I always thought redwood was weaker than sitka spruce, but recent posts on wood work and substitutions got me digging in old literature.
For instance, "AIRCRAFT WOODS Their Properties, Selection, and Characteristics" , FPL, 1941
file:///C:/Users/Steven/Downloads/FPL_R1079ocr.pdf
indicates that redwood is slightly better than Sitka spruce in strength properties. In shock resistance and stiffness, it is rated 99% of Sitka spruce. Despite properties across the board of no less than 99%, Bending and compressive strength at 133% and hardness 110% of Sitka, that report weights specific gravity and puts the over all comparison of redwood to Sitka at 93% because they find the specific gravity to be 110% of Sitka.
Other recent research finds redwood to be slightly lighter than Sitka spruce. Including Wood database with Sitka @ 27lbs/cu ft, and redwood @ 26.
However, that source finds redwood to be significantly weaker, lumping old growth with new growth averages. Then they add this note:
I've never heard of a redwood airplane, though. Perhaps during the era that redwood was plentiful and hence cheap everywhere as a mere utility wood, Sitka spruce was probably almost as common (ladder stock, e.g.) and even cheaper? Is it superstition, or intrinsic defect that makes it a liability for AC construction?
For instance, "AIRCRAFT WOODS Their Properties, Selection, and Characteristics" , FPL, 1941
file:///C:/Users/Steven/Downloads/FPL_R1079ocr.pdf
indicates that redwood is slightly better than Sitka spruce in strength properties. In shock resistance and stiffness, it is rated 99% of Sitka spruce. Despite properties across the board of no less than 99%, Bending and compressive strength at 133% and hardness 110% of Sitka, that report weights specific gravity and puts the over all comparison of redwood to Sitka at 93% because they find the specific gravity to be 110% of Sitka.
Other recent research finds redwood to be slightly lighter than Sitka spruce. Including Wood database with Sitka @ 27lbs/cu ft, and redwood @ 26.
However, that source finds redwood to be significantly weaker, lumping old growth with new growth averages. Then they add this note:
IOW, right in with Sitka spruce averages.
I've never heard of a redwood airplane, though. Perhaps during the era that redwood was plentiful and hence cheap everywhere as a mere utility wood, Sitka spruce was probably almost as common (ladder stock, e.g.) and even cheaper? Is it superstition, or intrinsic defect that makes it a liability for AC construction?
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