King Canute, king of Denmark, Norway, and -- after a series of battles -- England circa 1015-1035.
The fable is a mistelling of the story. Allegedly Canute had his throne carried to the shore where he sat as the tide came in (he did not drown), in order to prove to flattering courtiers who were saying that he was "so great he could command the tides" that of course he was not, that even kings were as nothing in the face of God's power.
For those that don't know, nethack is an ASCII-based graphical RPG with movement controls inspired by vi.
To elaborate further, nethack is a latter-day version of hack, which in turn was a descendant of the original rogue. (Which, as the man said, is an ASCII/curses based RPG.)
Depends where it was in the flight profile. The center engine of the S-V did not gimbal (the opposite layout of the N-1).
A single engine failure shortly after launch meant the S-V would just be too heavy to control and they'd abort the launch. Ditto a two engine failure of two engines on the same side of the vehicle -- that meant an automatic cutoff of all outboard engines before the vehicle tilted too far. If they'd burned enough fuel at that point for the center engine alone to lift the vehicle they kept on going, otherwise they'd abort at that point. At some points of the flight they could tolerate two opposite engines out (balanced thrust) but a single engine out would require changing the angle of the vehicle to the point where dynamic loads on the side would threaten to break it up.
About 68 seconds into the flight (first stage burn was about 160 seconds) it had burned enough propellant (about 2 million pounds) that it could keep going on three engines, for the first about 13 seconds it was still too heavy to fly on four engines, so yes there's about a 55 second window where it could fly on four -- but that's also the time where dynamic pressure is increasing so you really don't want to be presenting too much of an angle of attack. (Not to say that there isn't a window in there where it'd be okay to fly on the centre plus three outboard engines.)
(BTW, look at those times again, and recall that it took quite a few seconds to clear the tower. Basically if you lost an engine after hold-down release and before clearing the tower, you'd get a really big BANG a few seconds later as the rocket "settled" back down. That's one reason the launch control room was a couple of miles from the pad and had blast shutters over the windows.)
The Delta also started as a missile, the Thor IRBM. Granted there were a lot more changes from Thor to the first Delta launch vehicles than from Atlas or Titan to the first LV versions of those.
Re:Use it if you got it.
on
Soviet Moon Rocket
·
· Score: 5, Interesting
The article does say that, but the article is wrong. The N-1 actually had a pretty ingenious system for balancing the thrust of those engines, with engines on opposite sides of the vehicle linked together in terms of fuel feed and control. If one shut down, its mate on the opposite side automatically shut down to balance the thrust. (The Saturn V had similar control logic.) Although the number of engines made it a bit of a plumbing nightmare.
The real problem with the N-1 was (probably) pogo oscillation, which is the result of a feedback loop between engine thrust and rate at which fuel flows into the engine (influence by acceleration). The Saturn V was plagued with this in its early development too, since it's a problem that only shows up in flight.
To clarify, the name "Saturn V" refers to an assembly of several stages: the S-IC, S-II, and S-IVB. The first and biggest stage, the S-IC, was a pure LOX-kerosene stage. Its F-1 engines (1.5 million pounds thrust each) burned kerosene, only the upper stages burned hydrogen.
This makes a lot of sense -- "efficiency" (in terms of Isp) is only one figure of merit in rocket engines. It's more relevant when the engine no longer has to lift the mass of the vehicle against gravity. For lifting power (as with a first stage), you care about thrust, which is proportional to the mass of the exhaust products (and thus the mass of the fuel). Hydrogen is just too light to generate useful thrust except at very high exhaust velocities, which means very high engine pressures, which means heavy engines, etc, etc. (Also, because of LH2's low density, you need bigger fuel tanks, which weigh more, etc, etc.)
Case in point, the three Shuttle SSMEs together (which burn LO2/LH2) have barely more thrust than a single F-1 engine, and run at a much higher chamber pressure.
There's a reason the Shuttle uses those god-awful, low Isp solid boosters -- to create enough thrust to get off the pad!
...that you're only allowed to access XP workstations with Microsoft keyboards and Microsoft mice. The truth behind MS's entry into those markets is revealed at last!
Better not let the BSA catch you with a KVM switch...
Congratulations, you've just invented the loopback file system;-) Or perhaps the 'ar' file format.
Seriously, it's way too much overhead for most use, disk is usually cheap enough to go with simpler systems that permit much faster I/O if at the expense of a bit of "wasted" space.
OTOH, the approach can have its uses. Years ago I had an account on a CDC Cyber NOS system with a "disk quota" based on the number of files, not the total size. I just implemented a simple version of "ar" and kept things in archive files except while I was actually using them.
It's an old technique. IIRC, BSD 4.2's fast filesystem for the VAX had this circa, what, 1984 or so? (Well, a variation of this. Normal block size was 4K but this could be reduced to 1K for the last block of a file, with the last 1K block of several files sharing a real 4K block).
This was actually quite a leap at the time, since blocks were typically only 512b or 1K then. The 4K made it fast, the 1K tail merging made it less wasteful of expensive disk space.
Blender's cool, and there's a sad dearth of (affordable) 3D modelling, animation and rendering tools for Linux. Okay, sure, using OpenGL for the GUI toolkit was a bit funky, but you got used to it.
That would be the F-1. Yes, 1.5 million pounds thrust is a bit of a kick, although RP-1 isn't exactly just kerosene.
And my comments above for the J2 go several times for the F1 -- starting that thing was a bit of a black art, the ignition sequencing had to be done just right -- it wasn't a matter of just opening valves in the 17-inch oxidizer and fuel lines and lighting a match underneath!
That would be the J-2. LOX-hydrogen engine. Mind, there's a lot more to building a rocket engine (and getting it to work) than just looking at the patent drawings and description. If you're not "versed in the art", there are a lot of subtleties that will lead to a few blown up or burnt through engines before you get it right.
That's a lot of data. There were something like 10,000 engineering drawings for the LM alone, at the peak Grumman's design group was cranking them out at 400 a week. (I just finished Tom Kelly's semi-autobiographical book on the project, "Moon Lander"). And that's just the drawings. The documentation overall probably took warehouses to store -- and because of the cost of that storage, a lot of it is probably long gone.
However, a surprising amount is starting to turn up on the web, as the personal collections of old retired (and in too many cases, dead) Apollo-era engineers become available and enthusiasts put them on line. The NASA sites have some stuff too, but it's mostly the watered-down stuff they release to the general public.
Well, "ecofreaks" aside, my main point was the fuzziness of the term "species". I've had that argument before in a different context -- with anti-evolutionists declaring that one species can't evolve into another.
The thing is, even genetically "identical" individuals can have very different morphology and behaviour, depending on what genes get expressed (obvious examples: different breeds of dog; less obvious: lions and tigers, which can produce fertile offspring but look different and prefer different habitats (their ranges used to overlap). Eventually, of course, different habitats will lead to enough accumulated genetic difference that interbreeding is no longer possible. But where do you draw the species line? It's worse when you're looking at fossils -- all you have to go on is morphology. Would a fossil chihuahua and a fossil St. Bernard (to use someone else's example) be considered the same species?
(And as for "environmental activists" -- hey, housing developers are environmental activists too, they just prefer environments more suited to humans than to some random critter.;-)
"Species" is one of those fuzzy terms that everyone thinks they know the meaning of, but on closer examination it's hard to pin down. Kind of like "teal" (is it blue? green? dark turquoise?) or "pr0n".
The current usage of the term can denote two groups of genetically identical (well, allowing for normal variation) animals but that do not share overlapping habitat ranges as separate species. Given the opportunity, they could interbreed and produce fertile offspring (the "classic" distinction of a species -- which fails utterly for things that reproduce asexually and for morphologically distinct animals -- like lions and tigers -- that can interbreed and produce fertile offspring, but generally don't).
Thus you get ecofreaks complaining about the imminent extinction of the left-handed mottled weed rat because the two fields where they live are about to be paved over, when in reality that critter is genetically identical to the right-footed fuzz-backed bush mouse and the big-eared worm-tailed ground squirrel that just happen to live in different areas and were originally described by different biologists.
Where'd you pull those numbers/dates from? Somewhere dark, I imagine.
If we confine the discussion to microprocessors (reasonable, since there were 60-bit mainframes in the 1960s) we don't even start counting until the 8-bit 8008 circa 1972 (although we could start with the 4-bit 4004 in 1971 -- giving a four-bit increase in one year. Oops). (And actually, the picture is more confusing than that -- most of the early 8-bit chips supported 16-bit addressing, although some of them multiplexed the address lines).
If we stick with the Intel line, the (also 8-bit) 8080 appeared in 1974, the 16-bit 8086 in 1978, and the 32-bit 80386 in 1985. At that rate, doubling in bit width roughly every 7 years, Intel is ten years late with its 64-bit chip, and should have already introduced a 128-bit chip.
If we ignore the 8008, we get a width increase of about 2 bits/year, which actually works out closer to the real numbers -- the 64-bit x86 successor appearing circa 2001/2002. At that rate, look for a 128-bit Intel chip circa 2034, or just a few years short of the Unix clock rollover date (but by then we'll all be on 64-bit time).
Well, if NuSphere had actually included a written offer of the source as per 3(b), then you'd be right. But they (AFAIK) didn't.
A short blurb in one section of the manual that "sources will be available in some future release" (or whatever the exact wording) is not a specific offer to supply source.
Slashdot Mirror
King Canute, king of Denmark, Norway, and -- after a series of battles -- England circa 1015-1035.
The fable is a mistelling of the story. Allegedly Canute had his throne carried to the shore where he sat as the tide came in (he did not drown), in order to prove to flattering courtiers who were saying that he was "so great he could command the tides" that of course he was not, that even kings were as nothing in the face of God's power.
However, I take your point about Linux.
how much is Bill Gates worth now?
To whom?
I mean, it's getting to the point where the dang keys are gonna have to be longer than the message!
Heck, I just "vi /var/spool/mail/$USER".
For those that don't know, nethack is an ASCII-based graphical RPG with movement controls inspired by vi.
To elaborate further, nethack is a latter-day version of hack, which in turn was a descendant of the original rogue . (Which, as the man said, is an ASCII/curses based RPG.)
Depends where it was in the flight profile. The center engine of the S-V did not gimbal (the opposite layout of the N-1).
A single engine failure shortly after launch meant the S-V would just be too heavy to control and they'd abort the launch. Ditto a two engine failure of two engines on the same side of the vehicle -- that meant an automatic cutoff of all outboard engines before the vehicle tilted too far. If they'd burned enough fuel at that point for the center engine alone to lift the vehicle they kept on going, otherwise they'd abort at that point. At some points of the flight they could tolerate two opposite engines out (balanced thrust) but a single engine out would require changing the angle of the vehicle to the point where dynamic loads on the side would threaten to break it up.
About 68 seconds into the flight (first stage burn was about 160 seconds) it had burned enough propellant (about 2 million pounds) that it could keep going on three engines, for the first about 13 seconds it was still too heavy to fly on four engines, so yes there's about a 55 second window where it could fly on four -- but that's also the time where dynamic pressure is increasing so you really don't want to be presenting too much of an angle of attack. (Not to say that there isn't a window in there where it'd be okay to fly on the centre plus three outboard engines.)
(BTW, look at those times again, and recall that it took quite a few seconds to clear the tower. Basically if you lost an engine after hold-down release and before clearing the tower, you'd get a really big BANG a few seconds later as the rocket "settled" back down. That's one reason the launch control room was a couple of miles from the pad and had blast shutters over the windows.)
The Delta also started as a missile, the Thor IRBM. Granted there were a lot more changes from Thor to the first Delta launch vehicles than from Atlas or Titan to the first LV versions of those.
The article does say that, but the article is wrong. The N-1 actually had a pretty ingenious system for balancing the thrust of those engines, with engines on opposite sides of the vehicle linked together in terms of fuel feed and control. If one shut down, its mate on the opposite side automatically shut down to balance the thrust. (The Saturn V had similar control logic.) Although the number of engines made it a bit of a plumbing nightmare.
The real problem with the N-1 was (probably) pogo oscillation, which is the result of a feedback loop between engine thrust and rate at which fuel flows into the engine (influence by acceleration). The Saturn V was plagued with this in its early development too, since it's a problem that only shows up in flight.
Nope, sorry, but thanks for trying.
To clarify, the name "Saturn V" refers to an assembly of several stages: the S-IC, S-II, and S-IVB. The first and biggest stage, the S-IC, was a pure LOX-kerosene stage. Its F-1 engines (1.5 million pounds thrust each) burned kerosene, only the upper stages burned hydrogen.
This makes a lot of sense -- "efficiency" (in terms of Isp) is only one figure of merit in rocket engines. It's more relevant when the engine no longer has to lift the mass of the vehicle against gravity. For lifting power (as with a first stage), you care about thrust, which is proportional to the mass of the exhaust products (and thus the mass of the fuel). Hydrogen is just too light to generate useful thrust except at very high exhaust velocities, which means very high engine pressures, which means heavy engines, etc, etc. (Also, because of LH2's low density, you need bigger fuel tanks, which weigh more, etc, etc.)
Case in point, the three Shuttle SSMEs together (which burn LO2/LH2) have barely more thrust than a single F-1 engine, and run at a much higher chamber pressure.
There's a reason the Shuttle uses those god-awful, low Isp solid boosters -- to create enough thrust to get off the pad!
I mean, nowhere on that page did I see how you'd write "Hello World!".
...that you're only allowed to access XP workstations with Microsoft keyboards and Microsoft mice. The truth behind MS's entry into those markets is revealed at last!
Better not let the BSA catch you with a KVM switch...
Congratulations, you've just invented the loopback file system ;-) Or perhaps the 'ar' file format.
Seriously, it's way too much overhead for most use, disk is usually cheap enough to go with simpler systems that permit much faster I/O if at the expense of a bit of "wasted" space.
OTOH, the approach can have its uses. Years ago I had an account on a CDC Cyber NOS system with a "disk quota" based on the number of files, not the total size. I just implemented a simple version of "ar" and kept things in archive files except while I was actually using them.
It's an old technique. IIRC, BSD 4.2's fast filesystem for the VAX had this circa, what, 1984 or so? (Well, a variation of this. Normal block size was 4K but this could be reduced to 1K for the last block of a file, with the last 1K block of several files sharing a real 4K block).
This was actually quite a leap at the time, since blocks were typically only 512b or 1K then. The 4K made it fast, the 1K tail merging made it less wasteful of expensive disk space.
Blender's cool, and there's a sad dearth of (affordable) 3D modelling, animation and rendering tools for Linux. Okay, sure, using OpenGL for the GUI toolkit was a bit funky, but you got used to it.
Not at all. The DMCA is US law, the companies involved here are European (with perhaps a dash of Australian).
and is secure, running WinXP
Does this strike anyone else as oxymoronic? (Firewall or not.)
F5
That would be the F-1. Yes, 1.5 million pounds thrust is a bit of a kick, although RP-1 isn't exactly just kerosene.
And my comments above for the J2 go several times for the F1 -- starting that thing was a bit of a black art, the ignition sequencing had to be done just right -- it wasn't a matter of just opening valves in the 17-inch oxidizer and fuel lines and lighting a match underneath!
That would be the J-2. LOX-hydrogen engine. Mind, there's a lot more to building a rocket engine (and getting it to work) than just looking at the patent drawings and description. If you're not "versed in the art", there are a lot of subtleties that will lead to a few blown up or burnt through engines before you get it right.
That's a lot of data. There were something like 10,000 engineering drawings for the LM alone, at the peak Grumman's design group was cranking them out at 400 a week. (I just finished Tom Kelly's semi-autobiographical book on the project, "Moon Lander"). And that's just the drawings. The documentation overall probably took warehouses to store -- and because of the cost of that storage, a lot of it is probably long gone.
However, a surprising amount is starting to turn up on the web, as the personal collections of old retired (and in too many cases, dead) Apollo-era engineers become available and enthusiasts put them on line. The NASA sites have some stuff too, but it's mostly the watered-down stuff they release to the general public.
Well, "ecofreaks" aside, my main point was the fuzziness of the term "species". I've had that argument before in a different context -- with anti-evolutionists declaring that one species can't evolve into another.
;-)
The thing is, even genetically "identical" individuals can have very different morphology and behaviour, depending on what genes get expressed (obvious examples: different breeds of dog; less obvious: lions and tigers, which can produce fertile offspring but look different and prefer different habitats (their ranges used to overlap). Eventually, of course, different habitats will lead to enough accumulated genetic difference that interbreeding is no longer possible. But where do you draw the species line? It's worse when you're looking at fossils -- all you have to go on is morphology. Would a fossil chihuahua and a fossil St. Bernard (to use someone else's example) be considered the same species?
(And as for "environmental activists" -- hey, housing developers are environmental activists too, they just prefer environments more suited to humans than to some random critter.
"Species" is one of those fuzzy terms that everyone thinks they know the meaning of, but on closer examination it's hard to pin down. Kind of like "teal" (is it blue? green? dark turquoise?) or "pr0n".
The current usage of the term can denote two groups of genetically identical (well, allowing for normal variation) animals but that do not share overlapping habitat ranges as separate species. Given the opportunity, they could interbreed and produce fertile offspring (the "classic" distinction of a species -- which fails utterly for things that reproduce asexually and for morphologically distinct animals -- like lions and tigers -- that can interbreed and produce fertile offspring, but generally don't).
Thus you get ecofreaks complaining about the imminent extinction of the left-handed mottled weed rat because the two fields where they live are about to be paved over, when in reality that critter is genetically identical to the right-footed fuzz-backed bush mouse and the big-eared worm-tailed ground squirrel that just happen to live in different areas and were originally described by different biologists.
So, what's their definition of "species"?
Where'd you pull those numbers/dates from? Somewhere dark, I imagine.
If we confine the discussion to microprocessors (reasonable, since there were 60-bit mainframes in the 1960s) we don't even start counting until the 8-bit 8008 circa 1972 (although we could start with the 4-bit 4004 in 1971 -- giving a four-bit increase in one year. Oops). (And actually, the picture is more confusing than that -- most of the early 8-bit chips supported 16-bit addressing, although some of them multiplexed the address lines).
If we stick with the Intel line, the (also 8-bit) 8080 appeared in 1974, the 16-bit 8086 in 1978, and the 32-bit 80386 in 1985. At that rate, doubling in bit width roughly every 7 years, Intel is ten years late with its 64-bit chip, and should have already introduced a 128-bit chip.
If we ignore the 8008, we get a width increase of about 2 bits/year, which actually works out closer to the real numbers -- the 64-bit x86 successor appearing circa 2001/2002. At that rate, look for a 128-bit Intel chip circa 2034, or just a few years short of the Unix clock rollover date (but by then we'll all be on 64-bit time).
At best a 128-bit CPU could do those calculations twice as fast as a 64-bit one.
Uh, four times as fast, actually.
Little chance of being moderated up with flamebait like that...
Well, if NuSphere had actually included a written offer of the source as per 3(b), then you'd be right. But they (AFAIK) didn't.
A short blurb in one section of the manual that "sources will be available in some future release" (or whatever the exact wording) is not a specific offer to supply source.