Aileron Trim Tabs

[jaywa]

I also did the usual aileron trim corrections by adjusting a single flap , plus installing a small aileron tab, and the plane now flies with neutral stick pressure - HOWEVER for all of us that have to do this we are of course creating additional drag because both the flap and the ailerons are active in level flight ,which is really not satisfactory.
I am thinking of readjusting the overall wing rigging by redrilling/reaming one rear wing tab attachment bolt hole in a vertical direction and moving it slightly to get a the wing rigged back to near perfect.
Has anyone tried this, any bright ideas to get the ideal drag free solution?

[mike.smith]

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

I chose to put the trim tab on the outside of the flap, instead, and it's worked perfectly for me. I made a piece about 8" long, bent one edge, and stuck it on with duct tape. I would bend it more or less after my test flights, until I found the right amount. Then I riveted it in place. It's underneath the flap with the trailing edge of the trim tab aligned with the trailing edge of the flap, so you hardly see it when you walk past it.

[rizzz]

I chose to put the trim tab on the outside of the flap, instead, and it's worked perfectly for me. I made a piece about 8" long, bent one edge, and stuck it on with duct tape. I would bend it more or less after my test flights, until I found the right amount. Then I riveted it in place. It's underneath the flap with the trailing edge of the trim tab aligned with the trailing edge of the flap, so you hardly see it when you walk past it.

Hi Mike,

Unlike when installing a trim tab on the bottom side of the aileron of the non-heavy wing to get it to raise the aileron, I'm assuming when you install it on the bottom side of a flap, you do it on the bottom side of the heavy wing?

Any chance you could provide a picture?

I currently have lowered my flap on the heavy wing a bit along with an adjustable flap stop which fixes the problem but I don't like the look of the flap not in line with the aileron in flight on that side. I know it's nothing to worry about but little things like that annoy me. Funny isn't it.
Your solution would be invisible from the cockpit.

Thanks,
Michael

[gammaxy]

I'm not sure what the benefit of a trim tab on the flap rather than the aileron is. I think a much smaller tab would have a greater effect when attached to the aileron since it will be able to actually push the aileron up and create a greater rolling moment.

[rizzz]

I'm not sure what the benefit of a trim tab on the flap rather than the aileron is. I think a much smaller tab would have a greater effect when attached to the aileron since it will be able to actually push the aileron up and create a greater rolling moment.

I think the idea is that much like a tab on the bottom of an aileron lifts the aileron, the tab on the bottom of a flap lifts the wing. Same principle no?

[gammaxy]

No, it's just like how you (almost?) never see a yaw trim tab stuck on the fuselage somewhere--instead it's attached at the trailing edge of the rudder. Due to leverage, a relatively small tab can move a larger control surface and cause a larger torque than it would be able to by itself.

[Sonerai13]

I think the idea is that much like a tab on the bottom of an aileron lifts the aileron, the tab on the bottom of a flap lifts the wing. Same principle no?

In a word, no. The trim tab is there to move the control surface, not to provide the correction by itself. Let's say your airplane has a tendency to roll to the left in level flight. You correct that by putting a trim tab on the RIGHT aileron, which will deflect the right aileron upward and thus the left aileron downward slightly, which will reduce the left-rolling tendency.

Putting a trim tab on the flap will only add a little drag, and will have negligible effect on rolling tendency.

[radfordc]

Putting a trim tab on the bottom of a flap does exactly the same thing as adjusting the flap down a bit....only it is less efficient and adds more drag.

[fastj22]

I put a bias spring setup to deal with roll trim. A long spring attached to each aileron rod and a way to adjust the tension of one or the other. In my case, it was a small 12V motor in the center with a spool on it a cable is wrapped around several times and the cable terminated on each spring. Winch turns one way, you get left roll, turn the other way you get right roll. All controlled through a high hat on the stick.

[achesos]

Why use a trim tab at all for roll? There are two equal but opposite surfaces that should balance the roll axis, unlike a single rudder can be balanced for yaw.

At the risk of sounding foolish, I thought that once I fly my plane, simply adjusting the length of the combination of aileron push tubes would eventually 'balance' any roll tendency (if present)? I'm also assuming that a little here will also go a long way,

The initial flap and aileron positioning when attaching these moving surfaces was to be just that - initial - and that I will be completely lucky to not have a heavy wing, stick centered first-flight.

Sean