FDR...verbose as you are , it is not correct on many fronts..
1. "I am looking at what was stated, and provide the aerodynamic reasoning behind it. Forget about stick feel."
stick force is a consequence of aerodynamics, control system architecture and modifiers.
That is what I stated, stick feel is a result of aerodynamics, not the other way around...
2. (A) "...going supersonic..."
High AOA is inconsistent with high mach numbers in general, wings tend to fall off Par 25 planes when pulling high AOA at high mach, available AOA is constrained by buffet in such cases, so the terminology used is vague... At low speeds, there is no transonic flow on a BAC447-450 type section at any AOA. The BAC airfoil section may have gone supersonic in the Silk air bingle, and possibly Adam Air splash, but otherwise it is rather unlikely to get to a point where the section is supersonic, e.g., has an oblique shock formation. It will usually have a normal shock at around 0.5c-0.6c in cruise, at say M0.78 and above, at 2.3 AOA.
You misquoted what I stated. Surfaces do go transonic, I did not mention only low speed, but high AOA...Boeing does mention low speed stall, AND high AoA AND high G ....not inclusive. Many surfaces go transonic on the wing, fuselage and cowlings...
Boeing DOES state that in testing, they found airflow over the wing went transonic, and tried to alleviate this issue with vortex tabs and changing the wing design...Boeing own words, not mine.
(B) "...lack of laminar flow...";
irrespective of what is being smoked, and how much was spent on the design, there is no laminar flow worth noting on any RPT jet transport. If you want laminar flow, go and look at a standard sail plane. the slat TE destroys laminar flow, as does the first rivet head, screw head etc that exists on the slat. For the first 1% of the chord, which more or less is in the radius of the LE, around the Kutta point, there may be laminar flow dependent on when the plane was last washed. FYI, the slat TE eats up the boundary layer, it is a discontinuity in the surface, and causes separation in the presence of a shear, and that always gives an initial span-wise vortex structure which is highly unstable as is any flow behind an aft facing step... That vortex structure starts to shed with a Strouhal number that is identifiable as a harmonic of the how frequency vibration that arises from the instability of the normal shock and the associated SBLI foot, which is observable oscillating on the wing in steady flight. Look out the window with the sun aligned down the mid chord span and you will have a Schlieren iamge of the shadow of the densty change in the foot of the shock. In essence, at any time, your Boeing, or Bus doesn't have laminar flow anywhere except in the idealised models of the airfoil in simplified CFD modelling. Sorry. That is not to say it can't be improved...
No laminar flow over the wing??? Really...explain this video:
(C ) "...induces a stall..."
not the way flow works. Sorry. A turbulent BL has one benefit over laminar and that is it can cope with adverse pressure gradient perturbations before becoming messy. Flow behind a shock is separated near the surface, but that is not a stall as such, which is defined in the regs... as a number of specific conditions that occur. separation may be a pain, particularly geographic ones, but it is a normal part of life. Stalls are stalls... per the regs. Taking your comment to an extreme, pulling say 10 AOA at M0.82 will still not end up in a stall, it will take the wings right off the aircraft, but before you get to that point, flow separation will have resulted in severe buffet, and reducing Cl/AOA, which put you back toward the beginning...
Again, as verbose as that is, how does it relate to the MAX stalling at relatively low AoA comparatively? On low speed final, it pushes the nose down 2.5 degrees to avoid stall...what AoA are you at on final?
4. Look at what they tried to do, adding vortex tabs, changing the wing design....
That is what happens with almost all designs, including Busses etc. The dog tooth on the Bus arises from a surprise in testing... VG's are a good tool for curing issues of separation and shock issues, they don't cook means well, but they have their uses. I would be happier if they did do more work on the wing, there is a lot of room for improvement on all of these designs which are the industrial engineers mass produced product rather than the ASW-21 or other embodiment of elegant design
.
Of course, that is why they still have vortex tabs running down the wing....but you say this cures issues of separation, but deny laminar flow over the wing?
5. "...Changing the wing design?? Do you change the wing design to make the stick pressure the same, or to prevent stall? The differential pressure on the yoke is a RESULT of the stall..."
There are a number of manners that the design could be tweaked in testing to attempt to achieve compliance with the stick force gradient requirements. As commented above, removing the strake would get rid of the issue, but comes at a cost, whereas MCAS had no cost had it been implemented competently. There are designs out there that have specific application of VGs to meet the same requirement. Almost every aircraft on the ramp has flow modifiers on them, and they are all specific in their application, what the defect was that was underlying their implementation. Each conventional VG has a drag count penalty, according to NASA research of around 0.0002Cd, so they are used sparingly and only when the gain from their use offsets the Cd increase from their installation. Not sure what a differential pressure on a yoke refers to, I only speak english, but if you are referring to the stick force gradient non linearity, that is not caused by stall. Consider that any premature stall around the nacelle will actually improve handling qualities of any aircraft; it will ensure that the lateral control requirements are met, that the aircraft will pitch down, that buffet on the airframe from impingement of wake on the stab and elevators is more likely to be encountered. These are good things. The GTF nacelle doesn't cause a premature stall, it does the opposite... Now if the wing tips stall, then you get great entertainment, and that is not the problem, nor would it arise from the nacelle.... Think of why simple wings have wash out, and why dog tooths, VG's vortilons etc are used on swept wing aircraft. I don't think I agree with your paragraph on that matter...
But we do appear to agree that he stick feel is a result, correct?
6. Stick pressure? I feel that is a half baked response by Boeing to mask the problems with the aerodynamics of the wing/engine design, and simply does not make sense. Maybe that is how is was presented to the FAA, but I dont think that is reality. Boeing will never admit that the aircraft was not aerodynamically stable.
If the aircraft was unstable at any point, which is pretty hard to see how that would be achievable, given the margins that exist between the normal aft envelope and the neutral point, then in any case, no TP would have signed off on the acceptability of the aircraft. It is a very straight forward matter to ascertain if the design is or was unstable, and for the record the data that has been published already is sufficient to show that the aircraft was statically and dynamically stable. Long ago I looked at an RPT aircraft that was on the limit of stability in flight, and it is not hard to detect in the data. THE MAX IS NOT UNSTABLE. PERIOD. Don't take my word for it, look at the public domain data on the control inputs. It had a trim issue, and that is all.
We are over 105 days on the grounding, and the FAA found another issue. Perhaps unstable is a bit harsh, but certainly, in many conditions , it is not predictable....
7. Is MCAS operational in AP? While I keep hearing the mantra, it only operation with AP off, it appears it is operational according to several reports that show turning off the AP resolves the problem. Wasnt it the case with the last crash, that when they turned AP back on, MCAS engaged again?
Again, as the aircraft IS NOT UNSTABLE, an autopilot doesnt need MCAS to meet any stick force per g compliance matters. That is the first big clue that the issue is and has always been about the force gradient compliance. MCAS would be redundant, a double negative, nonsense for an autopilot engaged condition.
What if MCAS is far more reaching than Boeing has stated? It certainly appears to be. Perhaps the half FBW design has inherent flaws that were either unintended or incorrectly implemented in the software?
8. "....In one incident, an airline pilot reported that immediately after engaging the Max 8’s autopilot, the co-pilot shouted “DESCENDING,” followed by an audio cockpit warning, “DON’T SINK! DON’T SINK!”
Autopilots are born of man (or woman etc... )per the bard and fail. The reported issue was a pitch down excursion which is an event that is required to be covered in certification, being an aspect that is considered in the minimum engagement and disengagement heights for autopilots. Had the MCAS not resulted in public misinformation and hysteria, then this particular matter would have been kept in its proper place, that being an APFD anomaly, with no association to the MCAS issue.
Again, over 100 days says that MCAS may be a lot more active than anticipated.
9. “I immediately disconnected AP (Autopilot) (it WAS engaged as we got full horn etc.) and resumed climb,” the pilot writes in the report, which is available in a database compiled by NASA. “Now, I would generally assume it was my automation error, i.e., aircraft was trying to acquire a miss-commanded speed/no autothrottles, crossing restriction etc., but frankly neither of us could find an inappropriate setup error (not to say there wasn’t one).
The crews getting into the Max deserved more than an Ipad briefing. However, the comment on the APFD anomaly has nothing to do with MCAS.
I completely agree the pilots deserve more. I also think that there are many unintended consequences that can line up in the software...and MCAS is far more active than thought...again, over 100 days, and still finding issues....
10. In reality, MCAS is anti-stall.
Nope, not even close. Refer preceding.
How is the low speed stall issue, not a stall issue? Stick pressure was not mentioned, simply low speed stall. MCAS was designed to push the nose down 2.5 degrees to prevent stall. Where is the interpretation here? 0.6 pitch up on DEP, okay, some lift and stick feel, but jeez, 2.5 on final? (of course, as we all know, its all 2.5 now) What about high G? Where the heck does MCAS come into play in this scenario?