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Costs of a Railgun system.

Posted by: James Summers - Thu Jan 11, 2007 6:50 pm
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Costs of a Railgun system. 
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Post Costs of a Railgun system.   Posted on: Thu Jan 11, 2007 6:50 pm
I don't think anyone has done this, but maybe you all know or read something that I don't.

Measuring how much it costs to get a pound of matter into orbit is the ultimate metric that one must use in any economic analysis.

It is what the engineers use when they design things, i.e. "this vehicle can lift X weight to Y height".

After R & D costs, the primary cost driver in terms of getting things into orbit is the fact that you have to build big rockets, either for your re-usable vehicles (RLV) or your one-shot wonders (SLV).

One has to provide lift for the vehicle and the rocket motors, and fuel. Fuel being the largest weight component of most rockets if my understanding is correct.

Here is a notion that has been kicked around a bit, but I think will ultimately win out over the long term:

Rail-guns. These are essentially a series of electro-magnets placed in a line that drags an object along by sequentially turning on and off the magnets. Imagine a large cannon.

If most of your energy/fuel requirements are from lifting the fuel itself, this method will mean that you can lift any given payload pound much cheaper. You only have to accelerate a small rocket, instead of moving a MUCH larger rocket.

This electro-magnetic technology is already in use at amusement parks. Many newer roller coasters use this to give the initial acceleration to the cars in the rides.

This technology is most applicable to unmanned payloads as you can accelerate them much faster than humans can stand, but given a long enough run, I think that even humans can eventually be lifted easily this way.

One other factor to consider is the location of such a facility, given that areas closer to the equator are cheaper in terms of energy required per pound of matter/payload to orbit.

An interesting development in materials to keep an eye out for is high-temperature super-conductors that would really make such a launch system more practical.

I can imagine a facility located at or near the equator being able to make good usage of solar power and large capacitors to provide some if not most or all of the power for such a system due to the long days. Whether such a facility could be powered entirely from solar power is something that would have to be looked into.

http://www.jatsgreenpower.com/map1-global.html

Provides a good global map for where solar power is most feasible.

The best areas for solar power are very close to the best areas for launching near the equator. This ignores the political instability of such areas though, and this must also be factored into any good economic analysis.

IN SUMMARY:
The energy needed to lift things into orbit can be substantially reduced.
The risk of catastrophic failure of a large rocket can be eliminated.
Since the system is mechanically much simpler it is very probable that it will end up being much more reliable because fewer things can go wrong.

Thoughts?

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Post    Posted on: Thu Jan 11, 2007 7:22 pm
What you are describing is not a rail gun, it is more like what is being discussed in this other thread:
http://www.spacefellowship.com/Forum/viewtopic.php?t=66
and by this company:
http://www.launchpnt.com/Space_Launch.32.0.html

In a rail gun, a conducting projectile touching two electrified rails carries current from one rail to the other which generates a force to accelerate the projectile. It has to slide on the rails to operate. That is totally different than electromagnetic coils being energized in sequence to accelerate the projectile without touching it.


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Post    Posted on: Thu Jan 11, 2007 11:03 pm
Forget about the energy production with solar cells - it's a secondary problem. The real matter is you have to store and release enough electrical energy in very short time - i.e. with capacitors. That's a trick only few have pulled off so far, and it's expensive. Typically, just the capacitors will cost more than the energy for 100 shots (I did the math but please correct me if I'm wrong :wink:), and then we haven't talked about infrastructure. That tends to be an important cost driver.
Solar cells (plus batteries) are nice when you need energy nearly continuously, but not ideal for occasional peaks. There you'd probably use conventional generation.

Ooh, and one more thing: really forget about humans. Even at 10g, your rail becomes impractically long. Do the math yourself, it's easy!

Regards
M

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Post    Posted on: Fri Jan 19, 2007 7:43 pm
HYPACC just needs pressure.

Look--spaceflight has more to do with good plumbing and margin than it does with computing. More TVA than MSN--you know that.

Keep computer/electronics people on the short leash.


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Post    Posted on: Fri Jan 19, 2007 8:27 pm
Fewer TLA please.

Oh, now I am on the short leash!


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Post    Posted on: Fri Jan 19, 2007 11:21 pm
Now you know the types--individuals with little mechanical aptitude who go around talking about "big primative rockets' and who think SSTOs are a cure all.


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Post    Posted on: Wed Jan 24, 2007 11:03 pm
publiusr wrote:
HYPACC just needs pressure.

Look--spaceflight has more to do with good plumbing and margin than it does with computing. More TVA than MSN--you know that.

Keep computer/electronics people on the short leash.



Publius,

could you explain what bearing that posting has to the topic, or the previous postings?

With all due respect to your HYPACC ambitions, energy storage in large high-pressure vessels is no solution in my opinion. The best approach might be an actual gun, but that whole discussion is leading astray from the point raised by "James Summers".

I'm incidentally rather for "big primitive rockets", but the theoretical merits of a railgun are manifest enough to have some people researching this with actual hardware. So if you have a valid contribution to make to this topic, why not provide some figures backed with solid research?

-- Nobody's putting me on a leash --

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Post    Posted on: Thu Jan 25, 2007 7:21 am
I'm more in favour of 'big, simple rockets' myself.


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Post    Posted on: Thu Jan 25, 2007 1:46 pm
I am in favor of small simple rockets. If there was an operational rocket that could launch 100 kg for one million to prove simple really is cheaper, and maybe an operational medium size simple rocket that could launch 500 kg for two million to prove the economy of scale part, then I would be all in favor of the big simple rocket. But I want the existence proof before I lobby for billions of dollars to make the big simple rocket. Nothing could be worse than wasting billions developing a big simple rocket only to find that all the paper predictions of low cost per kilogram to orbit were wrong! That is exactly what happened with the space shuttle. All the paper studies said that reusability would drop the cost dramatically. Now I am supposed to believe other paper studies that say a simple enough rocket can be made big enough and cheaply enough so that even though each one is only used once, it will dramatically drop the cost to orbit. I just don't buy it. Show me by building a small simple rocket that is cheap enough to launch small payloads at far lower cost than any other rocket of comparable throw weight before trying to convince me that giant and simple is the way to go. That is what SpaceX is doing. Falcon 1 may not be dirt simple, but at least it is iron simple instead of a golden rocket.


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Post    Posted on: Thu Jan 25, 2007 11:14 pm
Oh well, I never expected this to become a beauty contest :? about just what sort of rocket people like. I was just quoting.

Back to basics, anyone?

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Post    Posted on: Fri Jan 26, 2007 12:14 am
As I've posted elsewhere, I have no objection to starting small, it make sense to prove the concept that way. As long as the end goal of 'big' is kept firmly in mind. Not much point in hanging a small 3 stage under an airplane, for instance. No way to scale up much from that. :D

And my idea of big and simple doesn't preclude a reusable first stage. It just has to be a 'big and simple', reusable first stage. Which means no water landing and recovery, no wings, no fragile heat shield for high speed re-entry. So that pretty much leaves an almost straight up & down, VTVL launch assist platform type.


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Post    Posted on: Mon Jan 29, 2007 6:25 pm
publiusr wrote:
HYPACC just needs pressure.

Look--spaceflight has more to do with good plumbing and margin than it does with computing. More TVA than MSN--you know that.

Keep computer/electronics people on the short leash.


HYPACC?
TVA?
MSN?

(amused)
Forums like this should come with glossaries for acronyms...
I'm no dummy, but my expertise is more in accounting and finance than engineering.

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Post    Posted on: Mon Jan 29, 2007 6:42 pm
Yeah, those TLAs (Three Letter Acronyms) can get confusing. Same with the FLAs and SLAs and who knows what length As.


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Post    Posted on: Fri Feb 02, 2007 6:47 pm
Hypacc is just a big, simple stomp water rocket--very like a gun but not as violent. It can allow smaller rockets to carry a heavier payload (thought not a bigger one--HLLVs can't be beat for big payloads).

Railguns are going to use a lot more power than what is needed to evacuate Hypacc. Electricians might be kept in business for life with that--but simple water pressure is about foolproof.

http://www.hypacc.com/

This just seems to make much more sense than building Railgun sections what with very expensive components.

Hypacc just needs a big hole in the ground.


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Post    Posted on: Fri Feb 09, 2007 6:22 pm
publiusr wrote:
Hypacc is just a big, simple stomp water rocket--very like a gun but not as violent. It can allow smaller rockets to carry a heavier payload (thought not a bigger one--HLLVs can't be beat for big payloads).

Railguns are going to use a lot more power than what is needed to evacuate Hypacc. Electricians might be kept in business for life with that--but simple water pressure is about foolproof.

http://www.hypacc.com/

This just seems to make much more sense than building Railgun sections what with very expensive components.

Hypacc just needs a big hole in the ground.


Fascinating and simple.

All of these ideas really make me wish that I had about $100Bn US to sink into feasibility studies and test programs.

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