4 ms·
It's not the center of gravity that causes pitch-up - it's additional lift by engine nacelles at higher angles of attack; this lift increases the AoA further du
by sangnoir 8y ago
It's not the center of gravity that causes pitch-up - it's additional lift by engine nacelles at higher angles of attack; this lift increases the AoA further due to the position of the engines relative to the wing. This feedback loop leads to a stall when the angle gets high enough
- Gibbon1 8y agoThey should have put spoilers on the nacelles instead of trying to fix the planes bad aerodynamics in software.
- iamaelephant 8y agoYeah you would know.
- Gibbon1 8y agoHow do you know that I don't know. Please explain.
- subhro 8y agoProbably not completely true. An airfoil stalls when the critical angle of attack is exceeded. For most airfoils, this sits at around 17°. For all commercial aircrafts (I think 727 onwards) there is a mechanism called stick pusher that will not allow an airfoil to go over critical AoA. I am not sure if this has been overridden somwhere in the 737 Max 8 though.
- tostr 8y agoAre you saying 17deg from horizontal? Let's ignore wind and other influences. A normal plane can not climb more steeply than 17deg? I'm not implying you're wrong, just very surprised to see this low a number. I would have guessed much closer to something like 45deg, maybe even more.
- subhro 8y agoThe Angle of Attack is defined as the angle between relative wind and chord of an airfoil. So if your engine has enough juice to climb at 45° (and many aerobatic aircrafts do), your relative wind is coming at 45° from ground, but almost at 0° with respect to the chord. So your wing is still flying. Let me know if that makes sense.
- sangnoir 8y agoI was describing the physical "bug" Boeing was solving in software: MCAS is a stick-pusher because it forces down the nose - which led to the Lion air crash because of a faulty AoA sensor made MCAS avoid an imaginary stall, forcing the nose down into a powered flight into terrain.