Getting potential energy (altitude) is easy. Getting kinetic energy (speed) is hard. If you could figure out a way to fly your spacecraft up to 80-90,000 feet with air breathing engines, then deploy the spacecraft with rockets, you might be able to realize some cost efficiencies. However, the sheer size of an aircraft that could carry a useful (say, half Shuttle sized) payload up to that altitude, along with the rocket it would need to put it into orbit, is absolutely staggering. Consider that the U2 spyplane, which carried 1 dude, a pile of cameras, and a big honkin' engine to that altitude, had a wingspan of some 80+ feet. Some back-of-the-envelope calculations tell me you'd have to have a wingspan on the order of 400 feet or so to get a 747-sized payload up to that altitude. Sure, you could experiment with joined-wing advanced biplane ideas to get better structural integrity, but geez...why not just build a better rocket? You STILL have to accelerate like the proverbial bat out of hell to get into orbit.
I think that the most cost effective heavy lift transport system is going to be an advanced staged rocket, (maybe you could figure out a way to recover and refurbish the stages, maybe not...) shooting from the equator. If SeaLaunch scales up, it could be very cool.
If you let NASA try it, yes, it'll cost $100B. There ARE cheaper ways of exploring the solar system. All NASA needs to do is get out of the way. At the risk of polluting my argument forever by invoking the name of the Great Satan Newt Gingrich, he was advocating a plan that put bounties on certain tasks that would need to be completed before we can travel to Mars. For instance, $10B for the first organization to successfully land and return samples from Mars, $40B for landing and returning humans, etc. I'm pulling numbers out of my ass, but this sort of thing has worked before (just look at all the interesting developments in the X-Prize competition).
I'm not going to read the book to you, but it's a GREAT plan. Check it out, if for no other reason than to shore up your own argument.
For the record, the space station as it's designed is a total waste of money. Nobody's going to learn a thing that's worth its cost.
Wow, this is a catastrophically bad idea. LEO is at Mach 25. Fastest known "conventional" jets nowadays are Mach 3. You want to tie them together, snag them with a hook traveling at a relative velocity of Mach 23, and drag 'em up into orbit? I bet the airframes would make a noise a lot like the monkey with the clapping cymbals, just before killing everybody involved...
You're not far from another interesting idea though. The nutty geniuses over at Tethers Unlimited want to have a mini-space elevator, whose bottom half is ripping through the upper atmosphere at about Mach 17. You dock with this thing from your hypersonic passenger liner (like the X30 that got canned, and for good reason), and hop on up into space on a great big crane.
How you actually DOCK at Mach 17 is not something I'd care to contemplate. But the idea's there...
Re:Ram and Scramjets make sense for atmospheric li
on
X-33 Shuttle Problems
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· Score: 1
Any time you talk about a scramjet, though, you run head on into the low thrust per frontal area inherent in the scramjet design. (see my Offtopic post above...damn moderators...) It may well be the best way to travel at ludicrous speeds through the atmosphere (which seems like a kindof silly idea to me), but it's not going to be the most fuel efficient way to get into space, and I seriously doubt it will be cost efficient, unless somebody comes up with some pretty brilliant insights as to how to make these high speed airflows do neat tricks.
Multistage rockets WILL be more efficient in terms of pounds of fuel per pounds of stuff in orbit. However, the SSTO pundits say that they will realize cost savings by making the spacecraft easy to service and reuse. If they can make it REALLY easy to service and reuse, it may well wind up costing less dollars per pound of stuff in orbit than a conventional rocket. However, this servicing thing has yet to work well. The Shuttle was supposed to be the proof of concept on this idea, and it simply didn't work. (Yes, Virginia, it does shoot lots of tonnage into orbit, but it does NOT do so cheaply)
Because the Feds think that the moonshot was just an expensive way to thumb our noses at the Soviets. The people who REALLY got something out of the moonshots (that'd be the planetary scientists) can't WAIT to get back.
Read "The Case for Mars" by Robert Zubrin. $40B dollars, leaving extensible habitats on Mars, laying the framework for continuous habitation of the planet.
His rocket math works. I don't know how to estimate the cost of this project, but his figures are a lot more credible than NASA's Battlestar Galactica nonsense.
Getting to Mars is nothing more or less than an act of will. It IS valuable, the only question is whether we've got the balls to do it. I, for one, can't wait. I'll be sure to send you a postcard.
Re:The NASP(X-30) and X-33 are two different thing
on
X-33 Shuttle Problems
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· Score: 1
Whooops! Wow, look at all that work I put into an irrelevant post.
In that case, since I was confused, it's possible that other people were too. I hope. Or maybe I'm just a big idiot. : )
All my comments above are related to the big doorstop-shaped NASP. The littler reflex-hammer lookin' X33 (which might become the Delta Clipper) was not discussed. Its linear aerospike engine looks interesting, but I still think SSTO is not going to work well. At least it doesn't try to launch horizontally, though...
Well damn. Diggin' the egg on my face...
Re:Ram and Scramjets make sense for atmospheric li
on
X-33 Shuttle Problems
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· Score: 1
See my other post for more details, but scramjets do not make sense for orbital insertion, since their thrust throughput (thrust divided by cross sectional area, a calculation that will give you an off-the-cuff estimate of their net thrust potential) is two orders of magnitude below that of modern rocket engines. (or not so modern rocket engines: The V2 motor was absolutely brilliant)
Fuel is cheap. Maintenance is expensive. There is a certain amount of energy you have to dump into one pound of stuff in order to get that stuff into space. The least expensive vehicle is the one that weighs the least.
What makes a single stage craft horribly wrong is that it WILL weigh more than a staged rocket. End of story.
There's nothing magic about SSTO that makes it cheaper than the Shuttle (whose alleged cost savings have NEVER been realized). The economies are supposed to come from simplified servicing and maintenance. Therefore, IF you can service the thing for less than the cost of a similar capacity rocket, it's economical. This has not proven to be the case.
And before you start hollering about people who don't know what they're talking about, let's discuss this "fuel per square pound" idea you've got in your post. I'm REALLY sure that this measurement has nothing whatsoever to do with rocketry.
I'm studying aerospace engineering at the University of Texas at Arlington. On Monday, one of my professors hosted a seminar regarding the NASP (X-33), and what a really disastrously bad idea it was from start to finish. In case you're interested, here are a couple points I took away from the discussion.
The aerodynamics of the NASP were totally contrary to its mission. Drag forces at high supersonic and hypersonic speeds (from, say, Mach 3 and up) are dominated by the drag induced by the shock wave that develops ahead of the craft. Wave drag is minimized by using small frontal cross section vehicles. The NASP had two major design constraints, dictated basically by the politics of getting the thing funded, that made a slender vehicle impossible. The vehicle was supposed to use slush liquid hydrogen. Although hydrogen releases tons of energy when it's burned, it's density is very low. Other fuels, like propane and methane, would have been much easier to carry in a slender vehicle. The slush hydrogen fuel, however, had technical sex appeal for the people funding it. (Basically, the contractors thought they could make a lot of money developing this fuel technology, so they weren't going to fund the project without it). The aerodynamic chubbiness meant that most of the engines' thrust was used up opposing drag, meaning that there was little net force left over to accelerate the aircraft. Therefore, the vehicle had to fly at Mach 7-15 for about 20 minutes...making cooling the airframe one of the major challenges. Sure you've got a bunch of liquid H2 on board, but piping it to all the places whose temperature is starting to approach that of the sun's surface gets, well, complicated.
The air breathing scramjet propulsion system 0requires a huge engine "bell" (actually, the NASP uses a half-bell ramp), which drives up the cross-sectional area of the ship. The air-breathing nature of the "primary" propulsion system (one of FOUR separate propulsion systems to be carried on the craft!!!) saved the plane from needing to carry liquid O2 to burn with the hydrogen. A neat idea, however modeling the compression and combustion of the engine, operating with high supersonic intake velocities, went from astoundingly difficult to absolutely impossible.
The initial flight profile of the X33 was supposed to go something like this:
From 0 to ~ Mach 1.3: Propelled by a conventional turbojet or rocket engine
Mach 1.3-3: Propelled by a ramjet engine
Mach 3-15: Propelled by a supersonic compression ramjet (scramjet)
Mach 15-orbital insertion: Propelled by a rocket
So right from the get-go, you've got four different engine systems to integrate, three of which are dead weight for any given part of the flight. Never mind the difficulty of actually IGNITING these engines at the proper time...
From a project management perspective, this thing was dead from the get-go. Two separate airframe manufacturers had to coordinate with four separate engine manufacturers, leading to essentially eight different designs. The whole thing was classified, meaning that engineers were not given any information they didn't "need to know", and were not given the opportunity to evaluate the feasibility of their proposed solutions. This is a HELL of a way to run a railroad.
Maybe I'm slow, but for me the most profound insight was into the nature of rockets versus the nature of airplanes. With rockets, your thrust vector directly opposes your weight vector. This means that THE killer feature for a rocket is very light weight. In an airplane, your thrust vector opposes your drag vector, so aerodynamic cleanliness is the most important consideration for airplanes. When your goal is to get up to Mach 25 (LEO insertion velocity) doing so by flying horizontally is just plain stupid.
Anyhow, the moral of the story was, "Don't ever do a project this way ever." Probably the most fruitful hour-long lecture I've gotten so far.
I think I missed something. What legal obligation is it that Apple is not appealing?
As far as defection goes, there exists a core market of Mac users whose jobs cannot be done on other platforms. Apple caters to these people, quite profitably nowadays...
Quartz, and the Display PostScript stuff that runs underneath it, is an entirely different kettle of fish. The rendering and display engine has been the thrust of MacOS X development, and looks like it's going to be THE killer feature for the OS. Apple is under no obligation to port it to anything else, and they'd be foolish to do so as they make ALL their money on hardware.
If he did make an OS 9/8/7 emu, he'd lose his shirt, as MacOS X will come with one. It's REALLY hard to find old Mac apps that don't run quite happily on OS8 and 9.
If you don't like the (illegal) rules they want you to play by, feel ignore them and do whatever you want with the gizmo they foolishly mailed you. What's the problem?
I'm not saying that Microsoft will or won't succeed (I hope they succeed just enough to hemhorrage a bunch of cash into this disaster called X-Box, and then get the rug pulled out from under them...) but Sony was in exactly the same position a few years ago. They had a huge name, no experience in consoles. Nowadays, the Playstation accounts for a very significant fraction of their revenues.
I've never, EVER, encountered a neophyte who used filenames so descriptive. They name every letter "letter" and don't have the vaguest idea of what directory they put it in. Do you have some sort of new breed of superuser out there? (pun fully intended)
Re:Y'all may be too young to remember this, but
on
2001: A Space Laptop
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· Score: 1
Umm, the net force due to gravity (colloquially, "Weight") was zero (well, if you want to get SUPER technical, very near zero). Therefore, it was, weightless. It was most emphatically NOT massless.
They ARE evil. My momma taught me that if I give somebody something, they're allowed to do whatever they want with it (even break it) and it's very rude for me to object. Since DC gives people stuff, and then tries to tell them what to do with that stuff, they're doing something my momma told me not to do, therefore they're evil. QED.
I guess I want to go by their office here in Dallas, point and laugh, and ask "Well what did you THINK the geeks were going to do?!?!"
If you go check out the article, it says that the phone module will include a headset, which so far as I'm concerned is a requirement for any telephone I'm going to share my life with. Bully for Handspring for realizing this!
Non issue. The communications skills are important as measured in the environment where you're exercising them. My communications skills in English are excellent. My communications skills in French are abysmal. I wouldn't go to France, however, and complain that I wasn't being given a fair shake...
You can either do the job or you can't. Some jobs require you to be able to dead lift a certain amount. Some require you to be able to communicate in the language of your coworkers. This isn't complicated, nor is it unfair.
(my Hindi, Chinese, and Korean, incidentally, are non-existent)
Do you have any idea how much it would cost in terms of fuel expenditure to get 1lb of nuclear waste to the sun?
Lemme give you a hint. $1000/lb to low earth orbit is CHEAP. Now you have to get it out of Earth's gravity well and bowl it at the sun, which takes even MORE fuel.
Slashdot Mirror
Getting potential energy (altitude) is easy. Getting kinetic energy (speed) is hard. If you could figure out a way to fly your spacecraft up to 80-90,000 feet with air breathing engines, then deploy the spacecraft with rockets, you might be able to realize some cost efficiencies. However, the sheer size of an aircraft that could carry a useful (say, half Shuttle sized) payload up to that altitude, along with the rocket it would need to put it into orbit, is absolutely staggering. Consider that the U2 spyplane, which carried 1 dude, a pile of cameras, and a big honkin' engine to that altitude, had a wingspan of some 80+ feet. Some back-of-the-envelope calculations tell me you'd have to have a wingspan on the order of 400 feet or so to get a 747-sized payload up to that altitude. Sure, you could experiment with joined-wing advanced biplane ideas to get better structural integrity, but geez...why not just build a better rocket? You STILL have to accelerate like the proverbial bat out of hell to get into orbit.
I think that the most cost effective heavy lift transport system is going to be an advanced staged rocket, (maybe you could figure out a way to recover and refurbish the stages, maybe not...) shooting from the equator. If SeaLaunch scales up, it could be very cool.
If you let NASA try it, yes, it'll cost $100B. There ARE cheaper ways of exploring the solar system. All NASA needs to do is get out of the way. At the risk of polluting my argument forever by invoking the name of the Great Satan Newt Gingrich, he was advocating a plan that put bounties on certain tasks that would need to be completed before we can travel to Mars. For instance, $10B for the first organization to successfully land and return samples from Mars, $40B for landing and returning humans, etc. I'm pulling numbers out of my ass, but this sort of thing has worked before (just look at all the interesting developments in the X-Prize competition).
I'm not going to read the book to you, but it's a GREAT plan. Check it out, if for no other reason than to shore up your own argument.
For the record, the space station as it's designed is a total waste of money. Nobody's going to learn a thing that's worth its cost.
Wow, this is a catastrophically bad idea. LEO is at Mach 25. Fastest known "conventional" jets nowadays are Mach 3. You want to tie them together, snag them with a hook traveling at a relative velocity of Mach 23, and drag 'em up into orbit? I bet the airframes would make a noise a lot like the monkey with the clapping cymbals, just before killing everybody involved...
You're not far from another interesting idea though. The nutty geniuses over at Tethers Unlimited want to have a mini-space elevator, whose bottom half is ripping through the upper atmosphere at about Mach 17. You dock with this thing from your hypersonic passenger liner (like the X30 that got canned, and for good reason), and hop on up into space on a great big crane.
How you actually DOCK at Mach 17 is not something I'd care to contemplate. But the idea's there...
Any time you talk about a scramjet, though, you run head on into the low thrust per frontal area inherent in the scramjet design. (see my Offtopic post above...damn moderators...) It may well be the best way to travel at ludicrous speeds through the atmosphere (which seems like a kindof silly idea to me), but it's not going to be the most fuel efficient way to get into space, and I seriously doubt it will be cost efficient, unless somebody comes up with some pretty brilliant insights as to how to make these high speed airflows do neat tricks.
Multistage rockets WILL be more efficient in terms of pounds of fuel per pounds of stuff in orbit. However, the SSTO pundits say that they will realize cost savings by making the spacecraft easy to service and reuse. If they can make it REALLY easy to service and reuse, it may well wind up costing less dollars per pound of stuff in orbit than a conventional rocket. However, this servicing thing has yet to work well. The Shuttle was supposed to be the proof of concept on this idea, and it simply didn't work. (Yes, Virginia, it does shoot lots of tonnage into orbit, but it does NOT do so cheaply)
Because the Feds think that the moonshot was just an expensive way to thumb our noses at the Soviets. The people who REALLY got something out of the moonshots (that'd be the planetary scientists) can't WAIT to get back.
Read "The Case for Mars" by Robert Zubrin. $40B dollars, leaving extensible habitats on Mars, laying the framework for continuous habitation of the planet.
His rocket math works. I don't know how to estimate the cost of this project, but his figures are a lot more credible than NASA's Battlestar Galactica nonsense.
Getting to Mars is nothing more or less than an act of will. It IS valuable, the only question is whether we've got the balls to do it. I, for one, can't wait. I'll be sure to send you a postcard.
Whooops! Wow, look at all that work I put into an irrelevant post.
In that case, since I was confused, it's possible that other people were too. I hope. Or maybe I'm just a big idiot. : )
All my comments above are related to the big doorstop-shaped NASP. The littler reflex-hammer lookin' X33 (which might become the Delta Clipper) was not discussed. Its linear aerospike engine looks interesting, but I still think SSTO is not going to work well. At least it doesn't try to launch horizontally, though...
Well damn. Diggin' the egg on my face...
See my other post for more details, but scramjets do not make sense for orbital insertion, since their thrust throughput (thrust divided by cross sectional area, a calculation that will give you an off-the-cuff estimate of their net thrust potential) is two orders of magnitude below that of modern rocket engines. (or not so modern rocket engines: The V2 motor was absolutely brilliant)
Let's back up a little bit.
Fuel is cheap. Maintenance is expensive. There is a certain amount of energy you have to dump into one pound of stuff in order to get that stuff into space. The least expensive vehicle is the one that weighs the least.
What makes a single stage craft horribly wrong is that it WILL weigh more than a staged rocket. End of story.
There's nothing magic about SSTO that makes it cheaper than the Shuttle (whose alleged cost savings have NEVER been realized). The economies are supposed to come from simplified servicing and maintenance. Therefore, IF you can service the thing for less than the cost of a similar capacity rocket, it's economical. This has not proven to be the case.
And before you start hollering about people who don't know what they're talking about, let's discuss this "fuel per square pound" idea you've got in your post. I'm REALLY sure that this measurement has nothing whatsoever to do with rocketry.
I'm studying aerospace engineering at the University of Texas at Arlington. On Monday, one of my professors hosted a seminar regarding the NASP (X-33), and what a really disastrously bad idea it was from start to finish. In case you're interested, here are a couple points I took away from the discussion.
The aerodynamics of the NASP were totally contrary to its mission. Drag forces at high supersonic and hypersonic speeds (from, say, Mach 3 and up) are dominated by the drag induced by the shock wave that develops ahead of the craft. Wave drag is minimized by using small frontal cross section vehicles. The NASP had two major design constraints, dictated basically by the politics of getting the thing funded, that made a slender vehicle impossible. The vehicle was supposed to use slush liquid hydrogen. Although hydrogen releases tons of energy when it's burned, it's density is very low. Other fuels, like propane and methane, would have been much easier to carry in a slender vehicle. The slush hydrogen fuel, however, had technical sex appeal for the people funding it. (Basically, the contractors thought they could make a lot of money developing this fuel technology, so they weren't going to fund the project without it). The aerodynamic chubbiness meant that most of the engines' thrust was used up opposing drag, meaning that there was little net force left over to accelerate the aircraft. Therefore, the vehicle had to fly at Mach 7-15 for about 20 minutes...making cooling the airframe one of the major challenges. Sure you've got a bunch of liquid H2 on board, but piping it to all the places whose temperature is starting to approach that of the sun's surface gets, well, complicated.
The air breathing scramjet propulsion system 0requires a huge engine "bell" (actually, the NASP uses a half-bell ramp), which drives up the cross-sectional area of the ship. The air-breathing nature of the "primary" propulsion system (one of FOUR separate propulsion systems to be carried on the craft!!!) saved the plane from needing to carry liquid O2 to burn with the hydrogen. A neat idea, however modeling the compression and combustion of the engine, operating with high supersonic intake velocities, went from astoundingly difficult to absolutely impossible.
The initial flight profile of the X33 was supposed to go something like this:
From 0 to ~ Mach 1.3: Propelled by a conventional turbojet or rocket engine
Mach 1.3-3: Propelled by a ramjet engine
Mach 3-15: Propelled by a supersonic compression ramjet (scramjet)
Mach 15-orbital insertion: Propelled by a rocket
So right from the get-go, you've got four different engine systems to integrate, three of which are dead weight for any given part of the flight. Never mind the difficulty of actually IGNITING these engines at the proper time...
From a project management perspective, this thing was dead from the get-go. Two separate airframe manufacturers had to coordinate with four separate engine manufacturers, leading to essentially eight different designs. The whole thing was classified, meaning that engineers were not given any information they didn't "need to know", and were not given the opportunity to evaluate the feasibility of their proposed solutions. This is a HELL of a way to run a railroad.
Maybe I'm slow, but for me the most profound insight was into the nature of rockets versus the nature of airplanes. With rockets, your thrust vector directly opposes your weight vector. This means that THE killer feature for a rocket is very light weight. In an airplane, your thrust vector opposes your drag vector, so aerodynamic cleanliness is the most important consideration for airplanes. When your goal is to get up to Mach 25 (LEO insertion velocity) doing so by flying horizontally is just plain stupid.
Anyhow, the moral of the story was, "Don't ever do a project this way ever." Probably the most fruitful hour-long lecture I've gotten so far.
I think I missed something. What legal obligation is it that Apple is not appealing?
As far as defection goes, there exists a core market of Mac users whose jobs cannot be done on other platforms. Apple caters to these people, quite profitably nowadays...
The user interface.
Change "everything" to "anything" and I think you're right on the money.
Quartz, and the Display PostScript stuff that runs underneath it, is an entirely different kettle of fish. The rendering and display engine has been the thrust of MacOS X development, and looks like it's going to be THE killer feature for the OS. Apple is under no obligation to port it to anything else, and they'd be foolish to do so as they make ALL their money on hardware.
If he did make an OS 9/8/7 emu, he'd lose his shirt, as MacOS X will come with one. It's REALLY hard to find old Mac apps that don't run quite happily on OS8 and 9.
If you don't like the (illegal) rules they want you to play by, feel ignore them and do whatever you want with the gizmo they foolishly mailed you. What's the problem?
I'm not saying that Microsoft will or won't succeed (I hope they succeed just enough to hemhorrage a bunch of cash into this disaster called X-Box, and then get the rug pulled out from under them...) but Sony was in exactly the same position a few years ago. They had a huge name, no experience in consoles. Nowadays, the Playstation accounts for a very significant fraction of their revenues.
It's been done before.
I've never, EVER, encountered a neophyte who used filenames so descriptive. They name every letter "letter" and don't have the vaguest idea of what directory they put it in. Do you have some sort of new breed of superuser out there? (pun fully intended)
That assumes that a command line is ever "right".
(humor impaired, see above...)
Umm, the net force due to gravity (colloquially, "Weight") was zero (well, if you want to get SUPER technical, very near zero). Therefore, it was, weightless. It was most emphatically NOT massless.
They ARE evil. My momma taught me that if I give somebody something, they're allowed to do whatever they want with it (even break it) and it's very rude for me to object. Since DC gives people stuff, and then tries to tell them what to do with that stuff, they're doing something my momma told me not to do, therefore they're evil. QED.
I guess I want to go by their office here in Dallas, point and laugh, and ask "Well what did you THINK the geeks were going to do?!?!"
What a bunch of morons.
If you go check out the article, it says that the phone module will include a headset, which so far as I'm concerned is a requirement for any telephone I'm going to share my life with. Bully for Handspring for realizing this!
Non issue. The communications skills are important as measured in the environment where you're exercising them. My communications skills in English are excellent. My communications skills in French are abysmal. I wouldn't go to France, however, and complain that I wasn't being given a fair shake...
You can either do the job or you can't. Some jobs require you to be able to dead lift a certain amount. Some require you to be able to communicate in the language of your coworkers. This isn't complicated, nor is it unfair.
(my Hindi, Chinese, and Korean, incidentally, are non-existent)
Do you have any idea how much it would cost in terms of fuel expenditure to get 1lb of nuclear waste to the sun?
Lemme give you a hint. $1000/lb to low earth orbit is CHEAP. Now you have to get it out of Earth's gravity well and bowl it at the sun, which takes even MORE fuel.
Please tell me you're trolling...