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Old Oct 16, 2013, 04:35 PM
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converting one piece wing to two

Sounds easy, but it's a solid spar of spruce (roughly 1/4"x1/2" in a Wanderer) so I can't readily add a joiner tube.

Since this is a light 2m balsa plane, that will never see a winch, and prolly no hi start either (just light wind sloping) can I just "marry" a joiner tube right to the back side of the spar with some wood filler blocks to get the height same as the spar, and maybe wrap some kevlar thread for good measure?

I can't fit a 60" wing in my trunk, much less a 72"! Another plus is that it can then fit in my glider backpack instead of carrying it loose.
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Old Oct 16, 2013, 04:54 PM
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If you have access to the spar why not epoxy a 1/8" thick piece of plywood joiner on each side of the spar sticking out maybe 2-1/2". Then on the other wing make a box on each side of the spar for the joiner to slip into.

You could also wrap the plywood joiners around the spar as well as the box on the other wing.
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Old Oct 16, 2013, 05:18 PM
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http://www.rcgroups.com/forums/showt...1672934&page=4

Check out post 6. Not the same plane, but for what you're thinking about, I'm pretty sure this will work.

You'd be adding a joiner tube to the wing, gluing it all together, then cutting the two halves apart carefully with a jeweler's saw. Then install the joiner rod, dixie-pin, etc.
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Old Oct 16, 2013, 05:52 PM
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FYI, I haven't built the plane yet, so lots of options. I need to check the dimensions again. It may just be possible to kevlar wrap a brass tube directly to the top of the spar. hmm...
Prolly doesn't need much diameter either. Clearly 1/4" is overkill and 1/8" steel too small (in my mind anyways). Thoughts on that as well?


The idea from that Apache thread would be great, except there is no top/bottom spar; only a single piece of spruce.
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Old Oct 16, 2013, 08:33 PM
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CityEvader,

I took a look at my Wanderer plans and it looks to me like you can leave the spar alone. I circled what I believe to be joiner rods on the plans. Just use the traditional brass tube and music wire combo at the location circled in blue and you should be fine. I did the exact same thing on my recent 3 meter build and it has held up very well. The joiner tube does not have to run down the spar.

Wayne

Edit, it is possible that the area circled is actually a second spar system to reinforce the poly break but I still believe you could use the location for joiner tubes.
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Last edited by Windependence; Oct 16, 2013 at 08:43 PM.
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Old Oct 17, 2013, 09:25 AM
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Now that you mention it, the Speedo and others have a mere hole in the first three ribs for a single joiner rod, so shouldn't be a problem for this bird.
Always nice to bounce ideas around.
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Old Oct 18, 2013, 06:48 PM
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7/32" is more than adequate. 3/16" might be, and two of them, used intelligently, would be somewhat stronger than the 7/32, and about as stiff.

If you had access to a good sized drill press, you could drill the ends of the spars for the joiner tubes and make a really clean installation, though it would probably be a good idea to put 1/32" ply on front and back of the spars where the joiner tubes are. You could also set the dihedral precisely while doing this. I doubt if a kevlar wrap would be necessary if you used the plywood. Might be tempting to make the spar just a smidgeon taller within a few inches of the outer end of the joiner tube. 1/16" is probably enough, I'd guess, particularly considering the contribution of the plywood.

As I recall, the GL offered a three piece wing option using only 3/32" music wire for the joiner. That turned out to be enough, though it did flex quite a bit. The flex made it easier to tell how hard you were pulling with the winch. The wire was installed similar to the way you are describing.

The Windrifter SD100 joiners were done in a similar way to what you have in mind. I don't know how that worked out in service, though. Maybe someone else here has had one of those?
http://outerzone.co.uk/plan_files_04...fter_SD100.pdf
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Old Jan 01, 2014, 06:56 PM
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So here's what I decided to do. I had two 4.9mm carbon rods and 5.1mm stainless tubing, and with a little bit of measuring the dihedral angle is set and there's a perfect amount of fit to the rod... I'll be reinforcing the ribs with some thin ply as well.

I had debated on making a solid center section with removeable tips, but wanted the build to be as stock-ly constructed as I could...just because.

The fuselage is done, now onto the wings!!! I'm a slow-poke with a tight schedule.
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Old Jan 02, 2014, 01:48 AM
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If you're going to use carbon, and you don't go for total overkill (which you're not), suggest you carefully inspect the rods at the beginning of each flight session and after any violent landings or other abuse. The carbon's failure mode is disaster. Music wire's failure mode is extra dihedral. You probably should deburr and slightly round the end of the stainless tubing so it presents a smooth radius to the rod. Or maybe I'm just too paranoid.
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Old Jan 02, 2014, 03:23 AM
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The way I figure is, these rods are from Speedo's. I've flown in 60-ish mph more than doubled weigh in ballast bending a wing every single bank.

Speedo uses only one rod. This will be vastly less abused with two rods.
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Old Jan 02, 2014, 11:28 PM
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Quote:
Originally Posted by cityevader View Post
So here's what I decided to do. I had two 4.9mm carbon rods and 5.1mm stainless tubing, and with a little bit of measuring the dihedral angle is set and there's a perfect amount of fit to the rod... I'll be reinforcing the ribs with some thin ply as well....
Looking good!

Built the Wanderer when the Marks Models kits were readily available after seeing my friend's fly well, and an older friend, I considered him to be the local glider guru, provided me with some steel wire and brass tubing and sort of challenged me to build a two piece wing.

Placed the tubing for the 5/32" main joiner rod just aft of the main spar and the tube for the 3/32" alignment rod 1/2" behind the shorter secondary spar, with the rods and fitted balsa wedges enclosed with thin ply and cemented with epoxy. Also reinforced the ribs where the tubes pass thru with thin ply.

So far the joiner tubes have held up quite well, considering that this was my beginner's R/C glider (never mind what has happened to the outer wing panels or fuselage ).
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Old Jan 02, 2014, 11:49 PM
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Back in, oh, '87/'88-ish was when we first got into RC planes.
I had a crappy flying Drifter II.
My brother and a friend had the Wanderer and they flew great! My buddy would throw it into a loop. The Drifter II could never, ever do that. Plus, it seemed much more durable to boot.
Hence the nostalgia-driven purchase of this kit.

I'll do a few changes, such as 2-piece wing. Also, since the landing zone is quite harsh and gravel-y, the fuse will be gently glassed in 3oz (possibly 1.7oz in the rear), with additional patch of 8oz carbon cloth for 8 or 9 inches of the front belly.

I wanted the 2-piece addition to not be too stiff, as the wing is supposed to flex, so figured the first two ribs would be just right. I also may put a layer of 1.7oz cloth on the underside of the bottom sheeting just to add a little bit of load-distribution for the new stress from the rods. Certainly want to keep it way, way below overkill, which is SO easy to gravitate to!
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Old Jan 04, 2014, 09:58 AM
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Any further progress pictures?
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Old Jan 04, 2014, 08:49 PM
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You know I've had my boy the last few days, with a few more to go.
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Old Feb 18, 2014, 05:17 PM
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Curses!
When doing the initial thinking, I TOTALLY didn't!!
I gave full dihedral to BOTH panels, instead of remembering that one panel should have been flat on work surface. Sigh.

I wonder if a pair of 7mm aluminum rods would be strong enough after bending a negative-angle to them (and if I can even find some).

Thoughts?

.
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