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Wing tube

Old 11-29-2005, 04:33 PM
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Lomcevak Duck
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Default Wing tube

Hey guys. I'm rolling a massive plane for the first time (first one this size I've designed, but neither my first design nor my first giant scale) and I'm going to use an aluminum tube to join the two outer wing sections to the center section, but I need a few pointers if you all would be so kind. I am thinking that the tube should be at about 30-35% of the chord which will put it slightly behind my spar. But I am also thinking that the spar should be the strongest part of the wing, and I might need to move the tube foreward a bit. Like I said, I have done both my own designs before and flown giant scale, but this is the first of this size I have rolled, and I have never messed with multi peice wings before. I know full well it would be easier to just build it in one peice, and probably more structurally sound, but this plane is going to have a twelve foot wingspan. and that is far too large to transport in one peice. I have attatched the preliminary sketch of the wing center section at the bottom. If some of you with an engineering background could take a look at it for me and point out any major problems you see with it I would greatly appreciate it. I am going to redraw this section as soon as I get the spar location figured out. I also need a good source for locating a Clark Y airfoil section I can print out and blow up to the size I need (24 inch chord) and would appreciate if any one who has one in a file they could send me in an email would drop me a PM. I know there a thousand programs I can buy that will help me do this, but I only need one good Section to work with. Thanks in advance.
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Old 11-29-2005, 07:14 PM
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Balsacutter
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Default RE: Wing tube

Glider guys build multi-piece wings that withstand winch loads on zoom launches that you wouldn't believe, with very thin wing sections. I think many design for 160lbs wing load on launch. Their websites provide a wealth of info on wing joiners.

Re your design, if you assume the spar is by far the strongest structure in the wing, I can't see why you wouldn't focus on transferring the wing joiner loads to the spar structure. Maybe a much smaller pin aft for alignment.
Old 11-30-2005, 05:32 AM
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shag555
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Default RE: Wing tube

Do you have a ARF two piece that you could copy? Perhaps one of your friends do? I'm going through the same thing you are. Re-design of a WH Extra 300 to a tubed wing. Fortunately I've a 27% Extra 260 to reference. The wing tube layout you have drawn is pretty much what H-9 designed in their Extra 260 (IE wing tube behind the spar.

For lightening purposes, your rear anti-rotation tube could be made into pins instead of a tube. Just cut lengths and epoxy them into the wing halfs. If you want to affix them, you can drill them where they just enter the fuse and put a cotter pin, or hitch pin through the hole you drilled.

My re-design starts today. I'll be building the fuse and wings as per the H-9 design, only applied to the Extra 300 plans. I'll be putting up a post once under way.

MPB

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