in the Inputs or the mixer. If you do so in the Inputs then the trim is independent from the curve. If you do it at the mixer stage, then it "goes through" the curve.

So in my case, I was getting an unexpected response because I'd applied a curve where years of computer experience told me it *should* be applied, but it gave me a completely unexpected result!

I wonder if your problem is similarly related? In effect, the idle trim is "mixed" in to the main function in a similar manner to your throttle to elevator mix. Maybe what you need to do is set up a spare "dummy" channel to track the throttle *stick* rather than the throttle *channel* and use that as the source for your throttle-elevator mix?

Sorry about the length of the explanation, but it is quite complicated to get your head around unless explained in detail!

--

Pete

[Mike Blandford]

Posted by trebor on 17/09/2017 22:21:40:

I'm pretty sure I did the final bind with throttle in down position. Has to be related to the failsafe as I have had warnings when getting too close to the model with the transmitter.

I'm not sure where you got this from, I've never known FrSky receivers use this method to set the failsafe.

Normally you either set the controls as required and press the F/S button on the Rx, or, for 'X' receivers, you have the option of setting the failsafe on the Tx.

Mike.

[trebor]

I shouldn't have said "bind" I'm always saying the wrong thing, my other half will vouch for that. I did the F/S button on the rx as instructions. Will check it again though.

[Nicky Strahan]

I tried using the receiver failsafe button to set with throttle at minimum, but the motor still ran up to half speed when failsafe was tested. I found if you are using D16 mode you have the option to choose your type and settings for failsafe, as per my photos (can't see how to rotate them!).

[Andy48]

My thoughts would be the failsafe. I've had this problem with the stabilised receivers as the throttle moves to channel 3 and I forgot to change the failsafe.

My advice would be to use the Companion, this is the easiest, and IMHO the most foolproof way to set the failsafes. You can do this before you bind the receiver.

[Barry Cole 2]

Mike is quite correct, the failsafe is not set that way.. Either use the bind button, or in my opinion the best way is to set them up from the Tx.

BC

[Mark Elen]

I had problems setting the failsafe when I first started with my Tanaris, just couldnt get it to work correctly. On that first photo of Nickys above, I changed the failsafe from 'custom' to 'Receiver' and it now works perfectly.

I now set everything where I want it, press the F/S button on the receiver, cycle the power to the radio and receiver and that's it, everything goes where it is set on signal failure.

Cheers

Mark

Edited By Mark Elen on 18/09/2017 11:49:55

[Bob Cotsford]

Posted by Barry Cole 2 on 18/09/2017 11:22:36:

Mike is quite correct, the failsafe is not set that way.. Either use the bind button, or in my opinion the best way is to set them up from the Tx.

BC

A word of caution - if you are using an X series (X6R, X8R etc) receiver in D16 mode check the failsafe settings for the model in OpenTX. Unless it is explicitly set to 'Receiver' I wouldn't trust the bind button method. Certainly if it's set to 'Custom' in OpenTX then it sends what it thinks the failsafe settings to the receiver every few seconds, it may well do that for @hold@ and 'No Pulses' too for all I know. If you have a D8 mode set I think that failsafe can only be set by pressing the FS/bind button on the receiver.

I stand to be corrected!

[Martyn K]

Sorry - just realised I posted this on the wrong thread - sorry.

Back to my problem. (I should have created a separate thread)

I checked the transmitter last night. Definitely no weird mixes involving the throttle. The only thing I can think of is that while I was selecting the model, I spotted a duplicate (for a different model) just above the model I wanted to fly, so I deleted it. Whether that caused a corruption somehow I don't really know but that is the only odd thing that I had done.

Martyn.

[Bob Cotsford]

Martyn, was it in D8 or D16 bind mode? If it was D8 there's no model match, could you have selected the wrong model? I think it's always good practise to cycle the tx power after changing models just to be sure you have everything initialised. It's not as bad as a Windows PC but....

[Martyn K]

D16 Bob. I only use D8 for VII receivers and I definitely didn't select the wrong model..

I have never power cycled the transmitter before but I did think that after deleting that model from the memory it is perhaps something I should have done.

I am still very puzzled about this..