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-   -   contest balsa (https://www.rcuniverse.com/forum/scratch-building-aircraft-design-3d-cad-174/2417771-contest-balsa.html)

WILDMAN 420 12-09-2004 05:07 PM

contest balsa
 
I was wondering if anyone can tell me the weights of contest balsa sheets, ie. 1/6X3X36 inch and so on? MOst places around here won't grade it, and when i ask for it they say, well you can come and sort through it, so i am wondering what it should weigh to be contest grade? i have a digital scale to take with me. I am going to scratch build (sorry, Plans Build for the purists:)) a 1/3 scale stearman, aI want to keep it as light as possible(don't we all) Thanks for any help.

fritzke 12-09-2004 06:00 PM

RE: contest balsa
 
Lookie here:
[link=http://skyhooks.ca/basheet.htm#anchor407734]Balsa Sheet Weights, Size by Density Chart[/link]
Dave
PS Contest wood is in the 4-6 LB per cubic foot range. But it MUST still have a "Grain" or it is punky junk.
A 1/16 x 3 x 36 sheet is .0039 cubic feet of balsa!

BMatthews 12-09-2004 06:15 PM

RE: contest balsa
 
Unfortunetly it's hard to judge the stringiness of the grain until you buy the sheet, cut off a small strip and break it. If it breaks clean across with little or no sign of fibrous content then use it for non structural uses like thicker wing ribs or small lightly stressed parts. If it breaks with lots of fibers evident then it's good stuff and can be used for most anything where the weight is suitable. Just a little 1/4 wide by 1 inch long sample is enough. And watch out for this feature changing a lot over the width of a sheet. It can and does frequently happen.

Mike James 12-09-2004 09:39 PM

RE: contest balsa
 
The weight of any material, including balsa, ply, and foam is .009259 X Density, per cubic inch.


For example, a 4 inch X 36 inch sheet (144 square inches) of 1/16th balsa, (.0625 inches thick) at 6 pound density, is:
(144 X .009259 X 6) X .0625 = .49 ounces

I have some (free) info on my site, if you want to predict other structural weights, at http://homepage.mac.com/mikejames/rc...rediction.html


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