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So, I don't know why, I've thought about doing a SWT upscale for a long time, but could never rationalize getting the mechnanism to work and be solid enough with my preferred foam medium, and I like to pilot the boost anyway and don't like to chase pop pods. I also question the theoretical extra boost altitude with a fast burning motor and with extra fins and a swing wing having more wetted area than un unfolded wing without extra fins boosting on a slow burn motor. In any case yesterday I saw a posting by Richard Boyette on a 2.25x upscale SWT on FB he did that got me to thinking.
His glider version was 46" long, 34" wingspan and used G motors for a 46 ounce boost weight and 41 ounce glide weight. The original was around 2 oz glide weight I think so with the scaling of factors, it means a 2.25x gives you 5x wing area and 5x weight for similar wing load, but we know larger can carry more weight typically than a direct scale. His glide weight is around 20x for a bit more wing loading than I like of around 25-29 oz/sq foot. I thought a 2x upscale would give me 4x wing area, so if I could get around 9-10 oz glide weight for a scaled wing it might not be too bad.
So I looked at my components, a 9.5" long psII 2" cone, two 13.5" 2" diameter tubes and a coupler. I used a 5 3/8" long bt-60 tube for the tail and proceeded to scale some depron tail and wing surfaces that looked approximately correct. I used a 3mm spar in the horizontal stab and a 3.2mm spar in the wing.
The scale 2x length should be around 42" long ignoring the pop pod, and wingspan around 31.5". My length I had available with cone was 36.5 and the cone is longer than scale so for looks I shortened the wingspan to 28" and widened the chord a bit to give me a similar scale area. I'll use just split elevons on the tail for roll/pitch. I did some openrocket modeling to move components around to give me a boost CG of around 30% chord, since it's an eleptical wing, the % root chord is same as % MAC. I moved the wing back just a bit to reduce nose weight and came out with this. RTF should be 10.75 oz with 9.75 oz glide weight and 12.5 oz wing loading. Mark at stickershock is working his magic on markings. I like the look of it in glide mode, I put a fake black pivot circle and a dummy front wing hold down just to keep the asthetic.
Maybe I'll call it a an oblique wing transport where I've chosen 90 degrees....I was considering angling the wing for fun but then found this quote: ". Although the oblique wing is still considered a viable concept for large transports, the unpleasant flying characteristics of the AD-1 at extreme wing-sweep angles may have discouraged aircraft designers from adopting this configuration."
His glider version was 46" long, 34" wingspan and used G motors for a 46 ounce boost weight and 41 ounce glide weight. The original was around 2 oz glide weight I think so with the scaling of factors, it means a 2.25x gives you 5x wing area and 5x weight for similar wing load, but we know larger can carry more weight typically than a direct scale. His glide weight is around 20x for a bit more wing loading than I like of around 25-29 oz/sq foot. I thought a 2x upscale would give me 4x wing area, so if I could get around 9-10 oz glide weight for a scaled wing it might not be too bad.
So I looked at my components, a 9.5" long psII 2" cone, two 13.5" 2" diameter tubes and a coupler. I used a 5 3/8" long bt-60 tube for the tail and proceeded to scale some depron tail and wing surfaces that looked approximately correct. I used a 3mm spar in the horizontal stab and a 3.2mm spar in the wing.
The scale 2x length should be around 42" long ignoring the pop pod, and wingspan around 31.5". My length I had available with cone was 36.5 and the cone is longer than scale so for looks I shortened the wingspan to 28" and widened the chord a bit to give me a similar scale area. I'll use just split elevons on the tail for roll/pitch. I did some openrocket modeling to move components around to give me a boost CG of around 30% chord, since it's an eleptical wing, the % root chord is same as % MAC. I moved the wing back just a bit to reduce nose weight and came out with this. RTF should be 10.75 oz with 9.75 oz glide weight and 12.5 oz wing loading. Mark at stickershock is working his magic on markings. I like the look of it in glide mode, I put a fake black pivot circle and a dummy front wing hold down just to keep the asthetic.
Maybe I'll call it a an oblique wing transport where I've chosen 90 degrees....I was considering angling the wing for fun but then found this quote: ". Although the oblique wing is still considered a viable concept for large transports, the unpleasant flying characteristics of the AD-1 at extreme wing-sweep angles may have discouraged aircraft designers from adopting this configuration."
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