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Rig Elevator Trim

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Pat Stewart

Well Known Member
Today I attempted to rig my elevator trim tabs. I set up the cables per the drawing and then set by trim tabs at 35 degrees down as directed by the print. That is the last place they stayed together. While moving the trim tabs all the way up the right side worked well however the left side tab stopped just short of neutral. Anyone have this problem?

Pat
 
Todd

I'm wondering if having them both together is a good idea. Or are you going to have the correct amount of up trim but much more reduced down trim?
This might be a problem if you had a trim run- away in flight and had too much down trim.
If you think about it all the other vans have a trim only on one side so are asymmetric.

Peter
 
David, thanks for the link to the other site. I rigged it this morning per those instructions. It solved a couple of problems. Both tabs reach trail or neutral at the same time and both are either above or below the elevator at the same time. The result however was that there was very little travel (1/8 inch) above trail on the left elevator tab. Both tabs traveled below the elevator fine and the right tab traveled above the elevator fine. Am I to understand this is how it is designed to work. Why does Vans not go into more detail on this issue on the prints.

I really appreciated the help and I like Todd's design and may consider it in the future after I am flying.

Pat
 
As stated by somebody else, the fact that you get nose up trim with both but nose down trim by only one is by design. There is more than enough nose down trim authority so no changes necessary. You do however need both trim tabs for sufficient nose trim up when at slow speed during the flair especially with a forward CG.

Bob
 
Pat Stewart said:
David, thanks for the link to the other site. I rigged it this morning per those instructions. It solved a couple of problems. Both tabs reach trail or neutral at the same time and both are either above or below the elevator at the same time. The result however was that there was very little travel (1/8 inch) above trail on the left elevator tab. Both tabs traveled below the elevator fine and the right tab traveled above the elevator fine. Am I to understand this is how it is designed to work. Why does Vans not go into more detail on this issue on the prints.

I really appreciated the help and I like Todd's design and may consider it in the future after I am flying.

Pat
Click to expand...

It is my understanding that the reason the trim was designed this way was because Van's originally planned to have a system that would automatically apply trim when flaps were deployed. This is sometimes done in airplanes where excessive stick forces and trim requirements result when flaps are deployed. This proved not to be the case with the RV-10, so the auto-trim was eliminated from the design, but the trim actuator was left as is.
I have over 300 hours on mine now and I am very happy with the trim. You should have more than enough trim authority in both directions.
 
dmaib said:
It is my understanding that the reason the trim was designed this way was because Van's originally planned to have a system that would automatically apply trim when flaps were deployed.
Click to expand...

That is what I was told also, so far the trim has been a non issue for me in my limited testing period.
 
Thanks guys, without this forum I would have never believed that it was designed to work that way and Vans drawing certainly has the rigging process wrong.

Thanks again.

Pat
 
As pointed out - the most important thing is to get them lined up at neutral.

On the heavy nose - I found that if you are on your own (like I am now during test flying) you will have a nose heavy plane even with full aft trim. This is easily cured by landing with 15 degree flaps. Works very well for me at least.
 
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