Balsa Wood Properties
By Kurt Krempetz
Balsa Wood

Balsa wood is a very interesting material and is typically used for construction of model airplanes. Balsa is technically a hard wood, because of the shape of the leaves. It is not the lightest wood, but it is the lightest wood which has some strength. Actually Balsa wood’s strength to weight ratio and stiffness to weight ratio is very good, better than any man made material that I am aware of. It is not considered to be a great material to use for the design of most things because its properties vary greatly.

Like with most woods, balsa wood does not have well defined mechanical properties. Its properties vary greatly with the gain direction of the wood and the moisture in the wood. But if one wants to do some design calculations some rough properties are needed. Below is a table of balsa wood properties which I use to do design calculations. These values were obtained for other books and websites, along with some of my own measurements.

Lightunder 5 lbs/ft^3.00289lbs/in^31.31 g/in^3
Medium5 to 9 lbs^ft3 .00289 to .00521 lbs/in^31.31 g/in^3 to 2.36 g/in^3
Heavyover 9 lbs/ft^3.00521 lbs/in^32.36 g/in^3

Compressive Strength
Light680 lbs/in^2
Medium1750 lbs/in^2
Heavy2830 lbs/in^2

Tensile Strength
Light1100 lbs/in^2
Medium2890 lbs/in^2
Heavy4670 lbs/in^2

Elastic Modulus In Compression
All66700+-10300 lbs/in^2

Elastic Modulus In Tension
All185,300 +- 65400 lbs/in^2

Formula to Calculate Wood Pounds in Ft^3.
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