Justin wrote (and this may have already been addressed but here goes anyway)-
>Looking at something that someone wrote about another airplanes spars was >about >the grain of the wood not being correct for a spar. On the edge of the spar >material the grain is at a 45degree angle which is incorrect due to the >load >direction will crack against the grain in a 45 degree manner. Grain orientation really doesn't have to do with how the spar will fail or crack. Grain orientation has to do with how the shape of the spar might change as the wood gains or loses moisture. If the grain is not straight and orthogonal to the spar axes, the spar could bow, cup, or otherwise deform. The orientation and tightness of the grain, as well as the clarity of the wood, is of great concern for uniform strength of the spar. As a starter, get (and study) the EAA "Wood Book" (EAA Aircraft Building Techniques- Wood; $11.95) for much more detail on selection and grading of wood for homebuilts. And remember that the spars, more than any other structural piece in the airframe, are what holds your present and future together. >Can duglas be used for the spars? Douglas fir, properly graded and applied, can certainly be used for your spars. It costs less than spruce, is stronger than spruce, but weighs more. Again, refer to the "Wood Book" for more detail on comparisons between commonly available materials. Oscar Zuniga San Antonio, TX mailto: taildr...@hotmail.com website at http://www.flysquirrel.net _________________________________________________________________ STOP MORE SPAM with the new MSN 8 and get 2 months FREE* http://join.msn.com/?page=features/junkmail
