What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Elevators not even

Tbarsic

Member
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
 
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.
 
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.
 
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.

Plus one for Terry's comment, this to be done after Carl's suggestion to make sure they are indeed offset. Even though it will fly OK as it is, why leave it sub standard if it can be fixed.
 
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.
 
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.
 
Last edited:
Even if you get the elevators perfectly aligned, the elevator trim tabs won't be. I was surprised to find that the trim tabs do not move together, but rather are asymmetric. I called Van's builder support when I first installed them and found they didn't move together, and was told that this asymmetric movement is by design.

Not saying you shouldn't try to get the elevators aligned, but just that it won't make a difference in handling, as pointed out by Mel above.
 
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.

I really hate to disagree with Mel - he’s a much greater authority than I am, but when I purchased my RV7A 5+ years ago it had a misaligned elevator. It was QUITE noticeable in flight and wanted to cork screw the aircraft through the sky. The faster I went the worse it became. The builder even mis-rigged the flaps and ailerons to compensate for the elevator’s problem. This was not safe and definitely not comfortable. I spent several months getting things corrected and the flight controls properly rigged.

My suggestion is go ahead and make sure after you’ve gotten the push rod bearings and washers in correctly check everything thing out and if they’re still misaligned have the old holes welded back in and redrill the holes.
 
Last edited:
I really hate to disagree with Mel - he?s a much greater authority than I am, but when I purchased my RV7A 5+ years ago it had a misaligned elevator. It was QUITE noticeable in flight and wanted to cork screw the aircraft through the sky. The faster I went the worse it became. The builder even mis-rigged the flaps and ailerons to compensate for the elevator?s problem. This was not safe and definitely not comfortable. I spent several months getting things corrected and the flight controls properly rigged.

Not sure how far you elevators were off. They can certainly affect roll if off far enough. I have seen them misaligned almost an inch without any noticeable effect.
It sounds like you airplane had several rigging problems.

And, BTW, you cannot "rig" ailerons to trim "roll". Regardless of where they are rigged, they will balance themselves with the airstream. The only way to rig aileron for roll control is by raising/lowering the attach points or altering the shape of the trailing edge.
 
Back
Top