NewSpace 2010: Polywell and Vasimr

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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IntLibber
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Postby IntLibber » Sat Jul 31, 2010 8:12 am

AcesHigh wrote:
Betruger wrote:I don't think you can bet on such a skeptic paying a hundred bucks to supposedly read something that defies everything he knows. There's lots of free resources e.g. all the papers and powerpoints and articles for free on the net, that e.g. Paul March has linked to.

e.g.
STAIF-2007 MLT Powered Spacecraft
From this page with more resources to choose from.


who is talking about sketptics here? GIThruster just proved to be a skeptic about space elevators and lightcraft. He tells the guy to read about ME-Effect, but it seems some people here havent read enough about space elevators...


Nope, we've read a lot about space elevators. We know how many billion tons of mass must be put into GSO in order to build one. We know the tensile strengths of carbon nanotube, both theoretical and actual, and the current state of the materials science of it and how it is progressing.

The best carbon nanotube today cannot achieve more than one quarter of the minimum tensile strength required of a space elevator, and that is over an extremely short distance. Making thread from these nanotubes is difficult at best and the tensile strength goes down the longer the thread is, so there are some very vast distances to go in advancing the state of the science before you are even ready to start building it.

Once you achieve that point, you still have to plan on how you are going to manufacture and move many billions of tons of this material up to geosynchronous orbit. That is an economic problem that will NOT be solved until after mach effect thrusters make space elevators obsolete.

KitemanSA
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Postby KitemanSA » Sat Jul 31, 2010 2:35 pm

GIThruster wrote:I'm not a skeptic. I'm a realist.

Elevators, Solar Sat Power Stations, Lightcraft, Rail Guns shooting stuff to orbit--don't make sense because they cannot be economically viable.

If you need to spend a trillion dollars for a space transport system, then you're never going to have such a system.
What is ther pricetag for today's US railroad system? Trillions, right? Too expensive to ever happen, right? Then why is it here?

Please don't condemn a vision because you can't achieve it instantaneously. There are many intermediate steps to a full fledged space elevator that can be made functional now and could be profitable too.

Check out http://en.wikipedia.org/wiki/Non-rocket ... Structures . It shows some of the many intermediate steps to a full-fledged space elevator.

GIThruster
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Postby GIThruster » Sat Jul 31, 2010 4:16 pm

KitemanSA wrote:Please don't condemn a vision because you can't achieve it instantaneously. There are many intermediate steps to a full fledged space elevator that can be made functional now and could be profitable too.


The rail system began paying for itself from the first day the rails were laid.

Look, just IMHO, but pretending we'll ever have hundreds of billions of dollars to spend on human spaceflight ain't ever gonna get the job done. These schemes people share with wide eyes would cost many times what Apollo did. The Apollo days are over. Makes me as sad as anyone to say, but if we ever want to see a golden age of human spaceflight, we have to look to something better than these trillion dollar schemes.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

KitemanSA
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Postby KitemanSA » Sun Aug 01, 2010 1:09 am

GIThruster wrote:
KitemanSA wrote:Please don't condemn a vision because you can't achieve it instantaneously. There are many intermediate steps to a full fledged space elevator that can be made functional now and could be profitable too.
The rail system began paying for itself from the first day the rails were laid.
Absurd! It certainly took MANY days, weeks, months, perhaps even years, for a useful rail lines to be laid and most {of the rail laid down at the time "railroads" were started} were laid for horse/mule drawn carts before the "railroad" even began. The same can be done for tether launch facilities.
GIThruster wrote: Look, just IMHO, but pretending we'll ever have hundreds of billions of dollars to spend on human spaceflight ain't ever gonna get the job done. These schemes people share with wide eyes would cost many times what Apollo did.
Absurd! A valuable hypersonic skyhook can be launched with ONE Delta IV Heavy. and would soon be assisting in the launch of dozens of 5Mg payloads per year. Properly scheduled, this capacity could grow to hundreds per year in less that one year. {I know, I've done the spread sheet.}
GIThruster wrote:The Apollo days are over. Makes me as sad as anyone to say, but if we ever want to see a golden age of human spaceflight, we have to look to something better than these trillion dollar schemes.
Please don't condemn others for your own foolishness! The development toward space elevators via HASTOLs or Hypersonic Skyhooks, or Kite-Launchers is no "trillion dollar scheme"; any more than the current intercontinental aircraft business was a quadrillion dollar scheme.

Of course, if you equate space elevator SOLELY with NASA, then you might have a point, but you shouldn't.
__________
Added clarification on what I meant by "most" in the first response section.
Added last sentance in second section.
Last edited by KitemanSA on Sun Aug 01, 2010 1:38 pm, edited 1 time in total.

GIThruster
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Postby GIThruster » Sun Aug 01, 2010 4:14 am

Why don't you go ahead and outline what you think is a workable, cost-effective system and let us critique it?
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

cc
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Postby cc » Sun Aug 01, 2010 7:11 am

IntLibber wrote:Nope, we've read a lot about space elevators. We know how many billion tons of mass must be put into GSO in order to build one. We know the tensile strengths of carbon nanotube, both theoretical and actual, and the current state of the materials science of it and how it is progressing.

Both you and GIThruster have clearly demonstrated that you have not "read a lot about space elevators." Your wildly mistaken ideas about lofting absurd masses are a clear indicator of this. Furthermore, it would seem that you are unwilling to do so, so we can't have a meaningful conversation about them. (Not that this is the right thread anyway, which is why I haven't pushed the point, and instead referenced a book with which you might reduce your ignorance.)

The best carbon nanotube today cannot achieve more than one quarter of the minimum tensile strength required of a space elevator, and that is over an extremely short distance. Making thread from these nanotubes is difficult at best and the tensile strength goes down the longer the thread is, so there are some very vast distances to go in advancing the state of the science before you are even ready to start building it.

This is an engineering problem which will inevitably be solved. The materials exist, they just aren't manufacturable yet; in the worst case, we will have to wait for molecular nanotechnology. Anyway, the amount being spent on purely elevator-specific research is so insignificant, that it isn't even worth arguing.

Once you achieve that point, you still have to plan on how you are going to manufacture and move many billions of tons of this material up to geosynchronous orbit. That is an economic problem that will NOT be solved until after mach effect thrusters make space elevators obsolete.

It's a lot easier once you accept that an elevator doesn't require "billions of tons." In reality, it is nowhere even remotely near that.


More on-topic, what sort of thrust can we expect from a Polywell equipped rocket? While it will no doubt be great in space, will it even be sufficient for launches from Earth? 100MW is not a whole lot of power...

GIThruster
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Postby GIThruster » Sun Aug 01, 2010 2:56 pm

cc, I was involved in an elevator discussion a couple years ago, and it proved obvious the task was a macro-engineering task, not the simple "wait on engineering" issue you've painted it. There are lots of permutations. If someone here has one that fits on a single Delta IV heavy, please lets see it.

Otherwise, I gotta say looks like a lot of hot air to me. Cables from round to flat, from 20k-60k kilometers long, necessary tensile strengths varying by over 500%, stuff attached to asteroids. . .

Insane when you think you're gonna spend other people's money.

Here's the test, folks: you want an economically viable transport system? Sell it to private industry. Screw NASA. They'd just mess it up anyway by turning it into a project 3X over budget and 5X overdue.

If an elevator is a viable transport option, lets see a proposal for the private sector.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

AcesHigh
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Postby AcesHigh » Mon Aug 02, 2010 5:05 pm

GIThruster wrote: Makes me as sad as anyone to say, but if we ever want to see a golden age of human spaceflight, we have to look to something better than these trillion dollar schemes.


you mean, we should look at ME-Effect thrusters??? Well, I agree we should look into them. ANd I HOPE they will work. But so far there is no proof. And humanity should not look into only ONE solution that may prove to be false hope in the end.

EVERYTHING should be considered. Including space elevators. The bickering wont help anyone. And with bickering I mean ME-Effect supporters saying space elevators are bullshit, space elevator supporters saying ME-Effect is pseudoscience, and ultra-skeptics saying BOTH things are bullshit and we should only look at chemical rockets forever to get out of Earth´s gravity well.

AcesHigh
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Postby AcesHigh » Mon Aug 02, 2010 5:08 pm

GIThruster wrote:Otherwise, I gotta say looks like a lot of hot air to me. Cables from round to flat, from 20k-60k kilometers long, necessary tensile strengths varying by over 500%, stuff attached to asteroids. . .


maybe it is hot air. Maybe it isnt. The ridiculous part is someone who defends a system which 99% of the physics community considers as pseudo-science (thus they dont even consider it as hot air... I mean... at least current physics consider the elevator possible, unlike ME-Effect) calling the space elevator hot air.

AcesHigh
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Postby AcesHigh » Mon Aug 02, 2010 5:12 pm

cc wrote:
IntLibber wrote:Nope, we've read a lot about space elevators. We know how many billion tons of mass must be put into GSO in order to build one. We know the tensile strengths of carbon nanotube, both theoretical and actual, and the current state of the materials science of it and how it is progressing.

Both you and GIThruster have clearly demonstrated that you have not "read a lot about space elevators." Your wildly mistaken ideas about lofting absurd masses are a clear indicator of this.


exactly, I tried to point them out about it and they simply refused. It seems their idea about a space elevator is stuck to Fountains of Paradise by Clark (the book is excellent anyway) and the Martian Trilogy.

For their info, if the elevator breaks up, we are not even talking about a cataclismic global event as described in the Martian Trilogy books, we are talking about the elevator falling down as a FEATHER, so low will be its density by cubic meter.

TallDave
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Postby TallDave » Mon Aug 02, 2010 5:34 pm

Well, NASA's still holding contests and giving awards for SE tech, so they seem to think there may be a path to viability.

Of course, they're probably assuming a fusion-powered rocket is even less likely. The great thing about the future is no one's been there yet.

Here's a nice SE reference: http://www.spaceelevator.com/

On tensile strength:

http://wiki.spaceelevator.com/@api/deki ... dwards.pdf

The primary technical hurdle for construction of
the space elevator is the production of the highstrength
material with a tensile strength of 100
GPa. At the current time, carbon nanotubes
(CNTs) have been measured with tensile
strengths of 200 GPa.


And that was 5 years ago.
n*kBolt*Te = B**2/(2*mu0) and B^.25 loss scaling? Or not so much? Hopefully we'll know soon...

MSimon
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Postby MSimon » Mon Aug 02, 2010 6:01 pm

The ridiculous part is someone who defends a system which 99% of the physics community considers as pseudo-science
Chapter 28 of Book 2 of The Feynman Lectures on Physics.
Unexplored science is a better term. The general mass of physicists are a singularly incurious lot.
Engineering is the art of making what you want from what you can get at a profit.
http://protonboron.com/
THE OPEN POLYWELL FUSION CONSORTIUM

GIThruster
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Postby GIThruster » Mon Aug 02, 2010 6:39 pm

AcesHigh wrote:
GIThruster wrote: Makes me as sad as anyone to say, but if we ever want to see a golden age of human spaceflight, we have to look to something better than these trillion dollar schemes.


you mean, we should look at ME-Effect thrusters??? Well, I agree we should look into them. ANd I HOPE they will work. But so far there is no proof. And humanity should not look into only ONE solution that may prove to be false hope in the end.

EVERYTHING should be considered. Including space elevators. The bickering wont help anyone. And with bickering I mean ME-Effect supporters saying space elevators are bullshit, space elevator supporters saying ME-Effect is pseudoscience, and ultra-skeptics saying BOTH things are bullshit and we should only look at chemical rockets forever to get out of Earth´s gravity well.


This isn't an "us vs them" dichotomy. If I thought elevators were an economically viable approach, I'd be a supporter. What I'm saying is, even if we had the technology necessary, I have never seen anything that made me think elevators can possibly be economically viable--same as lightcraft and rail guns for shooting stuff to orbit.

Just being practical and saying again, if you need a fantastic investment in order to have a space transport system, you're never going to have that system. We can't even get a billion dollars to develop TRITON. What makes you think we'll ever get hundreds of billions to launch high tech rope into the sky?
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

GIThruster
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Postby GIThruster » Mon Aug 02, 2010 6:42 pm

The ridiculous part is someone who defends a system which 99% of the physics community considers as pseudo-science


Completely false statement. 99.999% of the physics community doesn't know a thing about M-E physics, let alone have an opinion on it. There are only about a dozen people on the planet who are current on the physics.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

TallDave
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Postby TallDave » Mon Aug 02, 2010 8:27 pm

I have never seen anything that made me think elevators can possibly be economically viable


Hmm? Economics is actually the main argument for SE.

http://en.wikipedia.org/wiki/Space_elevator_economics

The NIAC study by Edwards was pretty optimistic.

Launch loops are an interesting variant I hadn't run across before.

http://en.wikipedia.org/wiki/Launch_loop
n*kBolt*Te = B**2/(2*mu0) and B^.25 loss scaling? Or not so much? Hopefully we'll know soon...


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