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RV-10 rudder trim ideas

JackinMichigan

Well Known Member
I ordered the Aerosport under-panel rudder trim kit and spent this past weekend attempting to install it. I finally gave up - it's waaaayy too busy under that panel for that mechanism to peacefully coexist with everything that's currently there.

I definitely need some sort of rudder trim and I want it to look at least a little bit thought out (as opposed to a bendable tab slapped on the rudder trailing edge). I thought briefly about attaching the springs that came with the Aerosport kit directly to the rudder cables somewhere in the tail section, but that could create more problems than it fixes.

So I'm mining the community for ideas.
 
I used the hinge method with a Ray Allen servo. Hard to see in the photo but the servo is mounted on the inside of a removable access panel to the left of the threaded rod fairing. I installed during the build but it still would be an EZ retrofit to a flying plane with minimal paint touch-up. IIRC I used about 10" of hinge and That would give a little over a full ball either side. I found it an invaluable accessory on my -10, especially with various loading and winds aloft.
41682471265_1f70f46e45_c.jpg
[/url]DSC01477 by David C, on Flickr[/IMG]
 
I ordered the Aerosport under-panel rudder trim kit and spent this past weekend attempting to install it. I finally gave up - it's waaaayy too busy under that panel for that mechanism to peacefully coexist with everything that's currently there.

I definitely need some sort of rudder trim and I want it to look at least a little bit thought out (as opposed to a bendable tab slapped on the rudder trailing edge).
So I'm mining the community for ideas.

I just described a rudder trim tab that I made, which requires no special attachment. I cut a piece of scrap to match the tail light mount on the right side, and left most of it squared off on the left side. Then bent a relatively large radius bend to put the protruding part at oh, perhaps 20 degrees less than right angle to the rear. Drilled holes to fit tail light screws and slotted on right side for tail light wiring. Amazingly enough, my first attempt at the angle proved to be absolutely correct for no rudder input in straight and level.
The force needed for climb or descent is so little, I can't imagine having an adjustable trim that is only needed for perhaps 10 min at each end of flight if you go up fairly high.
 
The hard part with that approach looks like it wouldn't be mechanical, but electrical. I'll assume you have a control switch somewhere on your panel.
 
I ordered the Aerosport under-panel rudder trim kit and spent this past weekend attempting to install it. I finally gave up - it's waaaayy too busy under that panel for that mechanism to peacefully coexist with everything that's currently there.

Doh, this was going to be my solution. Is it because there are items such as wiring, mounted items ect that interfere with the kit?
 
Doh, this was going to be my solution. Is it because there are items such as wiring, mounted items ect that interfere with the kit?

Yes. I was originally going to mount it on the co-pilot side, but that's where my radio stack and Garmin GTN-750 is. The structure built into the panel to support all that makes it near-impossible without significant structural reworking, and I wasn't about to do that laying on my back over the seat hump with a Dremel tool.

The pilot side is the same story, that's where all the computer 'guts' are. I would have to remount a couple units deep in the bowels of the panel layout to make it happen.

That being said, you might have better luck. I'll sell you mine for cheap.
 
I just described a rudder trim tab that I made, which requires no special attachment. I cut a piece of scrap to match the tail light mount on the right side, and left most of it squared off on the left side. Then bent a relatively large radius bend to put the protruding part at oh, perhaps 20 degrees less than right angle to the rear. Drilled holes to fit tail light screws and slotted on right side for tail light wiring. Amazingly enough, my first attempt at the angle proved to be absolutely correct for no rudder input in straight and level.
The force needed for climb or descent is so little, I can't imagine having an adjustable trim that is only needed for perhaps 10 min at each end of flight if you go up fairly high.

I did the same. Simple to do and no lasting damage if you don?t like it.

Carl
 
Here is the simple trim tab I mentioned in my earlier post. Not my idea - I stole it. Hard to see, but the tab is bent aft perhaps 30 degrees.

Carl
Rudder_trim_tab_6-2-16.jpg
 
Yes. I was originally going to mount it on the co-pilot side, but that's where my radio stack and Garmin GTN-750 is. The structure built into the panel to support all that makes it near-impossible without significant structural reworking, and I wasn't about to do that laying on my back over the seat hump with a Dremel tool.

The pilot side is the same story, that's where all the computer 'guts' are. I would have to remount a couple units deep in the bowels of the panel layout to make it happen.

That being said, you might have better luck. I'll sell you mine for cheap.


I PM'd you for that kit.
 
Cleveland tools sells the plastic trim wedge for 15 dollars. It?s paintable. I Installed it just above the lower rudder fairing on the trailing edge of the rudder. The plane was 1/2 ball out, now the ball right in the middle at cruise.
 
Rudder Trim

Here's how I built my electric driven spring bias rudder trim. Works well.

i-VJfDhfn-S.jpg
i-RsdddPS-S.jpg
 
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Rudder trim

Paddy - your attachment didn't show up. I'm interested is seeing all the options..
 
Here is the simple trim tab I mentioned in my earlier post. Not my idea - I stole it. Hard to see, but the tab is bent aft perhaps 30 degrees.

Carl
Rudder_trim_tab_6-2-16.jpg

I?m confused by this set up. The tab is pronounced on the right side of the rudder, which in turn would cause a left rudder deflection as a result making most trim situations worse.

My Christen eagle and most aerobatic planes have a small
Tab on the left side of the rudder to offset the right rudder needed
To stay in trim. Am I missing something in this setup?
 
I?m confused by this set up. The tab is pronounced on the right side of the rudder, which in turn would cause a left rudder deflection as a result making most trim situations worse.

My Christen eagle and most aerobatic planes have a small
Tab on the left side of the rudder to offset the right rudder needed
To stay in trim. Am I missing something in this setup?

Depends on the plane, my ball was about 1/6th out to the left in cruise, needing just a dab of pressure on left rudder in cruise. Applied about 1? length of the Cleveland trim tab wedge to the right trailing edge of the rudder, problem solved.
 
......... I found it an invaluable accessory on my -10, especially with various loading and winds aloft. ......

I'm curious about your comment regarding winds aloft. How would winds aloft require a change in rudder trim?
 
I?m confused by this set up. The tab is pronounced on the right side of the rudder, which in turn would cause a left rudder deflection as a result making most trim situations worse.

My Christen eagle and most aerobatic planes have a small
Tab on the left side of the rudder to offset the right rudder needed
To stay in trim. Am I missing something in this setup?

All I can say is when I'm in straight and level cruise at 75% power I have to keep steady pressure on the left rudder pedal to keep the ball centered.
 
I?m confused by this set up. The tab is pronounced on the right side of the rudder, which in turn would cause a left rudder deflection as a result making most trim situations worse.

My Christen eagle and most aerobatic planes have a small
Tab on the left side of the rudder to offset the right rudder needed
To stay in trim. Am I missing something in this setup?

Put the tab on whatever side of the rudder you want. For the RV-10 the ball was just touching the left side line in cruise (as in a little left rudder needed). Other planes will be different.

Note - do not add a rudder trim tab until after very carefully rigging the plane, including the wheel pants and gear leg faiinrg. If these are off just a little, you can get half a ball out on either side. Do not think ?once and done? on rigging. This can be a multi-month process.

Carl
 
Pictures fixed

I fixed the missing photos in post #15 if anyone's interested in seeing a version of an electrically operated spring bias design.
 
Here's how I built my electric driven spring bias rudder trim. Works well.

i-VJfDhfn-S.jpg
i-RsdddPS-S.jpg


Wow, that is a really clean setup. I like the fact that a guy doesn't have to cut pieces out of the rudder and run extra wiring to the back. What type of servo are you running for it?
 
Rudder Trim Details

The servo used in my setup is a standard Ray Allen unit, T3-12A if I recall, the one with the long throw. The pulley in front was turned out of a piece of 6061 rod and runs on a bronze bushing captured by an AN-4 bolt through the center. The idler arm is a length of 6061 C channel and also runs on a bushing. There's a piece of 1/16" angle riveted to the underside of the tunnel between the pulley and the arm for stiffness. I bought the springs and arms from Geoff at Aerosport. The mechanism works well, I do use it in flight, especially on long climbs and descents. I like that the spring tension keeps the rudder from flopping around so much in the breeze at fuel stops, although I wouldn't walk away from the plane without the control lock installed.
 
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