Electric trim

[Concorde]

I have decided to go with electric trim instead of dail a trim that I bought and never opened the package. Question? RA has 3 serves, 1- with.7" travel. 2- 1.0". 3- 1.25". Which one do you guys recommend.
Thanks

[fastj22]

You will want the longest throw available if using the bias spring configuration. If using a trim tab, I can't say. I have a waiex.

[Concorde]

With the lack of response to my question makes me think that nobody is doing this.
I will go with the 1.25" . Thanks John.

[fastj22]

One of the complaints of using the dial a trim and the spring system is running out of travel range for all trim conditions. Finding the sweet spot on spring tension is challenging. If the electric system you use has a shorter throw than the dial a trim, it will be even more challenging.

[vwglenn]

I have RA electric trim with a trim tab on my Sonex. Not sure which servo it is. Works really well for cruise flight. In the pattern the tab doesn't have has enough oomph to keep the nose down on final. You have to keep pressure on the stick. The stick forces are so light on the plane it doesn't really bother me. Defection isn't an issue. It looks more like a speed brake than a trim tab when deflected full down (nose up).

[Concorde]

Glenn,
I was told that by another builder also. RA 1.2 is longest they have but the travel time is 19 seconds.
Thanks

[dirkverdonck]

Hi Glenn,
I am planning a real trim tab on my OneX, one incorporated into the elevator and not attached to the trailing edge and have already made a 'proof of concept' tab on excess elevator material that comes with the OneX as you receive Waiex parts that need to be cut to fit.
It works well and looks good but I'd like to know the surface area of your tab in order to calculate mine taking into account the hinge placement is further forward.
As a control mechanism, I'm thinking of a car seat-back positioning system that you can turn several turns for just a little movement of your seat-back and both would be linked with a piano wire.
Dirk
OneX 117

[vwglenn]

Glenn,
I was told that by another builder also. RA 1.2 is longest they have but the travel time is 19 seconds.
Thanks

I've never timed the thing but it's certainly not fast (somewhere between snail and turtle). I'm not sure it takes quite that long but, admittedly, I can't remember running it from stop to stop and wouldn't be surprised. It could be faster but the transitions in the pattern are easy because all you do is hit the switch and wait. My switch is on the panel. If I built the plane I would've put it on the stick with a hat switch. I honestly don't think the slow speed of the thing is much of a factor. It's great for fine tuning your cruise in my opinion.

Hi Glenn,
I am planning a real trim tab on my OneX, one incorporated into the elevator and not attached to the trailing edge and have already made a 'proof of concept' tab on excess elevator material that comes with the OneX as you receive Waiex parts that need to be cut to fit.
It works well and looks good but I'd like to know the surface area of your tab in order to calculate mine taking into account the hinge placement is further forward.
As a control mechanism, I'm thinking of a car seat-back positioning system that you can turn several turns for just a little movement of your seat-back and both would be linked with a piano wire.
Dirk
OneX 117

I didn't build my plane so I can't tell you what the surface area is. I suppose I could measure it for you but I don't know that it would be a 1-1 comparison considering the Onex is 15% smaller than the Sonex. I probably have a picture of it somewhere if you want to get an idea of the size relative to the elevator.

[vwglenn]

[sonex892.]

I measured the cable travel on mine which is a standard lever controlled trim tab on a sonex. The travel is 1.5".

Just out of curiosity Concorde where do you intend to, locate the servo, and drive the tab? A guy in the hanger here with a KR2 has a his servo inside the elevator.

Steve
Sonex 892