Originally Posted by Clandestino
Now about stick pusher: it is not stall recovery device, it is stall prevention device!
Maybe a bit semantic, but it is primarily a
stall identification device. I fail to see the the distinction you make between recovery and prevention. On some airplane it is set to fire after the point of maximum lift (see fig. 5.25 in HTBJ) to provide the stall identification prescribed ("a nose-down pitch that cannot be readily arrested") with minimal loss of performance.
From HTBJ page 111 (my bold):
Hence, on aeroplanes capable of super-stalling, the 'stall' speed needs to be positively identified by a completely unmistakable, sharp, forward movement of the control column causing the aeroplane immediately to pitch down and reduce its incidence.
And on page 131:
... the pusher is required to work only when the wing arrives at its 'stalling' incidence ...