Inspector Scott
Member
I'm at the point where I have to make a decision on how to power my trim and looking for some input
Perhaps if you are wanting to fly coupled IFR approaches electric trim would be ideal, but I have an autopilot and am completely happy with manual trim. Works great for the VFR flying I do. My Dynon lets me know with an indication if I need to adjust the trim up or down. I first purchased the electric trim but switched to manual during the build. It was part of my KISS approach to building that 700 hours later I'm glad I took.If you plan on installing an auto pilot, electric pitch trim is a must.
I flew my transition training in an RV-7A with electric trim and found it too sensitive, could not find the "just right" spot
Yes, the servo typically moves too fast, making adjustment very sensitive. I had to play around with adding resistors until I found the sweet spot, which turned out to be a voltage just above the point where the servo didn’t respond at all. Trim sensitivity is of course also very dependent on air speed. Just a very quick touch of the button is noticeable at cruise speed, but I need 2-3 seconds to trim the nose up when I slow down to pattern speed.
I can't imagine building a modern airplane w/glass panel and manual trim, makes no sense.
All modern glass panels have auto trim and speed control based on airspeed
Well, not really. I have a modern glass panel, and it doesn’t have auto trim, or speed control based on airspeed, and I have a two axis autopilot (GRT). It depends on what primary system you are using. The Garmin G3X has an auto trim system, so if you want that feature to work, you’ll need electric trim.
On my airplane, and many others without auto trim, the autopilot performs very well without it. My EFIS indicates when it needs some trim (seldom) and I can then move the trim - either electrically or manually doesn’t matter. I have electric pitch trim in my RV6 and manual aileron trim. My autopilot almost never asks me to change trim. When it does, the pitch trim is controlled by the RAC rocker on the IP right next to my throttle. One bump on that switch moves the trim a tiny amount. I can hold it down for increased trim rate.
Saying you need electric trim for autopilot equipped airplanes just isn’t true, and that’s what the OP was asking for. Depends on what other systems you have in your airplane, and what geewhiz options you want to have.
Saying you need electric trim for autopilot equipped airplanes just isn’t true, and that’s what the OP was asking for. Depends on what other systems you have in your airplane, and what geewhiz options you want to have.
Anyone have their manual trim on the LEFT side, against the fuselage side? I like to fly aerobatics with my right hand on the stick, and the left hand on the throttle, so will have my trim on the left.
I'm going with a UL engine with fuel injection and electric CS prop, which uses a prop control on the panel and not on the throttle quadrant. So my plan is to have a throttle quadrant on the left, with a second handle on the quadrant that will be the manual trim. Think of a throttle quadrant with a throttle and mixture, but the mixture handle would be the trim, instead.
Mostly I'm wondering how the manual trim cable might get routed. I don't have my fuselage kit, yet, so I don't have anything to look at and scratch my head about.
Here is another option if you have older glass or steam gauges. I installed it during the build 15 years ago and it has worked flawlessly.
https://www.tcwtech.com/product/safety-trim-intelligent-servo-controller/
Thanks,
Joe
Side note: I guess I’m getting old, but I find it annoying when internet posters use the expression ‘is a must’ to mean ‘is nice’, when the common English dictionary interpretation of ‘must’ is ‘required’. Looking at the comments I see others are bothered, too.
Guess it depends on definition of “modern”, Garmin, Dynon/Skyview, AFS all provide auto trim w/speed defined trim speed.