My Letter to the Editor of New York Times Magazine

Re:My Letter to the Editor of New York Times Magazine by bumby on Monday October 14, 2019 @09:55AM (#21248272)

Thanks for the clarification. Do you know if there are rules/regulations regarding the control inputs? I.e. is linear feedback necessary or just a preferred/expected feel? Without much knowledge of the system, wouldn't a non- linear input be the "expected" feel of a purely mechanical system because the drag increases proportionately to the square of air speed?

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Re:My Letter to the Editor of New York Times Magazine by sokoloff on Monday October 14, 2019 @10:34AM (#21248703)

Yes, there are certification requirements spelled out in FAR 25.175.

https://www.law.cornell.edu/cfr/text/14/25.175

The requirements have the form of "In configuration <XYZ>, the stick force curve must have a stable slope at all speeds within a range which is the greater of <range definition> above and below the trim speed."

It is this linear stick force curve requirement that was failing that MCAS was implemented to address. The airplane is still aerodynamically stable.

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