Actually, with this system, unlike other elevator concepts, it is only a one-way ticket. To get down, you have to have a vehicle capable of surviving reentry.
So what would it be like to hit turbulence at Mach 7.6? Or for that matter if a rivet was not quite flush? I'll bet you'd get a lot of Gs then, maybe too many to notice.
The higher the altitude, the less turbulence. The Concorde travels at 50,000 feet. It has almost no turbulence. This scramjet would travel more in the neighborhood of 80,000 feet. The turbulence would basically be zilch.
In response to an earlier poster: Humans can withstand Mach 7.6. The withstand Mach 25 in rockets. What matters is the acceleration. This scramjet would likely accelerate no faster than a regular jet liner. Fighter pilots only need pressure suits when they do high-g turns. No jet engine has enough thrust to cause blackouts during acceleration.
2 traditional jet engines and 2 scramjets, you take off and land with the traditional engines and cruise with the scramjets.
Actually, you would need three sets of engines: Turbojet to reach supersonic speeds, ramjet to Mach 4 so the scramjet can operate.
The practical limit of turbojet engines is about Mach 2.5, not nearly fast enough for the scramjet. The reason the SR-71 exceeds Mach 3 is that it uses a turbo-ramjet engine. When it gets to a certain speed, all the air and fuel is bypassed and burns independant of the turbines (which completely shut off). This allows the turboramjet to reach higher speeds that a turbojet.
There was one supersonic ramjet cruise missile that actually reached hypersonic speeds. I forgot the name. But during one test, the fuel feed got stuck on full throttle, and the cruise missile reached Mach 5.5 with no problem.
Ramjets have been around for years and can reach Mach 5. Why not use them? All that you would need is a couple of turbojets to reach transonic speeds, then you can fire the ramjet and your are off.
(BTW, a scramjet would need a turbojet to reach supersonic speeds, a ramjet to reach low hypersonic speeds, and finally a scramjet to accelerate to high hypersonic speeds)
Why do we need this story at all. The Pusher robots already shove around the blind people for us.
Re:Impact on the environment (and the ground)
on
Going Up?
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· Score: 2
The whole idea is that you are going to be lofting very heavy objects without thrust systems, a breakage would mean that this thrust-less heavy equipment would also come hurtling down.
You mean, they would come down just like a rocket if it failed?
The payloads would weigh much less than a fully fueled rocket.
Also, they would be launched from the middle of the pacific. So unlike Cape Canaveral, if the cable failed, the payload would just land in the ocean. If the payload was near GEO orbit and had close to orbital speed, it would just burn up in the atmosphere.
Also, structures just don't "fall down." This is engineered twice as strong as it needs to be. It cannot break during the worst hurricane.
Re:15 years - yeah right
on
Going Up?
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· Score: 2
Sounds great and all - but 15 years? Yeah right. I'm still waiting on flying cars, jetpacks, and robotic sex slaves.
I doubt in 15 years, yes. We have the technology to do lots of stuff right now or within 5 years. In fact, we already know how to build nuclear detonation engines that can send people to the outer planets or slow missions to the stars. We did that with Project Orion in the 60's. (If NASA really worked on it, we could have the tech to do a manned Satrun mission in 5 years with the non-nuclear VASIMR engine.)
Re:Falling down - why does it not fall down?
on
Going Up?
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· Score: 2
Simple. The rope extends way past GEO orbit. The rope past GEO has tension on it because of centrifugal force. So if you have a rope that is 50,000 miles long, it will remain in tension.
I don't think anybody reading slashdot, myself included, will ever join the thousand mile high club.
Re:Impact on the environment (and the ground)
on
Going Up?
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· Score: 1
EVERYONE!! THIS IS AS THIN AS A SHEET OF PAPER!!!
Use your heads. Do you think a sheet of paper will cause planet-wide destruction!!!
Re:Impact on the environment (and the ground)
on
Going Up?
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· Score: 2
Farthur in the future, I see no reason why you can't make an airtight cylindrical one.
Re:Good idea for nuclear waste?
on
Going Up?
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· Score: 2
"You could lanuch self-guiding ships full of the stuff straight into the sun...the sun sure wouldn't care."
This space tether looks pretty failsafe. According to the companie's FAQ, it will be able to support twice the weight of the tether and it's cargo. You could simply just fling the waste off the end into interplanetary space. (To a higher orbit, obviosly)
Of course, it still would be expensive. This will launch shit at 1/100 of the cost of the shuttle. That is still $100 bucks a pound. Anyway, we can store nuclear waste safely here on earth. And we might want that spent fuel later on, anyway.
Also what about the risk of it falling down? An orbital tower will wrap about the earth more than once if it falls. The description in Red Mars was particularly though provoking.
Actually, it's not a tower. It's a tether. The best way to build a space elevator is to have a 15 mile high tower. Above that, you have a carbon nanotube robe that extends to GEO orbit. At GEO, there is some kind of counterweight like an asteroid. Or just a tether extending out another 24,000 miles, which can be used for interplanetary travel.
Interestingly, the thickness of the rope is greatest at it's end near GEO. The thickness on earth would be very thin.
The best material would be nanotubes in a fiberglass matrix.
BTW, if it came crashing to earth, it wouldn't cause much destruction. It would not wrap around the earth at all. It would fall straight down just like anything else. After all, it's speed is synchronized with earth's rotation. Most of the wreckage would land within a few miles of the base. And since the base would probably be in a remote equitorial island like one in the Maldives, it would not kill very many people.
That's not just romanticising the past, there really is a lot less jobs available these days per capita - clearly because of technology.
Unemployment was lower in the 90's than during most of the century. Even with our bad economy now, I think it is still pretty low.
Technology usually only eliminates worthless crap jobs, like harvesting wheat, and being a clerk, and allows people to move into more productive fields.
Advances in technology often cost jobs. Just look at robotics. But however, with technology to produce goods and services with less manpower and money, we consume more. This increased consumption leads to the job market holding steady with no more than a few percent unemployment.
Combined with the factors you cite (it doesn't pollute, and the fuel cost is almost peanuts ) the plants will being generating enormous profits. From such profits, more plants are built.
I'm not saying these plants won't be profitable. It would just be a while before they got to be cheaper than sources such as coal.
nuclear plants are forced to shut down down between this and 25 years...
I don't think they will in France. I believe in the next 20 years we will se wider use of nuclear power. What other power sources will we use? Of course coal will last another 200 years. But we can't afford to pollute like that much longer.
I have heard that to supply the world with fuel ethanol, we would have to farm an area slightly larger than Alaska. That is ridiculous.
A much better thing would be to farm sea kelp and decompose it to produce biogas. Sea kelp grows over a foot a day. Much better than corn. The decomposition process of course realeases methane and CO2. But the methane is utilized for fuel. The CO2 off gassing is offset by CO2 the kelp absorbs.
Growing kelp in large areas would not harm the environment at all. Kelp forests are like the rain forests of the ocean. They provide haven for all sorts of sea life.
So, you make some ethanol, then use that ethanol to make more ethanol, use that to make even more ethanol,... eventually you've got an endless supply of fuel.
Toriods are expensive because you need a huge vacuum chamber that is surrounded by ridiculously powerfull superconducting magnets and heats up plasma to millions of degrees.
Slashdot Mirror
Actually, with this system, unlike other elevator concepts, it is only a one-way ticket. To get down, you have to have a vehicle capable of surviving reentry.
So what would it be like to hit turbulence at Mach 7.6? Or for that matter if a rivet was not quite flush? I'll bet you'd get a lot of Gs then, maybe too many to notice.
The higher the altitude, the less turbulence. The Concorde travels at 50,000 feet. It has almost no turbulence. This scramjet would travel more in the neighborhood of 80,000 feet. The turbulence would basically be zilch.
In response to an earlier poster: Humans can withstand Mach 7.6. The withstand Mach 25 in rockets. What matters is the acceleration. This scramjet would likely accelerate no faster than a regular jet liner. Fighter pilots only need pressure suits when they do high-g turns. No jet engine has enough thrust to cause blackouts during acceleration.
2 traditional jet engines and 2 scramjets, you take off and land with the traditional engines and cruise with the scramjets.
Actually, you would need three sets of engines: Turbojet to reach supersonic speeds, ramjet to Mach 4 so the scramjet can operate.
The practical limit of turbojet engines is about Mach 2.5, not nearly fast enough for the scramjet. The reason the SR-71 exceeds Mach 3 is that it uses a turbo-ramjet engine. When it gets to a certain speed, all the air and fuel is bypassed and burns independant of the turbines (which completely shut off). This allows the turboramjet to reach higher speeds that a turbojet.
There was one supersonic ramjet cruise missile that actually reached hypersonic speeds. I forgot the name. But during one test, the fuel feed got stuck on full throttle, and the cruise missile reached Mach 5.5 with no problem.
Ramjets have been around for years and can reach Mach 5. Why not use them? All that you would need is a couple of turbojets to reach transonic speeds, then you can fire the ramjet and your are off.
(BTW, a scramjet would need a turbojet to reach supersonic speeds, a ramjet to reach low hypersonic speeds, and finally a scramjet to accelerate to high hypersonic speeds)
Why do we need this story at all. The Pusher robots already shove around the blind people for us.
The whole idea is that you are going to be lofting very heavy objects without thrust systems, a breakage would mean that this thrust-less heavy equipment would also come hurtling down.
You mean, they would come down just like a rocket if it failed?
The payloads would weigh much less than a fully fueled rocket.
Also, they would be launched from the middle of the pacific. So unlike Cape Canaveral, if the cable failed, the payload would just land in the ocean. If the payload was near GEO orbit and had close to orbital speed, it would just burn up in the atmosphere.
Also, structures just don't "fall down." This is engineered twice as strong as it needs to be. It cannot break during the worst hurricane.
Sounds great and all - but 15 years? Yeah right. I'm still waiting on flying cars, jetpacks, and robotic sex slaves.
I doubt in 15 years, yes. We have the technology to do lots of stuff right now or within 5 years. In fact, we already know how to build nuclear detonation engines that can send people to the outer planets or slow missions to the stars. We did that with Project Orion in the 60's. (If NASA really worked on it, we could have the tech to do a manned Satrun mission in 5 years with the non-nuclear VASIMR engine.)
Simple. The rope extends way past GEO orbit. The rope past GEO has tension on it because of centrifugal force. So if you have a rope that is 50,000 miles long, it will remain in tension.
I don't think anybody reading slashdot, myself included, will ever join the thousand mile high club.
EVERYONE!! THIS IS AS THIN AS A SHEET OF PAPER!!!
Use your heads. Do you think a sheet of paper will cause planet-wide destruction!!!
Farthur in the future, I see no reason why you can't make an airtight cylindrical one.
"You could lanuch self-guiding ships full of the stuff straight into the sun...the sun sure wouldn't care."
This space tether looks pretty failsafe. According to the companie's FAQ, it will be able to support twice the weight of the tether and it's cargo. You could simply just fling the waste off the end into interplanetary space. (To a higher orbit, obviosly)
Of course, it still would be expensive. This will launch shit at 1/100 of the cost of the shuttle. That is still $100 bucks a pound. Anyway, we can store nuclear waste safely here on earth. And we might want that spent fuel later on, anyway.
Also what about the risk of it falling down? An orbital tower will wrap about the earth more than once if it falls. The description in Red Mars was particularly though provoking.
Actually, it's not a tower. It's a tether. The best way to build a space elevator is to have a 15 mile high tower. Above that, you have a carbon nanotube robe that extends to GEO orbit. At GEO, there is some kind of counterweight like an asteroid. Or just a tether extending out another 24,000 miles, which can be used for interplanetary travel.
Interestingly, the thickness of the rope is greatest at it's end near GEO. The thickness on earth would be very thin.
The best material would be nanotubes in a fiberglass matrix.
BTW, if it came crashing to earth, it wouldn't cause much destruction. It would not wrap around the earth at all. It would fall straight down just like anything else. After all, it's speed is synchronized with earth's rotation. Most of the wreckage would land within a few miles of the base. And since the base would probably be in a remote equitorial island like one in the Maldives, it would not kill very many people.
Hey! This computer is flagged! You just take your toilet-computer and get out of this store!
That's not just romanticising the past, there really is a lot less jobs available these days per capita - clearly because of technology.
Unemployment was lower in the 90's than during most of the century. Even with our bad economy now, I think it is still pretty low.
Technology usually only eliminates worthless crap jobs, like harvesting wheat, and being a clerk, and allows people to move into more productive fields.
Agreed.
Advances in technology often cost jobs. Just look at robotics. But however, with technology to produce goods and services with less manpower and money, we consume more. This increased consumption leads to the job market holding steady with no more than a few percent unemployment.
I just noticed this post. What do you mean?
They won't be running at a loss. I just wonder whether they will provide cheaper power than coal or nuclear initially.
Combined with the factors you cite (it doesn't pollute, and the fuel cost is almost peanuts ) the plants will being generating enormous profits. From such profits, more plants are built.
I'm not saying these plants won't be profitable. It would just be a while before they got to be cheaper than sources such as coal.
nuclear plants are forced to shut down down between this and 25 years...
I don't think they will in France. I believe in the next 20 years we will se wider use of nuclear power. What other power sources will we use? Of course coal will last another 200 years. But we can't afford to pollute like that much longer.
Assuming that ethanol and gasoline have the same number of BTUs/gallon
Ethanol has far less BTU's that gas. It has only about 60%.
I have heard that to supply the world with fuel ethanol, we would have to farm an area slightly larger than Alaska. That is ridiculous.
A much better thing would be to farm sea kelp and decompose it to produce biogas. Sea kelp grows over a foot a day. Much better than corn. The decomposition process of course realeases methane and CO2. But the methane is utilized for fuel. The CO2 off gassing is offset by CO2 the kelp absorbs.
Growing kelp in large areas would not harm the environment at all. Kelp forests are like the rain forests of the ocean. They provide haven for all sorts of sea life.
So, you make some ethanol, then use that ethanol to make more ethanol, use that to make even more ethanol,... eventually you've got an endless supply of fuel.
Hmm. Endless supply of booze. Er, fuel.
I should have said "indefinitely" instead of "forever." Obviously they only have a life of a few decades. I just meant one that could run continously.
I'm talking about the forseeable future anyway.
Toriods are expensive because you need a huge vacuum chamber that is surrounded by ridiculously powerfull superconducting magnets and heats up plasma to millions of degrees.