tomfiorentino

Hi everyone,

I have a book on aerodynamics that includes a section on the above as it relates to rectangular, tapered and elliptical semispans. I continue to be confused by one concept presented that is dogging my understanding . Any thoughts would be appreciated as would any references for additionla reading (I didn't see anything come up in my RCUsearch).

In particular, the book references:

" Because the lift is proportional to chord and angle of attack, the effective angle of attack at each spanwise section is also different. Notice that for the rectangular wing the section with the highest angle of attack is at the root. The tapered wing has the highest angle of attack at about 2/3rds of the semispan. The elliptical wing has a constant angle of attack across the span."

Footnote: "The Ilustrated Guide to Aerodynamics" 2nd Edition by H.C. "Skip" Smith pages 40 - 41.

The section then goes on to describe the first region of stall to be at the root trailing edge for both the rectangular and elliptical wings and 2/3rds on the tapered wing. The progression of the stall is shown as being different for each as well. There is no mention of relative wind and/or dihedral effects so I am assuming everything is straight on.

So, few things:

1. How is the angle of attack across the semispan different (particularly hard to understand on the rectangular wing)?
2. If the rectangular wing has the highest AOA at the root and the elliptical AOA is constant across the whole span, then why is the first region of stall for both the same....at the trailing edge root?
3. What consideration shoud be given to the wing tip vortices? I guess I don't understand why the rectangular wing, for example, stalls last at the tip given the vortices are lift killers at any angle of attack.

What say ye RCU!

Tom