Electric Pitch Trim Interface

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1Bad88

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I am working on my pitch trim and would love to know opinions on what is the best human interface option. I am considering a 3 position momentary switch (like Ray Allen), a rotary potentiometer, and a slide potentiometer but I am open to other suggestions too.
 

huVVer

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3-position switch. Standardized, easy to use. Operates by feel, doesn't need to be in field of vision.
 

Victor Bravo

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The (not politically correct) "coolie hat" switch mounted on the stick or yoke is very much worth considering.

I would love to try a rotary potentiometer on the yoke of my airplane, with a point or arrow or notch in the knob somewhere that is tactile. That way it also doesn't demand my concentration to operate, knowing where I'm positioning it by feel.

Another very promising version woul,d be the rolling thumbwheel, essentially a rotary pot turned 90 degrees so that your thumb is rolling the heel fore and aft.

I think the rocker switch type probably sucks, it would be mu last choice.
 

AdrianS

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For a non-aircraft project (darkroom enlarger timer) I have used a rotary switch with various resistors soldered to it, to give a pseudo potentiometer.
This allows the user to rotate it a number of "clicks" without looking at the position of the knob. It also avoids the potential issue of wear in the pot - position 3 is always exactly the same resistance.

Alternatively, you can get a pot with 10 or more "detents", so it clicks from one setting to the next.

Sample search
 

BJC

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I am working on my pitch trim and would love to know opinions on what is the best human interface option.
3-position switch.
The (not politically correct) "coolie hat" switch mounted on the stick
A (momentary)-off-(momentary) on the stick is my first choice. If you also have aileron/ roll trim, spring for the expensive coolie hat switch. In either case, install a connector so that the stick will be easily removed.


BJC
 

1Bad88

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Jul 18, 2012
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So the slide potentiometer seems to be the least desirable option which is interesting since it would be the same as the trim on the gliders I fly. I guess an Arduino nano may be required for this project. Right now I am using an Actuonix L-12-P with an LAC board.
 

Pops

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I have used the P16-S with their rocker switch since 2007 without any problems and I like it for my elevator trim servo. 12 volt, 50mm stroke, 256 to 1 ratio.
Speed is just right.


 

bhooper360

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Dec 9, 2021
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I am working on my pitch trim and would love to know opinions on what is the best human interface option.
I can complain all day about how terrible it is that Pipers only have rudder trim but no aileron trim, and how important trim is in general. Yet I've never flown a 1-26 with a working trim system. Meanwhile the 1-36 has my favorite type of trim, lever with detent that zeroes the stick at the current position, but it also confuses pilots, and the glider's less fun when people keep breaking it. The LSA I flew had electric servos in the control surfaces, pushbutton, readouts on the PDF. It worked fine. When I flew the PW-5s I had the CG as far back as I could get it (because I'm hot ****, bruh) and the trim was hardly usable, and hardly necessary anyway.

If I were to design a trim system, I'd have a lever with a friction lock, a hex key to adjust the friction lock, and a mallet on a chain. That way I could tap the lever with the friction lock engaged to make finer adjustments.
 
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