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Old Nov 18, 2012, 03:21 PM
Hey was that a Thermal ????
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spars on solid core molded wings?

For those of you doing solid core molded wings, how are you doing your spars? A routed in spar is pretty straight forward but if the spar was a layer of Uni-Carbon how would you line it up in the mold?

Thanks, Paul
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Old Nov 18, 2012, 04:25 PM
Whisper Model Aircraft
heliwill10's Avatar
Greensburg, PA
Joined Feb 2008
558 Posts
Good question been wondering myself....

Kennedy shows the cross section of their spars:

http://www.kennedycomposites.com/maxa.htm

The spar thickness must be so critical... I'd like to know how the halfs come together.

I think the samba stuff is tow piled up, but not sure....
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Old Nov 18, 2012, 05:05 PM
Hey was that a Thermal ????
Joined Nov 2009
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The the uni strip you simply make it part of the lay-up and the mold presses it to the foam core like a set of mylars. The problem is knowing where to place it. I have lines on the "outside" surface of my mylars I use for lining stuff like this up but in a mold situation there would be no such marks.

You are dead on though for a hollow molded wing in that the thicknesses and placements are very critical.
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Old Nov 18, 2012, 05:38 PM
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Are you asking about how I do spars?
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Old Nov 18, 2012, 08:50 PM
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Cody, WY
Joined Nov 2007
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I would make a spar alignment template that indexes in the alignment pin holes of mold.
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Old Nov 18, 2012, 10:15 PM
Hey was that a Thermal ????
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Quote:
Originally Posted by wyowindworks View Post
I would make a spar alignment template that indexes in the alignment pin holes of mold.
That makes sense, the other option would be marks on the flange. Eventually the template will get coated in resin. I could also paint the mold with a pattern and incorporate the spar into that so it gave me reference points,

Paul
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Old Nov 19, 2012, 06:51 AM
Father of Fr3aK, DLG Pilot
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Make a template, and you can even lightly sharpie the spar lines in place after your mold release / paint is applied. Why not have a light black line on top of your black carbon spar?

For the shear web, sometimes I use just the foam and other times I add some end grained balsa. On my current models I use a 4" long 3/16" wide balsa shear web that is cut 1mm shorter than the core and splooged into place to fill the gaps. That 4" length gives me really good rigidity out past the hole where the servos are cut in. This was a problem with a few of the early solid core airplanes (folding at the servo bay)

My current wing is overkill but it's still easily under 120g. (Maybe I take too many pictures)
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Old Nov 19, 2012, 07:04 AM
Hey was that a Thermal ????
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Tom, I don't see a full span spar? If you get a minute give me a call I really want to move on this over the upcoming Holidays so I can have a molded wing in 2013.

Paul
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Old Nov 19, 2012, 07:42 AM
Father of Fr3aK, DLG Pilot
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Paul,

The sparcap is a piece of 4oz uni that is laid up in the skins.
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Old Nov 19, 2012, 08:38 AM
Hey was that a Thermal ????
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That makes perfect sense. Thanks Tom.

Paul
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