> Symmetrical airfoils will not generate lift if the angle of attack is
> zero. The F104 has a symmetrical airfoil and cruises at about 3 degrees
> positive AOA. Similarly, constant altitude inverted flight is possible
> only if the airfoil has a positive angle of attack relative to the
> earth. Lots of forward stick, in other words. In knife flight, the
> fuselage is yawed so it has a positive angle of attack and is
> generating lift and it is usually symmetrical, too. The slab-sided F4
> flew fine on its side at 500 KIAS. As for the 'true' explanation of
> lift, any time you have to juggle four simultaneous differential
> equations, pilot instruction becomes very unwieldy and the students
> doze off. This approach, to me, is picking nits.
>
> Walt BJ
It is very easy to see the im****tance of AOA (Angle of Attack) for
creating Lift of the Wings, when military aircrafts like Saab 37
Viggen.or Saab 39 Gripen, makes its approach for landing, at 11
degrees for normal landing and 15 degrees for short runway (800 m)!
The only way to physically create a local pressure gradient is to "turn
the airflow/ change direction" ( curved surface or wing at AOA)! Air
can tolerate maximum 8.5 deg, before separating from surface.
All new airliners of Airbus or Boeing make and all top bizjets, have
low drag "supercritical wings", with almost flat upper surface and
curved lower surface (to host wing beam and fuel)!
I have never seen Scientific American explain that wing and why it
physically create Lift!
Jan-Olov Newborg
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