mikegarrison
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Posts posted by mikegarrison
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8 hours ago, Meecrob said:
In fact, unless required for performance reasons, Transport Category aircraft will always use a de-rated takeoff.
That's not completely true. They often use derated takeoffs, because they are easier on the engines, but it's not true that they *always* do, even if they otherwise have enough runway length to do it.
Most operators will have policies to use derated takeoffs when possible, but it is always up to the flight crew what they do.
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8 hours ago, farmerben said:
The longest span of the Key bridge was 366m. Current state of the art suspension bridges can go to 2000m. Make the pillars 5 times as far apart and then there is plenty of room to steer and to run aground before hitting a pillar.
Longer spans are more expensive. They are generally only used when they are needed.
There is a lot that goes into bridge design in this respect, but to the best of my knowledge the key factors are usually the available support. If the water is shallow and the bedrock is solid, they use supports. If the water is too deep or there is no solid ground, they use longer spans. (Or where I live, they sometimes use floating pontoon bridges.)
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On 3/30/2024 at 12:09 PM, Kerbart said:
The Jones Act prevents unloading cargo on board of foreign vessels in US ports that was loaded from US ports. The FMC really doesn't care what your circumstances are, you will need to get an extension for that. Last time a Jones Act extension was granted, if memory serves me right, was after hurricane Sandy to allow repositioning of empty containers, just to give an idea on how rare those occasions are. Now, I don't think it will be an issue in this case, but it does need to be cleared first and it's not an insignificant administrative hurdle.
Because of laws that protect US Maritime interests.
Most countries have laws about cabotage (picking up people or cargo inside of a country and delivering them to another place in that same country). Typically they protect their own industries by not allowing foreign operators to do that. https://en.wikipedia.org/wiki/Cabotage
In air travel, the Chicago Convention defines the "freedoms of the air" that include these concepts. https://en.wikipedia.org/wiki/Freedoms_of_the_air
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Launching straight up from the Mun to a return at Kerbin is totally doable. If you are on the equator at the trailing terminator, and you launch perfectly straight up, you can simply make sure you are at 0 velocity relative to Kerbin as you leave the Mun's SOI. That will let you just drop straight down the well to Kerbin.
However, it's not the most efficient way to do it, because you fight the Mun's gravity the entire time. If you choose a path that spirals around the Mun until it reaches the SOI boundary point with the same 0 speed relative to Kerbin, it takes more time but uses less fuel.
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4 minutes ago, tater said:
Definition would be that what sat on the launchpad gets restacked (or whatever, might be SSTO), and reflown with no major components having to be new by design.
So by that definition there has not yet ever been any reusable space launch?
(Except, I guess, Blue Origin's New Shepard? Or, perhaps the X-15 and the Virgin Galactic?)
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3 minutes ago, tater said:
I never said it wasn't fantastic—but it was not reusable in the sense that they are attempting with Starship (or even F9 boosters). Sorry, that's simply fact.
$1.3B per flight is not a real reusable vehicle. When Shuttle was proposed, they literally talked about flying it enough to make it cheaper than Titan—which required a cadence of about 1 per week on the nominal budget... that in the real world flew just a few times a year. I don't care how many parts were "reused," it needs to result in cheaper use, and higher cadence or it's a waste of time. It must be economical to reuse.
That's ACTUAL reuse. Cars are reusable. Planes are reusable. Ships are reusable. Shuttle wasn't. Orion isn't, DRAGON isn't, either. They are refurbishable.
The Space Shuttle was a fully functioning small space station that could house more than half a dozen people for a week in orbit, and you are comparing it to the cost of a titan launch?
Yes, an uncrewed reusable booster would have been cheaper for routine sat deliveries to orbit. Like most of crewed space flight, there is some question about whether it should even be done at all. The shuttle was designed to do everything for everyone, which usually doesn't end up making it ideal for anything or anyone. But the things you are complaining about here are ridiculous in terms of apples versus oranges.
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On 3/26/2024 at 1:41 PM, tater said:
What mistakes? When was the last 100% reusable (actually reusable, unlike Shuttle) rocket tested by anyone?
Why do people in this forum continue to take potshots at the Space Shuttle?
It was a fantastic system, that absolutely pioneered the practical reuse of space vehicles. Nearly every part of a shuttle was reused -- the only thing that wasn't was the external tank.
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17 hours ago, sevenperforce said:
We should be able to do it with only a little more theoretical work, really.
I've been hearing that about fusion power for the past 45 years.
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I still remember the time before the breakup of the USSR when the official story from the Soviet Union was that there had never been any attempt to make a manned lunar mission.
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Here's how it works, to the best of my knowledge. You write a plan of what you are going to test. The plan gets approved. You conduct the test.
If things go according to the plan, that's fine. If they don't, that's what needs to be investigated and resolved.
It's up to SpaceX what they write in their plan. If it had just said "Splashdown of the first stage, destructive reentry for the second, both at predetermined spots..." then that would have been good enough. Obviously the plan must not have said that, though.
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TRL2, at best.
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11 hours ago, AckSed said:
Can you make a staged combustion engine more reliable? Peter Beck of Rocket Lab says you can: by building it to withstand and run at extremes, then under-driving it, you end up in the same level of reliability as a gas-generator rocket engine. Neutron's Archimedes is ox-rich, not full-flow, but building to run at max, then under-running at a more comfortable level is a solid path to good reliability.
That's just standard engineering. You always have to balance margins of performance between the risk that you unexpectedly exceed the limits versus the risk that you overdesign and fail for cost, weight, etc.
The skill and experience is in knowing how close to the edge you should get. Race car engineer Carroll Smith wrote in one of his books: "An engineer is someone who can do for a dime what any fool can do for a dollar."
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19 hours ago, Meecrob said:
Mikey, my boy, stop trying to snipe at me re: Elon Musk. Do you really think that the guy pushing to go to Mars, who is an engineer, and owns a space launch company that is building a rocket aimed at Mars has his feet kicked up on his desk while his minions do his bidding? You're an engineer, don't you love creating things? You confuse me, buddy.
If you don't believe me that he is an engineer, listen to "IRL" Rocket Scientist Lauren Lyons:
Edit: The higher you go in Public companies, what you say is true. Do yourself a favour and read up on Elon's Management style. I know you have decades of Boeing experience so you are used to beurocracy and appeasing shareholders and all that fun stuff. Bottom line is, Elon knows how to run a company. He gets specialists in to do tasks, unlike other companies who get one of the 500 or so CEO's that float around and have no real experience in anything other than management. Go look at Boeing and Blue Origin. Research their leaders, form your own opinion. I doubt you will listen to me.
Anyways, have a great day.
My name is not "Mikey", I'm not your boy, and why are you trying to make this argument personal? (Against the forum rules, I will add.)
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35 minutes ago, Deddly said:
He did make it more pointy. I think that counts as engineering.
Seriously though, isn't he the head engineer?
He's the CEO (and has about 80% control of the voting shares). He can call himself the "head engineer" if he wants -- nobody who works for him is going to tell him otherwise.
But the higher you go in management, the less actual engineering you do, despite sometimes being the person who ultimately says yes or no about major decisions.
FWIW, he has an economics degree, not an engineering degree. Not that I'm saying having a degree is necessary, but it is somewhat indicative. If you look at his history, it's not at all clear he has ever worked as an engineer.
Shotwell, on the other hand, does have an engineering degree and clearly has worked as an engineer in her professional background.
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4 hours ago, Meecrob said:
Look man, with all due respect, would you please let Elon Musk design his own rockets? He is an actual engineer, and a decent one at that. He is 12 steps ahead of what you are thinking of here. just let him show you what he has planned. We are getting really close to the test flight campaign actuallty getting started.
I am quite confident that Elon does approximately 0% of the engineering on any SpaceX rocket.
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1 hour ago, Deddly said:
Falcon 1 failed a few times though, right? As I understand it, Falcon 1 was basically just one step in the development process for the Falcon 9.
Everything can be said to be a step in the development process for everything else that comes after, but as I understand it, Falcon 1 was originally expected to be a viable launcher, not just a step on the way to Falcon 9.
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I know a guy who was a professor at UAL-Fairbanks for a while. Got a lot of ice climbing practice in the winter.
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Of course the main issue is that metallic hydrogen may not even exist.
But the reason hydrogen has the potential for a high ISP is because it is the lightest atom. Any other atoms added to the reaction mass will only lower the ISP if they are also carried onboard. If they are drawn from outside (ramjet, etc.) then yes ... but that obviously only works in the atmosphere and has so many other problems that it has never been done except for "Stage 0" of air-launched rockets.
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On 2/23/2024 at 10:32 PM, Casey James said:
We're going to see a few crazy new technologies and vehicles this summer, and by the following summer (2025), these personal VTOL WAEVs will be all over the place.
Pics or it didn't happen.
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On 2/23/2024 at 6:40 PM, StrandedonEarth said:
Well, it is still sending (whispering?) data. Call it a partial success. Certainly not a full success if some instrumentation wasn't working on descent. Sort of the equivalent of "Any landing you can walk away from"
More like the equivalent of a landing you can crawl away from, with two broken legs. Like, it *could* have been worse, but not by very much.
16 hours ago, StrandedonEarth said:Too bad the switch could not be flipped remotely....
Manual lockouts are intentionally unable to be flipped remotely. They didn't want any chance that somebody was staring into a non-eye-safe laser when somebody remotely flipped a switch to turn it on.
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14 hours ago, magnemoe said:
Pretty sure animals know that humans are not very dangerous outside of hunting season and not dangerous in suburban settings where hunting is illegal.
If you are a herbivore, a lack of fear tends to be dangerous. But running away from harmless things is also dangerous (unnecessary caloric output, plus the chance that you alert or even blunder into something actually dangerous). At some point many animals learn to be cautiously trusting around other animals that don't seem hostile.
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1 hour ago, PakledHostage said:
I'll admit to knowing very little about AI or how our own brains work, but my impression that I mentioned above comes from watching my kids learn as they grew from infancy into childhood and my own reflections on the subject. But having said that, how does the passage above support your argument? Current AI is basically pattern recognition, and LLMs can do all of what you describe as "true language processing"? One can ask it questions and give it instructions in plain language and it does a reasonable job of responding appropriately. Surely doing that requires contextual understanding of nouns, verbs, modifiers, and the like?
Edit: Thinking about it some more, even your scenario of the elephant can be interpreted as an example of pattern recognition. Your brain learns that that combination of shapes and colours is an elephant. It learns how that combination of shapes and colours changes as the elephant is viewed from different angles. It learns object permanence. These are all patterns. Putting them together allows the brain to formulate an expectation or model of the world it is experiencing. Some of these patterns that it learns, like object permanence, arise out of interacting with the physical world, but that interaction still breeds a recognition of patterns and expectations that future situations will follow the same pattern as was previously encountered. Babies learn object permanence early in their development. They learn that things fall. They learn what elephants and petunias look like. They learn to expect that falling petunias don't think "oh no, not again!"
It's 30 years old now, but a decent place to start if The Language Instinct, by Pinker.
When I was in college, my gf was working in Pinker's lab. She was doing things like searching through transcripts of kids' recordings, looking for very specific grammar errors. One thing that you find is that, unlike LLMs, kids learn language by figuring out the rules, rather than just associating the words from the usage that they hear. This can be shown by how they will make a certain kind of grammar error that they never hear adults say -- regularizing irregular constructions. A kid has likely never heard an adult say "Joe goed to the store," so it's clearly not the kind of learning that a LLM does where they just regurgitate the things they were trained on. Instead, the kids internalize the rule that you add -ed to the verb, but don't (at first) pick up the irregular nature of the verb "to go". They aren't just using things they have been taught by hearing other people say, because other people don't say it.
Yes, it's a "pattern" that they learn -- add -ed to the end of the verb -- but that implies that have already recognized some words are verbs and some are not, and that different tenses have different suffixes, and so forth. If they were learning like LLMs, they would always use "went" instead of "goed", because all their training data uses "went".
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4 hours ago, PakledHostage said:
I've often thought that our brains are largely just pattern recognition machines.
They are not. Pattern recognition is only one sub-system of the brain.
Human brains are mostly focused on a few things: keeping you alive (breathing, heart, etc.), controlling your body (walking, etc.), language, and vision processing. But they also have a lot of other specific and general capabilities.
Vision processing is much, much more than pattern recognition, which is why robots find it notoriously difficult. Essentially what you are doing is doing a real-time mapping of a 2D image into a 3D model. It's the much-harder task that 3D video games do in reverse, when they take a 3D model and project it into a 2D image. The reverse mapping is basically impossible (not enough data to find a unique solution) unless you already have a bunch of built-in concepts about the 3D world, like object permanence and the idea that objects obscure what is behind them. You also have to know, for instance, that an elephant seen from the side and an elephant seen from the front is the same elephant, even though the 2D patterns look much different.
True language processing is also much more complicated than pattern recognition, and involves grammar like nouns, verbs, modifiers, and the like. Moreover, for it to be useful, you have to be able to use the same (or close enough) meanings as other people, as well as the same grammar.
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8 hours ago, NFUN said:
This thread has approximately eight hours before it becomes solely a discussion on the Chinese Room problem
Good luck
Nah. Chinese room problem is silly.
No, wait, let me re-phrase that. The Chinese Room does not describe how human minds work. But it *is* a pretty decent analog for how these LLMs work. And that's why LLMs are not what people think/hope/fear that they are.
I'm not saying human minds aren't computational devices. I think they are. But the LLM is not how human minds are built, and it's not a path toward anything we would think of as being actually intelligent. IMO, of course. But it's a pretty educated opinion on this subject.
"Great American Eclipse" II: April 8 2024
in Science & Spaceflight
Posted
So did the world end? I heard from a friend in Texas that some of the locals were worried that might happen.