PPRuNe Forums - View Single Post - New (2010) Stall Recovery's @ high altitudes
Old 19th Jun 2010, 09:11
  #36 (permalink)  
DFC
 
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To pick up on two very important points mentioned previously.

1. Stall has absolutely nothing to do with airspeed. It has everything to do with angle of attack. It is entirely possible to fly any aircraft at an airspeed of less than 10 Knots but not stalled - because the angle of attack is less than that at which the stall occurs.

2. Unless one is intending to do some aerobatics or aligning the aircraft with the centerline on landing, with all engines operating the rudder is only used to prevent yaw. Yes that is to prevent yaw. Or as some people like to say - keep the ball in the middle.

In order to "pick up a wing" using rudder - stalled, near the stall or at Vmo - one must yaw the aircraft. The only time I would expect anyone to intentionally yaw the aircraft at or close to the stall is when they want to experience the combination of stall and yaw = spin.

The stall recovery (or prevention) actions are basic and simple - reduce angle of attack and prevent yaw.

Height loss above 20,000 ft in a stall recovery (or avoidance) is not an issue that is worried about. If you are 20,000ft above the MSA then where is the problem in using some gravity to assist a prompt and effective recovery.

Finally, in a multi, it is not simply Vmca and engine failure that is an issue in stall recovery which involves accelerating to TOGA thrust / firewalling the levers but simple things like unequal acceleration times that can introduce unwanted yaw at the critical time when it is least desired.

Reduce AOA and prevent yaw.
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