Quote from me, addressed to CONF_iture:
You didn't pick up on my query of your alpha-max figure for Flaps/Config FULL (15 deg). Where did you find that?
CONF_iture's reply:
Actually I did here.
No: you didn't! Your post merely restates the figures. Please state a specific reference for the Flaps FULL figure, if you have one.
Quote from C_Star:
I seem to remember from aerodynamics classes that higher flap settings yield lower critical AoA (but of course higher CL values) - that could explain why Conf Full has lower alphamax than Conf3.
Then, there's higher slat deflection for Conf Full, which should increase the stall AoA, but maybe the flaps effect offsets the slat effect?
That seems to be born out to some extent by the figures of alpha-floor in my BCAL/BA Tech Manual of 17FEB1988, which I quoted in a previous
post four days ago:
"Alpha-floor is activated when:
- alpha > alpha-floor (9.5 deg in conf 0; 15 deg in conf 1, 2, 3; 14.5 deg in conf FULL, or [...]"
But, as you see, the difference is only half a degree. Confit's figure suggests:
(1) the difference is 2.5 deg;
(2) alpha-max with Flaps FULL was only 0.5 deg above alpha-floor, which also seems improbable.
Unlike the Airbus FCOM extracts I quoted in the same post, those figures from the BCAL/BA Technical Manual (Ch 09 Section 10) -
17FEB1988 revision - were still current at the A320's entry into service in April 1988, so may be the most reliable information available (so far) for the Habsheim a/c. They appear at the foot of the familiar curve of Cz-versus-alpha.
The equivalent page on the preceding version, dated
25AUG1987, is a duplicate of the Airbus FCOM Flight Controls chapter (1.09.10 P8, REV 03, SEQ 001) that I also quoted in that post. As you can see, there are no specific values of alpha for alpha-floor or the other two protection levels. The figures provided define each of the 3 protection levels simply as the alphas associated with factors of Vs in any weight/configuration at low Mach, but neglect to define Vs itself. It may be that, with certification still pending, the definition of Vs was still under discussion. (The A320 was type-certificated in February 1988.)