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Old Jun 01, 2012, 08:40 PM
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How can I mount a dihedral wing on a pylon?

Hi,

I've been really enjoying building my models, but one thing bugs me: the wing mount. I definitely want to mount my wings on a pylon, but I'm always running into issues with alignment on dihedral wings. Particularly, the v-shape of the bottom of the centerline of the wings is always hard to mount.

I know a lot of you guys are working with composites and a fairly large scale. I'm working in the 750mm to 600mm wingspan range so things tend to be small. I'm using all wood except for the boom.

How do you mount your dihedral wings?

Do you know how to mount them so things like incidence angle can be adjusted?
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Old Jun 01, 2012, 10:25 PM
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Below is an example of what I'm talking about. At the top is a dihedral wing which has been glued together. On the bottom is a cross section of the boom and the pylon. What I'm struggling with is that v-shape. I've tried cutting a v-shape into the pylon, but that hasn't worked well. I just tried to do mounting screws and just made giant holes in my wings, lol. There must be a good trick to how to mount a dihedral wing...
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Old Jun 01, 2012, 10:33 PM
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United States, VT, Castleton
Joined Dec 2007
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I don't know about the adjustable incidence, but if you want the top of the pylon to have a "V" to match the dihedral, you could try this: Make the pylon out of 2 layers of wood. Cut the top edge of each at the appropriate angle, then glue them together to create the "V". I would use a table saw, because it's quick and accurate, and I have one :-) That's how I make the wing saddle on the foam pod of my small DLGs. But it could be done with a razor knife then touch up with a sanding block to fine-tune the angle.
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Old Jun 01, 2012, 10:46 PM
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relaxnfly's Avatar
Knoxville, TN, United States
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Here are Sporters instuctions for his SuperGee style post Pylon mount.
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Old Jun 01, 2012, 10:55 PM
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Interesting....I was thinking of a single full-span pylon, but those carbon tube posts do allow for incidence adjustment. I'm guessing that a well shaped full span pylon might have less drag than 2 cylindrical posts?

edit: thinking a bit more, my method in post #2 above works if the wing is fairly flat-bottomed. I've used it with the AG03 foil, but if you have a lot of under camber the pylon would need some fancy compound curves.
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Last edited by JimZinVT; Jun 01, 2012 at 11:01 PM.
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Old Jun 01, 2012, 10:55 PM
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Both of these ideas are great. I've been racking my brain, and both of these seem way easier that what I've been trying.

Thanks so much!
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Old Jun 01, 2012, 11:04 PM
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Half the fun (for me) is in the designing and problem solving and exchange of ideas.



Well, maybe not half......the flying is pretty great!
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Old Jun 01, 2012, 11:20 PM
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Quote:
Originally Posted by JimZinVT View Post
Half the fun (for me) is in the designing and problem solving and exchange of ideas.



Well, maybe not half......the flying is pretty great!
lol. I'm going to try your two-halves laminated idea first, because I have the material, but the other pylon dock idea is pretty darn neat. I have some spare carbon boom, so maybe I can rig that style up to.

I have to admit, I enjoy coming up with the production/construction techniques as much as flying too!

Thx!
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Old Jun 02, 2012, 12:06 AM
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United States, CA, Tehachapi
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If you use the posts like on the sporter pods make sure your posts aren't pultruded carbon. They need to have fibers running lengthwise as well as around it. Otherwise it splits really easily.
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Old Jun 02, 2012, 05:56 AM
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Canada, ON, Puslinch
Joined Apr 2010
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For yrs now I use a method called: potting the wing. Im not sure where I first heard the term but many have used this method.

Once your mount is shaped close enough try taping the underside of the wing with packing tape, then mix up a fairly thick batch of epoxy with your favourite filler and place a blob on the pylon. Now, place the wing into the curing resin until cured. The packing tape will act as a release agent and the wing will now match the pylon perfectly
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Old Jun 02, 2012, 09:02 AM
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Quote:
Originally Posted by DLGjunkyard View Post
For yrs now I use a method called: potting the wing.
Since my wings so far have been non-removable I actually combine this method with what I mentioned in #2. It fills the gaps between the nice straight saw-cut pylon and that annoying airfoil shape

JZ

(been pondering how to make my "structureless" foam & film wings removable....but that's for another thread)
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Old Jun 02, 2012, 11:10 AM
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Ah, I see how I could use the potting method too. That's a great idea.

This forum is awesome. Thanks for the help everyone!


Quote:
Originally Posted by JimZinVT View Post
(been pondering how to make my "structureless" foam & film wings removable....but that's for another thread)
Me too.
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Old Jun 02, 2012, 03:46 PM
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Here is another solution supplied by derk from my micro SAL thread. In this set up, you screw the wing into a threaded insert on the pylon near the front of the wing where it's strongest. The pylon itself is starts at a positive angle, and each very thin wedge you insert under the trailing edge will push the incidence toward zero, or even negative. Mostly, I'm looking for positive incidence (at least on the models so far) so this is great for me.

These kind of ideas are exactly what I was looking for: a way to quickly test ideas, and configure things, then sort of set it in stone with an RC version.
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Old Jun 02, 2012, 05:00 PM
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Is that going to be strong enough for SAL/DLG launches, or is it just for preliminary test glides? Seem like the wing might pivot. Some sort of spline under the wing mating to a groove in the pylon would fix it.
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Old Jun 02, 2012, 06:28 PM
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Quote:
Originally Posted by JimZinVT View Post
Is that going to be strong enough for SAL/DLG launches, or is it just for preliminary test glides? Seem like the wing might pivot. Some sort of spline under the wing mating to a groove in the pylon would fix it.
That's a good point. What if the top part where the screw is were potted as described at the top of the thread, and the pylon goes a little wide there?

derk made the same comment as you and thought maybe two screws would be needed.
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