Qantas747300 From Australia, joined Dec 2006, 70 posts, RR: 0 Posted (3 years 2 months 4 days 5 hours ago) and read 5389 times:
I am trying to source the accident behind a VMC diagram. I believe it was a B707 that experienced a loss of control due to excessive bank (following engine failure perhaps) which resulted in a vertical fin stall.
Countless hours of research hasn't sourced what I am after, thus, you have control.
747classic From Netherlands, joined Aug 2009, 2618 posts, RR: 16
Reply 4, posted (3 years 2 months 3 days 8 hours ago) and read 5159 times:
I only am aware of 707 VMC problems in 1959, that were at last solved by modifying (increasing the height of the vertical tail.
British certification requirements relating to engine-out go-arounds forced Boeing to increase the height of the tail fin on all 707 variants, as well as add a ventral fin, which was retrofitted on earlier −120 and −220 aircraft. These modifications also aided in the mitigation of dutch roll by providing more stability in yaw.
Operating a twin over the ocean, you're always one engine failure from a total emergency.
How in the hell do you do that? It never entered my mind that was even possible, unless you are doing an extreme maneuver like a lomkovac...
In a typical Vmc accident, you just happen to get the aircraft below the speed at which the rudder has the authority to counteract the yaw due to assymetrical thrust... as far as I know, the rudder is still creating lift. If you find it happening to you in real life, the quickest way to recover is to throttle back the good engine, point the nose down, and pick up airspeed (assuming you aren't really low, like base to final traffic pattern turn low )
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
Generating a sideslip angle of more than the fin stall angle, about 14 degrees or thereabouts. If the aircraft was rolling the fin AOA could be effectively increased, making a stall happen at lower sideslip.
Quoting KELPkid (Reply 6): If you find it happening to you in real life, the quickest way to recover is to throttle back the good engine, point the nose down, and pick up airspeed
That's fine in a steady state case where you've chosen to reduce thrust on one engine, a training scenario. With a real engine failure you might have to reduce thrust on the good engine to get directional control back. But increasing airspeed is always a good idea.
The glass isn't half empty, or half full, it's twice as big as it needs to be.