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The Boeing 747 begins its final descent

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Re: The Boeing 747 begins its final descent

#341

Post by MisterTea »

chrisss395 wrote: post #156

I know less about the airframe differences across the -400 and -8, but I can say the 747-8 represented a major upgrade in Flight Management Software. I re-wrote the Central Maintenance System (portion inside the FMS) in C from scratch because no one had the original detailed design documents. The original -400 code was written in Pascal if I'm remembering correctly. I gleamed what I could from the source and relied o…

> The original -400 code was written in Pascal if I'm remembering correctly.

Could it have been Ada 83?

Re: The Boeing 747 begins its final descent

#342

Post by microgpt »

rlt wrote: post #332
microgpt wrote: post #252

Earlier quoted context omitted.

They won't be economical for many reasons - one of them is cooling. Putting several kilowatts of radiators on a Starlink satellite is a justified cost because the Starlink satellite must be in space. Putting a hundred megawatts of radiators on your AI DC in space is ridiculous because that's too big of a radiator (how do you keep it structurally sound?), air cooling on the ground is a million times better and there's…

> won’t be Again, “What I find silly is the certainty that critics have that SpaceX will fail”. I doubt you’ve done enough investigation to conclude that. Watching a couple a YouTube videos about how data centers in space are dumb doesn’t count. For one, it’s not one big hundred megawatt-scale datacenter, but many smaller rack-sized satellites. Two, there are many trade offs SpaceX can make to reduce the overall cost…

Materials other than silicon would be an interesting idea, but I doubt even SpaceX is that crazy.

Not only does cooling increase with 4th power of temperature as you said, but power is abundant, so it may actually be practical to use more power to run chips of a different material at a higher temperature. That's a great idea, if it can actually be pulled off.

There's nothing inherent about electronics that makes it stop working around 120 degrees - that's just the practical limit of silicon. Other materials can withstand higher temps but may not be as practical in other respects like bandgaps.

Re: The Boeing 747 begins its final descent

#343

Post by SR2Z »

lukan wrote: post #274
SR2Z wrote: post #262

Earlier quoted context omitted.

Sure, but when the 747 was new and gas was a few cents a gallon? An airplane is a very efficient way to move people. There is no ground friction, the route is pretty direct, and once the airplane is loaded 100 passenger-miles a gallon is not unreasonable. Even today the EU has to ban short-haul flights along rail corridors because jets are still competitive. I say this as someone who likes trains and chooses them whe…

"because jets are still competitive" Yes, because airports and everything around is heavily subsidized and there is no tax on jet fuel. "There is no ground friction" And that argument is not so strong considering that air friction grows quadratic with speed. And considering side effects like climate change - contrails combined with lots of other chemicals in the jet fuel are really not helping, their effect is worse…

I cannot fathom why you think airport subsidies matter here. Airports are way, way cheaper than HSR.

Yeah drag grows quadratically with speed but reduces with altitude. At 40k ft a modern jet delivers up to 150 pmpg.

Yes the carbon emissions argument is a good one, and I personally prefer taking trains when they're available. I think that people are not appreciative enough of how efficient air travel is.

Re: The Boeing 747 begins its final descent

#344

Post by rootusrootus »

Rover222 wrote: post #326
wolvoleo wrote: post #127

Earlier quoted context omitted.

Not American but I feel the sentiment. I'm planning to change nationality soon as 'my' own country is also on the same right-wing conservative track. I'm not interested in making things better anymore. I just want to break with them forever. They deserve no more admiration or loyalty. I don't believe in national pride or even of sports teams. My loyalty is always conditional, as long as my ethics align. I can imagine…

I think labeling all things right-wing as bad is part of the problem. The left goes too far, and pushes people to the right. That's why Trump got back into power.

What is something the right wing supports that you would say is good, by contrast?

Sometimes I hear that it is because the right wing is perceived as strong on the economy, despite the facts showing that the left wing consistently performs better. Or that the right wing has better foreign policy chops, despite consistently starting wars. Or that the right wing is about smaller, limited government, despite consistently using government power to push their social agenda.

Maybe it was the pronouns thing.

Re: The Boeing 747 begins its final descent

#345

Post by mjg59 »

KolmogorovComp wrote: post #113
mjg59 wrote: post #101

Earlier quoted context omitted.

All else being equal, potentially - although as I mentioned there have been cases where one engine falling off a 4 engine aircraft hit another in the process. But ETOPS certification is based on it being demonstrated that engines are sufficiently reliable that the probability of an independent failure is incredibly unlikely, and also requires that operators have a stricter maintenance process. The only dual engine fa…

No, the highest risk for dual engine failure is bird strike.

There's US1549 and FR4102 - are there any others? But yes, the assumption about failures being independent is obviously violated by large flocks of birds, although this has also resulted in the loss of 4-engined aircraft.

Re: The Boeing 747 begins its final descent

#346

Post by HeyLaughingBoy »

jeronimobomfim wrote: post #293
chrisss395 wrote: post #156

I know less about the airframe differences across the -400 and -8, but I can say the 747-8 represented a major upgrade in Flight Management Software. I re-wrote the Central Maintenance System (portion inside the FMS) in C from scratch because no one had the original detailed design documents. The original -400 code was written in Pascal if I'm remembering correctly. I gleamed what I could from the source and relied o…

> "no one had the original detailed design documents" Is this normal for a comany like Boeing? It's not my area, but I would have guessed they would keep the documentation for everything on a product as important as a 747.

Not avionics, but I've spent most of my career in medical devices. A project's Design History File would indeed have the detailed design documentation of the system. The problem would be that word "detailed." The relevant standards state that the documentation should be sufficient for a normally-skilled engineer to recreate the (software) system, but how stringently that is applied can be very hand-wavy. And then there's the problem of drift where the software changes and the docs are updated, but perhaps not as precisely as they should be, and different people have different levels of documentation rigor. Well, you can see how it ends up 20 years later.

I'm actually dealing with exactly this problem on an old project right now :-(

Re: The Boeing 747 begins its final descent

#347

Post by buildsjets »

budsniffer952 wrote: post #295
nehal3m wrote: post #227

Earlier quoted context omitted.

I hope you replied something like 'No, meeting this project deadline is more important than YOUR child dying, to me this is a paycheck.' That's what I would've been thinking in the shower 2 days after the conversation, anyway.

I'm shocked people here believe that this was actually said. Or maybe I'm not. It's laughable, but Hackernews loves a good, "everyone in management is evil" story.

I guarantee I am closer to the situation than you are. I have many heard similar, and worse statements, from executives of The Boeing Company many times in my career. Every single Boeing CEO that has left the company in the past 30 years has either been fired, or resigned in disgrace, for their various ethical, moral, and business management failures.

That’s 5 flamed out CEOs since 1996.

Does it shock you that a CEO who is on the record for preferring that his employees “Cower under their desks” in fear of him would also require that their employees prioritize the schedule of a flying barge over their child’s personal life?

https://mynorthwest.com/local/boeing-ceo-apologizes-for-sayi...

Or how about "When people say I changed the culture of Boeing, that was the intent, so that it is run like a business rather than a great engineering firm" - can this statement by former CEO Harry Stonecipher be justified as anything other than evil, in the context of the damage and injury that has been caused by intentionally reducing Boeing’s engineering capability?

Re: The Boeing 747 begins its final descent

#348

Post by buildsjets »

fransje26 wrote: post #278
bobthepanda wrote: post #257

Earlier quoted context omitted.

I would have to imagine that the newer 747-8 would have the much lower pressurization and other comfort standards of its generation of aircraft in the 2000s; the problem is that it didn't really sell so most people did not get to fly in one.

> I would have to imagine that the newer 747-8 would have the much lower pressurization Two small corrections: 1) If it would have had a change in internal pressurization, the -8 would have a higher pressurization to allow for a lower cabin altitude pressure. 2) The -8 does not have a higher pressurization, because they did not change the fuselage construction. Newer airplanes have lower cabin-altitudes thanks to the…

The -8 also has a lower maximum certified altitude than the -400. The -400 can go to 45,100 feet, the -8 is limited to 43,100 feet.

This is actually because the -8 wing is MORE efficient than yhe -400. There is a regulation that in case of a pressurization failure the airplane has to be able to descend below 15,000 feet in a certain time. The -8 wing has less drag, so it is easier to overspeed in descent, and they had to limit the maximum operation altitude to compensate.

Re: The Boeing 747 begins its final descent

#349

Post by dotancohen »

jojobas wrote: post #286
tetris11 wrote: post #267

Earlier quoted context omitted.

I feel like people on HN who have comfortable passive incomes from stocks or other sources forget that people need a paycheck to sustain their lifestyles.

You can always find another job, even if it's worse than your current one. A prick who thinks my family is less important than a transportation project, and has the audacity to assert that to me, can do the project himself or in the company of spineless worms.

I'd take a mid-2000's Boeing engineer's salary for an asshole boss. Hell, I've been told worse here on HN.

Re: The Boeing 747 begins its final descent

#350

Post by dotancohen »

WalterBright wrote: post #143
GMoromisato wrote: post #124

Earlier quoted context omitted.

You should read the book, if you're interested. From the book (p.84): "Time and time again there appears in print the logical but false assumption that Boeing took its losing military C-5 bid and revamped it as the commercial 747. In fact, the 747 would be an entirely original design that owes nothing to the C-5." That said, in the same chapter he talks about how GE developed a high-bypass turbofan engine for the C-5…

The engines drive the design.

I understand that the payload typically drives the design, and the wings drive (or rather, limit) the generational improvements. Aircraft are reengined quite often.
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