Nacelle not lift

[BugBear]

MAX...
Nacelles disturb airflow, reducing lift. Reducing Lift decreases alphaSTALL
When A/C is trimmed, engines increase Pitch on their own.
This is PITCH Divergent.
This Power/Pitch couple increases PITCH RATE as Pitch increases.

MCAS lowers AoA incrementally. It moves at a steady rate, by definition it does not follow actual AoA as it (AoA) increases autonomously. It lags. It is good for ONE input only, in ten seconds.
By definition, MCAS does not function in unison with divergent Pitch. .... (IMO). If it did, well that's Airbus

As MCAS removes it's ND trim (~2.7 degrees), it lowers STALL AoA . What an unwelcome surprise when actual STALL meets cycling ND Trim.

DeFacto accelerated STALL? How does MCAS muddy up Stall entry/recovery?

NO WONDER BOEING wanted no part of a waiver.
Maybe the reason Boeing withheld some test data from FAA then badgered them for expedited approval?

[CVividasku]

I didn't completely understand what you wrote.
But I would be very curious to fly a stall with an uncompensated 737 MAX. Does it really go to the stall by itself ? Can you counteract it easily, when warned ?

[BugBear]

Originally Posted by CVividasku

I didn't completely understand what you wrote.
But I would be very curious to fly a stall with an uncompensated 737 MAX. Does it really go to the stall by itself ? Can you counteract it easily, when warned ?

It doesn't have to. The controlling language in the regs are "divergent". Any divergence has to be controllable to be airworthy. I dispute whether MCAS actually manages the uncontrolled PITCH.
I also dispute whether MCAS smoothes controls. MCAS is linear, as is feel. Divergent Pitch is logarithmic .

Happy to expand on what was misunderstood.
I may have wandered into AIRBUS "It cannot STALL" TERRITORY
MCAS also impinges on STALL entry, and recovery.

One of the reasons (many) Boeing didn't spill about MCAS to pilots, or the FAA? Did Boeing use MCAS to ostensibly "smoothe controls?" Only?

Does Actual STALL get computed with MCAS or without, because if it doesn't, divergent Pitch is screwing with STALL.

[jimtx]

Originally Posted by CVividasku

I didn't completely understand what you wrote.

Neither did he.

[BugBear]

Originally Posted by jimtx

Neither did he.

Pretty common dodge. Need help?

[Vessbot]

This reads more and more like Timecube the more it goes on. First I was annoyed, but then realized it's better off in its own thread instead of polluting others. The mods should consider leaving it open for this purpose.

[jimtx]

Originally Posted by BugBear

Pretty common dodge. Need help?

Yes I need help understanding what you think "diverges". I thought the stick force per g was not linear at high AOA and the FAA does not like that for humans at the controls but there was an increase per g in the windup turn flight test.

[BugBear]

Failure Analysis

Originally Posted by Vessbot

This reads more and more like Timecube the more it goes on. First I was annoyed, but then realized it's better off in its own thread instead of polluting other. The mods should consider leaving it open for this purpose.

Failure..
Any clean sheet design needs to be vigorously attacked ... approaching a proven design that is struggling, same.
Looking at failure as a "know it all" doesn't work, and can be dangerous.

[BugBear]

Originally Posted by jimtx

Yes I need help understanding what you think "diverges". I thought the stick force per g was not linear at high AOA and the FAA does not like that for humans at the controls but there was an increase per g in the windup turn flight test.

In unaccelerated flight, the airframe must be stable, "hands off". The LEAP 1-B, as mounted on MAX, produces an increase in rotation of Power/Pitch couple at high angles of attack, approaching Stall.
(As I understand it). MCAS WAS Installed to lower AoA, to prevent early Stall.

[BugBear]

Originally Posted by jimtx

Yes I need help understanding what you think "diverges". I thought the stick force per g was not linear at high AOA and the FAA does not like that for humans at the controls but there was an increase per g in the windup turn flight test.

In unaccelerated (trimmed) flight, the airframe must be stable, "hands off". The LEAP 1-B, as mounted on MAX, produces an increase in rotation of Power/Pitch couple at high angles of attack, approaching Stall.
(As I understand it). MCAS WAS Installed to lower AoA, to prevent early Stall. Whether mitigated or not, uncommanded Pitch up is divergent, imo.

MCAS increases THS AoA. Reducing elevator authority, increasing back force on stick. But it does not do so uniformly with increased rate of Pitch up

Unless you're flying an Airbus. (What's it doing)
"Unfamiliar" is not allowed, and what killed AF447. Not entirely, but played an important part.
Let's don't go there?

[jimtx]

Originally Posted by BugBear

(As I understand it). .

You don't understand it. So long.

[Chesty Morgan]

Originally Posted by BugBear

In unaccelerated flight, the airframe must be stable, "hands off". The LEAP 1-B, as mounted on MAX, produces an increase in rotation of Power/Pitch couple at high angles of attack, approaching Stall.
(As I understand it). MCAS WAS Installed to lower AoA, to prevent early Stall.

No, MCAS was installed to increase stick force per g.

[BugBear]

Originally Posted by Chesty Morgan

No, MCAS was installed to increase stick force per g.

​​​​​​I said that.

[Chesty Morgan]

No, you said MCAS was installed to lower AoA.

[BugBear]

Originally Posted by Chesty Morgan

No, you said MCAS was installed to lower AoA.

Yes, that is how it increases stick force, by reducing authority of the elevators but it does not do it in unison with the Power Couple, which increases without linearity.

When MCAS stops, the power Couple keeps going, so it stops meeting the regulation.

[EXDAC]

Please make it stop!

[BugBear]

Originally Posted by EXDAC

Please make it stop!

Ignore, or help with a reply? If I start looking too smart, well-informed, well, I think Boeing made some fairly dumb blunders...

MCAS operates with linearity, the stick force without it. So the AD is not functioning per regulation, to wit, "smoothe". It should be tuned to the Power Pitch couple ..

[Chesty Morgan]

Originally Posted by BugBear

Yes, that is how it increases stick force, by reducing authority of the elevators but it does not do it in unison with the Power Couple, which increases without linearity.

When MCAS stops, the power Couple keeps going, so it stops meeting the regulation.

That is not the same as lowering AoA. It doesnt lower AoA at all, it creates an increased stick force per g requirement.

[DaveReidUK]

It's like deja vu, all over again.

[BugBear]

Originally Posted by Chesty Morgan

That is not the same as lowering AoA. It doesnt lower AoA at all, it creates an increased stick force per g requirement.

So, Lionair didn't happen? Ethiopian? It is driven by the AoA vane, but doesn't relate to Pitch....seems like MCAS is a Trim system, that flies (maneuvers) the aircraft ...?
Attitude controls stick, seems arse about.