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Old 16th Apr 2019, 07:03
  #4074 (permalink)  
Join Date: Jan 2012
Location: Welsh Marches
Posts: 36
Stab Trim Simulation Inputs

OK, not a pilot or anything to do with aviation, but being basically housebound for the past few months have followed the LIon Air and Ethiopian accidents and the resulting Max saga on here and elsewhere (and have tried to DMOR before asking questions). They are fascinating from so many aspects which the ongoing debate on here and other forums have sought to draw out, it is just sad that it has to be on the back of such a tragic loss of life.

This post is promoted by watching the Mentour video, and in particular the struggle they had trying to use the manual wheel trim to restore stab trim. My understanding is that a flight simulator is programmed to simulate real aircraft behaviour by using test flight data from all of the flight envelope and no doubt from wind tunnel testing and other research?

So watching the struggle to manually trim under the flight conditions they were attempting to simulate gave me the obvious thought that manual trim reaction was being supplied by some algorithm, look up chart, whatever which said in my layman understanding “these are the simulated flight conditions, therefore apply a force of x to the manual trim wheel”.

If this is correct, if I were a regulator looking to recertify the MAX, or more so if I was a lawyer looking to build a case, I would be very keen to see this background data, and exactly how much of the flight envelope is actually covered while still allowing the manual trim wheel to retain authority, and not assuming the pilot was superhuman.

Alternatively, probably not sure how realistic, but if the data wasn't complete, wouldn't it be “relatively easy” for interested parties to commission wind tunnel testing to obtain the countering manual trim force required throughout a complete range of speed, altitude, stab trim angle and with say a maximum countering column elevator force being applied ?

Apologies if this is ignorant nonsense, if it is “move on nothing to see here!” If there is any logic in what I say I'd love feedback.

Alchad is offline