Van's Air Force
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Rudder trim tab
- Thread starter jimbo
- Start date
Norman CYYJ
Well Known Member
Fly it first. If built properly you won't need one.
Kyle Boatright
Well Known Member
There are at least two common methods of installing a trim tab.
One is to pop rivet or glue a balsa wedge along the trailing edge of the rudder. The wedge is 6" tall or thereabouts, and is flush with the trailing edge. With wedges like this, you make one, tape it to the rudder, fly with it, adjust, and repeat until you have determined the right size. Then you finish it (I used model builder's monocote to cover mine, then proseal and pop-riveted it to the rudder) and attach it.
Others install aluminum tabs that can be installed or adjusted after the first flight. Pop rivets are a typical installation method, although I'm sure there are other options. I'd suggest a 6" tab of .032 or so, extending 1.5" beyond the trailing edge. If you don't install one before your first flight, it should be easy to retrofit. Structurally, it would probably be best to attach it to the stiffening angles in the rudder.
One is to pop rivet or glue a balsa wedge along the trailing edge of the rudder. The wedge is 6" tall or thereabouts, and is flush with the trailing edge. With wedges like this, you make one, tape it to the rudder, fly with it, adjust, and repeat until you have determined the right size. Then you finish it (I used model builder's monocote to cover mine, then proseal and pop-riveted it to the rudder) and attach it.
Others install aluminum tabs that can be installed or adjusted after the first flight. Pop rivets are a typical installation method, although I'm sure there are other options. I'd suggest a 6" tab of .032 or so, extending 1.5" beyond the trailing edge. If you don't install one before your first flight, it should be easy to retrofit. Structurally, it would probably be best to attach it to the stiffening angles in the rudder.
chrispratt
Well Known Member
Jimbo:
Rudder tabs are pretty common on RVs as with other airplanes. Don't pre-install it.
Fly the plane first to determine if you need one. If you do, then I suggest buying the tab that Avery Tool sells (about $10). It's made of a pvc type plastic, is 6 inches in length. Tape it flush with the trailing edge of the rudder (I used a piece of the heat shield material you get from Van, cut it a bit oversize and used it to cover the whole tab and attach it to the rudder. The foil removes easily but is plenty tough enough to stay on during flight.)
Once you've flown and tested, if the tab proves to be too long, trim it. try about a half inch at a time and repeat the process until you have it right. Once satisfied, you can paint it the same color as the rudder, then attach permanently. I used 3M weather strip adhesive and it works great. Plus you can remove it later if your trim changes (This can happen after the airplane settles in. After all things such as wheel fairings move with use and may affect the trim after a hundred hours or so.)
Chris
Rudder tabs are pretty common on RVs as with other airplanes. Don't pre-install it.
Fly the plane first to determine if you need one. If you do, then I suggest buying the tab that Avery Tool sells (about $10). It's made of a pvc type plastic, is 6 inches in length. Tape it flush with the trailing edge of the rudder (I used a piece of the heat shield material you get from Van, cut it a bit oversize and used it to cover the whole tab and attach it to the rudder. The foil removes easily but is plenty tough enough to stay on during flight.)
Once you've flown and tested, if the tab proves to be too long, trim it. try about a half inch at a time and repeat the process until you have it right. Once satisfied, you can paint it the same color as the rudder, then attach permanently. I used 3M weather strip adhesive and it works great. Plus you can remove it later if your trim changes (This can happen after the airplane settles in. After all things such as wheel fairings move with use and may affect the trim after a hundred hours or so.)
Chris
chrispratt
Well Known Member
I bought the avery trim tab but found that I could take my 3 or 4 inch wide plyers or metal benders and lightly bend the trailing edge of my rudder. A little goes a long way so be careful. If you go to much you can undo it. Very easy and you don't have to have the ugly trim tab. I ended up putting the avery trim tab on the kitfox. I have a perfect rudder now on both airplanes.
Last edited:
Rick6a
Well Known Member
It it attached to the LEFT side of the rudder.
http://www.vansairforce.com/community/showthread.php?t=2271
I suggest you follow the instructions and temporarily affix it to the rudder as is. Bear in mind this wedge is a compromise and you adjust it to keep the ball centered at the airspeed of your choosing. You decide. Test fly. If necessary, trim the wedge down in 1/8" increments. Test fly each time you trim it. When satisfied with its overall performance, you can epoxy it in place or like mine is, affixed with double sided carpet tape.
Lycosaurus
Well Known Member
Offset vertical stab
The RV-9/A has an offset on the vertical stab if built to plans. I have found I don't need any rudder trim, flies 'feet off' .
The RV-9/A has an offset on the vertical stab if built to plans. I have found I don't need any rudder trim, flies 'feet off' .
using right rudder means you need to have air pushing on the left side of the rudder. either bend a little to the left on the rudder trailing edge or put the trim tap on the left side.
Rick_A
Well Known Member
Thanks
I'll start testing with it this week. I did a long x-country last week (Georgetown,TX to Jax,FL and back). I knew the rudder trim was off but the long trip convinced me that I have to fix it.
I also found that I picked up at least a 2 to 3 knots when I centered the ball.
I'll start testing with it this week. I did a long x-country last week (Georgetown,TX to Jax,FL and back). I knew the rudder trim was off but the long trip convinced me that I have to fix it.
I also found that I picked up at least a 2 to 3 knots when I centered the ball.
tc1234c
Well Known Member
I agree. My first rudder needed a small trim tab. After fixing the lower trailing edge that was popped open by wind gust while parked I need a trim tab three times as long. Not satisfied with the ugly rudder, I built a new one. Now I can cruise without needing a trim tab. When build the trailing edge straight your airplane will fly straight. Of course if you found that you have to keep your foot on the rudder paddle, you better put a trim tab on.
rocketbob
Well Known Member
another data point
I flew for nearly 10 years with the small rudder/VS and a trim tab about 8" long. Two weeks ago I replaced my VS/rudder with the taller, counterbalanced version, and while I was at it I offset the leading edge of the VS 1/8" to the left in an attempt to eliminate the need for a trim tab on the new rudder. To my delight it flew with the ball in the center with the new setup, no trim tab required.
I flew for nearly 10 years with the small rudder/VS and a trim tab about 8" long. Two weeks ago I replaced my VS/rudder with the taller, counterbalanced version, and while I was at it I offset the leading edge of the VS 1/8" to the left in an attempt to eliminate the need for a trim tab on the new rudder. To my delight it flew with the ball in the center with the new setup, no trim tab required.
