Originally Posted by
gums
Salute!
I shall stick with my interpretation of the reason MCAS was implemented.
It was to counter a nose up pitch moment.
If all it had to do was stiffen or increase back stick, there would not have been two crashes where the stab trimmed so far down that recovery was a big problem. Oh yeah, then the 5 sec pause and here we go again.
I would love to have Driver or another 737 jock fly the MAX with no MCAS and pull until the stall shaker. Let us know if the stick got lighter and if it was a problem. Real plane, not a sim.
PLease see the other forum where the pitch versus AoA charts are shown/discussed. and somewhere here we have the same chart.
Gotta see the dentist. So later..
...
Gums...
Lost in Saigon is correct. I’ll ad some to his post:
If there really was a pitch up moment at high AoA/stall that is not an acceptable behaviour and in that case the model would need a stick pusher to keep it from getting there.( § 25.203 Stall characteristics )
Also, if the Max had a pitch up moment, the MCAS downtrimming of the stab could easily be overridden by more elevator( elevator pitch up canceling out the stab downtrim) making sum= status quo. Then the pitch up moment still would be there. If there was a pitch up moment it could only be fixed with a stick pusher.
There is a pitch up moment from the engine nacell’s at high alfa but it is allways less than the pitch down comming from the CG being forward of the centre of pressure center. The nacelles pitch up moment ease the elevator work to pitch up /decrease speed, making the stick force gradient to low.
Gums, you have my respect for many excellent posts and a very good carreer! Thumbs up :-)