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Another question on scaling up plans.

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Another question on scaling up plans.

Old 06-27-2003, 09:13 PM
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Default Another question on scaling up plans.

Do you scale up WS and chord, or just scale up the wing SA, and use the same AR? The methods sound the same, but end up with 2 completely different results.

eg:
WS 60
Chord 13.5
gives a SA of 810 in^2

Say you want to scale it up by 1.47%:
WS 88.2
Chord 19.8
which gives a SA of 1746.4 in^2

BUT 810 scaled up by 1.47% = only 1190.7? ? ?

Which way would be correct, to give approx the same WL?
Old 06-27-2003, 10:35 PM
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Default Another question on scaling up plans.

hmm. when you scale something up. If you scale it up by 1.47 (both span and chord) you scale the area up by 1.47^2
Thats a huge jump. As far as keeping the wingloading the same, its often not possible. At some point, the material weights get you. But, the good news is, the bigger the plane, the higher the wing loading it handles before becoming a handfull to fly.
If you want to maintain approximately the same flying characteristics, you must keep the ar the same, or you wil lose roll rate (you'll always lose a bit when scaling up, it just happens).
Old 06-27-2003, 11:09 PM
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Default Another question on scaling up plans.

So which way do people usually do it? Scale the ared or the span and chord?
Old 06-28-2003, 02:25 AM
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Default Another question on scaling up plans.

it depends, i guess. Scaling up the wing area by 47% equates to scaling the chord, and span by 1.21 (square root of 1.47). To get the fuse length and size, its much easier to scale every dimension by a much smaller number, instead of trying to scale the wing, and then figure out what % you scaled it up. So, if you wanted to scale the area up by 47%, you only need to scale all the dimensions by 20%, or there abouts.

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