Originally posted by Steve Lewin
Do you know, some people even take the shear webs all the way out to the wingtips despite there being almost no load out there 
?
Just when you think you're making progress, some bloke comes along with his own theories.
Steve, we are talking about SHEAR....
SHEAR!!!
Take two pieces of 3/8 x 3/8 stock, lay them parallel on the table 1 inch apart so they run from left to right. Now slide one to the left, and one to the right.
Did the tips move less than the rest of the sticks? No??? Then what makes you think that the shear is less at the wingtips???? Shear webs do NOT need to come in contact with the ribs. They need to keep the upper and lower spars from
shearing (moving in opposite directions from on another) That is why the grain goes vertical, if it went horizontal, the webs themselves would shear. (see pic)