Originally Posted by
Fly Aiprt
This demonstration will settle the matter of the airplane "not being unstable" etc. that Boeing and some observers have kept repeating.
The fact that Boeing has yet to perform this demonstration, which could have been done months ago with any of the grounded airplanes, is a cause for concern.
One wonders what the hundreds of test flights since the accidents have been for...
A couple months ago I tried to make a back-of-the-envelope calculation on what the elevator forces/positions would be in the 10-14 AOA region. Ofc I had to make several assumptions, like that the full 2,4 degrees MCAS authority would be needed to make the stick force/position in line with the stick force requirements. I didnt get much response other than the calculations had no value whatsoever.
Anyway, what my calculations was suggesting is that without MCAS the stick force is not only increasing as it should, when going from say 10 to 14 degrees AOA, but that the stick force needs to be relaxed towards zero force and the stick position needs to be brought to near neutral position when going from say 10 to 14 degrees AOA. Such a pitch behaviour is ofc very undesirable in the case of a non operable MCAS system at the same time as a low speed/high AOA event which could happen for a number of reasons.
I think that if this would be near what is actually happening, then this would be a very good reason for Boeing beeing very reluctant to disclose the pitch behaviour of the aircraft with non-operational MCAS system.