wing tip alignment

[scrockard]

While installing the W-931 and W-916 wing tip ribs, I somehow caused the wingtip trailing edge to be misaligned by about 1/4" from the aileron neutral position. Before drilling out rivets and trying to fix this problem, I am curious about the following questions:

1. What are acceptable tolerances for trailing edge mis-alignment?

2. Will this trailing edge wingtip mis-alignment possibly cause a "heavy wing" tendency if not corrected?

[schristo@mac.com]

the wingtip alignment has very little impact on rigging but will nag your eye forever if you don't address it... it should align with the aileron at the tip but should also stay in plane with the flap to aileron line... to get this you might need to split the trailing edge and drill a new rib...

[scrockard]

Originally Posted by schristo@mac.com

the wingtip alignment has very little impact on rigging but will nag your eye forever if you don't address it... it should align with the aileron at the tip but should also stay in plane with the flap to aileron line... to get this you might need to split the trailing edge and drill a new rib...

My aileron and flap on this wing is very straight and aligned! I agree, I need to fix this wing tip trailing edge alignment!

I'll try to relieve the pressure which caused this mis-alignment by drilling out the W-916 rib first. Since the w-931 is glued in, I assume that removing it will be a lot harder so I'll put that off.

Now if I have to go so far as needing to split that trailing edge, do you have any advice on gluing it back together again? Is flox mixed with epoxy ok for re-gluing? I ask this because I would probably want to re-glue while clecoed back onto the wing so alignment is easy to check.

Should I consider any additional fiberglass layups inside (where it's not visible) to try to restrengthen the re-glued edge?

[BillC]

Originally Posted by schristo@mac.com

the wingtip alignment has very little impact on rigging

Contrary to the above comment, I found that the wingtip alignment had a SIGNIFICANT impact on the rigging. I had not paid attention to having the ailerons set to neutral when installing the tips and found that I had a heavy left wing. Problem went away after splitting the trailing edge and adjusting it properly.

I used a thick flox mix with one layer of glass inside cloth to rejoin the trailing edges. No sign of splitting in over 3 years.

[scrockard]

Thank you to you guys who answered my initial questions!

I finished this fix and here are my observations on what caused it and what not to do while splitting the edge.

After removing the w-916 rib, the trailing edge didn't move one bit back to correct alignment telling me that it was my w-931 causing all of the problems! I did two things wrong on w-931: I didn't cleco it up and verify alignment prior to gluing and riveting. I remember the slightly malformed fiberglass wing tip not meeting the rib in all places so I therefore put a weight on it while gluing - this is most likely what gave the trailing edge the mis-alignment!

Now for splitting the wingtip. I first used a dremel cutoff disc(s) and this didn't work very well. It wasn't large enough diameter to penetrate the whole distance into the fiberglass end. It also is darn hard to keep aligned down that edge when you can't line up on it with your eyes to verify your work. I ended up basically butchering that edge with the dremel tool. Huge gel coat chunks were breaking off as a result of this initial cutting. The second tool I used was a variable speed jig saw with a fine tooth blade. I could line my eyes up with this saw and basically verify that I was cutting straight down the middle the whole way. This is the saw I would recommend for splitting wing tips!

Gluing: I purchased some 2" fiberglass tape. I stretched plastic wrap onto the aileron for protection. I also covered two wood strips (my clamp edge) with plastic wrap. I then roughed up the inside fiberglass edge with a dremel sander drum. I then put a large diameter dowel attached to a string inside the split tip so I could pull this out of the way once the fiberglass was in place.

With the wingtip clecoed onto the wing and aileron in proper alignment, I wet the tape with a straight mixture of 1:1 epoxy using a rubber squeegee. Note: the epoxy was mixed together for 2 minutes first! I also pre-wet the inside of the wingtip fiberglass with epoxy and then applied the tape to the inside of this wingtip. I folded this tape so the two edges stuck beyond the end of the wingtip in as straight of a manner as I could. I pulled the spacer dowel down and then clamped the whole mess together. After curing, I now had a new fiberglass backing to help fix my chipped gelcoat areas with a microballoon based epoxy fill. Applying fiberglass inside also allowed a fiberglass to fiberglass "structural" joint to be made. If I put this on the gelcoat, I wouldn't have had as strong of a glued joint. My long-ez buddies tell me that I shouldn't glue fiberglass onto gelcoat anyway.

Now this is a lot a work for not checking the alignment prior to gluing w-931. Hopefully I can prevent someone else from making this mistake!