RC-Captain

I attempted to get help with changing my dihedral trainer wing into a flat wing and didn't get many replies. So tonight I bit the bullet and this is what I came up with. Please I may need advice on strengthening the built up center balsa stock so the spar doesn't break. I will definitely use nylon straps ,so to speak, underneath the wing to help hold it together. Or I just may use some downspout scraps.

smitymax

Not to good of an idea to splice...end glueing the center brace. Suggest you go to you local Home Depot or other lumber supply and get a piece of 1/4 inch hardwood such as oak etc, and make a one piece spar brace... You may have to trim the width a bit but would be much safer than the two piece modification.

the-plumber

Ditto.

That's a first-flight crash you're building into the model.

RC-Captain

thanks, will get wood tomorrow It keeps on breaking ,balsa is too weak.

Flyboy Dave

My Feedback: (21)

I agree... but a little dihedral is preferable.

FBD.

RC-Captain

I'm removing the dihedral to improve on my no dihedral wing and aerobatic flying skills. I jumped into the low wing Eztra 300 .28 and I swear it feels and looks as if this plane is going 150 mph. but of course we all know it isn't

RCKen

My Feedback: (9)

Splicing the wood like that is an accident waiting to happen. That brace needs to be on piece of wood.

TexasAirBoss

My Feedback: (22)

I agree with the comments above. I generally use 1/8 inch thick plywood. You might have to cut out two identical braces and glue them together to make them thick enough. OR three, or how ever many it takes to have a brace as thick as the original. And I would use epoxy to glue them together and when assembling wings center section . Practice assembling the wing several times and check to make certain that both wings have the same incedence . And check that there isn't a large gap any where.

RC-Captain

Hi, I found a piece of wood that is exactly the same thickness as the original brace. I had to cut off some of the width and of course shorten the stick which was about 4 feet long. Originally I was going to just make the spar and use screws to hold it to the wing. Then I figured I have enough wood to make a few mistakes and start over so I also drilled holes for a nuts to just fit in the brace and not spin when inserting the screw. Well take a look and let me know what you think.

Bill DCat

Good job with the new brace. But I have a couple of comments I hope you'll take as constructive criticism...

First, securing the brace with nuts and bolts will probably work for awhile. But with all the stresses on the wing while doing aerobatics, the holes will probably stretch out and the brace will loosen up. I'd go ahead and coat the brace with epoxy and glue it in.

Second, I believe you need to fill the gap in the top of wing. There's a couple ways to do it. One is to cut the ribs off of each end of the wing half and make new ones. Glue the new ones on with no dihedral. Then epoxy the two wing halves together (with the brace). The other way to do it (and probably easier) is to get a piece of wood (hardwood would be the best choice) and shape it and taper it to fill the gap. Then just epoxy the wood between the two wing halves.

Hope that made sense. I'm sure there other ways to do it, but that's what came to mind.

Good luck...

Bill

the-plumber

Um . . . couple of things . . .

You gotts to get rid of that _gap_ !!!

The screws will probably rip out the first time you load the wing in flight because they are the only things transferring wing load to the joiner.

Much better you should slather the joiner with epoxy and embed it into the wing halves, _after_ you've dry-fitted the parts and the two halves are aligned as closely as possible.

Ever see the video of the C-130 fire fighting tanker where the wings folded in flight ? Same result, different cause.

the-plumber

Yeowzzah !!!

One fast and dirty way to make a wedge to fill the gap is to snag a pack of floor shim wedges from The BORG. Fit the shim wedges (as many as are needed) up through the wing, front to back. When the wedges are fitted and trimmed, pull them back out, coat 'em with epoxy, and stuff 'em back into the wing.

Notcherly you gotts to dodge around the joiner . . .

RC-Captain

What are these? Thanks to the both of you , that was my next question, 'how to fill the gap?' Do you really think the wood brace would fold ? I will fill the gap , but I want the wing to collapse for transporting . I don't have a huge car . Also on the bottom ,servo side , I will make a top mounted brace. see pic

Flyboy Dave

My Feedback: (21)

Fill the gap with epoxy. Get it to fit as good as you can first. Put a piece
of tape on the underside so the epoxy stays in the wing. Then trim the
covering away and glass on a strip of fiberglass tape to the seam. Then
smooth it all down, and recover the seam with a slight overlap.

It will never break now !!!

Dave.

RC-Captain

OK I'm done , here is the finished conversion . I feel it will hold without a problem. . Keep in ming I will tape over the tiny gaps , but the wedges will definitely keep the wing from folding.