Originally Posted by
krismiler
The Trident was a rear engined, "T" tail design which is subject to deep stalling, where the tailplane and engines can have their airflow blanketed by the wings, resulting in loss of elevator authority, rudder authority and engine flame out. Much higher levels of stall prevention would obviously need to be applied at the design and certification stage.
The Trident had a T-tail and possible elevator blanking.
The 737 has a large nose up moment from underslung engines.
They each have a design issue at the stall that requires an anti-stall augmentation device (as do most large aircraft). Hawker Sidley went for a stick push, while Boeing went for a trim push. But which is best? The fact is, when a stick-push finally relents, you are still in trim and can easily pull out of the dive. When a trim-push finally relents you are left with full forward trim and cannot pull out of the dive.
Which system is best?
Silver
P.S. Obviously we are talking about old-fashioned cable-controlled aircraft here, as the 737 flight control system not computer controlled. The Airbus is more sophistcated, but must still choose between elevator stall augmentation and stabiliser stall augmentation. Judging by the AF447 incident, when in manual law there is no anti-stall augmentation device, as the crew held the aircraft nose up using elevators for some considerable time.
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Originally Posted by
FCeng84
Some on this thread have suggested that MCAS May have been added to compensate for an elevator authority shortfall. That is not the case. This function was added to address a pitching moment vs AOA issue.
Because the elevator could not cope with that pitching moment, without artificial augmentation. ... You should not have an aircraft that continues to pitch 50 degrees up, when the pilots are pushing full nose down. Something needs to be done to address that issue.
S