Originally Posted by CONF iture
Alpha max is an AoA that the FCS maintains at the fixed value Airbus decided to adopt depending on the configuration.
Agreed, I don't remember how many times I wrote that. It is the reason that the lift is proportional to airspeed-squared. Lift can only increase by increasing the airspeed.
The corresponding speed to that fixed alpha max value is called Valphamax and remains the same as well, be it in level flight descent or climb ...
That is basically correct also, but only in 1-g condition (lift equal to weight). Strictly speaking the load factor in steady climb and descent is less than 1, but that difference can be ignored for small flight path angles. The point is that changing the flight path angle requires a net force normal to (at an angle to) the direction of movement. In steady level flight lift equals weight. To increase the flight path angle requires a lift force greater than weight. At constant angle of attack (i.e. constant lift coefficient) you can only increase lift by increasing speed.
The amount of thrust will decide the V/S but the speed will remain at Valphamax.
That is basically correct for the steady climb at constant V/S and airspeed, but not for the transition from level flight to steady climb. During that transition the V/S increases from zero to the steady climb value due to the vertical acceleration resulting from the net vertical force of lift minus weight.