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Wingtips move, hinge method

SeanB

Well Known Member
Hello All,

I’ve just concluded installing the wingtips using the piano hinge method. Very happy with the results and was able to get the trailing edges to align with neutral ailerons. Used ProSeal under the hinges before riveting, and e-glass to cover the rivet heads. Added stiffeners. Had to modify the aft rib some to miss the hinges, which I’ve seen done by others.

Kinda disappointed though. If I grab the aft part of the tips and wiggle up and down, there is slight play in each. Maybe 1/4” or so. I’m guessing this is play in the hinge. Anyone else have this issue? When at rest, the tips are still aligned with the ailerons. In flight??? Could raise some. Wondering if this could cause heavy wing, and over time cause wear in the hinges.

Any ideas, feedback, suggestions are appreciated.

Thanks!
 

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I think most folks report some movement but don't think 1/4" as that seems excessive.
I have done mine and one side is rock solid and the other side has about 1/16 or slightly more but the pin slides in easier on the side that has movement. Wingtip has been known to have little to no affect on wing heavy so that is not going to be an issue. And I believe if the movement is not in such a way that each time the plane flys, the wingtips rocks up/down then this is not going to be an issue long term.
 
Wingtip hinge

How far forward did you install the hinges? Could that cause it? Mine are pretty solid. Hinge goes almost to the tip. I have to use a drill to get the pins in.
 
Hi Larry. Interesting thought. I do not have the hinges all the way forward. Could be a factor, as you describe. Pictures I’ve seen from prior builders seemed to leave a portion of fiberglass on the leading edge, then start hinges aft.
 

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Hi Larry. Interesting thought. I do not have the hinges all the way forward. Could be a factor, as you describe. Pictures I’ve seen from prior builders seemed to leave a portion of fiberglass on the leading edge, then start hinges aft.

Sean,
Mine are also go forward just as the photos or possibly a little more. I believe only one rivet hole on top was installed without the hinge which I put a dummy rivet.
 
Hinge needs to extend forward a bit more

This is the answer. It will secure the wingtip.

How far forward did you install the hinges? Could that cause it? Mine are pretty solid. Hinge goes almost to the tip. I have to use a drill to get the pins in.
 
Thanks for the replies, everyone. I did just use the standard pre-drilled holes of the aluminum skin to determine length. Wondering if I could add a bit more hinge material (4-5 eyelets) forward of the existing. Will have to be very careful with alignment or I imagine getting pins in will be difficult.
 
Wingtip hinges

Hi Larry. Interesting thought. I do not have the hinges all the way forward. Could be a factor, as you describe. Pictures I’ve seen from prior builders seemed to leave a portion of fiberglass on the leading edge, then start hinges aft.

Mine are almost exactly like the photos. It's a bit of work to get the pins all the way in but they don't move.
 
Sean. The tips on my plane are mounted just like yours and move a little (maybe 1/8") at the trailing edge on the ground. My hinge goes forward enough that the last bit of hinge pin can be difficult, but they go in. I may have used a drill motor when doing the final install to help drive them home.

180 hours of happy flying with all sorts of maneuvering and they show no signs of wear or getting looser. So that's good.

Cheers
 
One snug - maybe 1/16” play, one a bit looser with 1/8 to 1/4”. I can usually remove pins with fingers - sometimes vise grips on snug side. 850 hours with no sign of wear.
 
Initial Try

Thanks again for all the suggestions. I decided to try adding more hinge material to the lower left wingtip. Got it forward enough that I could barely drive the pin, with a drill. Result....No joy! Still about the same amount of movement at the trailing edge of the tip. Next move will be to extend the top hinge forward as well. Thinking to about to the yellow line. It seems to me this hinge will introduce more "resistance" to movement because of the increased amount of arc compared to the bottom one.

  • Thoughts about the yellow line? Forward enough?
  • Maybe extend the bottom hinge even one more eyelet forward of the red line?

I will eventually bridge the added hinge sections together with a doubler.
 

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Hinge

I don't think adding that much forward will help movement at the aft side. Plus, getting that pin in is going to be a challange. How far aft is the hinge?
 
Are you using the correct diameter pin for these eyelets? ie, you didn't swap the pin for a smaller diameter?
 
Larry,
Hinge material stops at the edge of the wingskins going aft. The wingtip support rib begins immediately aft. Pic in Post 1.

Jeff,
Hinge pin is what came with the hinges, I believe 0.090". Will check again though.
 
Well,
After Jeff's comment about the pin...I'm concerned. I see in a few of my photos, the hinge material is stamped, "MS20257-4 and -3". This may be hinge material referred to as P3 and P4 on Van's Order Form??? If so, it may come with 0.090 pins. Seems mine did. This could be the material intended for the upper engine cowl to get around curves better. Will call tech support later.

Now I'm wondering if 0.120 pins may be swapped into this hinge material.
 
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Hinge

Larry,
Hinge material stops at the edge of the wingskins going aft. The wingtip support rib begins immediately aft. Pic in Post 1.

Jeff,
Hinge pin is what came with the hinges, I believe 0.090". Will check again though.

Yep. That's same as mine. I used P4 hinge material.
Hope you find the fix. Keep us posted.
 
Tried it

Update…I added hinge material forward of the existing on both top and bottom runs. I got well into the curve of the leading edge with hopes of arresting play between the eyelets. Had to bevel a few eyelets to get them to interlace. It was quite a bit of extra work. Result? Right wingtip is still moving, but not as much. Maybe 1/8” up and down at trailing edge. Tighter than it was. Left one is about the same as before. Maybe 3/16” movement, but firm. Not sure if it was worth all the effort. In all other aspects, the tips are very solid.
 

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Sean, your setup is now almost exactly like mine with about the same amount of play.

The one thought I had a while back was to squeeze the barrels on the hinges slightly to tighten things up, but the fear is that they would not be uniform and would cause issues when reinstalling. For now, they fly like they are and get checked before every flight ...

Hopefully you're craftier than I and come up with a solution. Fly on!

Cheers
 
I also ground the tip of the pin into a point to help it make the turns and not hang up on eyelet borders.
 
Tip Rib to Aileron Stabilizer

I also used the hinge method to attach my wing tips on my -9A, but I also added small "L" brackets to the tip rib and the aileron bracket and added a bolt between them to prevent the wing tips from moving. It has worked well and I have no movement of the tips.

My build log is on the EAA Builders site: https://eaabuilderslog.org/?blproject&proj=7ZLY3oI53

Photos showing how I did the tips are under the Left Wing subfolder Left Tip entry: https://eaabuilderslog.org/?blproject&proj=7ZLY3oI53&e=7iPycLdUX&sid=&listcat=^left_wing

Not sure if you’ll be able to see the picture I’m trying to put here, if not hopefully the link will work.

showmy.php


For the finial assembly I used a drilled bolt head and safety wired it to the bracket. The bolt is easily accessed in the gap area between the tip and the aileron.
 
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Same problem here. My fix works well. Made a strap to connect the wing to the tip. Riveted to wing, screwed to tip.
 
Pictures added for clarity.
 

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Thanks guys! I was also having similar thoughts to mechanically stop top movement. Your ideas and pics are very helpful! I appreciate it.
 
why hinges

Guys, what is the purpose of the hinges in the wing tips? Why not nut plates and screws? Etc. Im not there yet, but am looking for good mods before I reach that phase.
 
Hinges vs screws/nutplates

Makes R&R fast and easy. Just pull the pin.

OK, granted it may be slightly faster than me spinning out 45 #6 screws per wingtip using an electric drill. ;)

OTOH, think I've had the wingtips off maybe 3 times since first flight. Once for paint, second time for a landing light upgrade, and third time to pull a new temp probe wire through the conduit. Other than needing to get in for landing/strobe/nav light access, there's no reason to pull the tips for any maintenance related job......at least on my airplane. Yours may be different.

Interestingly, the screws/nutplates addition to the wingtips is itself a change to the original plans. The 3/4/6 plans call for flush 1/8" pop rivets on the wingtips. Not sure about the later models.

Next time you see a T-34, take a look at the spar to leading edge connection. Held on with hinges and pins.....probably thicker hinges with larger pins than the ones being used for RV wingtips, but still pinned together. So, it does work to hold relatively important things together on a wing.
 
I agree with above post. This mod is just not worth it. Wing tips very rarely come off and when they do it’s a very quick job with power screwdriver.
 
I agree with above post. This mod is just not worth it. Wing tips very rarely come off and when they do it’s a very quick job with power screwdriver.

I agree that if the primary motivation is faster removal/installation, then this mod is not worth the effort. I have done the standard way and my latest plane has the hinge method. I did it primarily for the looks and I lucked out as mine has no movement.
 
Wingtip hinge movement

I just thought of something.
Is it possible the movement isn't due to the hinge?
Maybe it's because the wingtips are so flexible. Some builders stiffen the open areas top and bottom with various materials. I used 1/4" dowels. Two top and two bottom.
Just a thought.
 
Hi Larry,

I was also questioning the flexibility in the tips. But, I installed two upper and two lower stiffeners per tip. Foam, faired micro, then two layers of 9 oz. cloth to encapsulate. Made the oil canning go away very well. Same movement persists on aft tip though. When I lift the aft wingtip, I can see the movement uniformly going forward along the upper rivet line. This makes me think it is the spacing between eyelets, once more.

I wonder if Mark and Joe’s methods to arrest hinge movement includes installation of stiffeners or not. This could lend answers toward wingtip flexibility being a contributing factor.
 

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I decided to give Joe’s idea of a hinge spanner bracket a try. I elected to install mine near the aft part of the bottom hinge. Keeps the fasteners “hidden”, but not as easy to access. Also, I can see this location being overlooked while removing a wingtip and maybe causing damage when pins are removed. I definitely notice a difference on the right tip, that had the most movement. If it was a 1/4” movement before, it may be 1/16” now. Happy for that. Again…thanks everyone for your ideas of various solutions. Way too much time on the wingtips. Time to move on to the next bout of fiberglass fun…the empennage fairing!
 

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