rudder trim tab

[ken nougaret]

is there a preferred position for a rudder trim tab? i'm going to glue a plate on the back of my rudder before it gets covered, to mount a ground adjustable trim tab. is it better in line with the horizontal stab, below or above?
thanks, ken

[MotReklaw]

Ken, will you post a picture of what you end up doing? I would like to see it as I'm at that stage too.

Thanks

[jamesmil]

my turn and bank ball was off nearly 3/4 of the ball to the right.
after playing around with different rudder tabs made from 1/2 thick x 4 inch pvc board cut down to 1 3/4 x 6" and beveled i found the most effective position was about 12" above the h/s.
the tab is held on to the rudder with 3m moulding tape and does not stick past the rudder. i will get a pic posted when i get home. hope this helps:)

[HighWing]

I would think that the best place for the typical aluminum ground adjustable tab would be at the point of the longest chord on the rudder. this would give the greatest leverage and allow for a smaller tab.

My trim in my new Model IV rudder is a cam that warps the bottom two ribs. I used a RAC servo as a controller, but find that once trimmed, the servo just serves as ballast. If I were to do the rib warping again, I would design it so I could trim it with an Allen wrench through a hole in the fabric - save 8 oz. at a negative eleven foot arm.
Lowell

[airlina]

I started out with a ground adjustable rudder trim on my Series 5 way back when. After flying in this configuration for a few hundred hours, I began to realize that this setup was just not cutting it , especially on cross country flights. The fact that the kitfox rudder is not a balanced control surface means that it does not have a strong tendency to return to the same spot after a deflection and the slightest degree of offset means yaw until you correct with your foot. To make a long story short I went to model airplane servo controlled , cockpit adjustable rudder trim that has worked famously for 4 years now. As I recall the whole setup cost under 150 bucks and the hardest part of the process was routing the wiring thru my finished airplane from the rudder to the cockpit. If you type rudder trim in this websites search engine and go to the last page you can find some pictures of the setup. Bruce N199CL

[mr bill]

The attached picture shows what I did. It is controlled by an rc allen servo, controlled from the cockpit. Did the same on the elevator.

[ken nougaret]

Bruce, i found your pics of the servo controlled rudder tab, very nice. is the power for the servo wired to your aircraft or do you have a separate battery? as i remember these servos require 4.8 - 6v of power.
and thanks to all the replies. my decision as to what to do is getting more complicated, but interesting.
ken

[airlina]

Bruce, i found your pics of the servo controlled rudder tab, very nice. is the power for the servo wired to your aircraft or do you have a separate battery? as i remember these servos require 4.8 - 6v of power.
and thanks to all the replies. my decision as to what to do is getting more complicated, but interesting.
ken

Ken, the servo is powered from the ship's power and is controlled by a neat little rotary controller that I found online. Bruce

[jamesmil]

pic,s of fixed rudder trim tab. after a lot of trial and error this is the best position we found to center the ball on our ss7.

[ken nougaret]

here's what i decided on doing. what i thought looked the best was just above the horizontal. i also found a pic of paul's plane that has the wedge rather than the tab. i think this looks a lot better. so i glued an aluminum plate with 2 nutplates for future use.
ken4001

4002

4003

4004

[hansedj]

here is how we did it.