Did somebody say "select TOGA"? A recipe for disaster.
If the aircraft has underwing (low slung) engines, this will cause a further pitch-up against minimally effective elevator pitch down, significantly worsening the situation (Taiwanese Airbuses come to mind). If the engines are rear mounted, which they usually are for T-tail designs, you're lucky to get a response at all, as the engines too, are in the disturbed air aft of the wing. Both T-tail, swept wing aircraft that I've done full back stick stall testing on had rear mounted engines, and the pop pop bang of the compressor stalls were very evident - I know of no recommendation to advance thrust on an engine suffering compressor stall (unless you want additional dire consequences on your hands).
In the flight testing I've done, both aircraft fortunately had excellent roll response down to and beyond the stall. One of the two had minimally effective "push" augmentation, which necessitated deliberate attempts to enter the "deep stall" during testing, e.g. APPROACHING full back stick, apply high thrust (not compressor stalling YET), rotate to much higher than the normal stall attitude, chop the thrust, and apply full back stick, (Now much banging and popping from the engines, DO NOT increase thrust) and wait to see the effectiveness of the inbuilt recovery system. It always worked, albeit slowly, but it was well accepted that elevator alone may not have been enough, and running stab trim forward was the only pitch option available. As a DIRE LAST RESORT, roll to the vertical and let the aircraft fall through with relaxed elevator.
In all cases, thrust was not increased until the angle of attack had been reduced to the normal stall angle. Engine synch on and feet on the floor to prevent any unwanted yaw.
It may sound odd, but at all times one had to have a mental picture of what the airflow was doing at every point on the aircraft, observation of a lot of wind tunnel testing was good value for this.
Thank God I don't do it any more, but if I had to go back again, I'll do the sissy coffin corner stuff and engine cuts at Vef and leave the deep stall stuff to hardier souls.
Regards,
Old Smokey
Last edited by Old Smokey; 29th Apr 2005 at 09:35.