Originally published at: https://boingboing.net/2020/08/20/with-new-name-for-737-max-you.html
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The best part of this is the quote from Turdrump: “…I became president”. Not “elected” president. “Became”…sort of like magic…dark ugly magic.
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Better yet, he became El Presidente through a branding exercise.
Not by being the better candidate in any available metric, but by shouting advertising slogans.
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Which brings us neatly to the saga of “We Build the Wall”.
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Why didn’t they call me? I could have helped, I’ve got tons of great names:
- Boeing 737 DEATH METAL
- Boeing CrumpleMaster 2000
- Boeing Not Boing Boing But Crunch
- Boeing 737-MAX now without Crash-O-Matic Computers
Jeeze, branding is hard guys. You need to reach out for help from the Internet (“Not Just a Series of Tubes” TM)
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The problem with the name isn’t the MAX part. It’s the 737 part.
As far as I know, the MCAS computer system was there purely in order to make this new, very different aircraft fly enough like an older model 737 that pilots who were type-rated for one would be able to fly the other without needing a new type-rating.
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Well that’s nice. So now you need to pay extra attention to the names if you don’t want to fly on one. The previous generation, the 737 NG, uses the suffixes -700 ,-800, and -900, which are often abbreviated to -7,-8, and -9 online vs MAX-7, MAX-8, and MAX-9. Boeing knows damn well what it’s doing.
Maybe it’s time to change the old saying to ‘If it’s Boeing I’m not going’?
The older 737s are a solid platform. I’d fly an NG or a 2nd gen any day. The MAX not so much.
Boeing really messed up by not having something to compete with Airbus, and instead of doing the right thing, bolted some crap on an existing design to get it done quickly and papered over the defects. How anyone thought it was OK for a single sensor to be able to modify control surfaces is just beyond my comprehension.
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No. the MCAS system was there purely as regulatory compliance: at high angles of attack, the plane would not have the amount of force on the stick continue to increase with increasing angle of attack. It’s not that it wouldn’t be able to be considered a 737. It’s that it would not be able to be certificated for commercial flight at all.
Now, if they weren’t concerned about it still being a 737, they could use a FBW control system, which would avoid this issue entirely. But if they were not making it a 737, they’d probably do other things to clean up the design.
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In other words, it flies on the back side of the power curve by design?
Rebranding seems to be one of the core policies of the impeached. Run on a campaign bashing NAFTA? Rebrand it as USMCA. Fail to repeal Obamacare? Rebrand it as “we repealed Obamacare”. Have a depressing nearly empty inauguration? Rebrand it as “the largest audience ever to attend and inauguration”. Have policies that kill 200,000 Americans? Rebrand it as “We’re doing more testing than anyone else”. Be an incompetent narcissist? Rebrand it as “Very stable genius”.
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What? No! Where did you get that idea? It’s got nothing to do with the power curve. It has to do with how the plane feels near the stall speed.
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Misspoke: rather than ‘behind the power curve’ I should have said ‘in an unstable corner of the L/D regime’. If the back pressure on the yoke is falling with increased AoA, that’s a recipe for induced oscillations.
And what is going to cause the pressure to fall off? The airflow starting to separate so that the control surface is sitting in the wake? That’s going to be in a regime with high induced drag, and if that doesn’t put the machine on the back side of the power curve, it’s at least moving in that direction. The phenomena aren’t the same, but they turn up in the same low-airspeed, high-AoA configurations.
Flying machines that need FBW to be controllable are … perhaps not suitable for use in large-scale transportation systems.
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The pressure falls off because the forward position of the engine nacelles causes them to produce lift at higher angles of attack. The forward position of the nacelles being, of course, dictated by the fact that it’s a 737, and they couldn’t make the nacelles bigger to support a larger diameter engine without moving them forward to let them come in front of the wing. Or they could redesign the entire wing to get longer landing gear, but then it wouldn’t be a 737.
It doesn’t need FBW to be controllable, but it would obviate the control pressure requirement of the applicable regulations. Also, almost every modern airliner (defined as one who’s control system was designed after '90) has FBW controls.
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How anyone thought it was OK for a single sensor to be able to modify control surfaces is just beyond my comprehension.
I am much more interested in the logic which sits between the AoA sensor(s) and the elevator trim. Its this logic which should know never to put the aircraft dangerously out of trim. Even if it worked appropriately in the domain where it was expected to work (high angle of attack) the resulting nose down trim would make the aircraft difficult to control.
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How about Boeing Boeing to appeal to the happy mutants?
Yeah, the fact the trim cutout reset the logic allowing MCAS to put the plane in an extreme trim configuration is really messed up too. So much wrong with that system, it boggles the mind. But hey, allowing Boeing to self-certify sure cut that darned red tape, am I right?
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How dumb do they think we are? All one has to do is look at the engines,
OK, so center of thrust is too far forward of the CG. That’s a controllability issue right there, reflected in the decrease of back pressure with AoA. (Consider: AoA is less than desired. Pilot pitches up. Decrease in back pressure causes pilot to overshoot. Pilot pitches down to compensate. Back pressure continues to run in the wrong direction, causing an overshoot. Oscillation. Which FBW is needed to damp out. Not good.)
It at least used to be that runaway trim was a ‘memory item’ in type certification. There are several failure modes that can cause an uncommanded trim excursion, and the checklist for correcting one (with the the chief item being, pull the circuit breaker for the jack screw motors) had to be demonstrated from memory, since in that scenario there isn’t time to look it up. (There weren’t many in-flight emergencies that weren’t responded to with a printed checklist, but that was one of them.)
I don’t know what the current training standard is. While runaway trim is surely horrific, lack of pilot response is an identifiable contributing factor. (No, this does NOT exonerate the manufacturer.)
I am at work so I can’t really look it up, but I remember reading that on the old planes the cutout switch would disable auto-trim until manually re-enabled, but with the new system it would only cut it out temporarily then when MCAS detected it was ‘needed’ it would kick back in, but in the process forget that it had already trimmed down allowing the trim setting to move the full range (I think a few degrees) again. So if the pilots used the trim cutout as they would on the older planes, they were actually making the situation worse and worse with every cutout until the aircraft became completely uncontrollable.
I’m sure this will be taught in schools someday, the same way I learned all about the Therac-25 in my software engineering classes.
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