I just completed the right wing on my LT-40. Nows its time to join them together. I haven't actually done it yet, but I did a trial fit and it appears to be off just a bit. Included in the kit is a 3.75" dihedral guage. This is to be placed on the left wing tip flush against the last W5 rib and the wing rests of this. This elevates the wing tip to the height proper height to match up with the right wing panel which is flat against the table. In theory, the W1 ribs (which were placed at an angle to allow for this dihedral) should fit flush which each other. Well, mine don't.

The good news is that they come pretty darn close, but only at an angle less than the recommended 3.75". In fact my sanding block is the perfect height. Its about 2.5 inches high. I set it up per the instructions and they don't line up. Not sure how to fix this. I could follow a few steps (subject to replies here) to fix it or I could just go with the 2.5 inch dihedral which seems to work OK. Will this second approach affect anything later down the road?

Here are a few pictures of the wings mating together. These are taken with the sanding block dihedral. I should have taken a few with the 3.75" dihedral, but I didn't. When using the 3.75" dihedral guage, when the wings are bowed up, there is about a 1/4" gap between the bottom main spar ends.....anyway here are the pictures.

Thanks for your input.

If it mates up well at 2.5" then go for it as it won't make that much difference. The plane will fly just fine with that much dihedral, trust me!

Bryris

I agree with Art the plane will fly just fine with that much dihedral, but it will fly just fine a little different than what it would with the proper dihedral.

The dihedral pendulum effect will be slightly decreased which after a few flights will not be a problem , what is more critical is the wing incidence, you will find out later in the build the effect that the decreased dihedral will have in that regard and what needs to be done to correct it then.

on my mark II's I built one with dihedral and the other flat , one required a formed groove for the trailing edge at the fuse the other a I had to raise the trailing edge a little to achieve the proper incidence.

Highlander

If I go with the decreased dihedral, there are two angled wing braces or joiners that look to be angled at the 3.75" dihedral. The wings slide on to both ends and the joinders act as reinforcements to keep the wings from folding. If I go with a 2.5" dihedral, these wing joiners will not properly line up. How do I fix this?

Hi,

You may want to try using Elmer's Probond Polyurathane Glue. This glue is very strong and will requires some humidity to work - the instructions will ask you to wipe a damp cloth over 1 or both surfaces.

The glue will expand when setting and will fill in any voids. The only problem is that it is not a quick setting glue. I usually glue, and after 1 hour, wipe off any excess that expands and then let cure overnight.

I got my glue at Home Depot.

Hope this helps.

Wayne Miller

My advise is stick to epoxy for wing joining!

you can sand the joiner strips to the new angle, or cut new ones from scrap ply. Or add a piece of scrap balsa to the root rib and sand to the proper angle.

my choice would be to adjust the existing braces to the new angle. and use plenty of epoxy in the joiner pockets.

Does anyone have a few good pictures of where to epoxy? Perhaps of an epoxied wing?

I think I am going to set the wings up at 3.75" like recommended and use a piece of scrap balsa to fit in the gaps. With enough diligence, I can probably sand the balsa sheet into a little wedge and wedge it up in the gap and epoxy everything together. It'd probably work well that way.

This is my first kit and I got into it wanting to have a "perfect" plane in the end. But I knew that since this was my first, there'd be bumps along the way. There are little tips and tricks that I've picked up along the way that the instruction manual doesn't even alude to. This airplane will turn out fine! But my next one will be that much better. I guess that's whats the hobby is all about.

Thanks for those replies and for any others that might respond.

Bryris,

I had athe same thing happen. My LHS owner let me borrow a simple, home made sanding tool to beautifully correct this problem. He had a 10-12" flat board about 3-4' long with another board not quite as long or wide attached lengthwise at the edge at a right angle like a backstop. Then on the short end was a groove that a third board could slide back and forth in. He used a simple peice of angle iron to hold this board at a right angle when in the groove and glued sandpaper to the other side of the sliding board. To use it, one half of the wing is laid flat on the board and held firm against the backstop with the wing center-end against the sand paper. Slide the sand paper board back and forth for a square wing center. The same thing is repeated for the other wing half but this time with the dihedral gage clamped in place under the wing. The result was a perfect fit in less than 5 minutes. I was lucky because I could borrow the tool, but material cost would be next to nothing at the home store and they could probably make the cuts for you.

I hope you can make sense of my rambling and try this out. You will like the way it works.

Talon,

I have tried to visualize this and I am unable to without more data. Do you have a picture or perhaps a better description?

Thanks.

I just set the proper angle on my sander table and then sand each wing root for a perfect fit.

That's it! what I was trying to describe is a poor man's (me) sander table! Sorry no pictures.

All I have is a sanding block......I think if I study it for a while and don't do anything and I have it completely worked out in my mind, I'll be able to make it happen. Will see.

Just glue it like it is. I put 1/2" in mine. Shoulda made it flat. That Poly glue will fill gaps like crazy. I'd use epoxy on the joiner and Poly to fill in any gaps. Wipe while its foamy or it's heck to get off.

The epoxie goes on the first rib surface. I would let the dihedral as it is. Modify the dihedral braces. And not worry too much about it. You could use some 4 to 6 oz fiberglass cloth. And wrap the center joint after the wings are joined and sheeted. It would add a lot more strength. If the braces cannot be fitted the cloth would work in leu of the braces. Good luck with your project.

Mark Shuman

Well tis may sound like a very silly question but is your table flat? Sorry I got to ask the obvious. I would recomend building with the less dihederal as have the others. If you decide upon the more try using a piece of tapered aleron stock as a wedge (purchasede from your LHS) even if it is not exact a little planing would get it there. You can leave the excess running wild(past the wing profile) and trim it to shape after epoxy cures and walla problem solved and even better yet you got no wing sheeting to patch in