Originally Posted by Chris Scott
The process of changing the FPA requires a force. Can you go on and explain how that force is produced?
During high AoA demo where full back stick has to be maintained the FCS is constantly working at maintaining alpha max, therefore the FCS will not use a thrust increase or additional aport of energy to increase the speed but to increase the pitch and the FPA.
The initial comment that started our discussion :
"Although Airbus test pilots routinely made high AOA demonstrations with alphafloor switched off they invariably compensated for that by selecting a level of thrust commensurate with maintaining speed and altitude."
had to be corrected as the FCS is dealing with speed through AoA and the pilot is dealing with altitude through thrust.
The later comment :
"They know that to make a correct demonstration of alphamax it is necessary to have enough thrust not only to maintain altitude but also to maintain speed. If that is not so the EFCS will apply a nose down corrective pitch command that will prevent achievement of alphamax."
had also to be corrected as the level of thrust is strictly to maintain altitude and not speed. You could be idle thrust and still maintain alpha max at Valphamax.