Uses of Bulk Nano Materials (was beanstalks)

what else can be expected from a macintrash user.

Tensile strength of alumina whiskers is 42.7 GPa.

PS. This thread stinks! Even if cheap, long buckytubes are available, beanstalks/skyhooks will not be made for security reasons -- they are too easy to destroy. This is one reason why slings make much more sense than skyhooks. My favorite transportation system is made of a rocket which accelerates cargo to 2 km/s, a hoop electrotube (orbital eddy current contraption described in my space book), which accelerates the cargo to 4 km/s, and a bolo, which accelerates the cargo to 8 km/s.

BTW, that is one of the major arguments put forward to stop construction of the Chunnel.

snipped-for-privacy@spsystems.net (Henry Spencer) :

One problem I have with the person claiming that we will not have bulk NanoTube materials is that they seem to think all research is for thier use in beanstalks only. Ofcourse if this was true the amount of money and people devoted to the problems would be few indeed.

However the uses of such super materials is so wide that tens if not hundred millions of dollars a year are being spent because of the range of uses. Just about anytime that today is done with fiberglass or carbon firber structures could be done light and/or lighter with Nano materials. And a number of projects that today seem to be at the limits or even beyond the ability of present day technology become possible (IE a bridge link japan's islands).

There is plain too much money to be made by the successful producter of bulk Nano materials to believe that if it can be done that the method needed will be discovered.

Earl Colby Pottinger

One of the great stupid things to do that I have seen recently is to talk about nanotubes with cross posting to a lot of different newsgroups.

The real smarts and the pseudo-smarts get into wars with each other.

To a large extent, the information content of the messages is dwarfed by the emotional content.

Really dumb thing to do, but then there are people who enjoy the flurry of semi-intellectual activity.

I will read about a dozen more elements of this thread and evaluate the usefulness of the time consumed in reading it.

Enjoy yourselves, as evidently does seem to happen.

sci.space.policy ...... ?????

Dear Earl Colby Pottinger:

And yet the ignition of single flash bulb could ignite an entire structure? I think you are putting too much faith in a single technology. We need the stars, but in our eyes is the wrong place for achieving them.

David A. Smith

Why are beanstalks pushed so hard when cheaper alternatives, like say rockets or even giant em guns are doable with todays technology? They certainly don't seem cheaper; Building a structure in space longer than the earth compared to doing the EM launch gun on earth over several hundred miles... The only appeal I can see is, 'look ma, all statics'

Because the power needed compared to that for a rocket is much, much lower, as is the energy.

Rockets are currently higher than $1000/Kg.

There seems to be no theoretical reason why they can hit $1000/Kg (NASA seems to disagree, and hold it as one of their sacraments.

$100/Kg is more or less the fuel cost for optimistic assumptions. For a tether, it can go to $.1 for optimistic assumptions.

They're of interest because *in the long term*, amortized over very large amounts of traffic, they are the cheapest launch method imaginable, and free of the troublesome environmental issues of really-high-volume traffic using most other methods.

As I've noted elsewhere in the discussion, it is much harder to make an economic case for near-term first-generation versions, especially if you perversely :-) insist on using the same assumptions (e.g., sizable steady flow of small payloads) for the comparison systems, instead of stacking the deck in favor of the beanstalk by comparing it to today's off-the-shelf systems. In the near term, technological coolness factor is the beanstalk's main advantage. :-)

jbuch :

Welcome to the real world where a single invention/product can affect a number of people doing totally diffirent things. As it was I had trimmed out a number of newsgroups before I posted. It is my understanding that posting to more than three groups at a time is getting carried away.

Sci.Astro - Where the discussion started as far as I can tell.

Sci.Space.Policy - Where the discussion is make better rockets or can they be replaced with a beanstalk.

Sci.materials - What is the real state of the art in Nanotubes.

Earl Colby Pottinger

"N:dlzc D:aol T:com \(dlzc\)" :

No, it will not. That bright flash needs oxygen to get the burning going. You will not find oxygen available in either space or inside the resin bond fibers together - no to mention the resin will act like a heat sink preventing the rise in the nanotubes temperture. Check again, you claim only applies to single uncoated tubes under a very bright light.

Earl Colby Pottinger

And beanstalk launch costs are currently infinite (can't get there from here using that technology). A proper comparison is apples to apples; for example, if you propose to spend several billion on beanstalk development, you should compare to spending the same amount on rocket development, and if you propose a lean, efficient organization which doesn't have Boeing's overhead rates, you shouldn't compare the results to Boeing-made rockets.

There are lots of people who think they can get to $1000/kg -- the current guess for first-generation beanstalk payload costs, probably somewhat optimistic -- for less than a billion dollars of development money. That's an order of magnitude less than current estimates for the first beanstalk. You could fund five of them for less than a beanstalk, and at least one would probably succeed. (How credible are their estimates? Well, as Jordin Kare put it a year or two ago in a slightly different context: "they aren't Lockheed Martin, but neither are you".)

There is no theoretical reason why rockets cannot get stuff into orbit for $5-10/kg. The only fundamental limit is that you need $3-4 worth of LOX plus a cheap hydrocarbon (kerosene, propane, whatever) to get a kilogram of dry mass into orbit, and some of the dry mass will be hardware rather than payload, and there will be some overhead for wear and tear on the hardware.

Not unless you use unnecessarily expensive fuels. Even today's designs for SSTO RLVs -- SSTOs are fuel hogs, and current designs are only 15-20% payload at orbit injection -- shouldn't cost more than $20-30/kg if they burn LOX/hydrocarbon. Liquid hydrogen costs more but I don't think it would push them to $100/kg. To go that high you'd need to resort to hypergolics.

Amortized over huge traffic volumes, yes, beanstalks unquestionably beat rockets. (And the crossover point occurs somewhat earlier if you figure in a cost for rocket emissions, like stratospheric water vapor during ascent and nitrogen oxides during reentry, both of which are bad for the ozone layer if flight rates get really high.)

I think you show bad taste, nevertheless.

However, at least people who want to endlessly discuss this subject in the sense of a disconnected semi-shouting match have kindly been provided this opportunity for endless discussion over a whole bunch of newsgroups.

This may be the real world, to use your phrase, but this "discussion" actually will have almost no significance to any of the participants.

This is a bit fast and loose...

I assume that is $1/kg, not $0.1/kg, ideally, LEO takes about

10kWhrs/kg, inferring 10 cents per kWhr at the climber. Though elevators are more suited to GEO and need help in getting to LEO.

For an optimistic hydrocarbon SSTO with a 2% payload fraction I get less than $5/kg base fuel cost to LEO, (should be easy with CNT :-). Methane/coal might enable something a bit cheaper, as would rotovator augmentation.

When we consider the comparative structure/payload fractions, (payload over elevator weight vs. payload over rocket drymass weight), then the capital cost of the rocket is around an order of magnitude less than that of the elevator. (I am assuming here that the CNT elevator will cost a similar amount on a per kilogram basis as rocket drymass, you may question this). And further, say a two week climber turn around time compared to a two hour rocket turnaround time, (assuming LEO).

In summary, assuming development cost is covered, the elevator will have something like a thousand times the dry mass, (and hence capital cost), for a given mass flow rate to LEO. I would think that straight rocket approaches might ultimately achieve costs in the $10/kg range. Until then fuel/energy costs are in the noise and I do not see that an elevator is justified.

Depending on capital cost, an elevator may eventually be cheaper for bulk transport, though it only goes to one place and it takes a week to get there, very inconvenient. Hopefully there will be significant technological progress, (like high speed climbers), but this is also true of rockets.

Pete.

Dear Earl Colby Pottinger:

This is what is documented, yes. And was totally unexpected.

Lightning strikes near the "cable", will induce sympathetic current in the cable. The heating can delaminate your cable, delamination in an area that is in full atmosphere.

Note that the coating you mention will act as an insulator, retaining the heat, so that a second "event", soon enough, will get it even hotter.

The highest loading should be outside the atmosphere, but it will be non-zero in the atmopshere. It wouldn't do to go drifting off... but then we are not talking about shadow square wire, are we?

David A. Smith

You are forgetting that empty elevators going down for another load can help to lift the full elevators going up.

Too bad you can't pull off that trick with rockets.

Your calculation needs to count the elevators as part of the fixed mass of the beanstalk - a capital cost, not as an operating cost, unlike the cost of lifting and then lowering rocket shells.

Sci.nanotech is more apppropriate, but the moderator would likely reject crossposting.

And there's the unmoderated alt.sci.nanotech.

I was looking at Ultimate Rockets (Rockets so advanced that the main cost is fuel) last year. As far as I could tell, LOX is cheap ($0.10/kg) and H is expensive ($3.60/kg). In a lot of the systems the H2 was -the- cost-defining expendible material used.

For some reason I never got around to pricing standard fuels like kerosene. In any case, I don't think you will use up $3-4 worth of LOX per kg of dry mass. Maybe of payload...

The length of cable within the atmosphere -- especially within the region where lightning is an issue -- is such a small fraction of the total cable length that all kinds of special precautions can be taken there without increasing cable mass significantly.