H50% reduction of existing design
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H50% reduction of existing design
Hi all,
If I were building a half-size version of an existing model, would I be able to get away with using half-sized lumber? (1/2" square becomes 1/4" square, 1/8" thick ribs become 1/16" thick ribs etc.) or would that be likely to weaken the structure too much? I was debating between a 1/2 size and a 2/3 size Astro-Hog (~36" or ~48" span) but having access to just the right sized balsa without having to redraw as many slots would make me lean towards the 1/2 size.
Also, do smaller planes need a lighter wing-loading to fly in a well-behaved manner? Even if I used all of the original structure (probably overkill in a 1/2 sized model) I figured the wing-loading would drop (1/4 the wing area, but the lumber should only weigh 1/8 of the full-sized lumber) or at least not go any higher, so will I really need to weed out the excess lumber to have a good flying plane?
I'm sure there's a reason you can't just use a 1/2 sized plan with 1/2 sized lumber since it just seems like too easy of a shortcut, but thought it might be worth asking .
thanks,
Rick
If I were building a half-size version of an existing model, would I be able to get away with using half-sized lumber? (1/2" square becomes 1/4" square, 1/8" thick ribs become 1/16" thick ribs etc.) or would that be likely to weaken the structure too much? I was debating between a 1/2 size and a 2/3 size Astro-Hog (~36" or ~48" span) but having access to just the right sized balsa without having to redraw as many slots would make me lean towards the 1/2 size.
Also, do smaller planes need a lighter wing-loading to fly in a well-behaved manner? Even if I used all of the original structure (probably overkill in a 1/2 sized model) I figured the wing-loading would drop (1/4 the wing area, but the lumber should only weigh 1/8 of the full-sized lumber) or at least not go any higher, so will I really need to weed out the excess lumber to have a good flying plane?
I'm sure there's a reason you can't just use a 1/2 sized plan with 1/2 sized lumber since it just seems like too easy of a shortcut, but thought it might be worth asking .
thanks,
Rick
#2
Join Date: Oct 2002
Location: Chilliwack, BC, CANADA
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RE: H50% reduction of existing design
For this sort of reduction you could get away with halving the wood for MOST of the items. Where things would need to change would be retaining the use of 1/16 for ribs and such. But 1/4 sq for the leading edge on a 36 inch span sounds perfect. Just keep in mind that a 36 inch span model doesn't really want to come out much heavier than about 18 or 19 oz if you expect it to fly in a fairly fun manner. The amount of wood you keep in the design should reflect that. For example you may want to forego wing sheeting or reduce the amount of it to save some weight. The tail sections can be built up with open ribs instead of solid sheet or fully sheeted or use solid sheet but of a lighter thickness. Stuff like that.
The wing's rib spacing can be altered to use one rib every two inches but if the reduction puts them at 1 1/2 then I would just keep the scale number of ribs.
The wing's rib spacing can be altered to use one rib every two inches but if the reduction puts them at 1 1/2 then I would just keep the scale number of ribs.