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Elevators not even
I purchased a finished empennage and I am still checking to make sure things were completed correctly.
One questions, I have the elevators bolted together through the elevator horn hole where the push rod is bolted to. I checked and noticed the elevators are not perfectly even. Is this common, should it be corrected, is there a limit? The horizontal stab is bolted to a bench. See pics. https://imgur.com/gallery/hVrGFn5 Thanks |
Before you weld the drilled hole and re-drill, put in all the spacers and the pushrod journal bearing (with washers) and check again.
Carl |
Rod end bearings
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To circle back to your original question; The way you're supposed to set these during construction is to adjust the helm joints (screw in bearings that act as hinges) to get the distance from the center of the hole to the face of the elevator spar that is called out on the assembly print, then clamp the counterweight horns flush with the horizontal stab, then drill the hole for the bolt that goes through the center bearing.
The elevators are supposed to be symmetrical with each other, but the center steel horns may not be. This is all covered in the build manual. You can get a copy on a USB from Vans. |
Just as an aside, misaligned elevators will not significantly affect flight characteristics of your airplane. I've seen some that were pretty far off and you could not detect anything from the cockpit.
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Elevator alignment
There must be some clearance ( or cooling distortion) in the weld fixtures, because I have an RV3 and RV4 that the horn weldments were not aligned when the elevators are fixtured in the same plain. I believe that is a contributor to the
Rudder tab on my RV3 that is required to center the ball. I discovered the problem on my -4 project and corrected it. |
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Tip
I used a neat tip to adjust the Heim Joints.
Buy two sections of polished 3/16" rod. Debur the ends. Slide one through all the Heim Joints onbone side. One rod each side or use one twice. It's nice to work both sides the same time so all of them end up exactly the same. Now it's easy to get a measurement from the spar surface to the polished rod either side of each Heim Joint. They should match. Of course the measurement is short by 1/2 of 3/16". Do the math. Adjust by sliding it out, turn 1/2 a turn whichever direction, tighten the pinch nut a little and measure again. If the exiting holes in the weldments are off, find a Tig welder to fill them and redrill. |
You should only have to weld/redrill one side. The trailing edge of the elevators should line up with each other. The elevator horn may not, and in most cases, won’t line up with each other precisely. Once the trailing edges are lined lined up with hinge points set, drill through the horns for your bolt. Start a little smaller and work your way up. You can start with a bushing and a 1/8” bit through the hole you didn’t weld shut, and then work your way up to the correct size, drilling through the welded/repaired horn. Not a problem if it’s a clean weld and everything is cleaned up. Don’t forget to prime and paint the repaired area of the horn.
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Thanks
I appreciate, I slept on this and I am glad many of you agree to what I came up with.
Like Carl said I'm going to get the pushrod bearing in and the washers and recheck if it is still off I will have a friend that is a professional welder that can weld better then I can. I will get him to weld and I will redrill. I will post back the results. Overall the builder of the empennage did a great job, I am picky and I want my first plane to fly well. Thanks, once again. |
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