Originally Posted by
gonebutnotforgotten
The Trident in fact had an all flying tail, the column commanded the whole tailplane and what appears to be an elevator was in fact a geared tab, albeit quite a large one. So the pitch trim did not use an independent surface, unlike most subsequent CAT designs, and the distinction between a stick pusher and a MCAS-like device didn't arise. Hope that's clear
It matters not if that rear surface on the Trident is an elevator, a balance-tab, or a servo-tab - the same choice applies.
Do you fit the anti-stall aumentation system to the control column, or to the trimmer..? The diferrence being that the control column (usually) gives an instantaneous response, while the trimmer (usually) gives a slow response. So when in the recovering dive, after an incipient stall event, the stick-push will relent immediately, while the trimmer may take 10 or 20 seconds to get back to neutral.
So tell me, how long did it take for the Trident to get from full trim forward, to neutral? The 737 takes about 20 seconds, which will probably make a recovery from the dive difficult or impossible.
The Rostov incident appears to have demonstrated this problem very well. Even with the trim set to 1.5 units (instead of the normal 5 or 6 units), the FlyDubai aircraft plunged to the ground almost vertically. But MCAS does not trim to 1.5 units, it can apparently trim to 0 units. So what chance is there for a recovery, with the stab-trim at 0 units (full forward) ? I would suggest little or none....
Silver