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Ultralight Flaps

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Grimace

Well-Known Member
Joined
Jan 2, 2009
Messages
319
Location
Chicago, IL
If I've learned one thing in my 30+ years being tangentially (or more) involved in aviation, it's that no matter what you "invent", no matter how clever you are, whatever you think is new has already been done. If it works, it's got a name and it's being used. If it isn't being used, there's probably some glaring issue that makes your idea rubbish. But with that said, I had an idea the other day and I'll be darned if I can really poke any holes in it... at least insofar as ultralights are concerned. It has to do with the fact that as speeds slow down into the ultralight realm, aerodynamics become less esoteric and exotic airfoils have less of a hold. Ok.. so let's take that to the extreme.

I have an idea for an ultralight glider (under 155lbs). And specifically, I have an idea for flaps. You know those old-school ultralights with single-surface wings? Same idea, but upside-down. And just for the flaps. See? If you had carbon composite split flaps on an otherwise fabric wing, they could have the concave bottom surface without the troubles of creating a concave surface with fabric wings. So draw a circle. Then, from the 6 o'clock position, draw a horizontal line to the left, with a bit of a concave curve. That's it. A few layers of carbon, an almost straight (sort of concave) line, and a round nose. No upper surface like you'd expect - but let's face it, with the flap extended and the AOA up high, that air is messy anyway. And besides, aero doesn't play a big factor at low speeds anyway (figure a VNE for the entire aircraft around 80mph). So why not just have a few layers of carbon around a "nose", let the upper surface be completely un-aerodynamic, but let the bottom surface be smooth. I mean, it can't be any worse than normal split-flaps, right? But you can get a concave bottom wing, with rigid carbon, without having to add a bunch of extra ribs in an otherwise fabric wing. I would think that something between 3 and 10 layers of carbon fiber would be stiff enough to work at ultralight speeds without having to go through the whole ordeal of having an internal structure. And I don't think the unaerodynamic top surface would be much of an issue at low Re numbers either.

Any thoughts? Surely, there must be hole in this idea.
 
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