On Wednesday, July 22, 2015 at 9:40:48 AM UTC-7, wrote:


Page 3-17: There is a heading "sideslip", and a paragraph about sideslips, and then the authors insert a paragraph about dihedral-- yet fail to explain why the left and right wings experience different angles-of-attack during a sideslip due to the dihedral. In fact the authors imply that the only significant cause of a difference in angle-of-attack between the left and right wings is a rolling motion! The authors suddenly start talking about roll damping again, and describe again how a non-zero roll rate creates a difference in angle-of-attack between the ascending wing and the descending wing, still under the heading of "sideslip"! They are echoing the very same confusion that we saw in pages 3-12 through 3-13. Nowhere is the reader told how dihedral really works to create a roll torque during sideslip, and every time the subject of dihedral comes up, the authors veer off into a discussion of roll damping!

S

I didn't describe that one quite right-- this time they didn't start talking about roll damping again, rather they started talking about how if one wing was in an updraft and another in a downdraft, that would cause a difference in angle-of-attack.

Obviously someone told the authors that they should talk about a difference in angle-of-attack between the two wings when they talk about dihedral. Since they don't understand that dihedral creates a difference in angle-of-attack between the two wings during a sideslip, they are just sticking in some other random stuff about why there might be a difference in angle-of-attack between the two wings.

S