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Elec aileron trim ideas?

sf3543

Well Known Member
The RV3 kits only offer a manual trim on the stick for roll but I would like to have an electric trim
So, I was thinking about the trim kit used in the RV8
There isn't room at the stick mixer and it is a completely different set up, but, I was thinking about installing it in the wing, between two wing ribs, and attaching the springs to the aileron torque tube using a saddle or Adel clamp.
I don't see why it wouldn't work, but thought I would post for any comments
Any ideas or thoughts?
Thanks
 
Just an additional data point here...I didn't install any aileron trim and haven't needed it once in 300 hours. After correcting a heavy wing in initial flight testing the plane flies hands off. It takes roughly 5 gallons of fuel imbalance to induce a heavy wing. A cheap reminder to switch tanks!
 
I have a -4, and it flies hands off except when fuel gets imbalanced. Great reminder to switch tanks. I have the spring trim kit if you need it. I would fly it and get the ailerons right before you try to solve a problem that may not exist.
 
I would concur with Rob and Mike.

Obviously, this is for the 3B or 3's that had wing tank mods, not for standard 3's with fuselage tank. Probably don't need to add that in, but for those that may not know the differences....
 
The aileron trim in Tsam works just fine, but we don't have to adjust it very much. Fun project, nice to have, but I'd have a hard time arguing that it is needed, just desired.
 
I concur with the comments above... not needed. Get it rigged right and the slight imbalance caused by uneven fuel helps your fuel tank SA.
 
Well, you guys convinced me!
For now I'll fore go the roll trim; however, having a stick grip with the coolie hat it's tough leaving a function unused😜
Thanks for the input
 
My 2 cents...

To me, rudder trim would represent a better solution. The biggest reason is drag. Sticking an aileron down into the high pressure air below the wing, and up into the high velocity air flowing over the top of the wing produces much drag. This high drag can be offloaded to the rudder if rudder trim is available for far less drag penalty. Remember that yaw induces a roll, and so the rudder can pick up a low wing more efficiently than the ailerons will.

If the aileron trim condition exists for a over a long enough distance, the drag penalty will impact your flight plan, by reducing your range if you fly the planned speed.

Many people add a fixed trim tab to the rudder and set it to be optimum for cruise conditions. However, adding a movable tab to the rudder will provide more flexibility, meaning you can set it to level the wings at any given speed. You can also set it for takeoff to reduce the rudder input required.

A thought about trim settings for takeoff: Whether it be elevator trim of rudder trim, there needs to be a way to annunciate the current trim tab position, as well as annunciate the correct take off position. If full nose down is the take off setting for the elevator trim, this annunciation is pretty simple to set. But if the rudder trim needs to be set at 50% of travel for take off, the pilot can not identify the correct setting with any accuracy. So feedback in the form of an indicator may be necessary.

Mechanical push/pull cables are hard to beat for operating trim tab systems. No electrical load, no complexity. Flex cables can be bent around the control surface hinge. The control levers that connect to the cables can be easily marked to identify the range of motion as well as specific settings such as takeoff. Movement is immediate, and as quick as you move your hand so you don't have to hold a button for several seconds or more. Plus, the cable system might be lighter, and it will be cheaper.

Some food for thought...

Rick
 
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