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Rudder trim tab

Here’s a very simple solution that allows you to experiment on how much trim tab you need. https://www.cleavelandtool.com/products/rudder-trim-tab

Fly it with double sided tap until you define how much to shorten the tab and where best to place it. Once you’ve identified your trim tab needed size and location you can choose a more permanent attachment. It’s also easy to paint.

I use this as a aileron tab to help balance a heavy wing after trying just about everything else. It works great and frankly I’m still using double sided tape.
 
I just ordered the wedge. I am a half ball out. Do you recall how far out you were and how long you settled on?
 
Rudder Trim

Simple Solution....
 

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New to me RV8 needs a half ball trim. What's the elegant solution?

First make sure you are not putting a bandaid on a rigging issue. Fly with the wheel pants off. Ball still out? Do you have a heavy wing?

Then take small steps for rudder trim. The photo of the small rudder tab on the tail light will take care of perhaps half of your issue and is not permanent.

Carl
 
Pray tell, how do I tell if I have a heavy wing? Scales on the ground equal fuel? I am not the builder. The plane flies great and straight just laying a toe on the right rudder pedal.

Never thought about wheel pants off either. Is that a common touch point?
 
Rudder trim

I personally would not chase a simple problem that has such an easy fix . Put a trim tab on it and be done . I’ve yet to see an airplane without one . My solution has served me well and is Permanent to me .
 
Pray tell, how do I tell if I have a heavy wing? Scales on the ground equal fuel? I am not the builder. The plane flies great and straight just laying a toe on the right rudder pedal.

Never thought about wheel pants off either. Is that a common touch point?

“Heavy wing” is just pilot jargon for hands-off turning tendency. If you’re happy with the way your airplane flies you don’t need to do anything.
 
I have installed rudder pedal return springs on my -6 and -7. Differential tension on the springs can be used to trim the rudder for cruise flight. Also keeps the rudder cables taught when on the ground.
 
Craig,
I will snap a pic next time I'm over at the hangar. The installation is simple, you can shop the spring dept. at your local hardware store. All you need are a pair of light duty springs with the right pull and length, attach them to the back of the rudder pedals opposite to where the rudder cables attach. Attach other end to the firewall stiffener angle with a #40 hole. If you need right rudder in cruise, then adjust the right spring slightly tighter than the left. Usually takes a little trial and error until you get the differential tension required to center the ball.
 
A 1/2 ball off can be as simple as the pedal mount blocks causing too much drag on the tubing.
Reach down and pull the pedal towards you, it should be easy to swing with very little drag.
 
From half ball right to half ball left to ball centered

I didn't build my plane but I have made my first custom plane part! It started with a simple AutoCAD drawing that I printed true scale and taped to sheet aluminum. Easy enough to cut out the part with shears and file the perimeter smooth. Mounted behind the stern light with the stern light screws. First flight perfect guess from a half ball right to a half ball left since I wanted to extrapolate to center. First trim got me to a half ball left. Final trim got me to almost perfect. Just a smidge off center.

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. . . . g zero gets credit for sharing the design!
 
Rudder trim

I too had the half ball issue. Started with a piece of balsa wood that I cut with a band saw to a wedge. 3 1/2 in long and 1/2” thick. After looking at it, I just couldn’t glue a piece of wood on the tail. Also looking for a more elegant solution.
Found it at Vans. They sell a metal rudder trim tab for the RV12 for $7.
Asked Vas tech support your thoughts and they approved, so that’s what I did. Looks great and I actually had to take a bit of the delivered angle out, because now I had left ball.
 
I didn't build my plane but I have made my first custom plane part! It started with a simple AutoCAD drawing that I printed true scale and taped to sheet aluminum. Easy enough to cut out the part with shears and file the perimeter smooth. Mounted behind the stern light with the stern light screws. First flight perfect guess from a half ball right to a half ball left since I wanted to extrapolate to center. First trim got me to a half ball left. Final trim got me to almost perfect. Just a smidge off center.
. . . . g zero gets credit for sharing the design!

Unfortunately this blocks off the view to the left of your light, making night flight not in conformance with FARs.
 
Unfortunately this blocks off the view to the left of your light, making night flight not in conformance with FARs.

Methinks I am legal, viewable within the 70 degrees side to side required for a stern light:

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There is actually a shield on the stern light itself that blocks the view from the side.
 
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Most 8's have the mushroom rear rudder pedals, so it's easy to install an internal rudder trim....no aero drag, no additional mass aft of the hinge line, infinitely adjustable.

Drill a hole in the mushroom cap on the right side. Add a bungee and a bracket as pictured. Place the bungee hook in the hole and adjust the tension while in cruise to center the ball. Might need to re-adjust once a year. Unhook the bungee for descent, when the airplane may like a bit of left.
.
 

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Methinks I am legal, viewable within the 70 degrees side to side required for a stern light:

There is actually a shield on the stern light itself that blocks the view from the side.

My mistake. For some reason, I was thinking that the requirement was 180°.
 
Rudder trim....

During and after my flight testing with wheel pants off and on, heavy wing balanced, I still found I had a slight bit of rudder I needed in cruise. Seemed to be consistent regardless of speed. And I had built a little offset in the vertical knowing this was probably going to be an issue.

SO: got a piece of pine and carved it into a long, flat skinny wedge. Duct taped it on. It was on and off several times before I found how thick and where to put it. Then flew it for a while with that in place. When I was satisfied with where it was, made one out of a slab of scrap aluminum from my build. I still duct taped that on and flew it to make sure it was right. Has been on ever since. No adjustment necessary and cruises feet on the floor.
 

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My mistake. For some reason, I was thinking that the requirement was 180°.

No worries! When I was looking this up before deciding on this solution, I guessed it would be 135 degrees, same as ships. I wonder why it is different? I think ships came before airships!
 
No worries! When I was looking this up before deciding on this solution, I guessed it would be 135 degrees, same as ships. I wonder why it is different? I think ships came before airships!

Craig,

I like this solution; Well done.

B
 
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