Magrail launcher cost and completion estimates?

[braemarbat]

Hi all. Tried to post this last time I was here but had some trouble.

I'm trying to figure out an approximate costing estimate for a magrail. Including roughly how long it will take to build. Any additional info such as frequency of launches etc would be helpful. It's for a project I'm working on.

[man on the moon]

I take it you are wanting to launch into some sort of orbit, correct?

I would first look into whether a mag-lev train could even reach the speed necessary to launch something into an orbit before I went to the trouble of building one. Google is your friend!

Curious idea though. I think it was used in Star Trek: Enterprise in one of the early episodes. (Not that there were any particularly later ones). It will be interesting to see what people think if a discussion arises!

[OldGuySythe]

Possibly you are referring to a "Magnetic Linear Accelerator" (Gauss Gun) or even a "Rail Gun" type of launching device. Maglev will only remove friction as a factor and doesn't provide any propulsive force.

I am not aware of any attempt do create this type of launch device and it would have the serious limitation of G-force. Certainly no living thing could survive this kind of launch and few components could withstand the G-forces necessary in this kind of launch. Unless you used Magnetic Linear Accelerator over a really long distance and as a launch assist mechanism to reduce the work the rocket propulsion had to do to reach orbit. Think 6 G for 30 seconds...how long would that launch ramp need to be???

[alainprice]

Propulsion can be provided through the track.

Taken from wiki:
"An EMS system can provide both levitation and propulsion using an onboard linear motor. EDS systems can only levitate the train using the magnets onboard, not propel it forward. As such, vehicles need some other technology for propulsion. A linear motor (propulsion coils) mounted in the track is one solution. Over long distances where the cost of propulsion coils could be prohibitive, a propeller or jet engine could be used."

[antoniseb]

There are some threads about this on this forum from years ago.
The issue about the acceleration crushing human occupants can be overcome by having a long enough track. One of the biggest issues is making the track long enough that the vehicle is above enough atmosphere that it doesn't lose most of its energy before escaping. Building a structurally stable roller coaster ramp that is 100 km long and 30 km tall would be pretty pricey.

Building such a track to escape from the Moon is another matter.

[Van Rijn]

Hi all. Tried to post this last time I was here but had some trouble.

I'm trying to figure out an approximate costing estimate for a magrail. Including roughly how long it will take to build. Any additional info such as frequency of launches etc would be helpful. It's for a project I'm working on.

Is this a school project? Any estimates here would be guesses, but it would help if you gave a little more information: Is this an O'Neill style lunar mass driver? Is it a mass driver for Earth? Is it supposed to be able to carry people to Earth orbit without turning them into mush (relatively low acceleration/long)? And so on.

[Hornblower]

Arthur C. Clarke, in his novel Islands In the Sky of the late '40s, envisioned a magnetic launcher on the Moon. It was a track about 8km long, powered by a solar electric power plant and capable of accelerating heavy loads to lunar escape velocity. It was nearly horizontal and low to the ground, which was no problem in a vacuum. All the payload had to do after leaving the track was to clear any local high spot in the immediate area.

This launcher was used to launch fuel tanks for refueling passing spacecraft without having to burn most of the fuel to get the rest into orbit. The fuel was manufactured from raw materials on the Moon, in a refinery powered by the same solar power plant.

Mr. Clarke was taking some liberties with technical details, in my opinion not at all outrageously for the purpose of science fiction.

My calculations indicate about 36g of acceleration to reach escape velocity, which would be unsatisfactory for a manned spacecraft. To reduce the g forces by a desired factor, the track would have to be lengthened by the same factor.

For launching from Earth, such a launcher would need to be about 22 times as long for the same acceleration, and most of it would have to be well above the lower atmosphere, requiring a steep initial ascent similar to the trajectory used by rockets. The structural engineering of such a track, which would be virtually trivial on the Moon, would be formidable on Earth.

[neilzero]

As the others suggested, most varriations of a linear motor to get from Earth's surface to orbit are awaiting stronger materials and/or room temperature super conductors. If we throw a few billion dollars at the various engineering problems, we might get useful results. Depending on the approach there are hundreds of other problems that make the total cost extreemly high. A possible approach would be a track up the side of a steep mountain in Equador, South America. The track would need to extend perhaps 50 kilometers above the top of the mountain, then curve gently to almost horizontal. With present building materials, a million times a million dollars is a reasonable guess. We would need megawatts of PV = photovoltaic panels to energize the track as the track is much too long to energize from the mountain top. There are other variations such as The launch loop which are sort of like a linear motor and does use magnetic levetation. Neil

[antoniseb]

... a million times a million dollars is a reasonable guess ...

I would say it is a very low guess. To build a ramp 50km above sea level, and make it stable in the face of supporting a fast moving many-ton space craft would require hundreds of times as much steel as gets created world-wide in a year. I think we're talking about somewhere between 1014 and 1015 dollars.

A world-wide dedicated effort would take centuries to build it.

[Kaptain K]

A single-stage-to-orbit rail launch is ridiculous on the face of it, if for no other reason that it is hard enough to protect the shuttle from re-entry into the almost vacuum of the top of the atmosphere. Now, imagine starting from the bottom and blasting through the whole atmosphere! One would have to leave the launcher at several times escape velocity just to make up for frictional losses.

The big advantage of rail launch is that you can leave most (not all) of your fuel on the ground instead of dragging it along against a one gee field. The shuttle has a lift-off weight of 3 million Kg, most of which is fuel to get it started.
First stage - use a rail launcher to get to a couple of thousand Kph and a few thousand meters altitude (a mountain in the Andes would do nicely).
Second stage - winged scramjet (supersonic combustion ramjet). OK, we're not quite there yet, but we're close and several groups are working on it.
Third stage - rocket motor, either built into the second stage or a separate high-altitude-to-orbit vehicle.

[JustAFriend]

Maglev trains run about $50million per MILE (http://faculty.washington.edu/jbs/itrans/amtteam.htm)

So if you need a 20-mile long launcher you can pretty much double that and figure around $2Billion MINIMUM.... probably much more.

PLUS, I don't think anyone's EVER gotten any maglev to work at more than about 350mph, so spiral up the costs for research on how to make one ramp up to orbital-launch speeds. Throw on another $10-20Billion.... (hey, it's only government money...)

They wanted to put a maglev train from FortLauderdale airport to the Port Everglades cruiseship port (1mile distance) down here a few years ago and were talking $500Million, so you might have to REALLLY increase those budgets!!!!!!!

[Kaptain K]

Please note that I never mentioned mag-lev in my post. It isn't necessary for rail launch. Just a long (10-20 Km) track and either a linear induction motor or capacitive discharge "rail gun".

[NEOWatcher]

Please note that I never mentioned mag-lev in my post. It isn't necessary for rail launch. Just a long (10-20 Km) track and either a linear induction motor or capacitive discharge "rail gun".
I doubt there would be much difference. The technology is fairly identical.

[neilzero]

We can perhaps do as Captain K suggests in a decade or two, but the development costs are high and it likely will not halve the cost of putting a ton in orbit compared to present methods.
We like maglev instead of wheels as it reduces friction losses, vibration, and possibly improves safety and reliability. If the first stage wheels are 10 meters in circumfrence and turn 60 revolutions per sec = 3600 RPM, the centifugal force is likely to tear a wheel apart. Linear speed is 600 meters per second = 0.6 kilometers per second, which is fast enough for a few kilometers of rail at a human tolarant accelleration. We still need a second stage, and possibly a third stage rocket to get to orbit, so not much savings. Neil

[OldGuySythe]

There is a huge difference in the technology between magnetic linear induction and a "rail gun" type of accelerator.

[NEOWatcher]

There is a huge difference in the technology between magnetic linear induction and a "rail gun" type of accelerator.
Enlighten me. My expertise is limited to Wiki lookups, and I see them discussed on the same page (http://en.wikipedia.org/wiki/Linear_motor).


Two different basic designs have been invented for high-acceleration linear motors: railguns (http://en.wikipedia.org/wiki/Railgun) and coilguns (http://en.wikipedia.org/wiki/Coilgun).

[Jetlack]

I've been testing it our with my Scalectrix - wont work I'm afraid. I was only able to ramp launch the porsche through my Mums front window. She was not pleased.

[Noclevername]

I'm trying to figure out an approximate costing estimate for a magrail. Including roughly how long it will take to build.

Depends on who's building it. And on what scale it's meant to be used.

(Not to mention whether they're getting paid by the hour, or have a bonus for early completion, etc. And if the materials are being provided by the lowest bidder.)

[Larry Jacks]

A single-stage-to-orbit rail launch is ridiculous on the face of it, if for no other reason that it is hard enough to protect the shuttle from re-entry into the almost vacuum of the top of the atmosphere. Now, imagine starting from the bottom and blasting through the whole atmosphere! One would have to leave the launcher at several times escape velocity just to make up for frictional losses.

Exactly right.

The big advantage of rail launch is that you can leave most (not all) of your fuel on the ground instead of dragging it along against a one gee field. The shuttle has a lift-off weight of 3 million Kg, most of which is fuel to get it started.
First stage - use a rail launcher to get to a couple of thousand Kph and a few thousand meters altitude (a mountain in the Andes would do nicely).
Second stage - winged scramjet (supersonic combustion ramjet). OK, we're not quite there yet, but we're close and several groups are working on it.
Third stage - rocket motor, either built into the second stage or a separate high-altitude-to-orbit vehicle.

I'd suggest that the advantages of the scramjet are outweighted by the extra complexity and need to handle staying in a high temperature region for an extended time. If you can get the vehicle going a few thousand kph at an altitude of several thousand meters, it would be possible to go straight to a rocket for the rest of the trip. It wouldn't be a real single stage to orbit design because the first stage is the magnetic launcher. The sole rocket stage would have enough of a running start that it wouldn't need nearly so much propellant to make it the rest of the way to orbit. If you could make the stage recoverable and reusable, so much the better. You might want the final injection to orbit to be a throw-away stage (solid fueled, perhaps) to make it easier to recover the main rocket stage.

[neilzero]

There is a related discusion named 600 kilometer lunar space runway at www.liftport.com under the heading of Alternate SE systems. The two principle posters are both engineers, I think. There are more posts about the sling somewhere in the Liftport forums. Neil

[a1call]

For the record there is also a long thread on the Mars Forum:
http://www.marsroverblog.com/discuss-1000-milelong-maglev-track-where-on-earth.html

[MentalAvenger]

Possibly you are referring to a "Magnetic Linear Accelerator" (Gauss Gun) or even a "Rail Gun" type of launching device. Maglev will only remove friction as a factor and doesn't provide any propulsive force.However, as noted, the MagLev would reduce friction, reduce vibration, and probably be safer.


Certainly no living thing could survive this kind of launch and few components could withstand the G-forces necessary in this kind of launch. Unless you used Magnetic Linear Accelerator over a really long distance and as a launch assist mechanism to reduce the work the rocket propulsion had to do to reach orbit. That is the most reasonable use for a MagLev Rail, launch assist.

[MentalAvenger]

I would say it is a very low guess. To build a ramp 50km above sea level, and make it stable in the face of supporting a fast moving many-ton space craft would require hundreds of times as much steel as gets created world-wide in a year. I think we're talking about somewhere between 1014 and 1015 dollars. It is unlikely that any attempt would ever be made to create such a single-stage to orbit rail launch. It isn’t just the length of the track, but the fact that MaxQ for most vehicles would occur at too high an altitude. Acceleration would have to remain low at first, defeating the purpose. Else, the launch could actually begin in a deep tunnel.

[Kaptain K]

For bulk cargo launches, you could skip the scramjet and just use a box (with a nosecone and strap-on SRBs (ala the shuttle).

[braemarbat]

For launching from Earth, such a launcher would need to be about 22 times as long for the same acceleration - Hornblower

196km? That's pretty long.


Maglev trains run about $50million per MILE

If 350km per hour is the record then a wider track would probably be necessary as well as an aerodynamic vehicle to ride it.

If construction was completed then how expensive would launches be? Any idea. I was thinking of Indonesia or New Guinea. Close to the equator with many high mountains to choose from. I thought maybe wave power could be an option. When not in use the electricity could be fed into the grid.

[Hornblower]

Once we conquer the challenge of financing and building the launcher, estimating the electric bill for a launch is relatively easy.

Low earth orbit velocity is about 8,000m/sec.

That comes to about 32 million joules/kg.

Suppose we succeed in making the launcher about 55% efficient, which is comparable to the efficiency of the induction motor on my table saw. We would need about 60 million joules of juice from the power plant per kg of vehicle mass. That is about 17kwh. My residential rate is about 10 cents per kwh. Thus, $1.70/kg, or $1,700/metric ton.

On my 200km track at 36g, that would be an enormous amount of current for about 25 seconds. In our thought experiment I would use the juice from the generating plant to charge up an enormous bank of capacitors to provide the launching burst.

In Clarke's story, the Earth spaceport was in New Guinea, at an altitude of about 13,000 feet, and all of the launches were with rockets. He took some technical liberties, but I think he recognized that his lunar magrail launcher would have been impractical in Earth's atmosphere, even on mountaintops.