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Wing fit

RGaines

Well Known Member
We are putting everything together for the final time. Put the wings on again and marked for the rubber seal. Installed the seal and put the wings on. One was VERY tight, the other doesn't fit. Maybe as much as 1/8th short. Called van's and they said "push harder". Did a lot of pushing and that isn't the answer.

Anybody have any ideas?
 
Howard told me about your problem at an EAA meeting last night. Since both wings and pins fit before the weather strip, I'd remove it from both wings, refit the wings and pins and then carefully measure the wing to fuselage gap on both sides. It sounds like one wing has more clearance than the other. Either that or the non fitting seal is thicker than the other.
 
Just tried fitting left wing. There is quite a big discrepancy between the leading and trailing edge tabs. How much do these need to be filed to fit? Won't this change the wing incidence?

Any hints gratefully received...Keith
 
We are putting everything together for the final time. Put the wings on again and marked for the rubber seal. Installed the seal and put the wings on. One was VERY tight, the other doesn't fit. Maybe as much as 1/8th short. Called van's and they said "push harder". Did a lot of pushing and that isn't the answer.

Anybody have any ideas?

John Bender had this problem also. He invented a tapered pin that can be tightened up with a wrench to draw the wing skin into the seal.

Here is his post in another thread.

http://i568.photobucket.com/albums/ss124/JBender_photos/RV-12WingInstallPin100_1105.jpg

I had a local machine shop make this for me. Solid steel. Slightly under 1 1/2" diameter, with 2" taper from 1" to 1 1/2", then polished. 1/2" X 13 thread in both ends for pulling in from the rear, and pulling back out thru the front. Once it is pulled in, you can put in the other sides pin, and remove the special pin with the sleave and a bolt or threaded rod.

John Bender


Maybe he can let you rent it for a few $$$. I know I'm gonna....CHEAP!


Have you tried warming up the seal with a couple of hairdryers?
 
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Just tried fitting left wing. There is quite a big discrepancy between the leading and trailing edge tabs. How much do these need to be filed to fit? Won't this change the wing incidence?

Any hints gratefully received...Keith

There should not be anthing left to do on the wing. There is nothing left to fit or trim to fit at this point. Something is not right. Double check your rollers to ensure they are installed correctly.

Can you post a picture?
 
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Thanks Larry

In cool, or cold weather, it is nearly impossible to compress the seals after you have installed them. If you can trim the seals a little, you might make it. I have not had my plane together in warm weather, so I can't say if it will work ok then. It was about 50 degrees last fall when we tried to "push hard", and we could not get them. With my special tool, they just 'groan' pulling it. They are sure solid once you get the pins in. I don't plan to remove the wings very often, so it is ok with me. The special tool is on the bench at the airport !

John Bender
 
I used an electric palm sander to reduce the thickness of the seal, especially where the seal crosses a rivet or screw on the terminal block (F-1270C). The seal is very rigid and sands nicely. Just go slowly - lot of trial and error.
 
More detail

This was my first trial fit, so there's no trim involved.

I'm at least half-an-inch short of getting the spar hole to line up with the fuselage, so a tapered pin is premature.

At this point the tab on the rear spar seems to be centred in its slot. The tab on the front sub-spar is hard against the top of the slot with a big gap at the bottom. It looks to me that I would need to take at least quarter-of-an inch off the top of the tab to get it to go right into the slot, and I have already taken some off. And then I guess it would not make contact all the way around. The tabs fitted nicely into the holders when I was building the wings...

If I rotate the wing anticlockwise looking from the tip to the fuselage, I can get the front tab lined up, but then the rear tab is too high.

I don't know whether I should be removing material from the front, or rear, or both. Presumably removing material from the front leaves the wing at a higher incidence than removing at the rear.

Keith...puzzled
 
It looks to me that I would need to take at least quarter-of-an inch off the top of the tab to get it to go right into the slot, and I have already taken some off. And then I guess it would not make contact all the way around. The tabs fitted nicely into the holders when I was building the wings...

Keith, I cannot stress enough, IMHO, that no material should have been removed at this point. Doing so will not allow the front & rear spar to fit properly into their sockets. If they don't fit tight the wing can twist in flight.

Can you take pictures & post them?

Have you double checked the installation of the roller bushing?

This would be a good time to call Vans.
 
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Wing Fit

Keith

Look at page 14-2 Fig 2. You didn't by chance get the left and right stub spars reversed on the wing assemblies. That would cause the stub insert to be too high.
 
I only started filing because the plans say you can, but I was concerned about the amount of material I would have to remove - that's why I stopped.

I have looked at Section 14-02. I'm not sure what I am looking for here. If I had put the stub spars on upside down the profile of the tab would look completely different. These seem OK. I also checked the front receptacles to ensure I did not mount these upside down - again these look OK. I cannot see how to check the rear receptacles. And the rear spar cannot be upside down, fortunately ;-)

I cannot see how I could have done anything wrong with the rollers. In any case the spar hole seems to line up vertically with the fuselage hole.

Keith - now worried!
 
something is not right

I agree with Larry- something is not right. When I have installed mine, I find they sometimes need a bit of help in either the forward or aft direction in getting started in the slot but once they are in, they go easily and there was certainly no discrepancy in the vertical plane. The main spar really sets the incidence and the stub spars provide additional support to prevent twisting (as Larry mentioned). However, I don't recall seeing anyone else encounter a problem where they don't line up. Agree that a call to Van's is warranted. And I would be concerned if any significant amount of material has been removed such that one will no longer fill the receptacle.
 
Thanks

Thanks, guys for your help.

I thought the spar rolled on the larger diameter half of the roller, not the smaller diameter half. Makes sense now. So I need to reverse the rollers. That should do the trick.

I'll also check with Vans to see what they have to say about the material removed from the tab. I'd hate to have to take a wing to pieces.

Cheers...Keith
 
Keith, I cannot stress enough, IMHO, that no material should have been removed at this point. Doing so will not allow the front & rear spar to fit properly into their sockets. If they don't fit tight the wing can twist in flight.

Can you take pictures & post them?

Have you double checked the installation of the roller bushing?

This would be a good time to call Vans.

I strongly agree.
This is a rather important structural load connection.
My guess is that something is wrong with part assembly...bottom line, you should not need to remove material and if you do it could be detrimental.
 
One step forward, two steps backward

Ken Scott confirmed what I had been thinking - replacement parts required.

Now on order. Still kicking myself, but thinking rationally about it, it will probably just add another three or four days to the build. I am nervous about drilling out several hundred rivets with the attendant risk of causing further damage...

Happy days...Keith
 
Ken Scott confirmed what I had been thinking - replacement parts required.

Now on order. Still kicking myself, but thinking rationally about it, it will probably just add another three or four days to the build. I am nervous about drilling out several hundred rivets with the attendant risk of causing further damage...

Happy days...Keith

The key is to first use a 1/16" diam. pin punch and small hammer to drive the steel stem out of the center of the rivet. You can then safely drill right through the rivet with an 1/8" drill bit.
 
Ken Scott confirmed what I had been thinking - replacement parts required.

Now on order. Still kicking myself, but thinking rationally about it, it will probably just add another three or four days to the build. I am nervous about drilling out several hundred rivets with the attendant risk of causing further damage...

Happy days...Keith

We all make mistakes. I am just glad you posted the problem and we caught it now, rather than try to fly with it like that. :eek:

Glad I could help.
 
Marty & I were talking about a loosing fitting wing after the get the wings in place. If you grab the end of the wing you can get it to "rock" fore & aft. This is before you put the seal on. Any movement in this area is not good, IMHO. We took a .020 shim and cut it to fit in the front or rear spar. This took up the extra space and took care of the "slop". The wings are now rock solid.

If you are building the wings do not remove a lot of material on the front and rear spars that fit into the sockets. Easy does it with material removal in this area.
 
Shim

Does the shim you made slide into the receptacle in the fuselage alongside the spar tab?

Keith
 
Does the shim you made slide into the receptacle in the fuselage alongside the spar tab?

Keith

What I did was put them on the face of of the spar tab. They are about 1/4" wide x 4" long and I taped it to the face, or very inboard surface. That way it took up the slack for for and aft movement of the wing tip. This was to take up just a few thousands of an inch. In your case you have removed quite a bit of material and you'll need to replace the tabs.

If you can post some pictures it would really help.
 
Episode closed

Not sure photos explain anything.

The root cause of my problem was having the spar rollers the wrong way around. The plans are clear and correct. I just second guessed them. The wing won't fit that way, period.

I just tried again having reversed the rollers. Both wings slid straight in, and so did the pins.

Replacement parts are on order, including 500 rivets ;-) so I can redo the stub spars at my leisure happy in the knowledge that the wings WILL fit.

Thanks all for your help/advice...Keith
 
Murphy's Law

You had a 50-50 chance of getting the rollers orientated correctly. Anything that can go wrong will go wrong. At least you are going to fix it the right way. Some others might file down the tabs until the wings go in. The plans could be modified to add a couple of extra rivets next to the small end of the roller. This would ensure that the roller can only be installed one way. Two rivets cost less than a lawsuit, not to mention saving builder frustration.
Joe
 
Joe, The plans are more than adequate here. You gotta follow them!!!

You had a 50-50 chance of getting the rollers orientated correctly. Anything that can go wrong will go wrong. At least you are going to fix it the right way. Some others might file down the tabs until the wings go in. The plans could be modified to add a couple of extra rivets next to the small end of the roller. This would ensure that the roller can only be installed one way. Two rivets cost less than a lawsuit, not to mention saving builder frustration.
Joe
 
The best guidance for RV-12 builders that run into any situation similar to the one that perpetuated this thread (something not working the way it is supposed too), is to not do anything it does not specifically say in the construction manual unless you call technical support at Van's first.

In this case, the manual does not say to file on the stub spars if/as needed.
The only time the manual says to do any filing on these parts is during wing construction. Even then, it says to do only enough to get a close fit between the parts so that they fully mate together.

If something doesn't seem to be fitting like it should, it is pretty much a certainty that something is wrong.
 
In my defense ;) the note at the top of Page 30-03 says "If the stub spar interferes with installation of the wing the stub spar may require local dressing with a file". That's the point at which I got started. When I got beyond the point of "local dressing" (probably way past that point) I stopped to reconsider.

If the note had said "The stub spars are important structural components". They should fit without adjustment" it would be more helpful. I guess the instructions are fine for fools, but not good enough for **** fools ;-)

Murphy's Law (variation on) If it is possible to fit a part the wrong way, someone will. Enough said.
 
Wing fit.

Marty & I were talking about a loosing fitting wing after the get the wings in place. If you grab the end of the wing you can get it to "rock" fore & aft. This is before you put the seal on. Any movement in this area is not good, IMHO. We took a .020 shim and cut it to fit in the front or rear spar. This took up the extra space and took care of the "slop". The wings are now rock solid.

If you are building the wings do not remove a lot of material on the front and rear spars that fit into the sockets. Easy does it with material removal in this area.

Today we installed the wings for the first time. They fit very tight and solid. However, when I lift the end of the right wing something shifts a tiny bit, enough to make a bit of a clunk. I think there is just a bit of play in the front spar tab/socket. (I did not remove any material from the tabs during wing construction.) I wonder if I should consider adding a shim as you fellows did. Or maybe when the seal is installed the movement will go away. Thoughts?
 
In this case, the manual does not say to file on the stub spars if/as needed.
The only time the manual says to do any filing on these parts is during wing construction. Even then, it says to do only enough to get a close fit between the parts so that they fully mate together.

Scott,

Beg to differ a bit. The general instructions, tell you to remove the machining marks/nubs from the parts to eliminate any stresses. In this case, that is all I did. Yet still needed a small shim.

Maybe in this case, a special instruction in the plans is needed to ensure the builder removes ZERO material from these areas. When I fitted the parts per the plans, they fit just fine. Now I realize, a loose fit here would NOT be detected.

Your comment?
 
Today we installed the wings for the first time. They fit very tight and solid. However, when I lift the end of the right wing something shifts a tiny bit, enough to make a bit of a clunk. I think there is just a bit of play in the front spar tab/socket. (I did not remove any material from the tabs during wing construction.) I wonder if I should consider adding a shim as you fellows did. Or maybe when the seal is installed the movement will go away. Thoughts?

Do you notice the slight play when you rock the wing up/down or fore/aft. The shim I needed was for fore/aft.

The wing root seal will most definitively help here. All movement is lessened/eliminated with the installation of the seal.
 
Scott,

Beg to differ a bit. The general instructions, tell you to remove the machining marks/nubs from the parts to eliminate any stresses. In this case, that is all I did. Yet still needed a small shim.

Maybe in this case, a special instruction in the plans is needed to ensure the builder removes ZERO material from these areas. When I fitted the parts per the plans, they fit just fine. Now I realize, a loose fit here would NOT be detected.

Your comment?
I think you missed the context of the original discussion. (And it doesn't help that I messed up and wrote wing construction...I meant fuselage construction.)
The builder was fitting his wings to the fuselage. I said that their was nothing in the manual that said to remove any material when test fitting the wings, only at the time of fuselage construction when they were directed to test fit the fuse parts to the already built wings.

I don't see the need for a special instruction. The way the manual is written the builder is expected to only do something if the are instructed to. The manual would be ten volumes if they were instructed in all of the things not to do.
Even when they are told to remove material, they are told to only do so if needed. Because they are designed to be close fitting parts, it is possible for a slight mismatch just from tolerances of the CNC punch machines. It sounds like yours fit fine. Some of them require a very small adjustment (the Teen Flight fuselage parts did).
 
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Scott,

Thanks for weighing in on this. The only thing I did during construction was remove the burrs and "nubs" from the CNC machine to get a smooth mating surface. I only have this tiny play on the right wing. The play is up and down, not fore and aft. I cannot feel any movement, but I can hear it, and I think it is coming from the foreward stub. Certainly the wing isn't going to fall off, but I wouldn't want to hear that noise every time I hit a little turbulance.

Do you think I am being overly concerned, or does this warrant further investigation? I wonder how many others have experienced the same thing.

John
 
Big John

I know 3 planes, and they all did/do it. Shimming can solve it. Cut a thin piece and put in the slot, and try it. Adjust as needed. You can glue it in or whatever. After the wing seals, you likely won't know it. The seals really tighten things up.

John Bender
 
Wing repair

Allow me a little self-indulgence ;-) My wing is now essentially fixed, following recovery from a little over-enthusiastic filing during the trial fitting.

Vans shipped me replacement sub-spars and a mountain of rivets. I ended up removing top and bottom inner wing skins, and opening up the front of the middle skin. On reflection, I only needed to open up the rear end of the top inner skin.

Thanks to feedback from you good folk, I planned on tapping out the rivet mandrels and drilled out the rivets with an undersized drill. An added complication was I had filled all of the rivet heads in anticipation of painting the wings. I'm pleased I ordered two pin punches, as the first one fell to bits mid-way through the work.

The mandrel tapping turned out to be mandrel banging. After I had removed around 1000 rivets! I got inside the structure and removed the rivets holding on the sub-spars. Much easier with no filler in the rivet heads. Now I know that I should have drilled out the filler before tapping out the mandrels. As a consequence my wing now looks decidedly secondhand with many small indentations around the rivet holes - almost dimpling. May not look good, but my plane will now go faster than yours ;-) If I ever have to do this again (Heaven forbid) I won't fill the rivet heads until the very end, if at all.

My inspector found just two oversized holes that I will need to fill with a bigger rivet, not too bad after attacking 1000 of them. And I managed to drill an extra hole when the drill slipped, so I have a unique customisation as a reminder not to make such a big mistake again. Fortunately the hole is under the wing so only me and thee know it is there. Mega lesson learned, methinks.

So, I am back building again. My fuel tank still leaks after three attempts, so the fun is not over yet...

Cheers...Keith_the_wiser
 
Hi Keith,

Just in case your inspector did not mention it to you Cherry Max rivets come in two sizes for each normal size, which is to say for the 1/8 inch rivet they also make one just a little larger for projects like your that have had to drill out rivets and the holes are no longer standard size. You can google Cherry Max Rivets and you will find the details of size and drill size required. I hope that this may save you having to go to 5/32 rivets.

Best regards,
Vern
 
I had the same problem until ...

I had the same problem. Removed and replaced the wings a number of times
(easily) until the seals were installed.
One saturday morning a number of friends joined in to install the right wing. The left had finally succumbed. But that right wing refused every effort by seven men (all with idea's) to install that wing. It was sooo close. We pushed, we used a dead-blow (I know - I know), we lifted, trimmed the seal in places.
No-go!
Others dropped by until the hangar filled with people. Still no-go.
Then, almost as I decided to call it a day, my next door neighbor, an AP in the process of rebuilding a wrecked Cessna 172 RG, stopped by.
I saw him standing just outside the hangar door watching the keystone cop macabre actions taking place around that wing. I stepped over to say hi as he leaned over to whisper, "have any tie downs?"
"How many?"
In his halting english he said, "Four."
I probably stock no less than 20 tie-downs, so I found four new ratcheting types (orange 12 footers) and handed them to him.
All hands stepped back as he approached the devil wing. Without the rear window installed it made it very easy for him to loop one end of a tie-down to the bottom of the roll bar where it joined the fuse canopy ledge.
Looped another around the landing gear where it exits the fuse. Joined those two tie-downs with two more and laced the last through the hand hold at the wingtip. He then ratcheted the straps snug, walked to the spars and stuck his finger into the pin hole on the opposite side. Stepped back, put one more slight ratchet into the assembly. stepped back to the spar and put his finger into the hole for the inside pin. Made one more fianal adjustment by picking up the wingtip - walked to the spar and slipped the pin into the wing-side hole. Walked around to the other spar pin, and slipped it in.
You could hear a pin drop.
 
Nice Tip Using ratcheting Tie Downs to make the wings fit with the rubber seal in place... Thanx

If the rear window is installed you don't have that anchor point...so I wonder if one can put the threaded ring wing tie-downs into their wing locations Left and Right Wing then anchor ratcheting tie-down between these two rings, below the two wings passing under the fuse and then ratchet the two wings towards each other. I know you will get a slight side loading because you are pulling/ratcheting along the bottom of the wings, so one need to ensure you rock the wing slightly up and down while pulling the wings in, and only do a little bit at a time.

What do you guys think?
 
Pulling wings on

Instead of attaching the tie down straps to the airplane, how about making one giant loop through the wing tip handle, over the open cockpit, through the other wing tip handle, under the fuselage, and back to the beginning. Theoretically one could use a single very long tie-down to make the giant loop. But 4 tie-downs will give more precise control of wing position.
Joe
 
Or this

RV-12WingInstallPin100_1105.jpg


Works well. Takes 5 minutes to pull them in, and no damage to bushings.

John Bender
 
Trusting my memory - WATCH OUT

The solid steel pin ( 6" OA length ) is just under 1 3/4" if I recall. The end is 1 1/4" tapered for 2". Both ends are center drilled and taped for 1/2" X 13 thread. You can use a bolt or threaded rod. The SS sleave is to put over the bushing in front to pull it back out. It is only maybe 5 thousandths less than the bushng bore. Once pulled thru the second bushing, the pin goes into the other side easily, then pull the tapered pin and install the second pin. I use it on the pilot side.

Honestly, I have not tried taking the wings off in warm weather. May not need it then.

John Bender
 
Hey Joe

If it expands far enough it could work. Not sure if it would leave small marks inside. I'd guess not.

Went back to the start of this thread. The figures above SHOULD have said taper from 1" to 1 1/2". You'd need an expander with those dimensions. Sorry !

John Bender
 
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Installing wing pins

Yesterday we were having trouble getting the holes in the wing spars lined up to insert the pins. So I tried out the new tail pipe expander tool that I had purchased from Harbor Freight (pictured above). I wish that it was a little longer, but still was able to use it by centering in on the spars. It was a simple matter to put a 5/8" ratchet on the long shaft end and tighten it it up. The Pin then went easily into the other spar holes. Then I loosened the tool and removed it and replaced it with the pin. It was a piece of cake. The gasket is not installed at the wing root yet, waiting for painting. I do not know how the pipe expanding tool will work with that gasket in place. So far I am happy with the tool.
Joe
 
Joe, I'm curious. Did you do the steps yet to mark the wing skins at the roots for the 1/8" gap, and trim the skins back? My wings fit OK without the seal strips, but I suspect they would not fit so well with the gap seals in place, so I went ahead and did the trimming to the 1/8" line, so I won't be messing them up after paint.

Paint coming in the next couple of weeks.

John
 
Did not trim

John,
No, I did not trim the wing skins yet to make room for the seal. Some builders had trouble getting the wing pins in place when it was cold outside. That rubber seal does not give much when cold.
Joe
 
wing fit

regarding the wing fit against the seal, did you heat the seal enough to soften it. We recently installed a wing and had a heck of a time w/one of the wings, so we got out the ol' hair dryer (or heat gun) and gave it a little more heat. That and a bigger hammer, and the pin went right in.
 
Luggage straps

It's always cold in Scotland ;-)

As noted elsewhere, I am using luggage straps attached to the wing tie-down rings, to pull the wings together (with the seals in place). Works every time, no hammer needed.

Just make sure you screw in the rings as far as possible to minimise un-designed bending moments.

Cheers...Keith
 
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