At 11:01 AM 5/5/2005, you wrote: >You state that the strengthof a properly designed wooden spar does not >depend on the grain orientation. I believe this is missleading, would >you use wood that had a splope on th grain of 1 to 3 or 1 to 5 or 1 to >20?. >Jim
In the previous note, the context implied grain defined by growth rings. The slope criteria is based on the longitudinal orientation of the wood fibers. They have to run the length of the spar within the allowable slope. The growth ring orientation for aircraft use is typically known as quarter-sawed, meaning the growth rings are more-or-less parallel to the horizontal in a tall slender board. These two are very much related and sometimes confusing. It is much easier to show with sketches than say with words. A strength of a properly designed spar does not depend on the grain orientation of the growth rings, only on the fiber orientation. The orientation of the growth rings does have a direct effect on the dimensional stability with changes in temperature and humidity. Don Reid - donreid "at" peoplepc.com Bumpass, Va Visit my web sites at: AeroFoil, a 2-D Airfoil Design And Analysis Computer Program: http://aerofoilengineering.com KR2XL construction: http://aerofoilengineering.com/KR/KR2XL.htm Aviation Surplus: http://aerofoilengineering.com/PartsListing/Airparts.htm EAA Chapter 231: http://eaa231.org Ultralights: http://usua250.org VA EAA State Fly-in: http://vaeaa.org
