Terry, try an experiment. Take a piece of 1/16' balsa approx. 3" wide and maybe 12" long which has the grain running length wise. Take the sheet and grasp it across the 3" dimension and and bend it. The sheet will cup very easily into a partial cylinder. Next take the same sheet from end to end and bend it... much stiffer more difficult to bend.
When flaps deflect, the air pressure strikes the flaps and being supported at the hinge line, they tend to twist and cup if not stiff enough. Getting the grain off of parallel creates and somewhat stiffer structure against that load which helps.
Topic: Flaps..... (Read 740 times)
