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Re: Carbon Dragon structural limits 10 Dec 2013 22:00 #516

Well to answer the structural question, After further reflection, it might be more difficult than I was first thinking to clip the inboard skin. The skin isn't part of the spar structure, which carries the bulk of the wing bending, but it is part of the D-tube which carries the wing torsion loads. You might be able to clip it a bit, but enough would have to remain to carry the torsion loads (whatever those are).


I think, as suggested earlier, that it might make more sense to sit the pilot more upright so that his head was just above the wing, or at least far enough that the visibility is increased like the Woodstock. This will also move the CG desirably aft.


You are limited by the spar with regard to how far aft you can move the pilot. The only other way to change the relative aircraft/pilot CG (without adding ballast) is to sweep the wing forward a bit. My guess is that it wouldn't be such a big deal. The airfoil is the same (stall characteristics) but you move he lift CG forward a few inches. I'm a structural analyst, not a aerodynamist, so I don't know for sure, but as long as it wasn't radically changed I would expect too much behavior difference. Anyone actually knowledgeable about that?


The other super-tempting thing is to consider something with self-launching capability. With an engine, and ballistic chute, you would be allowed 254 + 25 = 279 Lb rather than 155 Lb; plus, you'd get self-lanching capability. In that case, I would definitely want to push the wings out and add one more rib inboard. I worked it out that it was around 47 ft wingspan (I think I also allowed 24 inches for the cockpit width. In the case of self-launching, you wouldn't have to sweep the wings forward since you'd have significant weight aft of the lift CG. to balance the pilot weight, and in fact you could pretty much make a 'standard cockpit


I REALLY like the small jet engines, but they want both nads in exchange -- not sure I can make that sacrifice...


Thoughts?


Kenny

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