Originally Posted by
Bleve
The MAX has larger engine casings that are mounted further forward than earlier 737's. At high AoA's, those engine casings start generating lift, which creates a nose up pitching moment. The MCAS is designed to counteract this by creating an opposite nose down pitching moment through the stabiliser.
And the engines are much more powerful - up to 30 k lb of thrust. All that extra thrust, low down on the airframe, generates a large pitch up moment - especially if the aircraft is slow and the elevator is becoming less efficient. You can actually get to a situation where the aircraft simply goes vertical, or flips over backwards.
S