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SIG Cap 231 rebuild


Old 06-08-2011, 07:20 PM
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Default SIG Cap 231 rebuild

I have never tried to repair anything. I have some pics of what I have done so far. I have no detailed drawings I just matched and sanded a lot to get to this point. The shape feels pretty close to the side that was not damaged but the balsa covering does a couple of high spots that I did not build very good. Should I start over is minor bumb in the wing ok?
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Old 06-09-2011, 10:29 AM
Join Date: Oct 2004
Location: Wyoming, MN
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Default RE: SIG Cap 231 rebuild

I don't see a bump by what the picture can show but the wing should be rebuilt to original. What I see as a greater concern is the angle of the servo to the aileron hinge line. Originally the Sig Cap was set up this way but it had a big issue with aileron flutter. When the aileron pushrod is at an angle to the hinge line, there is a possibility of flexing which is an invitation to flutter. Also the supplied control horns were flexible which contributed to the problem. I experienced flutter with mine and have read others have had the same problem. At first, I just put in stronger servos and heavy duty plastic servo arms without changing the angle and still had flutter problem. The servos held up but the plastic arms literally shifted on the output arms. I crashed twice due to the flutter problem. The fix was to straighten out the line of motion of the pushrod so it was 90 degrees to the hinge line of the aileron. Second a metal gear servo was installed with metal control arms, 4/40 pusrods and links and nylon reinforced control horns screwed into a sturdy base on the aileron. Also, the hinge gap, regardless how small, must be sealed. The servo will have to be repositioned with a new mounting set up but it is worth the effort.
I am flying my Sig Cap with a Saito 180 and have had no sign of aileron flutter. Still it makes me "gun shy" every time it come screaming out of a split S or backside of a loop thinking it will happen again. I hope never to hear that hideous buzz again on my Cap. Hopefully, you never will either if you make the mods. Good luck with the fix and mods.
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