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Maglev launch

Posted by: Garnetstar - Thu Sep 11, 2003 1:24 am
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Maglev launch 
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Post    Posted on: Sun Dec 24, 2006 10:32 am
Ekkehard Augustin wrote:
Hello, Stefan,

I don't know the kwh etc. required yet and would be interested in them and in the other data you are mentioning also.

But the article says that they calculated costs of $ 50,000 for the launch. So the electricity etc. required can't be too much - might that have to do with the superconductivity of the magnets?



Dipl.-Volkswirt (bdvb) Augustin (Political Economist)


Hi Ekkehard. I don't have any data, but my common sense tells me that it should consume a lot of energy. But that's just me. Can you give a link to that article?

If the costs are just 50k, then i think they 'fire up' those magnets for a very brief moment and if the object has passed it, they fire the next and so on. I think it would be interesting to check what those Maglev trains in Germany consume to make some sort of an comparison.

/edit/

Check this:
http://www.21stcenturysciencetech.com/a ... glev2.html

Somewhere in the middle i found this quote:

Quote:
Our 1966 paper sparked intense interest in Maglev in many countries. It was quickly realized that superconducting magnets made Maglev practical. Basically, superconducting magnets are extremely powerful and lightweight permanent magnets. Because they have zero electrical resistance, even when they carry currents of hundreds of thousands of amps, their power consumption is zero, except for a very small amount of electric power for the refrigerators which keep the superconductor at cryogenic temperature.


Interesting. Didn't know that.


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Post    Posted on: Sun Dec 24, 2006 10:53 am
Hello, Stefan,

up to I have the printed version only. The website of Wirtschaftswoche is www.wiwo.de and I wanted to search there for the article but didn't get the displayed the website up to now.

Next I searched for Launchpoint Technologies' website and randomly came across thisgerman article of the german version od Scientific American. The data are slightly different but similar. The article mentions that a small rocket might be added to incree the altitude achievable.

That article links to the company where an article "Huge 'launch ring' to fling satellites into orbit" ( www.launchpnt.com/Detail_View.43+M541a60ccc30.0.html ) is available. That article is speaking about 2 kilometers and test ring of 20 m to 50 m diameter.

It also mentions that the launch costs per kg depend on launch rate - at 3,000 launches per year the costs per kg were $ 189. But this is off-topic here - I should apply it in the Financial Barriers section.



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Post    Posted on: Wed Dec 27, 2006 7:31 pm
Hi Ekkehard,
Hi Stefan,
Popular Science also ran an article on Launchpoint Technologies: www.popsci.com/popsci/aviationspace/1bd ... drcrd.html

/s/ Willy


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Post    Posted on: Thu Dec 28, 2006 3:23 pm
Good link.

It doesn't say how a projectile would get through the lower atmosphere at mach 25 though though. Even if it had good thermal protection, rapid deceleration would start as soon as it encountered the air. How would it maintain speed until it got above the atmosphere?


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Post    Posted on: Thu Dec 28, 2006 3:31 pm
And beside, 220 pounds, just 100kg or so?, is not really worth the effort. I'm curious about the turn around time of this contramption. Will the sled simply stop when the cargo is exiting the ramp or will it plunch itself into a nearby cactusdesert?


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Post    Posted on: Thu Dec 28, 2006 6:32 pm
Although details do not appear in the article, it seems the launcher is a closed ring with a straight exit tunnel off one side. The sabot would be cut loose from the sled at just the right microsecond to enter the tunnel leading out of the ring while the sled itself would continue to circle within the ring.

My guess is that 99%+ of the $50,000 cost per launch is labor, replacement parts, administrative overhead, and other costs. The actual power requirements are probably negligibly small.

(EDIT) OK, I found the true source; the LaunchPoint Technologies company web site. Here is the story in their own words. Note that the focus is on magnetic levitation rather than hypersonic aerodynamics, which is not an area in which this company claims to be an expert.

http://www.launchpnt.com/Space_Launch.32.0.html


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Post    Posted on: Fri Dec 29, 2006 9:42 am
Hello, Stefan,

I in between think that the numbers available allow to find out how much power the system will consume.

The article at Launchpoint Technologies' website I linked to in my previous post tells several costs per kg at several different launch rates.

It seems that the numbers are approaching a particular number of $ costs. These are the total variable costs per kg - and thus a maximum for the costs of power. Since there are more variable costs than those of power only the actual power costs will be below that maximum.

If the californian system of power tarifs is applied to that maximum the maximum power in kwh is got. From there engineering and physical conclusions to the superconductive electromagnets should be possible - and so on.

I don't want to do Economics etc. here but the data seem to fit into a fraction-rational function the simplest form of is Y = b + m/X with X being the number of launches per year and Y the total costs per kg. Several pairs (X;Y) are konwn - so it might be that no regressional analysis is required.

...



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Post    Posted on: Fri Dec 29, 2006 9:26 pm
Its featured inside the new Popular Science magazine--with the SUSTAIN craft on the cover. (The project I told you about involving Franz Gayl--the GS-13)


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Post    Posted on: Sun Dec 31, 2006 4:28 pm
Hello, Stefan,

I in between thought about it a bit more.

Obviuosly the velocity of 27,500 km/h is achieved in the ring already which contains a vacuum. This menas that the payload would reach 100 km altitude in 3600 seconds/275 = 13.09... seconds if it would leave the ramp vertically. The maximum time would be neede if the payload would leave tangentially to the location of the ramp. It then would have to 6,478 km to reach 100 km altitude 3600 seconds then would have to be divided by 27,500 km/6,470 km = around 4.26. This would mean 3600 seconds/4.26 = 845.07... which are 14 minutes 5.07... seconds.

This seems to be much less time than with rockets - nearly on notice or on demand like QuickReach.

Of course the atmosphere will increase the time - but to what number will depend on the aerodynamics.

The concept sound to me as if the sled will be left in the ring and slow(ed) down again. This will enable the 3,000 launches per year they are speaking about - 3000/365 = around 8.2 launches per day, a bit less than one launch every 3 hours.

That the payload will be disconnected from the sled by lasers seems to assit that thought.

What I am wondering about is if the vacuum inside the ring will be given up at launch and reestablished later or if there will be an airlock between the ring and the ramp. If so then the ramp could be filled with air once the payload entered the ramp and the aurlock is shut again. This could be done a way that additional thrust is caused.

On Moon and Mars the complete probelmes with the atmosphere are removed totally or to less than a hundredth.

On the Moon much more than 100 kg could be launched - this would mean a first component for Prof. Komerath's concept in principle which uses a maglev (or a railgun more precisely) to launch lunar metals into space to build something by them via tailored force field.

On Mars there would be the advanatge of the much thinner atmosphere - for this reason I will try to get the data required to calculate the maximum consumed electrical power and add it to the kwhs already used in the Electricity-for-Mars-thread. This will be a very small step further towards an idea about the financial and other economic requirements of enabling and establishing areal martian colony.



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Post    Posted on: Mon Jan 01, 2007 12:59 am
I can't imagine maglev launch ever being practical on earth. The atmosphere makes it a non-starter. Conventional launchers don't get to high mach numbers until they are very, very high up, where the air resistance is not so great as to destroy the vehicle.

Some day, when there is a robust economic infrastructure on the lunar surface, maglev could make a great deal of sense for propelling inert materials into lunar orbit. But not here on earth...Popular Science notwithstanding.

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Post    Posted on: Mon Jan 01, 2007 8:49 am
Hello, Enthusiast,

the essential point is that at least one of the articles explicitly says that inside the ring there will be a vacuum. And the sled will be accelerated up to 27,500 km/h inside that ring - it will be accelerated within a vacuum.

Because of this there will be no air resistance and no friction by air before the 27,500 km/h are achieved.

In so far the concept seems to be quite realistic. Air restistance and friction become a topic only after the 27,500 km/h are achieved. This might reduce the problem significantly because the initial velocity by which the atmosphere will be passed is muchhigher than in the case of conventional rockets launched from ground.

Also the payloads are much lighter than those rockets - and smaller it seems. This too reduces resistance and friction.

And then there is the possibility mentioned by the articles that a small booster can be added to the payload. This booster might compensate velocity reductions occuring by resistance and friction.

To install such a system on the Moon seems to be not such a large problem - neither technically nor financially - because it officially has been said that a system could be swimming on the ocean. This means that it can't be too heavy. May be that it requires tanks filled with air to get sufficient buoyancy. But the scale of such tanks is limited and perhaps they aren't larger than those of oil platforms.

In so far the investemnt will fit financially as well as technically into the requirments of the intended and planned permanent lunar station. Because of this this will be valid for Mars also.



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Post    Posted on: Mon Jan 01, 2007 12:48 pm
The kinetic energy required for 100kg at 27,500 km/h is about 820 kwh.
Which at domestic electricity prices is maybe $50 to $100. Of course the launcher won't be 100% efficient, so it might be up to 10 times that much in practice.

Current launch costs would be $500,000 to $1,000,000 for 100 kg, because rockets have to burn fuel to accelerate the fuel they will burn later to accelerate the fuel they will burn later... etc. A linear accelerator is only adding energy to the payload.

Almost all the atmosphere is below 30 km, so at a moderate angle, air drag is only a problem for a few second. There are suggestions to punch a hole through it with lasers, or a path maker projectile, to reduce that. There's a limit to how fast air can move to fill a vacuum, so a fast moving projectile can be through before the air rushes back in.


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Post    Posted on: Mon Jan 01, 2007 9:15 pm
Hello. I'm new here, and I really don't have an extensive knowledge of physics or engineering, but I was wondering about the possibility of a maglev assisted launch. I read somewhere that a very large portion of a rockets fuel was consumed to get it not very far off the ground. Would it be feasible to accelerate the launch somewhat with magnetic rails alongside a rocket as it launched, to give it a boost? Would the additional acceleration offset the weight of the extra systems necessary to take advantage of the rails, and still provide sufficient additional force to be worthwhile?

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Post    Posted on: Mon Jan 01, 2007 9:57 pm
Well if the fuel tanks were made of steel, which a lot of them are, you wouldn't really need any extra equipment on the rocket itself. Might play havoc with the avionics though.

But it would be difficult to gain much. A launch to LEO needs about 9500 m/s Delta V. Applying 5 G for 5 seconds would only supply 250 m/s of that, but require a tower 660 m high, and leave the rocket almost supersonic.

Easier to replace engine turbo pumps with electrical pumps, and trail a power cable for the first 20 or so km.


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Post    Posted on: Sun Jan 07, 2007 11:17 am
To mention it merely - Launchpoint Technologies' magelev would allow to launch a mass of 300 tons into LEO by 3,000 launches of 100 kg mass.

This would largely assit in-space construction - and the 100 kg could be delivered every three hours.

This compares to the rate of deliveries to locations where houses are built on Earth.

And the 300 tons into LEO over one year would be launched at costs of 56.9 mio only.

This obviousl is waaay cheaper than launching the 300 tons by heavy lifters.



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