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Building Tips and technical articles. => 1/2 A building. => Topic started by: minnesotamodeler on September 15, 2010, 08:25:05 AM
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Next iteration of my canard project:
Swept-forward wings should alleviate the noseheavy condition. Also fuselage is extended aft to render any tailweights more effective "just in cases".
Other numbers pretty much stay the same.
Larger wing (28" span, 7" nominal chord, = 196 squares) should be enough, even in inefficient canard layout.
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Not much sweep -- will it be enough, based on your experience so far?
It seems like the rear landing gear is pretty far back to allow for rotation on takeoff. Is this by design, with lift just accomplished by the stance?
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The sweep amounts to 2", CL moving ahead 1". I'm assuming that would also move the ideal CG 1" forward, all else being equal (which they're not; see next). The original CG needed to be moved back from about 2 3/4" ahead of LE to 1 1/2", accomplished with 1 1/4 oz. of lead! With the swept wing, that figure should translate to 2 1/2" ahead of LE, pretty close.
Add to that the extended fuselage behind, with rudder located further back accordingly; subtract from that the added wing mass forward, and I'm thinking the balance should work out close to right, maybe a tad noseheavy, easily adjusted with minimal weight at the aft end.
Landing gear is actually located at the strongest part of the boom/wing combination. The booms are only 1/16" ply, with a 1/16" ply doubler coming out of the wing to the wheel mount. Plus I want to keep as much weight as possible behind the CG. Anyhow, canards don't take off by depressing the tail, but by lifting the nose. I think it will be fine.
As you have no doubt guessed, I design by the "TLAR" process, and mods based on flight characteristics of prototype. So it ain't scientific; but it's fun.
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Rather than notching the stabilizer, why not sweep it forward too? Or at least a straight leading edge?
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Rather than notching the stabilizer, why not sweep it forward too? Or at least a straight leading edge?
Yup, that's a thought...I kinda like the swept-back LE there though, that and the wing sorta form a closure, like parentheses or something.
I did enlarge the stab, extended it beyond the booms as suggested by you earlier IIRC. So see I do listen...
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ok, why have booms at all ?
You look like it has a center fuse running through the ship?
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Yup, profile fuselage--but, notice how far in front of the wing it extends. Very flexible at that length, Seemed to me the extra support of the booms was needed. Besides, I needed some structure out there for a leadout guide.