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Building Tips and technical articles. => 1/2 A building. => Topic started by: Bootlegger on March 18, 2021, 08:01:17 PM
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Guy's I am thinking about "expanding" a Sig model up to 125% of its kit size it is a 1/2A Sig Sky Ray.
I am thing about going to a 30" wing span with the rest of it increased by the 125% factor also..
I am looking for some advice/suggestions, and couldn't think of a better place to ask, much obliged... H^^
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Have you checked with John Miller for design advice?
He’s a regular on hangouts and is quite knowledgeable about such things.
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That would be a 56% increase in area. Might be a bit much unless you are going to use an 061.
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Larry, I am not well versed in math, what would you suggest and why? I am thinking about the 30" wing span with approate size increases to keep in fly ably with a B Widow 2 port cyl or a Golden Bee set up the same. Any suggestions will be appreciated.. H^^
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Larry,
Can you share the info on the Big Flattie that I have seen over at the Narrows? Seems like a relevant comparison here. I just can't remember any details.... It might have been painted silver?
The Divot
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My sheet wing Skyfire was about the size he is considering at 230 sq. in., but it had a spruce spar and a tapered wing. Even so, there was some flutter problem and eventually I cut the span down 4”.
Also, it was 061 power. I had a Skyray with a Black Widow, and it was just fine as is. If it was to be enlarged, it would have to some how be made much lighter.
If I were to mess with it, perhaps a 5% upsize, go for a 1/16” thick wing with a spruce spar and carbon veil covering, a hollowed, laminated fuselage, and lightening holes in the tail surfaces. Nose moment adjusted to eliminate need for ballast, of course.
Or, on second thought, why bother. Buy a Cox Medallion and build an PINTO from an RSM kit and have a really superb model.
Or, I modestly offer, an 061 and my own RSM kit SkySport.
Either of these will do a 500 point pattern in the right hands (not mine, sadly to say).
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Mark Mc who recently posted on his needle conversion made some beautiful Skyray stunters a year or two ago. Mark has a exceptional talent for building multiple models at a time. I believe he did upscale the Skyray with a built up wing which I would highly recommend. His models were all designed with one thing in mind which was to keep flying in the event of a accident. I also believe they were Medallion powered but my memory could be wrong. I hope he sees this post and offers the pictures as they were impeccable.
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Sorry to take so long to notice this, Ken. Yes, I did a built up wing 1/2A Skyray. I did not upscale the plane. I just took a copy of the full size Skyray 35 wing rib and reduced it to 53% of original size so that the chord was the same as a sheet wing Skyray. All other dimensions/aspects of the fuselage/tail surfaces are identical to the 1/2A Skyray except the motor mount. I built it for a Medallion/TD .049 engine rather than a Bee engine. I did do a build thread and post it here back in August of 2017, but that thread seems to have lost all its pictures. I'll copy and clean up the build posts from the CEF thread and re-post here.
Mark