Gliders > Slope Soaring
I'm drowning, in bits of an Mu28
Happy Days:
Yes Richard, this is hard to explain.
Let me try again………….
Here is a picture of three sections which make up one wing half. In this picture they are stacked on top of one another. If each of these sections are placed end to end they would be 2mtrs long. (One wing half of a total wing span of 4mtrs)
This next picture shown that each of the sections are themselves made up of three farts…(oooppss y sorry, that should read ‘three PARTS’) I’ve slid the bottom, middle, (wing core) and top parts back to try and make them easier to see
1 A bottom (or what I call a base ) piece
2 A middle part, which is what will become the core of the wing . It’s been cut to the airfoil cross section. (This one is semi symmetric)
3 And a top piece which lays on top of the wing core.
Look, here is a picture of just the top & bottom parts without the center core. You can see the semi symmetric hole.
Now, imagine just taking the bottom part of each of the three sections and laying them on a table. (Remember, the top part and the wing cores of each section have been taken away) So just the bottom parts are placed, end to end, on the table. As the edge of one bottom section butts up to the edge of the next bottom section there should be a smooth, (flush) continuance of the airfoil shape. But there isn’t. Instead there is a ridge where the edge of one section meets the next.
Unfortunately I can’t get a clear picture of the problem, it just comes out as a mass of white.
Think of two railway lines being joined end to end. (In my day of steam locos the rails were joined using what were called fish couplings. Bit before your time I expect) Now imagine that instead of the two rails meeting at the same height end to end, one rail was two inches taller than the other one. (the bottoms of the rails were level, but as I said, one rail was taller.) The passengers on the train would get a very bumpy ride!!!
That’s what’s happening to the airfoil cores of these three sections. The bottom parts of each section are different thicknesses, therefore the core sits at different heights within each section.
Tell me if you understand or not? :(
K.
johnfireball:
Hi Keith,
Why not join the wing sections without the outer waste being used. pack the leading and trailing edges with wood spars laid on your flat building board and glue wing together.
John.
Happy Days:
Good idea John!
Must confess I’ve never built a wing of this type before. In fact I haven’t done very much building at all. (Plenty of repairs :oops: , but not much building! )
I’m thinking that the only problem I can see with your suggestion is the question of how to accommodate the wings thickness taper. Like most wings it’s thinner at the tip than at the root. :!:
Anyone else got any input on this idea?
Keith
johnfireball:
Hi again Keith,
The taper is usually on the top surface so the bottom is flat unless you need washout whereby you pack the tip trailing edge.
John.
johnfireball:
What I would do,
Glue it together on the flat best as you can (eyeball is pretty accurate). When you go to veneer and gluing all will probably change(warping, glue shrinkage and whatever) steam from the kettle is a great corrector. Glue something, get going and it'll work out.
John.
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