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Old Jun 18, 2012, 05:19 PM
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United States, UT, North Ogden
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Question
Making separable wing halves

Hi All! I'm looking for some direction as to how to make/rig foam wings that separate at the center, so they may be transported easier, but are still durable. You see, I found a potentally really great slope near my place that requires a significant hike. These are solid foam wings.
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Last edited by Element B; Jun 18, 2012 at 05:34 PM. Reason: Needed to add more info
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Old Jun 19, 2012, 01:14 AM
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Thomasville, GA 31792
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I'd recommend making the wing in three pieces with some dihedral built in at the joints. That will put the joints further out where the stress is much less, and the three straight pieces will be easier to transport.

Each panel of a two-piece wing will probably be longer than the fuselage.
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Old Jun 19, 2012, 02:02 AM
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Fresno CA
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Make it 3 pieces. Bascily some kind of joiner goes into a box located in the spar.

Here are a few pictures of a 100 inch foam wing that I'm currentley working on. The center spar has a heavy layup of aircraft plywood and wrapped to the upper and lower spars. The mid sections have plywood plates between the spar caps to form a box. This wing has 6061 T6 aluminum joiners cut from flat plate. You could use steel or carbon also.

Blue Skies..........................Tim
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Old Jul 01, 2012, 04:05 PM
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United States, UT, North Ogden
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Thanks much for the input, guys, the photos are especially helpful!
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Old Jul 02, 2012, 10:16 PM
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United States, MA, Waltham
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It would help if you told us more about the size and construction of the wings. Three piece wings are fine, but so are two piece. The two piece may weigh a bit more, but the weight is close to the c.g. so it won't hurt the maneuverability.

Are you saying there's no wood or composite on the surface of the foam? The way the Easy Glider and Radian are done is to have long holes in the wing in which you stuff half of a 1 meter long, 10mm diameter fiberglass tube.

If there's a spar, brass tube epoxied into space between spar caps, with music wire joiner is a good way to go. Diameter depends on span, weight, and use of glider. Then a dowel or much smaller music wire pin to keep the wing aligned in pitch.
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Old Oct 05, 2012, 01:46 PM
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Sorry, I didn't note your input. I'm sure there's a way to have to forum notify me of posts on the thread, but I don't know what it is. Its a two meter foam wing, no wood or composite on the surface, with a balsa spar. Looks like your second recommendation would work.
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Old Oct 05, 2012, 08:40 PM
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If you hit the "Go Advanced" button, you can subscribe to the thread.

http://charlesriverrc.org/articles.htm#On-Line%20Plans
For three piece wing method, check out Gentle Lady plans here:
outerzone.co.uk
Looks flimsy but stands up to moderate winch launching, though it's bendy.
For two piece wing, maybe check out the Bird of Time plan at same place, or some of the designs at:
http://charlesriverrc.org/articles.htm#On-Line%20Plans

For a balsa spar in a two meter, you would probably want either 7/32 or 3/16 inch, I would guess, for a two piece wing. Balsa isn't the strongest spar, so perhaps the smaller of the two. You want the rod to bend before the spar lets go. Music wire is very strong and a good wing rod choice for anything up to a quarter inch (6mm).
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Old Oct 06, 2012, 08:18 AM
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I'm no expert in foam wings, but I've used this technique building woodies.... if using brass tubing and a rod as your joiner, build up the halves (or tips as the case may be). Then, take your brass tube and score it fairly deeply in the middle. Mate the wing pieces together, making any adjustments necessary for a perfect fit, and install and glue in place the brass tube with the score right where the wing will come apart. Allow to cure and then snap the tube and it will break at the score line leaving both sides perfectly aligned with each other.

I use this method because it makes for a perfect alignment without having to prop up both sides and trying to get everything aligned and glued without getting glue inside the tubes.
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Old Oct 13, 2012, 12:15 PM
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Thanks for the input and the links! I think I got the thread subscription thing figured out now, too.
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