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Sticky throttle

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Peter Christy13/04/2019 18:57:27
1554 forum posts

There was a thread hereabouts a few months back about a "sticky" throttle for OpenTx" - ie: Where the throttle could not open when the "Hold / cut" switch was released unless the throttle stick was also actually shut.

I thought I'd book marked it, but I haven't, and now I have an application where this would be very useful!

Can someone point me towards it?

Cheers,

--

Pete

Kevin Fairgrieve13/04/2019 19:47:21
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1593 forum posts
2848 photos

This one?

 

https://www.modelflying.co.uk/forums/postings.asp?th=121261&p=5

Edited By Kevin Fairgrieve on 13/04/2019 19:48:04

PatMc13/04/2019 20:27:37
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4200 forum posts
521 photos

Peter, if you want a copy of the eepe or otx file drop me a PM with our email addy.

Peter Christy13/04/2019 22:01:00
1554 forum posts

Yes, that's the one! Thanks, Kevin!

PatMc: Thanks for that, but i think I'll be OK.

Funny thing is, I tried something very like that and couldn't get it to work! Mind you, I'm in two minds about it..

I've just finished completely refurbishing an original Schluter Huey Cobra from about 1971. I've converted it to electric, and being a very large, fixed pitch machine, you don't want it starting accidentally!

(The fuselage alone is about 6ft long!)

I always initialise with the throttle hold "on", and only arm the motor when positioned for take-off. However, there is always the possibility of accidentally knocking the switch with the stick open. On the other hand, should you accidentally knock the switch in flight, you don't want to wait while you shut the throttle and open it up again! An unlikely scenario, I grant you, but possible. So at the moment I'm tending towards TWO throttle hold switched in series, rather than a sticky throttle.

I already have this set up on a scale heli that runs at constant 60% throttle and is flown on the collective, and its proven very effective.

I'll have a play on the simulator and see where I went wrong, but thanks for the info, folks!

--

Pete

MattyB14/04/2019 11:27:59
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1949 forum posts
30 photos
Posted by PatMc on 13/04/2019 20:27:37:

Peter, if you want a copy of the eepe or otx file drop me a PM with our email addy.

No need PatMc; when I made those posts I also posted up an eepe on the RCSettings site and linked it from the thread.

Edited By MattyB on 14/04/2019 11:29:15

Peter Christy14/04/2019 12:24:46
1554 forum posts

In the end I've decided to go for the double hold solution rather than the sticky throttle. This is simply to ensure that should a switch get knocked in flight, the motor will restart instantly when the switch is put back, and not wait for the throttle to be shut when my brain is in panic mode!

I have, however, set up logical switches to play audio warnings when the motor is armed (SF AND SA away from me) or disabled (SF toward me OR SA NOT away from me).

Now all I need to do is figure out how to enable a switch warning at turn-on when SA is NOT away from me....!

wink

--

Pete

John Lee14/04/2019 13:10:21
653 forum posts
48 photos

Pete I use one of these locking switches for throttle hold on my Jeti coupled with a voice warning. If a similar accessory available for your radio I'd highly recommend it, for belt, braces & a piece of string!

MattyB14/04/2019 13:28:41
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1949 forum posts
30 photos
Posted by Peter Christy on 14/04/2019 12:24:46:

In the end I've decided to go for the double hold solution rather than the sticky throttle. This is simply to ensure that should a switch get knocked in flight, the motor will restart instantly when the switch is put back, and not wait for the throttle to be shut when my brain is in panic mode!

I have, however, set up logical switches to play audio warnings when the motor is armed (SF AND SA away from me) or disabled (SF toward me OR SA NOT away from me).

Now all I need to do is figure out how to enable a switch warning at turn-on when SA is NOT away from me....!

That’s an easy one - just set your audio to be triggered by a logical switch with !SA↑ (Plus any additional conditions you want using AND function).

PS - I actually designed an “unknockable” safety switch for my Dad’s IC models that addresses your concerns with the sticky throttle cut. It requires a sequence of movements on a three position switch to activate and deactivate across to states (for instance ignition ioff and ignition on).

It’s more complex to setup but works very nicely - downloadable example and documentation here.

Edited By MattyB on 14/04/2019 13:31:41

Peter Christy14/04/2019 14:06:05
1554 forum posts

Hi Matty,

Yes, I've already done that (para2 of my previous post). What I would like to get is a "switch warning" call when powering up the Tx (or changing models) if SA is NOT up. Perhaps I should just bite the bullet and add a separate switch warning every time SA is not up, but that could get a little irritating when you move it deliberately to take the safety off!

John: Yes, good suggestion - and I'm quite happy to do that on my old X9D, but I'd rather not open my my shiny new X10s just yet! wink

Also it might pose a problem on some of my other helis where I use the same switch for auto-rotations....!

--

Pete

Mike Blandford14/04/2019 15:40:51
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531 forum posts
22 photos

Totally confused now!

If the "Switch warning" is set to require SA to be UP, then surely you get a warning if it is NOT UP, which seems to be what you require!

Mike

Peter Christy14/04/2019 16:38:47
1554 forum posts

Hi Mike,

Sorry, I'm obviously not explaining this well! SA is a 3 position switch. I want a "switch warning" at power on if its not in either the middle or down positions. (I'm only using it as a 2 position switch).

In either the mid or down positions, the motor is "safe". If its in the "up" position, the motor is potentially armed.

At the moment, I've got it set to warn if its not fully down, but that generates a spurious warning if its in the middle. I can live with that, but its just a bit untidy!

Does that explain it better?

--

Pete

MattyB14/04/2019 22:01:40
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1949 forum posts
30 photos

You need to switch on the preflight checks at startup from the Model Setup menu. Rather than give an audio warning it lists all the switches in their current positions after you switch on, with any that are in a position you haven’t specified clearly highlighted. It won’t transmit until you either set all the switches into the right state or manually accept the current state via the Enter button.

You can enable this from the TX itself, but it’s a little easier from Companion:

Edited By MattyB on 14/04/2019 22:06:44

MattyB14/04/2019 22:37:16
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1949 forum posts
30 photos
Posted by John Lee on 14/04/2019 13:10:21:

Pete I use one of these locking switches for throttle hold on my Jeti coupled with a voice warning. If a similar accessory available for your radio I'd highly recommend it, for belt, braces & a piece of string!

The problem with physical mechanisms like this is that if you want to cut the throttle quickly for safety reasons you can’t. On an electric model it’s less of an issue as closing the throttle stick should always stop the prop, but that won’t be the case for an IC engine. Given the huge functionality available in modern radios (particularly the Jeti’s and those which use open source firmware such as OpenTX) that allow software based safeguards to be put in place without that disadvantage I no longer believe physical safeguards on the TX are necessary. YMMV.

Edited By MattyB on 14/04/2019 22:44:06

Martin Harris14/04/2019 23:01:02
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8805 forum posts
216 photos

I use a dedicated throttle cut button on my IC models so any throttle lock (one is available by default on all models with Jeti) is instantly overridden in an emergency.

However, I now use a locking switch on my electric models but the reasoning was the opposite - after accidentally disabling the throttle on an electric model necessitating a visit to the adjoining field, I added it to avoid repeating that mistake!

Mike Blandford14/04/2019 23:01:03
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531 forum posts
22 photos

As I now understand it the switch warning doesn't handle this requirement. There are TWO correct positions for this switch and one incorrect one in this application. The switch warning currently only handles ONE correct position and two incorrect ones.

It looks to me that the switch warning would need to be enhanced to support this.

Mike

Peter Christy15/04/2019 08:50:11
1554 forum posts

Mike: Yes, that's what I suspected. Sorry if I didn't explain clearly enough initially. I'm sure there are more applications where this extra functionality could be useful (retracts?), but the limiting factor might be the displays on the lower spec Txs.

MattyB: Yes, I understand that. The problem is that the logic doesn't allow for an alarm in a NOT situation. Mike has got what I'm trying to achieve and has explained it succinctly.

Thanks everyone for your thoughts and input!

--

Pete

MattyB15/04/2019 12:48:18
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1949 forum posts
30 photos
Posted by Peter Christy on 15/04/2019 08:50:11:

Mike: Yes, that's what I suspected. Sorry if I didn't explain clearly enough initially. I'm sure there are more applications where this extra functionality could be useful (retracts?), but the limiting factor might be the displays on the lower spec Txs.

MattyB: Yes, I understand that. The problem is that the logic doesn't allow for an alarm in a NOT situation. Mike has got what I'm trying to achieve and has explained it succinctly.

Fair enough. I doubt the developers would take that one on though, purely because it is pretty niche - the vast majority of users want this functionality to result in their TX having all the switches in exactly the same positions every time they power on, and the current system does that.

The other advantage of having your switches in the identical position every time is it enables you to do a simple visual check of your TX prior to switch on; for instance I always set all mine to be "everything away from me/up" at power up. This gives a small amount of additional safety in my eyes, particularly if you do it consistently across all your model setups. The only other alternative I can think of is swapping that 3 positin switch for a 2, but it may not actually give you what you want at startup as the software will still be looking for a 3 position.

Edited By MattyB on 15/04/2019 12:48:57

MattyB15/04/2019 12:56:29
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1949 forum posts
30 photos

One other alternative - you could effectively add in a "dual" throttle cut functionality by linking the switch to certain flight modes. For instance throttle activation/dactivation could be enabled in Takeoff flight mode, but not in Acro or Cruise so if you knocked the switch whilst flying then it wouldn't do anything. The only disadvantage is that if you swtiched to that flight mode without noticing you'd knocked the switch you might end up plummeting quickly(!), but that should be easily remedied by an audio callout on the switch in question.

Ron Gray15/04/2019 13:09:53
1450 forum posts
363 photos

You could always put a slight delay to the throttle cut, this plus audible warning gives time to switch back to normal. Not ideal as throttle cut is usually instant but is a, say, ½ second delay that big a deal?

IanR15/04/2019 13:47:42
775 forum posts
4 photos

Would it be possible to cut the throttle by flicking a switch 3 times making it go through zero 3 times within, say, 1 second, or so - similar to the way in which the self-test is initiated with the S6R and S8R?

This would not be too onerous when cutting the throttle on purpose but would be unlikely to happen accidentally whilst flying or any other time.

I take the point about accidentally knocking the switch whilst flying. I am using switch SF as the sticky throttle cut switch but have reversed it so that when towards me the throttle is off and when away from me it is on. This maintains a larger gap between it and the adjacent SE switch so that my fat fingers are less likely to inadvertently cut the throttle. Also, when putting the TX down on its back, the switch is already in the "towards me" position and the throttle is off. If it was the other way round, then putting the TX down on its back might inadvertently flick the switch and enable the throttle.

However, I still think the 3-way flick would be the ultimate safe way of not accidentally cutting the throttle.

Anybody know how to do this?

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