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Nov 15, 2016, 10:00 PM
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Mini-HowTo

Taranis: Conserving Switches, Part 2


Getting The Most Out Of Your Trim Switches

A Continuation of Taranis: Conserving Switches, Part 1

When you're flying a full-house glider you need your elevator and aileron trim switches, but you probably have no need for throttle or rudder trims. That means those switches are free for other purposes, and there are plenty of useful things they can do.

When a trim switch is set to Own Trim in a particular flight mode, a trim switch adjustment that's made while in that flight mode will store a unique value in memory that applies only while in that flight mode. And through a mix, the trim switch can have a unique function that's also only active in that flight mode. You can see an example of a trim switch serving two different functions in Mike Shellim's F3J/TD setup, in the mixes for CH20 and CH22:
Code:
CH20 (Snap)
 Ele Weight(+100%) Flight mode(T3-speed) NoTrim Function(x<0) [Ele]
*= TrmT Weight(-50%) Offset(50%) [TrmT]

CH22 (SpComp)
 CH16 Weight(GV7) Flight mode(Landing) Curve(2) [Spoilr]
*= TrmT Weight(+50%) Offset(50%) [CompAdj]
Here, TrmT (the throttle trim switch) adjusts snap flaps while in T3-speed mode, and adjusts elevator compensation while in Landing mode.

But you can go way beyond that.

Here are Mike Shellim's aileron camber and flap camber mixes from his Version 3, F3J300_X:
Code:
CH10 (AilCm) 
MAX Weight(GV3) Flight modes(Launch, Zoom, KAPOW, T1-thermal, T3-speed) [CmBase]
*= LS Weight(+50%) Flight mode(T1-thermal) Offset(-100%) [CmAdjT1]
*= S2 Weight(-50%) Flight mode(Launch) Offset(-100%) [CmAdjLau]
*= S1 Weight(+50%) Flight mode(Zoom) Offset(50%) [CmbAdjZm]
+= CH16 Weight(-GV3) Offset(GV3) [Spoilr]
+= CH20 Weight(0%) [Snap]

CH11 (FlapCm)
MAX Weight(GV4) Flight modes(Launch, Zoom, KAPOW, T1-thermal, T3-speed) [CmBase]
*= LS Weight(+50%) Flight mode(T1-thermal) Offset(-100%) [CmAdjT1]
*= S2 Weight(-50%) Flight mode(Launch) Offset(-100%) [CmAdjLau]
*= S1 Weight(+50%) Flight mode(Zoom) Offset(50%) [CmAdjZm]
+= CH16 Weight(GV4) Offset(-GV4) [Spoilr]
+= CH20 Weight(0%) [Snap]
+= CH18 Weight(+100%) [FlNeut]
The left slider (LS) adjusts camber in T1-thermal mode, the S1 knob adjusts reflex in Zoom mode, and the S2 knob adjusts camber in Launch mode. There's no in-flight reflex adjustment for T3-speed mode, so reflex for that mode can only be preset by adjusting GV3 and GV4 while on the ground.

By programming the throttle trim to make all of these adjustments and more, I was able to free LS, S1, and S2 for other functions. In fact, since I had no use for potentiometers S1 and S2, I converted them to 3-position switches, as I've described in Taranis: Change S1 & S2 to Switches.

Here are my mixes for CH10 and CH11, based upon Mike Shellim's Version 2, F3J_200_X:
Code:
CH10 (AilCm) 
    MAX Weight(GV4) Flight modes(Launch, Zoom, Thermal, Speed) [AiPreset]
 *= TrmT Weight(-100%) Flight modes(Launch, Thermal) Offset(100%) [Camber]
 *= TrmT Weight(+100%) Flight modes(Zoom, Speed) Offset(100%) [Reflex]
 += CH16 Weight(+100%) Flight mode(Crow) Curve(1) [Spoilr]
CH11 (FlapCm)
    MAX Weight(GV3) Flight modes(Launch, Zoom, Thermal, Speed) [FlPreset]
 *= TrmT Weight(-100%) Flight modes(Launch, Thermal) Offset(100%) [Camber]
 *= TrmT Weight(+100%) Flight modes(Zoom, Speed) Offset(100%) [Reflex]
 := TrmT Weight(+100%) Flight mode(SetFail) Offset(-100%) [Setfs]
 += CH16 Weight(+100%) Offset(-19%) [Spoilr]
I removed the snap flap function but the TrmT mix for adjusting landing elevator compensation is still in my CH22 mix:
Code:
CH16 (Spoilr)
    MAX Weight(+100%) [Fixed]
 := CH23 Weight(+100%) Flight modes(Flap, Crow) [RawSpl]

CH22 (SpComp)
 CH16 Weight(GV7) Flight mode(Landing) Curve(2) [Spoilr]
*= TrmT Weight(+50%) Offset(50%) [CompAdj]
However, I made a small change to the way elevator compensation is adjusted: On the Flight Modes page I changed the throttle trim setting for Landing mode to Use trim from flight mode 0 instead of Own Trim, so that I'm able to adjust landing elevator compensation while I'm in either Landing mode or Cruise mode.

My throttle trim switch now serves six different functions:
  1. In Cruise mode or Landing mode it adjusts landing elevator compensation. (up for more down elevator)
  2. In Launch mode it adjusts launch camber. (down for more camber)
  3. In Zoom mode it adjusts zoom reflex. (up for more reflex)
  4. In Thermal mode it adjusts thermal camber. (down for more camber)
  5. In Speed mode it adjusts speed reflex. (up for more reflex)
  6. In SetFail mode it adjusts the failsafe flap setting. (down for more flaps)
And because these settings are all stored in memory rather than in the position of a potentiometer, there's no worry about a knob or slider getting inadvertently moved after it's been set!

Last edited by Miami Mike; Nov 23, 2016 at 09:30 PM.
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Nov 16, 2016, 07:39 AM
Registered User
mikeshellim's Avatar
Nice explanation. Great to see the setup being modded in this way!
Dec 09, 2016, 08:42 PM
Registered User
Gordysoar's Avatar

Very nice Mike!


A couple of things to point out.

In-flight trim adjustments are basically used .... once. No need to change things after the settings are set.

Snap flap isn't used in Speed because speed is the "come home" mode so that last thing you want is to cause added drag via elevator inputs. Many don't use Snap flap in Thermal because of increasing camber causing drag. Same for rudder to aileron mix.
Version 3 has Snap flap only working with up elevator but it should work both directions, that can be changed by heading to the Elevator Mix line and changing the 0< in the Diff line to simply zero or adding a value that gives more down flap with down elevator than up flap (reflex) with down elevator. (this is helpful to keep speed up as your push over at the top of the zoom).

A line to add 100% rudder to aileron mix during launch is a good thing, since ailerons are of almost zero value during the launch, rudder is king.

Zoom isn't used in TD because we get "zoom" when launch is switched off at the ping, which allows the Mode Switch to activate in Speed. It could be a slight short cut to remove the need to switch out of Speed to Cruise after the model is pushed over, but really not worth the switch. (F3J is different because of the high speed launches.)

So in fact Version 3 could be considered the "Setup" version, and Version 3.1 would be it with some of the in flight stuff removed.

I like your Throttle Trim multi use setting, especially for flight line launch camber adjustments.
Thanks for doing the work! Mike Shellim has created a masterpiece for us guys. Especially in Version 3 where curves are used to create matching subtrim "points" instead of the basic Subtrim adjustments was have been stuck with using Big Brand TXs.

Thanks Miami for doing even more work to help us understand the power of the Taranis and OpenTX.
Gordy
Latest blog entry: Check out my YouTube Channel
Dec 10, 2016, 12:40 PM
Registered Taranis User
Miami Mike's Avatar
Thanks for the input, Gordy!

Quote:
Originally Posted by Gordysoar
In-flight trim adjustments are basically used .... once. No need to change things after the settings are set.
Maybe someday I'll find that my in-flight trims are finally perfect and there will never be any need to adjust them further while I'm in flight, so I'll keep that in mind just in case that day ever comes.

Quote:
Snap flap isn't used in Speed because speed is the "come home" mode so that last thing you want is to cause added drag via elevator inputs. Many don't use Snap flap in Thermal because of increasing camber causing drag.
I've never played with it and don't have it enabled. I figured maybe it's for F3B or F3F where they make those quick turns around the bases.

Quote:
Same for rudder to aileron mix.
I've never heard of rudder to aileron mix.

Quote:
Version 3 has Snap flap only working with up elevator but it should work both directions, that can be changed by heading to the Elevator Mix line and changing the 0< in the Diff line to simply zero or adding a value that gives more down flap with down elevator than up flap (reflex) with down elevator. (this is helpful to keep speed up as your push over at the top of the zoom).
It's the same way in Version 2.
Code:
Version 2:
CH20 (Snap)  Ele Weight(+100%) NoTrim Function(x<0) [Ele]
      *= TrmT Weight(-50%) Offset(50%) [TrmT]

Version 3:
CH20 (Snap)  Ele Weight(+100%) Flight mode(T3-speed) NoTrim Function(x<0) [Ele]
     *= TrmT Weight(-50%) Offset(50%) [TrmT]
Quote:
A line to add 100% rudder to aileron mix during launch is a good thing, since ailerons are of almost zero value during the launch, rudder is king.
I'm way ahead of you on this. Here's my rudder mix:
Code:
CH06 (Rudd) [I1]Rud Weight(+100%) NoTrim [Rudder]
            += [I3]Ail Weight(GV7) Flight modes(Cruise, Flap, Crow, Zoom, Thermal, Speed) NoTrim [Combi]
            += Ail Weight(GV7) Flight mode(Launch) NoTrim [LaunchRd]
            := TrmR Weight(+50%) Flight mode(SetFail) NoTrim [Setfs]
            := Rud Weight(+100%) Flight mode(Calibrate) NoTrim [Cal]
Ordinary aileron to rudder mix (or "combi", as Mike Shellim calls it) is implemented in Line #2, where the mix is linked to the aileron input after rates and expo settings on the Inputs screen are applied. That mix applies to all regular flight modes except Launch, and is individually set for each flight mode with LS, which has to first be enabled with a switch as I describe in my Taranis: Lock In Your Slider Settings post.

I added a special combi mix for Launch mode in Line #3 that's linked directly to the aileron stick so that the rudder response is unaffected by the aileron rates. Like the other combi mixes, this mix is also adjustable with LS.

As to whether 100% mix is best, maybe yes, maybe no. I have mine set to 100% right now but I can easily experiment with different mixes from one launch to the next.

Line #4 is for setting the rudder to a gentle turn for failsafe while I'm in SetFail mode, and Line #5 is Mike Shellim's original mix for Calibrate mode.

And by the way, I've been told that ailerons should only go up during launch, never down. At first I thought it would take some time to figure out how to program that, but then I realized that what it amounts to is 100% aileron differential. All I had to do was edit Curve 5 (which has the same function in Versions 2 and 3) to allow me to vary differential in each flight mode from 0% (equal travel up and down) to 100% (no downward travel), and then run the TrmR setting all the way to the left in Launch mode.

Quote:
Zoom isn't used in TD because we get "zoom" when launch is switched off at the ping, which allows the Mode Switch to activate in Speed. It could be a slight short cut to remove the need to switch out of Speed to Cruise after the model is pushed over, but really not worth the switch. (F3J is different because of the high speed launches.)
So you're using the same flight mode for Zoom and Speed? I have the option of having different settings for each, both easily adjustable.

It seems to me that in Zoom mode your plane is a ballistic missile fired straight up, so you're not looking for any lift at all from the wing. All you want is minimal drag in the direction you're going, which is the direction directly opposed to gravity. I'm skeptical that Speed mode can be assumed to be the ideal configuration for that.

Quote:
So in fact Version 3 could be considered the "Setup" version, and Version 3.1 would be it with some of the in flight stuff removed.
I'm sticking with Mike Shellim's Version 2 because I have so much time invested in it, but I'm working on switching part of my Outputs setup procedure to using curves, like he does in Version 3. I like that better for the flaps and ailerons, especially since I use protractors stuck to the ends of my center section to get the angles right. I plan to stay with the Version 2 method for my rudder and elevator though. I don't see any utility in using curves there.

Quote:
I like your Throttle Trim multi use setting, especially for flight line launch camber adjustments.
Thank you.

Quote:
Thanks for doing the work! Mike Shellim has created a masterpiece for us guys. Especially in Version 3 where curves are used to create matching subtrim "points" instead of the basic Subtrim adjustments was have been stuck with using Big Brand TXs.
Yes he has.

Quote:
Thanks Miami for doing even more work to help us understand the power of the Taranis and OpenTX.
Gordy
You're welcome!

And please, call me Mike.
Last edited by Miami Mike; Dec 10, 2016 at 11:34 PM.