This is a perfectly legitimate thing to bring up, and I used to wonder about it all the time. As it turns out, the real problem here was that the "classic Bernoulli" most of us learn below the uni level isn't really the full explanation for how a wing generates lift. It really doesn't have much of anything to with the shape generating a pressure gradient. A wing just pushes a heck of lot of air downwards when it moves through the air, and the lift on the wing is just the -d(momentum of air pushed)/dt, i.e. conservation of momentum.Thinking about this with a simple airfoil, the benefit seems to be in part driven by the different velocities of air over the top wing and the slower air under the wing. That's where the comment of putting covering on the bottom of the wing comes from. Keep that air in a straighter line and there is less distance to travel and a lower speed/higher pressure. This is classic Bernoulli.
> It takes a little practice. One way is to start with a strip of straight wire of the desired diameter, say 1/16 inch. Make some thinned glue. (I use Duco thinned 50-50 with acetone.) Cut a strip of japanese tissue the needed shape; say 3/8 inch by about 2 inches long. Gently spread a drop or two of the glue on about 2/3 of the strip, and wrap it around the wire wet end in. Then wait a bit until the glue is half dry. With care the rolled tube can be slid off the end of the wire. This is where the practice is needed. If you wait too long, the tube will stick on the wire. If not long enough, the tube layers will slide. Depending on how much glue you use, about 2-3 minutes is likely to be about right, but you can test gently to find the moment. Once the tube is free, let it dry. Then cut strip wood (say 1/16th square) and gently sand off the corners to make the wing post. If you check every few strokes, you can make the post just small enough to have a snug fit.>How do you slice ribs?
The easiest way is to create a template of the desired shape from either thin balsa (about 1/16 inch) or matboard. The edge should be sanded to ensure a smooth curve, because the slightest kink will be transferred to all ribs. Once the shape is right, glue a thin wire (about .020 inch) along the edge. When this is done, sand the edge of the profile with very fine sandpaper to remove any glue lumps. Then use this profile to cut ribs carefully with half a double-edge razor blade, or an exacto knife with a pointed blade.
> Should ribs be low or high density?
Doesn't matter much. Make them from the same wood as your spars.
>Approximately what simplex should the ribs be? And the ribs on the tail?
The exact profile is not very critical for SO purposes. But common would be a thickness of 4-6% compared to the chord, with a high point about 40% of the way back. An ordinary French curve can be used to obtain a reasonable shape.
How do you roll tissue tubes?
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