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Well one spar is ready for balsa sheeting, the other is having the wing joiner assembly glued to it.
Here is the wing spar before the front and back sheeting. Sheeting will be 1/16 hard balsa. One is supposeed to splice to make the length. I have always had trouble doing good scarf joints so one of the balsa bits in the middle at 36" is 1/8 balsa where the balsa sheeting will join. The rest are 3/32".
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Here is the spar tip. Made from 3/8" balsa. Again a departure from the plan. It is supposed to be spar to the tip with it steamed to shape. Me I made it out of light balsa. Hope I never do a wing tip landing to test its structural integrity! |
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Both spars are now done and have some sheeting added ready for drying over night.
The ruler below is a metre, the bar above the 24" wing joiner.
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Two long bits are the wing spars. Bottom is the ply for the root reinforcing of the spar. The 3 root ribs are 1/8 ply and the rest are 3/32 ply.
First time I have done the ribs individually. I spent 3 hours cutting the paper and joining it and then sticking to the ply and balsa. I had already spent 2 hours ages ago printing the ribs out.
Previously used the sandwich method which is a lot quicker especially the K3 as it is parallel chord appart from 3 tip ribs.
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Here is a pic of the main spars with the ribs cut out to give a feel for the shape.
The ruler at the root is 12" spars are 76" long, 28 ribs per wing, 3 at root are 1/8 ply rest are 3/32 balsa. The rectangular pieces of ply are the spar play doublers.
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This pic shows the root of the spar with the wing joiner brass in the root of the spars nice, secure and snug! The ply at the side is the strengthener for the root.
Next job is to smooth all the ribs (thank goodness I have a belt sander for the ply ribs and Permagrit for the balsa ones).
Then comes the fun part - cutting the spar slots for the ribs. Well this means taking a chunk out the middle, the width of the spar.
I used an electric planer to trim the ply root doublers for the spars then glued them.
All 58 ribs now sanded down to shape. Using prit stick to glue the paper to the ribs worked fine as it peeled easily off and left no residue.
Individual ribs (well pairs as I cut the balsa in pairs) takes longer than the sandwich method. Plus point is the ribs have no bevel on the surfaces so gluing the false LE and the sheeting on them will be better.
Next step cut the ribs in 2 and remove the bit in the middle.
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Here is the root rib. The Metal rule is on the False LEading Edge on the plan of the wing. The root rib is on the plan and the line is marked vertically where the spar is.
Then we make a tapered strip of wood, 36" long and 0 at one end and 6mm at the other. A thin wedge for the washout that starts at rib 15 to rib 28. This is secured to the plan and then ribs with washout out are marked up.
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Here is the penultimate rib to show it. As you see the rear of the rib is resting on the tapered strip. The lines are marked on the ribs as the root rib. However as the te is raised by 6mm the lines are still parallel and the washout twist will be in the whole outer wing not just the TE
Next I will cut the middle of the ribs out and drill the holes for the wires in the LE ribs. Then they will be added to the front of the spar which has been marked and that will form the basis of my D box.
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Here I have stuck the front portion of the ribs onto the front of the spars. So now I have two spars with their D ribs on.
You might just notice that the tip ribs seem to drop a bit which is the wing wash out. Next job is the false LE.
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Having spent a few hours doing this I thought lI would do something different. So took the fuz centre section ribs and cut the slots out to fix to the main formers.
Here is a pic of them dry fitted as need to put holes for main wing joiner spar, and holes for wires and rear drag spar joiner
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