Elevator attachment questions

This evening decided to work on attaching the elevators to the HS. I had seen other people talk about how you had to take the elevators off and put them back on several times to get the right fit.

I literally did this maybe 30 times each side. I was struggling getting what I felt was an even 1/8" gap between the or 1/8" gap between the outboard edge of the HS and the counterweight arm of the elevators. I got it as close as I felt I could get it without it rubbing and moved on with drilling the horns, making the wood wedge and drilling the bottom part of the horn. Happy with my progress I went to bed.....

However something wasn't sitting right. I start getting concerned that maybe there's a twist in my elevator counterweight sections... or maybe I backed the connectors out too much. Not being able to sleep I got searching the interwebs and found a post that in short said the #1 factor is that the Elevators must be parallel to the HS. And on top of that you need to have the connectors a minimum of 3/8 inch or about 9 turns in.

Went out to the garage and started losing one of the connectors... got 3 turns and then it was out. Did the other and got about 8 turns... if there's that much of a difference then it's obviously not parallel.

* So are the elevators parallel to the HS when properly installed?
Going off this new found assumption I decided to start this process over on the right elevator. I measured the 7/8 depth and move the nut down to that level. Set the other one to that level as well and screwed them both in.

I then drew a line between a set of inboard rivets and set of outboard rivets on both the elevator and the HS. This gives me a method to measure the distance between the gaps. If the distance is equal then they're parallel. Looks like this;



After tinkering with both sides I was able to get an even 1.5 inches between the rivets both inboard and outboard... so parallel I believe.

* There are still uneven gaps on between the HS ends and the counterweight arms. Can this be fixed?

So the end result of having both elevators on and spaced an evenly across the board with 1.5" between rivet lines still ends up with an uneven gap on the arms.

Left side is 1/8" aft and 1/4" at the tip of the arm.



right side is 1/8 aft and 5/16 far forward



Any help on this would be appreciated, going to now see what rivets I need to order with my new Horn pieces.

As a followup, I talked to Vans this morning.

The elevator doesn't necessarily need to be exactly parallel with the HS. Having the elevator not bind on anything and the arm gap as close to 1/8 possible is key.

So that said the only issue with my original installation was that I had some of the rod bearings backed out too far. So going to do a few adjustments to close those 1/4 gaps on the leading edge closer to 1/8th. However even if it's 1/4 it's not that big of deal.

On the elevator horns I don't need to replace them but instead have the holes welded closed and redo it.

One more thing you need to keep in mind-----------not only do the individual elevator halves need to be free from binding, but they need to work freely after being bolted together also.

A string pulled from all the way from one outboard hinge on the stab to the other side should be equal on all hinges.

Mike S said:

One more thing you need to keep in mind-----------not only do the individual elevator halves need to be free from binding, but they need to work freely after being bolted together also.

A string pulled from all the way from one outboard hinge on the stab to the other side should be equal on all hinges.

Click to expand...

Mike, not entirely sure what you mean. I have the hinges bolted in right now and the horns clamped together with a piece of wood between and it's bind free up to 30 degrees.



Now not sure if I should measure from the counterbalance arm or from the elevator surface as in the picture... If it's from the arm then that's 40 degrees or close to it.

AviatorJ said:

I have the hinges bolted in right now and the horns clamped together with a piece of wood between and it's bind free up to 30 degrees.

Click to expand...

Yes, that is what I was trying to get across, sounds like you are on top of things.

Justin are you saying that the left elevator when 100% even/parallel with the HS causes the right right elevator to be not 100% even/parallel?

And vans said that was okay?

Just getting clarification..

It is critical to get the rod ends the exact same distance from elevator spar. I have seen twist in the counterbalance arm, so being a little uneven there is acceptable. The most important point is that the HS brackets are all in line (sight from one end and all of the other holes should center on the end hole you are looking through. You should be able to sight the rod ends on each elevator the same way, making sure they are all centered first. I have done many elevators this way and they fit right the first time. Once you get a bolt in two rod ends, the third should slide in without too much trouble.

Put both elevators on this way individually and drill the pivot horn hole. Then assemble both elevators, align the counterbalance arms and drill the horns. They will not necessarily be even. The plans describe how to position the hole if they are not even. The elevator should hit both stops without any binding.

Palamedes said:

Justin are you saying that the left elevator when 100% even/parallel with the HS causes the right right elevator to be not 100% even/parallel?

And vans said that was okay?

Just getting clarification..

Click to expand...

No sorry, what i was trying to convey is that with the elevator parallel to the HS the gap between the outboard HS edge and the counterbalance arm isn't exactly 1/8 inch even down the entire thing. It flares out to about 1/4 inch at the most forward spot. That's what vans was fine with and seems Jesse has seen that too.

Jesse said:

It is critical to get the rod ends the exact same distance from elevator spar. I have seen twist in the counterbalance arm, so being a little uneven there is acceptable. The most important point is that the HS brackets are all in line (sight from one end and all of the other holes should center on the end hole you are looking through. You should be able to sight the rod ends on each elevator the same way, making sure they are all centered first. I have done many elevators this way and they fit right the first time. Once you get a bolt in two rod ends, the third should slide in without too much trouble.

Put both elevators on this way individually and drill the pivot horn hole. Then assemble both elevators, align the counterbalance arms and drill the horns. They will not necessarily be even. The plans describe how to position the hole if they are not even. The elevator should hit both stops without any binding.

Click to expand...

Thanks Jesse, I can look down the spar and visually all the bracket seem to be in line. Are you saying that both rod bearings need to be set to the same depth? I started at the suggested 7/8 from eyehole to base and ended up having to twist each a bit (maybe a turn each) to get equal distances on the rivet lines.

I do have a question on the elevator deflection. When measuring it, am I looking for 30 degree deflection from its starting "trail" position up or does the elevator go 30 degrees up from parallel to the ground?.... Might sound confusing but with the HS level on the bench the elevators are actually 5 degrees down when locked in the trailing position.

Also I ran through the drilling and it worked great. Unfortunately now I need to weld up my holes and do it over. Luckily I know some pro welder so so they're helping me next week.

I'm not sure what you mean by "equal distance from the rivet lines", but the center of the bearing should be 7/8" from the elevator spar. If the nutplates inside are sitting flat on the inside of the spar, then it should be the exact same number of turns on each.

You measure deflection from where the elevator is when the counterbalance arm is even with the HS. You may see 4 degrees down on the top of the elevator, but maybe it will be -4 degrees on the bottom. Both elevator counter balance arms should be flush with the HS at the same time when everything hooks up. Checking travel before bolting everything together doesn't help. One horn will limit up travel and the other will limit down travel unless they are perfectly even, which I don't think I've ever seen. Individually they should smoothly travel stop to stop as a starting point, though.

So the top picture shows the lines I drew, did that on both the outboard and inboard ends for each elevator. Then I measure pad the distance between them and if it was say 1.5 inch son the outboard I looked for 1.5 inches inboard. This was my method to ensure the rear HS spar and the forward elevator spars were parallel. I'll take it all off and start again with each rod screwed into exactly 7/8 and see if anything binds and how the gap looks... If all is good I'll go with that.

Thanks for the clarification of measuring the angle. That makes sense because when we measured the flaps on my 172 0 degrees is when it's inline with the cordline of the wing. When the flaps are at the 15 degree setting its actually 20 or so degrees down in relation to the ground.

Elevator Travel

I spoke with Vans when I was setting the elevator travel and just wanted to pass on what they said. In the plans, it shows 30 degrees up and 25 degrees down measured from the chord line. I queried the mothership on this and they said that there is actually a range for the deflection. They told me 25 -30 up and 20 - 25 down, measured at the chord line.

You may find that at the maximum up deflection, when all of the pushrods are installed, that the clearance on the control stick base bolts is very small when the stick is swept through it's full range of motion (specifically, full aileron, full up elevator). Reducing the maximum deflection by a degree will allow adequate clearance...

FYI

My left elevator doing the same thing.

Jesse said:

It is critical to get the rod ends the exact same distance from elevator spar. I have seen twist in the counterbalance arm, so being a little uneven there is acceptable. The most important point is that the HS brackets are all in line (sight from one end and all of the other holes should center on the end hole you are looking through. You should be able to sight the rod ends on each elevator the same way, making sure they are all centered first. I have done many elevators this way and they fit right the first time. Once you get a bolt in two rod ends, the third should slide in without too much trouble.

Put both elevators on this way individually and drill the pivot horn hole. Then assemble both elevators, align the counterbalance arms and drill the horns. They will not necessarily be even. The plans describe how to position the hole if they are not even. The elevator should hit both stops without any binding.

Click to expand...

So my left elevator is exhibiting the same thing as Justin's was.
I have a 4 to 5/32" gap aft and 12/32" gap forward.
My right elevator has a nearly perfect gap the entire distance.

I made sure my rod bearing ends were all screwed in the same amount on both.
I started by marking the threads of the rods at the 7/8" and screwing the jam nut to that location. I then screwed the first one in until the jam nut contacted the spar (about 11 turns) and measured from the spar to the bearing center point verifying the 7/8 distance again. I did a similar procedure for the other rods, but mostly relied upon using the same number of turns.

It sounds like there just might be a bit of a bow/twist to my left counterbalance arm and the more critical thing is that the rod bearings are the same distance from the spar (and no interference)

Mostly just wanted to make sure this is acceptable or if I should continue to take this off and on to try to make it better?
The first few adjustments I made didn't seem to make much difference.

Left elevator:


Right Elevator:

Adam-

If I remember right I had gone back through and ensured each rod bearing was screwed in enough (at least 3 threads I think) and that each elevator had the same distance from each rod bearing. That at least ensured a symmetrical fit to both side.

When I got to the point of securing the fiberglass tips that pulled in or untwisted my concerning parts. I ended up with bind free movement and a livable gap. Here are some pictures...

Thanks, Justin.

Prior to taking those pics today, I redid all of the rod bearings to make sure they were all the same length from the spar. Mine are certainly screwed in enough. I only have 3 threads showing between the jam nut and the bearing end.
So I guess I'll continue on and hope that it pulls in a little bit when doing the fiberglass work.

I also spoke to the mothership today, and they advised to either
1) make adjustments to the rod end bearings (move outboard inward and inboard outward) or
2) Drill out the 12 rivets (6 top, 6 bottom) that connect the counterbalance skin with the tip rib and elevator skins and then move the counter balance arm where you want it while re-riveting.

After doing 3-4 additional rod bearing adjustments cycles tonight, I just wasn't happy with either the gap or some binding I was getting at one point. So I gave up opted for #2.

The end result is much better. Only a 3/32" difference between the forward and aft ends. Compared to it being 8/32" difference prior.
my right side only has a 1/32" difference forward to aft.

So I'm happy with where it ended up, and with any luck it'll tighten up a little more when I put the fairings on.

I'm getting ready to rivet my elevators. Is ther anything I can do during the river process to prevent this possible issue? I would assume a square edge between the front spar and counterbalance tip would be helpful

mciaglia said:

I'm getting ready to rivet my elevators. Is ther anything I can do during the river process to prevent this possible issue? I would assume a square edge between the front spar and counterbalance tip would be helpful

Click to expand...

Yeah maybe checking squareness would help prior to riveting these 6 rivets on the top and bottom:



One other thing to note is that I did have a bit of a hump in that area on my left elevator. Looking closer last night I think I fluted the flanges of the tip ribs in the wrong direction at a couple of spots to get the holes to better line up. So the fluting "bumps" were pushing up against the skins. I flattened those out with my squeezer and that seemed to help get rid of the hump.
I wonder how much that mistake may have contributed to this issue in my case.

Getting ready to rivet the counterbalance tips. After clecoing and prior to rivetnig I put a square on it. Perfect on the left and the right one had about a 1/16" gap. As I rivet I will constantly check this alignment to make sure the issue from above doesn't happen....hopefully

Reviving an old thread here.

I have the exact same issue in that my counterbalance arms aren't square to the HS. Incidentally, they exhibit the same amount of "twist". I have 1/8" at the back of the counterbalance that then becomes almost 3/8" of an inch forward. However, I have no binding anywhere on both elevators and the distance between the HS rear rivet line and elevator forward rivet line are identical outboard and inboard, so I think that means the rod end bearings are the same length (7/8") at both positions.

I'm inclined to leave it be, looking for a second opinion?

echozulu said:

Reviving an old thread here.

I have the exact same issue in that my counterbalance arms aren't square to the HS. Incidentally, they exhibit the same amount of "twist". I have 1/8" at the back of the counterbalance that then becomes almost 3/8" of an inch forward. However, I have no binding anywhere on both elevators and the distance between the HS rear rivet line and elevator forward rivet line are identical outboard and inboard, so I think that means the rod end bearings are the same length (7/8") at both positions.

I'm inclined to leave it be, looking for a second opinion?

Click to expand...

It's funny you revived this when you did. I just fit my elevators to the HS this evening. 1. I placed an ink mark on the threads halfway, so I'd know when half the threads were left. 2. I tightened the jam nut as far as I could on the bearing and screwed the bearings all the way in. Because I knew the spar was true, I counted the rotations I had to unscrew the bearings to achieve 7/8". Then I unscrewed the other bearing the same number of rotations. 3. I verified this bearing was at the 7/8" mark.

My left side was perfect with a 1/8". The right side was a different story. I realized the counterbalance arm on the right was not square. After consulting with some other builders, I clamped the forward counterbalance arm to the HS. Then I measured the distance between the aft-most rivet line on the HS to the forward most rivet line on the elevator. I had to make a couple of minor adjustments to the bearings to ensure the distance on the left elevator perfectly matched the distance on the right elevator.

Then I unclamped the counterbalance arm, lowered the elevator and placed a block of wood on either side of the leading edge of the counterbalance arm. Then I slowly twisted the counterbalance arm in an effort to straighten it out. To my dismay, it only took a few mins and I was able to rectify the issue. My only complaint is that the right side has a gap that is 1/32" wider than the left. I also don't understand how this happened but my two elevator horns are perfectly aligned.

This worked perfect for me. I was afraid I might break something by twisting the counterbalance arm, but my friend talked me into it and I'm glad I listened. I hope this helps. I'm going to re-check everything in the morning before I drill the elevator horns.

rocketman1988 said:

I spoke with Vans when I was setting the elevator travel and just wanted to pass on what they said. In the plans, it shows 30 degrees up and 25 degrees down measured from the chord line. I queried the mothership on this and they said that there is actually a range for the deflection. They told me 25 -30 up and 20 - 25 down, measured at the chord line.

You may find that at the maximum up deflection, when all of the pushrods are installed, that the clearance on the control stick base bolts is very small when the stick is swept through it's full range of motion (specifically, full aileron, full up elevator). Reducing the maximum deflection by a degree will allow adequate clearance...

FYI

Click to expand...

Did you get anything in writing from Vans on the deflection range? I?m about 2 degrees short of up, and 2 degrees short of down. If what you said is correct, I?m in the appropriate range, but I?ll need to prove this to my inspector at the final inspection prior to flight. Something from Vans in writing would suffice I think.