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(To allow for larger, more fuel-efficient the engines were moved forward. This forward movement also moved the aircraft Center of Gravity (CG) 8 inches forward. This change in the CG creates a tendency for the aircraft to pitch up)
This is patently a false statement, moving the CG forward causes the nose to feel heavier and have a nose down effect. What did change was the design of the cowl now generated some lift and possibly a slight upward thrust vector from the engines. Which would tend to lift the nose in a REARWARD CG configuration, MCAS was put in as a safeguard to prevent the stall. It did the job on false data all too well.
Thanks for correcting the first point, it made no sense that moving it forward would made nose up a tendency if that alone is the only change.
(To allow for larger, more fuel-efficient the engines were moved forward. This forward movement also moved the aircraft Center of Gravity (CG) 8 inches forward. This change in the CG creates a tendency for the aircraft to pitch up).
Doesn't it make more sense that the center of lift moved forward.
Pitching up slows the plane until it stalls, the nose then falls through and it rapidly picks up speed.....even fatal speed if you now have a stab trim driving the nose down......the way out was to disable the "stab trim cutout" before it killed you. Should be noted several pilots did know what to do just like the jump seat rider on Lion Air the previous day.
I knew that, but they didn't say anything about it nosing down when they said it was picking up speed. I didn't want to read into it things that were left out. Since no one is talking about it I guess it doesn't mean anything.
Doesn't it make more sense that the center of lift moved forward.
The big birds balance point is usually expressed as Mean Aerodynamic Chord......
Mean Aerodynamic Chord. The distance between the leading and trailing edge of the wing, measured parallel to the normal airflow over the wing, is known as the chord. If the leading edge and trailing edge are parallel, the chord of the wing is constant along the wing's length.
CG and center of lift are pretty much the same thing. In any case it's pretty much balancing a long aluminum tube. Engineering works out the datum points and how much force is applied by weight. I am qualified in weight and balance on DC-9 all series-MD-80/88-Airbus A319/320 and Boeing 757......so this is what I did for 38 wonderful years back when the airlines were fun.
The goal in the airlines is to give the crew a setting that makes every takeoff the same for that bird. I got to know the Captains pretty well over time and they liked me to balance the A320 a little to the rear, to make it a little more responsive. If you look at the A320 the tail surfaces are a little smaller than usual because it increased efficiency with the fly-by-wire (smaller surfaces less drag). Balance it with CG forward and it was a little piggish in handling. You want to balance aerobatic birds and fighters a little towards the rear CG setting it makes them more responsive.
The ultra sophisticated stuff has the computers watch everything....example the F117 stealth fighter if it loses the computers it will tumble upside down and try to fly backwards. The Airbus group also uses flight modes to make things easier with computer power, where the pilot is a voting member sending input to the logic boxes........the computer looks at it and makes sure no limits are exceeded and then moves the surfaces with electric servos.
I'm not a pilot, not an engineer, no reason to know the answer to my question. But, I figured the following:
Path One
1.1)Moving two masses the size of the engines forward would move the center of gravity forward.
1.2)Moving the center of gravity forward would pitch the nose down.
1.3)However, the masses moved are actually the thrust producers.
1.4)So the source of thrust was moved forward.
1.5)So, not dead weight, but dynamic force source was moved.
Path Two
2.1)Moving the thrust source partway ahead of the wing raises thrust (i.e., windspeed) ahead of the wing.
2.2)Increased windspeed ahead of the wing raises the lift power of the wing.
2.3)The increased lift power leads to increased nose-up forces under some conditions.
The combination of Path One and Path Two lead to the problem that needed to be solved by MCAS.
Again, I know nothing about this. I am stating the above in order to learn. I appreciate any clarification anyone can provide.
The B737 Max 8 doesn’t have any problems mechanically, the software just needs updating. The fleet should be back in the air soon. This is a very safe airplane
The B737 Max 8 doesn’t have any problems mechanically, the software just needs updating. The fleet should be back in the air soon. This is a very safe airplane
The B737 Max 8 doesn’t have any problems mechanically, the software just needs updating. The fleet should be back in the air soon. This is a very safe airplane
People died software matters too. Why are you confused?
Trust the computers. They're safe. What could go wrong?
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