iamlucky13 wrote:B777LRF wrote:Not long ago, Björn postulated you'd have to pull 2Gs in order to stalll the aircraft. That was the exact same moment he lost all credibility.
You seem to be incorrectly recalling what he said. Please in the future verify statements you believe to be incorrect before citing them as a reason to doubt a person's credibility.
https://leehamnews.com/2019/11/08/bjorn ... sh-part-2/In daily operation, a 737 MAX flies with an Angle of Attack below 7° to 8° and never passes 1.2 G in load factor (in fact it rarely passes 1.15 G, the load factor for a 30° bank turn).
MCAS is programmed to activate at almost double this AoA value and the pilot need to pull around 2G or more to get to where MCAS will be active.
He estimated it would take 2G's to cause MCAS to activate, not to stall. He does not explain how he arrived at that value, which is reasonable to question. I assume this is based on the speeds and AoA it activates at, but I'm unclear if he is stating that in reference to the design of MCAS as originally presented to the FAA, or based on changes that as I understand it were made to extend its operation to lower speeds.
It's been discussed several times in this thread. Yes, it seems that he is is essentially discussing MCAS before its functionality was extended to low-speed regimes. However, this was published on Nov 8, 2019, so we can't use the "old news" excuse. He pretty unambiguously puts it in the present tense, saying "MCAS is programmed to activate at almost double this AoA value and the pilot need to pull around 2G or more to get to where MCAS will be active." If it's an oversight, then it ought to be corrected. I do not find his language to be unclear.
We know that when MCAS was extended to the low speed regime, the G sensor was removed, because now the system also needed to activate when the plane wasn't puling high G forces.
So, if what Bjorn meant to say was "MCAS was initially programmed to activate…", then by now, surely the article should have been fixed.
To me, it's strange that Bjorn never does go on to mention MCAS's activation in the low speed regime. It's an important detail in the story that MCAS initially had sensor redundancy, requiring both high G forces and high AOA. It wasn't until Boeing extended its function to the low speed regime that the G sensor was removed from the loop, and redundancy was lost.