RE: Hyperveloce (#4116)
Does anyone know how these alpha threshold are computed ?
No, you would have to ask Airbus Flight Test/Engineering. If you were in their shoes, this is what you could do:
You do a stall test (or several) in the particular configuration. Starting at a speed well above the stall, you gradually reduce airspeed until the airplane stalls. From the recorded data, you derive a curve of CL vs alpha (see for example page 5 in the Lutz presentation). On that curve you select an alpha-max. The CL at alpha-max defines the reference stall speed. If you want the minimum stall warning margin required by regulation, you calculate a speed equal to 103 percent of stall speed, and the corresponding CL. With that CL you go into the CL-alpha curve to find the stall warning threshold. Bear in mind that you may select a stall warning margin greater than the regulatory minimum.
regards,
HN39