Aero-Dynamics

[DanB]

This one is for any of our many aviation engineering types...Or if you have tried to solve this same problem.
I want to bounce this off of you to find out if my aerodynamic thought processes are correct.
Problem:
My Kitfox IV has been flying very well for the last year. When I first got the AW ticket, I went up and realized right off I needed a trim-tab on the rudder as I was needing to hold some right rudder to fly straight. The trim tab is about 6" long and bent off the trailing edge of the rudder to the port side. I ended up needing to bend this tab into the airflow at Approx 45 degrees to fly without right rudder. I know this generates quite a bit of drag which I would like to get rid of.
Solution ?
My thoughts lean towards shimming the engine mount canting the engine slightly to port side. If this thinking is correct, how much would one start shimming? Or is this even a practical solution?
Thanks in advance for your thoughts.

[Dave S]

Dan,

This is not an answer to your question, however, your comment inspired one I had.....you said the rudder tab is 6" long, what is the other dimension...i.e. how far does it extend back from the rudder trailing edge?

Curious because I am in the middle of engineering an adjustable rudder tab for our KF and trying to determine how big to make the tab.

Thanks,

Dave S

[DanB]

Dan,

This is not an answer to your question, however, your comment inspired one I had.....you said the rudder tab is 6" long, what is the other dimension...i.e. how far does it extend back from the rudder trailing edge?

Curious because I am in the middle of engineering an adjustable rudder tab for our KF and trying to determine how big to make the tab.

Thanks,

Dave S

Dave, It sticks out about 1" into the slipstream.

[Av8r3400]

Tab needs more chord, IMO. Mine is 2-3" aft of the trailing edge of the rudder by 5" high.

[jamesmil]

I tried to shim the motor on our ss7 also to center the ball with no help.
do a search under " rudder trim tab " where this was discussed with some good pic's of way's to do a trim tab.

[DanB]

I tried to shim the motor on our ss7 also to center the ball with no help.
do a search under " rudder trim tab " where this was discussed with some good pic's of way's to do a trim tab.

Thanks Jim,
I appreciate the reply. Was curious if someone else had gone down that road. How much shim did you try? I have a trim tab and it works fine...just trying to eliminate it.
Sure seems like there would be something that could be done. I know we have much more expertise on this list and it sure would be nice to get a discussion going about this learning more about the good, bad and ugly alternatives. I have a feeling that too many folks on here have stopped replying to technical questions because it too quickly turns into a shooting match. Is it that or more along the lines of knowing where the good fishing holes are and not telling?