Well its more of a streamline with an angle edge... So lets say the coefficient of a angled cube and a streamlined body is being used in designing the Bravesword line of racket... so ((0.8+0.04)/2) = 0.42 drag coefficient. I KNOW THE MATH IS NOT CORRECT but its logically right So get a BS and with this in mind i bet u can swing the racket faster...
Anyway, the shaft diameter is not just for aerodynamic reasons, but also changes the flex of the racquet so may feel quite different. Classic example would be the difference between an original Cab20 and a Cab21, both have almost identical frame shape sections, but the Cab21 has a much thinner shaft and feels quite whippy but not excessively so.
And on the point of aerodynamic shapes, you are forgetting that in most power stokes (when aerodynamics are most important) the racquet face is not perpendicular to the direction of travel most of the time, until the point of contact with the shuttle. Read up on the features of the Z-Slash and you will understand what I mean.
This is why the old Aerotus racquets actually felt worse or at least no better travelling through the air compared to a standard racquet despite its claims for lower air resistance. Structurally the "wing" shaped section is also quite poor making the aero shape terrible for control, feel and off-centre shots.