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Jun 25, 2018, 01:35 PM
e^(iπ) + 1 = 0
Miami Mike's Avatar
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OpenTX - A Note About Failsafe

In November of 2016 I described my SetFail flight mode, which allows you to experimentally determine your best Custom failsafe settings for each of your models, but it's a bit involved and some might consider it adequate to just set the failsafe option to Custom and set all your controls to neutral, except the throttle, which should be fully closed.

I just want to point out that if you decide to do it that way then you shouldn't assume that this will work, because it won't:

It's not as simple as that.

The values you enter on your Setup page for Custom failsafe are the actual values that will be sent to your servos and do not take into account any Subtrim, Min, or Max settings on your Outputs page, or any mixing, or flight mode-specific trim settings, etc. that occur when your sticks are in their neutral positions. To know what those Custom failsafe values really need to be for neutral control surface positions, or whatever positions you want them to take when control is lost, you have to read them from your Channels Monitor.

On a Taranis X9D+, before you begin setting up your model, it looks like this:

But after you've set up the model, with the sticks neutral and the throttle off, it'll probably look more like in this random example:

On a QX7 or X-Lite the screen would look like this:

And it's those numbers, in this example -100%, -7.0%, -7.9%, and -14.4%, that you have to enter on your Setup page to get neutral control surface positions:

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Sep 06, 2018, 10:07 PM
Flying in OZ.
iflylilplanes's Avatar
Common sense, thanks Mike. Is failsafe something that should be updated now and a gain? I find that foamies have a penchant for going out of trim on a regular basis, balsa models change trim after repairs.
Sep 06, 2018, 10:47 PM
e^(iπ) + 1 = 0
Miami Mike's Avatar
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It's a good idea to check if you think your model may have gone out of trim. If you used the SetFail flight mode to determine your best failsafe settings then those trim settings should still be in your model memory and should stay there indefinitely, even after you've transferred the data to your actual failsafe settings on your Setup page.

So any time you want to make sure the model still flies the way you want it to fly in failsafe, you just need to switch back to SetFail mode and check. That's a lot safer than turning your radio off in flight because if your model strays out of control all you have to do is move the stick and control will immediately come back.
Sep 15, 2019, 11:36 AM
Registered User
jims123's Avatar
Wow, awesome info.. I’ll definitely use it Thanks Mike

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