[SystemSafety] "FAA chief '100% confident' of 737 MAX safety as flights to resume"
Olwen Morgan
olwen at phaedsys.com
Thu Dec 3 12:59:48 CET 2020
Having admitted to my execrable knowledge of aerodynamics and
aeronautical engineering, I will now make a few ill-informed
speculations about the 737 MAX:
Consider the following situation without MCAS:
At a certain speed and AoA, the pitch-up tendency of the aircraft is
beginning and the force on the stick has started to lessen. AFAI can
see, lessening of stick force will be due to reduced aerodynamic
pressure on the HS and elevators. If the HS and elevators are exerting a
much reduced force against the oncoming air-stream, then their ability
to control pitch has been correspondingly lessened. At the same time,
the pitch-up tendency is bringing the wing closer to a stall condition.
If the aircraft progresses to a wing-stall condition and at the same
time is suffering reduced pitch control as a result of what is
happening/has happened to the air flow over the HS and elevators, then
that condition is very close to a much more dangerous *deep stall*
condition.
Call me a scaredy-cat - or even just a pig-ignorant old bag - but I
personally don't think that any civil airliner airframe should exhibit
aerodynamic behaviour that introduces such a risk of a deep stall.
And now I'll just let PBL hurl his customary bile at me.
Olwen
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