stunthanger.com
Design => Stunt design => Topic started by: Kim Mortimore on May 24, 2010, 09:33:33 PM
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On a flapless plane, does the aspect ratio of the elevator make a difference, or is it just the total area of the elevator that matters at any given angle of deflection (holding the fuselage length constant)? I'm thinking of desensitizing an oversensitive plane with an excessively large elevator without reducing the total tail volume by cutting the elevator longitudinally (without removing it) into 3 sections: a larger central section of functioning low A/R elevator and two smaller "tips" which will be made fixed.
This will allow me to bring the elevator deflection up into the range I prefer: 25 to 35 degrees. There may not be anything technically wrong with having very little deflection on a large elevator, I just prefer what seems to me like a "normal" range.
Thanks
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Beats me. Are you worried that a smaller travel would accentuate any funny properties around neutral?
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Partly, yes. Also, it's easier to adjust control sensitivity if there is more than one hole in the horn that gets you in the ballpark; the feel isn't right; and personal preference. Anyway you answered my basic question. Thanks.
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Are you sure it isn't just a too far back CG? Have you played with it?
(Tim, who always makes _sure_ the CG is too far back before he considers himself done trimming).
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On a flapless plane, does the aspect ratio of the elevator make a difference, or is it just the total area of the elevator that matters at any given angle of deflection (holding the fuselage length constant)? I'm thinking of desensitizing an oversensitive plane with an excessively large elevator without reducing the total tail volume by cutting the elevator longitudinally (without removing it) into 3 sections: a larger central section of functioning low A/R elevator and two smaller "tips" which will be made fixed.
This will allow me to bring the elevator deflection up into the range I prefer: 25 to 35 degrees. There may not be anything technically wrong with having very little deflection on a large elevator, I just prefer what seems to me like a "normal" range.
Thanks
The only limit is the hinge force needed to move the surface. Low aspect ratio on the elevator increases that. I ended up with a 4 in. bellcrank, 25 deg. of movement, and no more than 2-2.25 in. of elevator chord.