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Carl Goldberg "Sophisticated Lady" kit question

Old 12-03-2020, 01:16 PM
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Default Carl Goldberg "Sophisticated Lady" kit question

I've decided to get back into R/C aircraft. I started building a Sophisticated Lady kit that's been sitting on a shelf for about ten years. I don't want to use rubber bans to hold the wing on but I forgot how to go about installing wing bolts. Could someone help me out here?
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Old 12-03-2020, 04:51 PM
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I'd be curious how other folks do it as well. I think it would be fairly simple on a new build when everything is framed up and before covering. marking and securing in the blocks for either blind nuts or threaded blocks would be easier. Once it is covered it would be more challenging which is what I am facing. I have a coupl of older builds I want to convert and have been scratching my head on that.

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Old 12-04-2020, 03:00 AM
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Take a look here: LINK. He covers converting to bolt on wing. I'm not a glider pilot but I've absolutely loved the looks of the Sophisticated Lady for many years now.

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Old 12-18-2020, 05:38 AM
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I can tell you I found out one reason NOT to have a bolt on wing after torque rolling it on a go-around...

I had the electric power pod on it, but it did get repaired and flew many times after. I have done wing bolts on all of my Goldberg planes. I also recommend substitution of a plywood bulkheads at front and rear of the center section fuselage.
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Old 12-18-2020, 07:30 PM
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I hardened the trailing edge for wing bolt by poking a bunch pf holes with a pin from the under side and then soaking the area with thin CA, worked well. A cross block can be glued inside the fuselage, don't have space if you can help it between the block and the wing. When you do, a crash is trying to stretch the bolt instead of shearing it.

Most people use nylon bolts that are too big for the size of the aircraft. Look up a nylon bolt shear strength table. I have seen many planes with 2 - 1/4 x 20 nylon bolts holding the wing. It takes over 100lbs to shear one of them, so 2 would require over 200lbs. I don't think they would shear, but strange things happen in a crash.

I have tried to size the bolts by looking at the strength tables and making a guess at the stress involved. My engineering classes are helping.
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