They may find a physical fix for it later. Like adding weight where it can help.
Even then, perhaps nobody wants to fly with it plus it can't offer the same performance.
Boeing's software fix for the 737 Max overwhelms the plane's computer
51–60 of 72 posts
Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#52From the article ----------- Boeing says that it can again fix the software to avoid the problem the FAA just found. It is doubtful that this will be possible. The software load is already right at the border, if not above the physical capabilities of the current flight control computers. The optimization potential of the software is likely minimal. MCAS was a band aid. Due to the new engine position the 737 MAX vers…
I know military jets to have unstable flight characteristics to get advantages in maneuverability that need an operating flight computer. But I have problems accepting this fact for civilian planes, especially if the manufacturer just wanted to save development costs. Because you could simply design a more stable plane. Not trivial, but also not impossible.
Then you probably don't want to fly in a T-tail jet. [0] [1] Or a helicopter [2]. Or in a jetliner at cruise. [3] [4]
The fact is, every single airplane ever built is unstable in the wrong circumstances. They stall, they spin, they lose lift, they suffer mechanical failures. Aeronautical engineering, rigorous maintenance, and thorough pilot training have resulted in the safest transportation system that has ever existed, but the only completely stable aircraft is one that's sitting in a hanger.
[0] https://en.wikipedia.org/wiki/T-tail
[1] https://aviation.stackexchange.com/questions/1400/how-do-con...
[2] https://aviation.stackexchange.com/questions/35764/are-helic...
[3] https://en.wikipedia.org/wiki/Coffin_corner_(aerodynamics)
[4] https://www.faa.gov/regulations_policies/advisory_circulars/...
Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#53Earlier quoted context omitted.
I don’t have evidence, but most likely, it is to avoid the related costs and risks of certification of this « new » CPU for its intended usage. Not only the CPU but all the software stack needs to be re-proven safe, including compilers and test tools. Note: this is not necessarily a stupid decision.
A simpler solution would be to use the same CPU done with a slightly newer process to allow a higher clock rate. That would ease the recertification process. If you think they are at best 40 MHz 286 parts, the best that was available by then, running software derived from previous releases that ran on slower chips, there is plenty of room for improvement. IIRC, you can get a modern 65816 (the 16-bit descendant of the…
Yes, I'm familiar with second-source 6502. Also, I've seen the Rabbit2000 processor, it's basically a Z80 running at 50 MHz. But I wasn't aware that 80286 has any modern second-source clones. Are there?
Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#54Earlier quoted context omitted.
I know military jets to have unstable flight characteristics to get advantages in maneuverability that need an operating flight computer. But I have problems accepting this fact for civilian planes, especially if the manufacturer just wanted to save development costs. Because you could simply design a more stable plane. Not trivial, but also not impossible.
Then you probably don't want to fly in a T-tail jet. [0] [1] Or a helicopter [2]. Or in a jetliner at cruise. [3] [4] The fact is, every single airplane ever built is unstable in the wrong circumstances. They stall, they spin, they lose lift, they suffer mechanical failures. Aeronautical engineering, rigorous maintenance, and thorough pilot training have resulted in the safest transportation system that has ever exis…
By stable I meant gliding properties. If the center of mass is moved too close to the center of lift, planes tend to pitch up and then are in danger of stalling. Some people suggest Ed the heavy engines might be responsible for this, but I believe this was misinformation.
Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#55Earlier quoted context omitted.
This is entirely false. Stop spreading disinformation. Myth: the 737 MAX 8 is not inherently stable, has relaxed stability, etc. Fact: it's very much inherently stable. Myth: the 737 MAX 8 is easier to stall than other planes. Fact: no it isn't. The pitch-up characteristic of the MAX 8 is less strong than of e.g. the 757 and that plane flies just fine. The actual problem with the MAX 8 is that Boeing added MCAS to al…
Ironically, I believe that your information is also inaccurate. MCAS is required in order to meet federal airworthiness requirements . Without it, in certain flight conditions the back-pressure on the control yoke gets less as the yoke is pulled further back. It's like over-steer in a car, and is simply not allowed. Yes, the plane is dynamically stable; if you leave the yoke in one position it won't pitch up even mor…
I don’t think this is correct.
Your reference suggests that this tweak is to match the expectations of pilots certified to fly 737s, which handle in a certain way.
Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#56It amazes me how Pilots are required mainly for the purposes of being able to act as a last resort against a computer which has gone haywire, and the public feel better thinking that the pilot can "take control" and then at the same time aircraft manufacturers are removing the ability for the said Pilots to override the computer. That's progress!
Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#57From the article ----------- Boeing says that it can again fix the software to avoid the problem the FAA just found. It is doubtful that this will be possible. The software load is already right at the border, if not above the physical capabilities of the current flight control computers. The optimization potential of the software is likely minimal. MCAS was a band aid. Due to the new engine position the 737 MAX vers…
Damn, I hope those senior engineers charge Boeing an arm and a leg when they are asked to come back.
What's the over/under on the executives and senior management who made that decision getting fired for it?
Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#58Earlier quoted context omitted.
Ironically, I believe that your information is also inaccurate. MCAS is required in order to meet federal airworthiness requirements . Without it, in certain flight conditions the back-pressure on the control yoke gets less as the yoke is pulled further back. It's like over-steer in a car, and is simply not allowed. Yes, the plane is dynamically stable; if you leave the yoke in one position it won't pitch up even mor…
I don’t think this is correct. Your reference suggests that this tweak is to match the expectations of pilots certified to fly 737s, which handle in a certain way.
See edit 2, citing regulation which must be met by all transport aircraft. I think also §25.255 Out-of-trim characteristics, (b) (1) The stick force vs. g curve must have a positive slope at any speed up to and including VFC/MFC
Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#59Earlier quoted context omitted.
I don’t think this is correct. Your reference suggests that this tweak is to match the expectations of pilots certified to fly 737s, which handle in a certain way.
See edit 2, citing regulation which must be met by all transport aircraft. I think also §25.255 Out-of-trim characteristics, (b) (1) The stick force vs. g curve must have a positive slope at any speed up to and including VFC/MFC
I don’t see how the FAAs assessment that the 737 MAX was easier to put into a stall for greater that 12 degrees AoA is the same as a “reversal of controls” or a “sudden or excessive reduction of elevator control” stipulated in 25.253
What am I missing?
I am not an aviation expert in any sense.
Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#60Earlier quoted context omitted.
This is entirely false. Stop spreading disinformation. Myth: the 737 MAX 8 is not inherently stable, has relaxed stability, etc. Fact: it's very much inherently stable. Myth: the 737 MAX 8 is easier to stall than other planes. Fact: no it isn't. The pitch-up characteristic of the MAX 8 is less strong than of e.g. the 757 and that plane flies just fine. The actual problem with the MAX 8 is that Boeing added MCAS to al…
Ironically, I believe that your information is also inaccurate. MCAS is required in order to meet federal airworthiness requirements . Without it, in certain flight conditions the back-pressure on the control yoke gets less as the yoke is pulled further back. It's like over-steer in a car, and is simply not allowed. Yes, the plane is dynamically stable; if you leave the yoke in one position it won't pitch up even mor…
"MCAS is required in order to meet federal airworthiness requirements"
Cite this. Specifically this. The rest of your comment agrees with mine without this being true, and I have not seen any evidence of this being true.