Posted on 01/31/2024 8:22:01 PM PST by SeekAndFind
???
I'm using unstable as the FAA defines it in Federal Aviation Regulation Airworthiness Criteria Sec. 25.173 — Static longitudinal stability.
The 737 MAX, while more stable than the F-16, is not a stable aircraft as evidenced by the MCAS system Boeing installed.
So you’re saying when a 737 MAX is flying straight and level and not accelerating, if the pilot pushed or pulled on the yoke and then let go, the 737 MAX would not return to its original trimmed position?
Are you saying the MCAS is needed for this, and without the MCAS the 737 MAX would not return to its position as trimmed before the upset?
I never said that and neither does the FAR, posted again below. Pay particular attention to 25.175(b). The Boeing 737 MAX is unstable because in certain climb profiles, it will NOT "return to within 10 percent of the original trim speed when the control force is slowly released". The plane would climb until stall without the MCAS system stopping it.
Appendix: Federal Aviation Regulation Airworthiness Criteria Sec. 25.173 — Static longitudinal stability.
Under the conditions specified in §25.175, the characteristics of the elevator control forces (including friction) must be as follows:
(a) A pull must be required to obtain and maintain speeds below the specified trim speed, and a push must be required to obtain and maintain speeds above the specified trim speed. This must be shown at any speed that can be obtained except speeds higher than the landing gear or wing flap operating limit speeds or VFC/MFC, whichever is appropriate, or lower than the minimum speed for steady unstalled flight.
(b) The airspeed must return to within 10 percent of the original trim speed for the climb, approach, and landing conditions specified in §25.175 (a), (c), and (d), and must return to within 7.5 percent of the original trim speed for the cruising condition specified in §25.175(b), when the control force is slowly released from any speed within the range specified in paragraph (a) of this section.
(c) The average gradient of the stable slope of the stick force versus speed curve may not be less than 1 pound for each 6 knots.
(d) Within the free return speed range specified in paragraph (b) of this section, it is permissible for the airplane, without control forces, to stabilize on speeds above or below the desired trim speeds if exceptional attention on the part of the pilot is not required to return to and maintain the desired trim speed and altitude.
[Amendment 25–7, 30 FR 13117, Oct. 15, 1965]
You’re dancing around. The 737 MAX is aerodynamically stable. Because in extreme maneuvering that will not be encountered if the plane is flown properly within its specified envelope, the 737 MAX is not stable enough to meet the criteria of the FAR. That doesn’t mean the 737 MAX is an unstable design.
It’s like if a sports announcer said a driver did not meet the qualification time, you would take that information and then tell someone the driver was going in reverse.
Extreme maneuvering??? There were two routine flights that crashed and killed everyone on board.
Enough. I get it; you work for Boeing. Boeing installed the MCAS system because the aircraft needs it because it's unstable as per the FAA and Boeing.
I don’t work for Boeing. I’m not even in the aviation industry.
The two MAX planes did not crash due to the planes being aerodynamically unstable.
They crashed because insanely poor Boeing engineering whereas a single sensor failure would cause the plane to fly itself into the ground. I am not defending Boeing here. That was an insane design and Boeing deserves all that it gets for that.
But the 737 MAX is not aerodynamically unstable. I will leave you alone now. Have a good day.
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