SonexBuilders.net

Lots of trim ideas. All sound god. As a current Onex builder, I ask the question...IS MANUAL TRIM REQUIRED ON A ONEX? OR IS IT WELL ENOUGH BALANCED i DON'T NEED IT?

Sounds like some of you are saying the controls are so naturally light trim is not really needed. Should I even bother to incorporate it?

Ed
Onex 209
t/d, Aerovee(?), I donno electronics
should I say center stick?
parts still in the boxes
look of utter confusion on my face
what am I doing here?
Help, help, help me, Rhonda

Hi Wes,
I used a motorcycle teflon coated cable housing and bought the stainless steel piano wire, 2mm, from a .....piano shop. The cable is run through a soft aluminium pipe which is attached with D-clamps to the left fuselage side and runs through the holes for the rudder cable. From the last bulkhead, the cable runs up to the top of the rear fuselage and exits under the rear corner of the left upper fairing. The cable housing is then attached to the side of the elevator with a riveted P-clamp. The piano wire is the attached to the trim tab in such a way that it can rotate around the attachment point to allow rotation of the trim tab around the piano hinge. The sensitivity of the system can be changed by changing the attachment point to the idler. I also deleted all springs in the elevator control system.
Hope this is of any help,

Onex Trim Question.........?

Hey EdW...........I now have 10 hours on my Onex and yes you do want to have a "trim control" of some kind. Once the airplane is "trimmed" you hardly change it whether in the pattern or in cruise.....but I sure wouldn't want to be with out it. I have the Sonex "dial-a-trim" which I find stiff and cumbersome to use but the Onex requires so little trim adjustment I guess I can live with it.

The Onex is nothing like the RV's that I am used to flying that required a large trim change from "cruise trim" to "on final trim".

If I were doing it again (the Onex or Sonex) I would go with a standard trim tab and lever.

Gordon.....Onex.....Hummel 2400

dirkverdonck wrote:Hi Wes,

Hope this is of any help,

Hi Dirk,

That helps.

Thanks a Bunch,

Wes

Hi Guys,

While waiting on some bits from ACS to get the brakes installed I decided to get the elevator trim out of the way. As it turns out, the routing that Dirk pointed out is really the only way to do it. The trim cable has to enter the fuse on the hinge line so that a constant amount of cable will be external regardless of elevator position.

I still haven't set in the plane and made airplane noises but, just going by appearance, it looks like the flap handle is already going to be pretty much in my lap so I think the trim handle will be forward of the flap handle. I remade the flap angle and left some material ahead of the detents. Once the brakes are installed and the plane is on it's gear, I will sit in it and decide exactly where the trim handle will be and set the bend angles for flap, trim, and brake levers to avoid "reach" interference.




EDIT!! The following is not going to work at all!

Hi Guys,

Well, after sitting in the cockpit, what seemed like tons of room shrank to nothing. There is no way to put the trim where I wanted. No way to de-conflict.

View of tons of room.


Same as viewed by the left shoulder.


Haven't given up. May try to mount it just aft of the flaps with an "L" lever actuating up and down instead of fore and aft. There is too little room aft of the flap handle to move fore and aft without my elbow hitting the seat back. Starting to understand Dirk's placement of his trim control :-) Still thinking.

We'll See,

Wes

Hi Wes,
I did not have any issues with installing my trim wheel as I do not have manual flap control but an electrical one which is buried low on the left side of the fuselage and connects to the flap the same way as the manual lever.
The trim wheel sits near my hip and is marked with a neutral position to be easily checked during pre take-off checks. During flight, I rotate the wheel without looking at it, just by feel.

Hi Ed,
About the requirement of a trim system: After about 30 hrs on Onex 117, I can confirm the control forces are very light and the aircraft is very responsive to inputs. Only slight movements of the wrist are required to make it change direction and after a while, just thinking about a change is enough to make it happen.
This also means that if you let go the controls, the aircraft starts drifting away very quickly as it can only be in trim for one specific flight regime without the installation of a trim system.
To solve this, I added a fixed rudder trim tab and bent it so I can let go the rudder pedals in cruise flight; 2900 revs.
If you want to write down ATC instructions for example and you're right handed, you'll have to let go the stick and the aircraft will immediately change attitude, therefore an elevator trim of some sort is useful imho. ( I added an external trim tab which is connected by a piano wire to a classic trim wheel )

dirkverdonck wrote:Hi Wes,
I did not have any issues with installing my trim wheel as I do not have manual flap control but an electrical one which is buried low on the left side of the fuselage and connects to the flap the same way as the manual lever.
The trim wheel sits near my hip and is marked with a neutral position to be easily checked during pre take-off checks. During flight, I rotate the wheel without looking at it, just by feel.

Hi Dirk.
I'm just wondering if you purchased your trim wheel or made it yourself? I would like to use something similar for my elevator trim. I find a standard trim wheel on the side or center is more intuitive than the Dial a trim on the dash. The other option I am considering is a servo operated trim with a Hat switch on my stick.

dirkverdonck wrote:Hi Wes,
I did not have any issues with installing my trim wheel as I do not have manual flap control but an electrical one which is buried low on the left side of the fuselage and connects to the flap the same way as the manual lever.
The trim wheel sits near my hip and is marked with a neutral position to be easily checked during pre take-off checks. During flight, I rotate the wheel without looking at it, just by feel.

Hi Dirk,

Since I was just now able to sit in the plane and reach for all the controls (even the ones that aren't installed yet), I shouldn't have tried to guess where to put the trim lever. Before sitting in the plane I imagined how natural it would be to pull flaps, move my hand forward and adjust trim, then continue forward back to the throttle. Now I see that is not workable using the "as designed" flap and brake systems. Once that sunk in, I started looking for other places to mount the trim control. I did notice that it felt quite natural to just straighten the left arm and reach down by my thigh, close to where your trim control is, just a little forward and maybe higher. We'll see. I might have to resort to the volume knob solution ;-)

Wes