Originally Posted by
PashaF
I just have a wild (and scary) thought. If with this new fancy engines a 737 might has a deeper nose-up tendency in some corners of the flight envelope. Can it has a deeper nose-down tendency in some corners of the flight envelope as well?
They are installed much further forward than usual.
Maybe in in both crashes it was a moment when after reaching the certain angle the planes were suddenly pushed nose down because of that?
From fundamental aerodynamics, the answer is definitely yes.
The position of the engines cause increased drag at high AoA, which in turn causes a pitching moment around the CG. The reason for this is that the protruding engines cause the projected frontal area (Ap) to increase with pitch, and drag is proportional to Ap. The effect should be symmetric, since this is drag and not lift, but I guess it is unusual to see high values of negative AoA. It would be interesting to see how strong this effect is at a few degrees negative AoA.