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Design => Stunt design => Topic started by: James Mills on August 20, 2010, 04:04:35 PM
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I wanted to ask this of some of you who have more experience in designing your own plane. If you wanted to change an existing design to look like a semi scale, say a Bearcat as an example, can you take the wing/stab (say from Randy's Tempest) and draw the fuse sides while keeping the moments the same or is there more involved?
James
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Is it a profile?
There's some considerations about the height of the stab vs. the wing -- some don't like the idea of putting the stab right behind the wing.
You also want the leadouts to exit the wing at the vertical center of gravity, so the thing will track straight -- get the vertical CG off too much and it'll fly differently inverted than upright (there's a recent FM that published a pair of models -- the "Encore Twins", I think -- one full fuse one profile -- the author puts the prop at a different height to keep the vertical CG the same from one to the other.
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Yea, this is the reason that you will see most of Pat Johnston's semi-scale planes with dihedral in the wing. He puts the wing at scale position then uses dihedral to get the leadouts to exit where they are supposed to be.
If you keep the center lines of the wing and stab in the same position relative to the thrust line of the engine (sames as the Tempest, that is) and keep the moments the same along with a side area that is at least in the ball park of the original, then you should be fine.
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Hi James,
You will simply be following the long honored tradition of CLPA! LL~ Many, many planes back in the late '50s and early '60s were modified Noblers. y1
Follow what Randy P said. A semi scale might need dihedral, but a lawn dart can be built just by redrawing the fuselage outlines, etc., to suit yourself.
Big Bear