Dozy,
That's an interesting hypothesis, i.e., the EFCS might deliberately keep a margin to alpha-max in idle thrust. I wonder.
AFAIK, however, we haven't established what config/flap GC was using for that demo, and in any case I currently disagree with Confit's figure of 15 deg for alpha-max with config FULL (see my post).
HN39,
That's a good call, although 3.04.10 was re Flight Instruments, and not included in my issue. However, 3.04.01
"Operating Speeds Definition" may provide the best explanation of how the peculiarities of certification for the A320 in Normal Law - which (as you know) was unique in being incapable of meeting the contemporary norms of stall testing - were addressed, and a compromise reached to avoid it being unfairly disadvantaged, field-performance-wise, relative to types like the B737.
Airbus FCOM 3.04.01, REV01 SEQ001 (still current at SEP 1987, prior to formal type-certification) (my emphasis):
"For a conventional a/c the stall speed which is used for reference is VSmin based on a load factor lower than 1G, which therefore gives a stalling speed less than that obtained at 1G. All operating speeds are expressed in relation with this speed (for example Vref = 1.3 VSmin). Since the A320 icorporates a low speed protection feature (alpha limit) which cannot be overridden by the flight crew, the airworthiness authorities have reconsidered their position regarding the stall speed definition.
"All the operational speeds have to be referenced to a speed which can be demonstrated by flight test. This speed is VS1g for A320 and VSmin for previous a/c types. As a result the Authorities have agreed to allow A320 to have the following factors:
V2 = 1.2 x 0.94 = 1.13 VS1g
VREF = 1.3 x 0.94 = 1.23 VS1g
"It can be seen that these speeds are identical to those that would have been achieved, had the a/c been conventionally certificated to the 94% rule. Compared to a conventional a/c the A320 has exactly the same manoeuvre margin at its reference speeds.
"In the FCOM VS1g will be designed [designated] VS. " [*]
* VS = "
Reference stalling speed (equal to VS1g)."