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Europe says 737 Max won't fly until it completes it own design review

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Re: Europe says 737 Max won't fly until it completes it own design review

#201

Post by volkk »

magduf wrote: post #169
ubermonkey wrote: post #109

Earlier quoted context omitted.

I think you're absolutely right. The approach on the MAX is horrifying. But airplane tech moves kind of slowly, no? Non-MAX 737s can't really change, and so are as safe today as they were 6 month or 6 years ago. The MAX debacle makes me SUPER SUPER leery of any new airframe, though.

The non-MAX 737s are still shitty planes to fly on. It's an ancient airframe: it's cramped, it's noisy, it just sucks. And it's a fuel hog too (which is why they made the MAX version). The competing aircraft are all much newer and nicer. The only reason anyone was buying the MAX was 1) because they had already bought into Boeing and the 737 and it's cheaper to just get a 737MAX which doesn't require any pilot retrain…

i've read that for pilots, the 737 is better and more manual (if the need arises to fix things or do overrides) compared to the airbus a320 which is a bit newer and has more electronics and sort of does a lot of things for you, but also obv more likely where things can go wrong

Re: Europe says 737 Max won't fly until it completes it own design review

#202

Post by computerex »

marvin wrote: post #132
yardie wrote: post #122

Earlier quoted context omitted.

They lengthened the plane without redesigning the rest of the components to compensate. This changed fundamental aerodynamics on how it flies. The plane is dynamically unstable and that instability was masked in software.

Dynamically unstable means that it will leave controlled flight if it does not receive control input, and that the departure from controlled flight will accelerate after it starts, therefore requiring constant computer-assisted control inputs. Pretty sure this is not the case, but it will have different and potentially dangerous behaviors for some speeds, angles of attack and thrust settings.

That's literally what happens to the 737 max airframe. Specifically, the angle of attack is prone to increasing at high angle of attacks.

Re: Europe says 737 Max won't fly until it completes it own design review

#203

Post by LoSboccacc »

huslage wrote: post #170
LoSboccacc wrote: post #138

Earlier quoted context omitted.

> there is nothing inherently unsafe about those handling characteristics this is not entirely true. applying throttle to the max causes a pitching momentum, something you don't want during a deep stall when control surfaces are totally unresponsive, because it would make the exit procedure (throttle up, nose naturally pitches down, gain airpseed and regain control) unsafe (throttle up, whops the plane is now pointin…

Applying throttle to any airplane with engines under the wings causes a pitching momentum. The pitching momentum is different in the MAX than other aircraft, but that doesn't make it less safe than anything else as long as a pilot is trained to understand it. The MAX is not naturally more likely to enter a stall regime than its predecessors.

well yes, but there's more to a big plane stall. wings washout makes them stall at the root first, so that the center of lift moves backward, slightly helping overcome the engine momentum

moving the engine forward increased such momentum

large planes are finely balanced machines, it doesn't take much to get outside their flying boundaries, wether authority or loading, especially because the trim on them has buttload more authority than the elevator controlled from the yoke

Re: Europe says 737 Max won't fly until it completes it own design review

#204

Post by ernesth »

ShinTakuya wrote: post #118

I mean while I'm all for continuing to punish Boeing for their blatant disregard for human lives, you could also say it's in the best interest of the EU to attack Boeing in a way that doesn't seem hostile on a political level since it indirectly benefits Airbus.

It is perfectly clear that the US is at economical war against Europe.

However, Europe is not obviously at war against the US.

Re: Europe says 737 Max won't fly until it completes it own design review

#205

Post by LoSboccacc »

foldr wrote: post #140
LoSboccacc wrote: post #138

Earlier quoted context omitted.

> there is nothing inherently unsafe about those handling characteristics this is not entirely true. applying throttle to the max causes a pitching momentum, something you don't want during a deep stall when control surfaces are totally unresponsive, because it would make the exit procedure (throttle up, nose naturally pitches down, gain airpseed and regain control) unsafe (throttle up, whops the plane is now pointin…

I don't think recovery from deep stalls is actually much of a safety issue with airliners. Are there any instances where an airliner has deep stalled and then successfully recovered? By definition, a deep stall is one where standard stall recovery procedures won't be effective.

> much of a safety issue with airliners

yeah because they tend to pitch down way before reaching a full wing stall, but the max pushes the partial stall deeper.

Re: Europe says 737 Max won't fly until it completes it own design review

#206

Post by [deleted] »

radcon wrote: post #40

Is anyone else extremely reluctant to fly on a Boeing plane after this? A lot of people say "It's no big deal, they just need to update the MCAS software" , but I see this entire situation as a sign of much deeper issues at Boeing, issues that can't be fixed with a simple software update and could affect every plane they make.

[deleted]

Re: Europe says 737 Max won't fly until it completes it own design review

#207

Post by foldr »

computerex wrote: post #202
marvin wrote: post #132

Earlier quoted context omitted.

Dynamically unstable means that it will leave controlled flight if it does not receive control input, and that the departure from controlled flight will accelerate after it starts, therefore requiring constant computer-assisted control inputs. Pretty sure this is not the case, but it will have different and potentially dangerous behaviors for some speeds, angles of attack and thrust settings.

That's literally what happens to the 737 max airframe. Specifically, the angle of attack is prone to increasing at high angle of attacks.

That's not dynamic instability.

Re: Europe says 737 Max won't fly until it completes it own design review

#208

Post by cjbprime »

salawat wrote: post #197
foldr wrote: post #157

Earlier quoted context omitted.

There is no source in those comments for the claim that the 737-MAX would not satisfy these regulations without MCAS. Note that the actual regulations are a tad more complex than the incomplete sentence quoted: https://books.google.co.uk/books?id=5tAhOC4KC8MC&pg=PA200&lp...

I'm one of the originators and principle repeaters of the theory, and the various facets that go into it are admittedly built up via synthesis of many different slices of life. The principle source that moved me in the direction that the MAX may not be certifiable without MCAS was from this interview from the Royal Aeronautics Society with D. P. Davies, a well known test pilot for the U.K. ARB, and the past woes that…

> the entire horizontal stabilizer needs to be moved to ensure the nose is brought back down in short order

Doesn't MCAS take a long time to significantly move the stabilizer? Like tens of seconds? It's hard to square needing to decrease AoA so dramatically with the actual mechanics of MCAS.

Re: Europe says 737 Max won't fly until it completes it own design review

#209

Post by ummonk »

radcon wrote: post #40

Is anyone else extremely reluctant to fly on a Boeing plane after this? A lot of people say "It's no big deal, they just need to update the MCAS software" , but I see this entire situation as a sign of much deeper issues at Boeing, issues that can't be fixed with a simple software update and could affect every plane they make.

Don't mind any of the planes that aren't 737-Max or 787. Definitely reluctant to fly 737-Max anytime soon even after it has been approved. As for the 787, while I have a little bit of hesitancy, I figure it's been around long enough that we at least know it is safer than driving a car, so probably okay to ride in it, although it might not be as safe as other planes.

Re: Europe says 737 Max won't fly until it completes it own design review

#210

Post by foldr »

computerex wrote: post #199
foldr wrote: post #64

Earlier quoted context omitted.

This is not the case. The 737 MAX has different handling characteristics to a regular 737, but there is nothing inherently unsafe about those handling characteristics. The purpose of MCAS was just to prevent the need for pilots to recertify by masking the difference.

That's categorically not true. https://spectrum.ieee.org/aerospace/aviation/how-the-boeing-... 737 Max experiences dynamic instability, where a high angle of attack is prone to increase the angle of attack at an increasing rate.

That is not dynamic instability.
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