Custom Aileron Trim Tab

[GAHco]

Even though I did this a while ago I just took pictures of it last week.

I just could not put piece of hinge for an entire trim tab assembly, on my aileron and have it truly look like a total afterthought.

If you want to see what I thought would look better, go to

http://www.gen-aircraft-hardware.com...plane_proj.asp

It gives more text and details. or just look below and let the pictures talk.

Wait a while for all the pictures to load, and then go toward the last few entries.







Have fun!

[gvgoff99]

The aileron trim tab is nice and very creative. Since I have never needed more than the spring loaded aileron trim that Van's sells I was wondering why you put a tab on? Judging by the pictures your building skills are good so I am going to bet you won't need it much after you start flying. It looks like you are building a clean and straight airplane. Keep up the good work.

[mark manda]

Very nice, you got one in the rudder too?

I could use one; my right wing is 10 gals heavy.

[kentb]

I have the Vans under the seat spring trim system. I have been thinking about doing what GAHco has done to replace it.

Why. I was thinking that the current system seems to be correct only at one speed. If you change speed you need to change the trim again.

Now would the trim on the aileron be consistently set for any given speed?
Also would there be any difference in drag between the two system once they were trimmed?

Kent

[PCHunt]

Originally Posted by kentb

.....I was thinking that the current system seems to be correct only at one speed. If you change speed you need to change the trim again..... Kent

Isn't that exactly what adjustable trim is for???? So you can change the trim as speed/conditions warrant? Otherwise, you'd only need a fixed tab. Or am I missing something? (Entirely possible, BTW.) FWIW, I'd like to have cockpit-adjustable trim on all 3 axes! But probably not worth the weight/$$/build time, etc.

[kentb]

Originally Posted by PCHunt

Isn't that exactly what adjustable trim is for???? So you can change the trim as speed/conditions warrant? Otherwise, you'd only need a fixed tab. Or am I missing something? (Entirely possible, BTW.) FWIW, I'd like to have cockpit-adjustable trim on all 3 axes! But probably not worth the weight/$$/build time, etc.

The spring on the stick will have differing effect at different speeds. If you are trimmed for climb and then level off and build speed the spring will need to be adjusted to hold the same aileron position.
My thinking was that the aileron trim tab would not have this problem in that it just adjusted the angle to the airstream, no matter what the speed was. I was hoping that some of the aero engineers would confirm my thoughts.

Kent

[John Clark]

Originally Posted by kentb

The spring on the stick will have differing effect at different speeds. If you are trimmed for climb and then level off and build speed the spring will need to be adjusted to hold the same aileron position.
My thinking was that the aileron trim tab would not have this problem in that it just adjusted the angle to the airstream, no matter what the speed was. I was hoping that some of the aero engineers would confirm my thoughts.

Kent

Sorry, but the tab is airspeed sensitive just like the spring. Do you use the same control deflection at all airspeeds? The trim will be more effective as the speed goes up. On the same subject, I haven't moved the aileron trim on my '8' for some time. No need, if the fuel is somewhat balanced (10-15 gallons) it goes straight.

John Clark
RV8 N18U "Sunshine"
KSBA

[rvermeland]

Hinge moments are directly proportional to dynamic pressure (q) and the spring constant is just that--constant. As you change speeds, the aileron deflection due to the spring system will decrease, but the trim tab should maintain a nearly constant deflection. With that said, the rolling moment you are trying to overcome will be both aerodynamic and due to weights. The weight based rolling moment (eg. I'm in the left seat and the right seat is empty, or I'm burning the left tank, etc.) does not change with q, but the aerodynamic rolling moment does. So.... in my opinion, both trim systems will require adjustment during flight.

-rob

[kentb]

Originally Posted by rvermeland

Hinge moments are directly proportional to dynamic pressure (q) and the spring constant is just that--constant. As you change speeds, the aileron deflection due to the spring system will decrease, but the trim tab should maintain a nearly constant deflection. With that said, the rolling moment you are trying to overcome will be both aerodynamic and due to weights. The weight based rolling moment (eg. I'm in the left seat and the right seat is empty, or I'm burning the left tank, etc.) does not change with q, but the aerodynamic rolling moment does. So.... in my opinion, both trim systems will require adjustment during flight.

-rob

As the weight changes (fuel burn) the left right trim will need to be adjusted (either type). As the speed changes the spring trim will need to be adjusted, but the trim tab will be selfadjusting (so to speak).

Kent

[hecilopter]

has to be adjusted with speed, why would the aileron trim be any different?