SonexBuilders.net

Hey all

I am going to have to put a trim tab on my aileron, just wonder who else has done this and how big of trim tab is needed..

I also need to know if any one that has done this has any drawing or dims of the trim tab and how much it needs to be bent.

Thanks
Mike

It's going to be trial and error Mike. What I've done is to take a piece of AL about 4x3 inches and bend about 1 inch from an edge approximately 20 degrees. Duct tape it to the underside of aileron on the light wing and fly. If it doesn't raise the heavy wing enough, increase the bend and lessen the bend if it raises the heavy wing too much. Once you have it where you want it rivet it to the aileron. Also, I put my trims in the center of the aileron, lengthwise. If you mount the trim trailing edge slightly ahead of the aileron trailing edge it's not immediately noticeable.

David

Check out my video on trimming an airplane on the EAA Hints for Homebuilders site. It contains quite a few photos of trim tabs on the factory Sonex aircraft. Here' the link: http://bcove.me/pa2hjbxk

Cheers!

onex28 wrote:It's going to be trial and error Mike. What I've done is to take a piece of AL about 4x3 inches and bend about 1 inch from an edge approximately 20 degrees. Duct tape it to the underside of aileron on the light wing and fly. If it doesn't raise the heavy wing enough, increase the bend and lessen the bend if it raises the heavy wing too much. Once you have it where you want it rivet it to the aileron. Also, I put my trims in the center of the aileron, lengthwise. If you mount the trim trailing edge slightly ahead of the aileron trailing edge it's not immediately noticeable.

David

Thanks for the info David.

I will have to figure out another way of attaching it though, the duct tape would remove my paint, maybe I can use a few clecos..

Mike

Mike
I was going to suggest duct tape also. If you remove it after each flight your paint shouldn't come off. I did the same for a trim tab on my Sonerai elevator. If you really don't want to use tape you could use aluminium rivets while testing.
I wouldn't use clecos, apart from the obvious risk of them falling from the plane. I reckon clecos will add weight where you don't want it and also aerodynamic force.

Steve
Sonex 892 VH-ZSX

Some other things others have done...

1. Flap stops. I do not have heavy wing syndrome with both flaps snugging up to a custom adjustable flap stop on each wing. It takes up any slack in the RH flap which tends to flop around a little and make that final adjustment to trim out the heavy side elusive. The angle pieces on the fuse that the plans show perform the same function but aren't adjustable. I suppose they could be taped on initially.

2. A piece of sticky loop Velcro attached to the rear underside of the light side aileron, usually RH if you're heavy on the LH wing solo. To this you attach the hook half of the Velcro and a small tab or wedge, or even a round drinking straw attached to it. This will bias the aileron up and provide the trim force required. If you stick a passenger in the RH seat you can easily remove the Velcro and stick it in your pocket if it goes heavy towards the passenger.

3. The RV trick of squeezing the aileron edge to deform it slightly and provide trim force, could be non reversible though if you pick the wrong one.

4. I have also seen a spring bias arrangement on a single stick Sonex to provide a similar function as the dial a trim control on the elevator. A small lever at the base of the stick provides the spring bias to pull the stick left or right.

Cheers
Tony

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Sonerai13 wrote:Check out my video on trimming an airplane on the EAA Hints for Homebuilders site. It contains quite a few photos of trim tabs on the factory Sonex aircraft. Here' the link: http://bcove.me/pa2hjbxk

Cheers!

I just watched this video that Joe Norris did, I encourage every one that has a trim issue to watch.. I didn't realize how many things can affect the trim of an airplane..

Mike

I recently tried the trick of lowering my right flap two turns to correct a slightly heavy right wing in cruise. While this corrected the heavy right wing at cruise speed it caused the left wing to become heavy when the flaps were deployed. With the flaps deployed it also caused additional yaw during slow flight. My right flap has more play than the left flap. So, in my case, I will need to install a flap stop on my aft spar near the outboard edge of the right flap.

SonexN76ET wrote:I recently tried the trick of lowering my right flap two turns to correct a slightly heavy right wing in cruise. While this corrected the heavy right wing at cruise speed it caused the left wing to become heavy when the flaps were deployed. With the flaps deployed it also caused additional yaw during slow flight. My right flap has more play than the left flap. So, in my case, I will need to install a flap stop on my aft spar near the outboard edge of the right flap.

I talked with Kerry yesterday about adjustments needed to counter act a heavy wing. He told me NOT to go more than two turns down on the flap or it will get them out of sync with each other, so if you have lowered them down more than two turn that is why you are probably having this problem..

Mike