Magnetic Launching Points

Dragoneye · 2005-08-18 08:50:34

What about a type of Rail gun system to launch the shuttle in the general direction and have it be under almost constant deceleration on the way there...

you can have it so its a controlled launch, like pick up speed and just gain acceleration as it goes down the track, and then in the second half, it kicks it into high gear....

roller coasters can get things moving from 0-100 in like 1-2 seconds... so it could be a feasable way to do it with this.. heck you could send with a whole train like system with the shuttle so that you can build one for the trip back home too...

it also doesn't mean you cant do it land based too (such as the moon or something to that effect... in reality that would be the most logical)

I know they were thinking of doing something like this for one of the concepts for a land based clean launch but they scrapped the idea unfortinately.

GCNRevenger · 2005-08-18 09:30:51

Yes I have seen this concept tossed around a bit... there are a few problems however:

-The contraption will be huge, and preferably close to the equator. Building such a site will cost a tremendous amount of money, and so you can't afford to build many of them. This isn't a short-term problem, but in the long run medium-lift spaceplanes will need to be operated much like an airline today, with many regular flights. If the rail can support a launch every two hours or so (time to mate, load, and prepare the vehicle), thats only a dozen flights a day non-stop.

Plus, all traffic would have to come to your launch site, which especially if it is near the equator will be a signifigant impediment, with all payloads and passengers having to fly a quarter or half way around the world to get to the rail, and things like rocket fuel or sensitive payloads would have to be carefully handled on-site with appropriatly equipped and staffed facilities, which would not come cheap.

There is also a technical drawback with the rail launch, that it can only reach speeds somewhere below Mach-1 with a practical arrangement. The biggest bennefit of rail launch is supposed to be making the spaceplane lighter and simpler, but unless it can push the vehicle considerably faster (say, Mach 3-4) then it will still have to carry jet engines or burn heavy rocket fuel to reach a high enough speed to ignite a special hypersonic jet engine. You really need the hypersonic jet engine to keep the vehicle from getting too big & heavy for the rail to effectively pull too. You can't reach a very high altitude with the rail launch either.

What should be done instead is one of two things:

-Build a large carrier plane with the money you would spend on the rail instead, with engines much like those on the SR-71 Blackbird, except bigger and boosted with LOX/water mixture. Such a vehicle could probobly reach Mach 5-6 and altitudes in excess of 100,000ft, and could perhaps even carry its own LOX/water generator to minimize takoff weight.

-Build a larger carrier plane likewise, except equip it with conventional subsonic jet engines modified for extra-high altitude operation (say, 60,000ft?) and carry a set of large reuseable kerosene rocket engines. This would not be as efficent, but it would be easier then building the purely jet-powerd one.

Either model would carry a smaller spaceplane on its back or underside that would be fueled by semi-solid slushed liquid hydrogen and LOX, fed to a next-generation reuseable rocket engine like the COBRA. It would seperate at high altitude and airspeed, nose up, and boost the rest of the way into orbit. It would probobly be a lifting body shape with stubby winglets, since this shape would have good internal volume as well as not need silica tiles for the heat shield. Build two or three versions of it, one it to carry a payload the same mass and maybe a bit smaller then a Proton or Atlas-V 551 unmanned, one to carry just rocket fuel unmanned, and one for 12-14 passengers with an airlock.

It could take off from anywhere with a runway and a supply of liquid hydrogen, you could build copies so you can fly as often as you want, and the big carrier plane could become a high-speed airliner for Earth-only travel.

The more exotic option, which I reguard as a third-generation (the next thing after the two-stage concept) spaceplane, would be a single piece vehicle with SR-71 style jet engines, the special hypersonic jet engine, and perhaps a rocket engine or two for the final push to orbit. It would be very hard and extremely expensive to build, but it would be much cheaper to fly since it would be only one piece.

Dragoneye · 2005-08-18 09:51:20

actually i was thinking about having it as an orbital space launching system.... that way you dont have to worry about weight as much..

sure you would have to think about recoil, but that can be over come with standard propultion engines....

in space since there isn't really any resistance, you can easily reach over those speeds of mach 5-6

just drop off the peices needed in space with a few shuttle launches, and then bring up the ship in peices and there you go.

GCNRevenger · 2005-08-18 10:22:38

Ohhh you mean like put a ship in orbit with rockets or something, and then using an orbital rail to push them to the Moon/Mars/etc?

Four problems:

-It will weigh alot, tens of thousands of tonnes easily, which will make launching and assembling all the pieces very difficult. A few Shuttle launches wouldn't even total 100 tonnes.

-It will be very large, which makes construction challenging, but also makes accurate pointing more difficult, perhaps kilometers long

-High power demands, which will be difficult to meet with available storage technology without becomming very heavy too

-High payload accelerations required to avoid the rail from becomming too large, and this will be a difficult issue since you can't use rocket engines to minimize the G-forces. If you did that, then you would slow down your rocket, and never get out of Earth orbit.

Dragoneye · 2005-08-18 10:40:03

yup basicly, and i was thinking some of the main problems would be aiming it... it wouldn't be able to get an EXACT shot, but pretty damn close with such a long range... (the way they use Hubble to aim)

the weight wouldn't be too bad seeing as you would only need magnets and a truss system.

as far as power is concerned it isn't like your going to be launching it every day or something.. so even for a monthly launch the batteries could refill via solar power, or even use a power plant thats on the ship (like a reactor or something) and have it hooked up via teather till its launched and then at that point contact is lost with the launching strip so you keep the power to the ship after that...

it wouldn't have to be THAT long... im thinking maybe.... 4 football fields long..

and even if it is decently pricey, it can be reused LOTS of times....

it doesn't have to toss you at near light speeds or anything, heck even if it eliminates the need to slingshot the planet for saving fuel, it would be worth it, like a launch on demand setup...

GCNRevenger · 2005-08-18 10:57:02

There is also one big problem that wasn't immediatly obvious to me: recoil

That if you were to fire the railgun in space, you would push the payload sure enough, but the rail would be pushed the opposit direction with equal force.

So, if the rail were to push things in the same direction as its orbit, the rail itself would be pushed in the oppsite direction just as much, and after a few firings would literally fall out of the sky.

"the weight wouldn't be too bad seeing as you would only need magnets and a truss system."

Yes it would, because magnets and trusses strong enough to resist the forces involved without bending are heavy.

"so even for a monthly launch the batteries could refill via solar power"

Batteries are too heavy, and so are all the other available power storage methods. A reactor or other source of power isn't going to have a high enough output either, you are looking at needing billions of watts of power during firing, so the only option is to store up this energy somehow.

Four football fields is nowhere near long enough either to accelerate several kilometers per second

"and even if it is decently pricey, it can be reused LOTS of times"

Are you sure? With the kind of stresses involved, the structure might warp and not be easy to maintain.

Dragoneye · 2005-08-18 12:42:52

im open to suggestions instead of shoot downs lol im just simply throwing out ideas to see if people can feed off of them... please if you have any ideas let me know i would be glad to try and work off of them.

but as for the design.... it looks like it will have to be some where stationary, so the moon with weak pull should do the trick....

Grypd · 2005-08-18 16:01:27

A lunar mass driver has been envisaged for a long time and there are quite a few plans for its use. There are benefits to a lunar mass driver as it can use the abundant power from the sun to power the driver. Still there are problems.

1) A lunar mass driver will need materials that only high technology ie Earth can make so these materials must be delivered from the Earth. But a lot of the structure can be made from the indigenous Lunar materials.

2) Aiming will rely on when the Moon is in the right position

3) Mass Driving materials is a very high acceleration mission if we need to send people we will need a long track. Probabily the better method is to use indigenous aluminium prepared with Oxygen to make rocket fuel to get people off the Moon with materials and exports sent by the driver.

4) And finally most of the materials are high tech and will have to come from the Earth anyway so you save very little in the way of delta V. But if there was a larger size industrial capacity that a big prescence on the Moon this would be less of a problem so for intial Mars plans it is impractical.

Though if you want a bit way out option for a Mass driver capture an asteroid fire of parts of it from the mass driver you set up and travel using that. A long trip but it would work.

reddragon · 2005-08-20 10:25:33

I once suggested that since a space elevator would require cables going in the opposite direction from Earth to keep it in the correct orbit, these could be used for a rail gun launcher like what Dragoneye describes. However, I forget about the problem of recoil, and when I was reminded of that it essentially killed the idea. I do wonder, however, if recoil could be dealt with somehow, that is by using something to push stuff back in the other direction. Shooting something back at Earth seems like a simple solution, but it might annoy the guys down there. Rockets could be used for repositioning, but would require a lot of fuel. Perhaps some system where you could send payloads both directions without having any of them aimed at Earth would work. I'm not really sure what, if anything, would be a viable solution to this.

For some of the other problems:
Construction: If this is part of a space elevator you will need the basic cables anyway so the extra work will be mostly adding the magnets (still, admittedly, quite a bit of work). If this is not part of a space elevator, then having a space elevator will still be crucial for bringing up the parts. Rockets would be unable to bring up all the material in a decent number of launches. The good new is that the chances for carbon nanotube space elevators are looking better as discussed in Space Elevator, Ho! http://www.newmars.com/forums/viewtopic.php?t=3801

Aiming: It might be possible to make the last few kilometers of the track adjustable to allow aiming without moving the whole length of the thing.

Power: Since you will need a long track anyway, you could attach solar panels along the length of it to make a very large solar array. Each electromagnet could perhaps have its own solar panel and relatively small battery. The downside is that this would cost a lot and be a lot of work to put together and more weight to bring up. Using a reactor and a solar array together and having all launches at times of maximum sunlight would minimize the need for power storage.

For something like this, there are a lot of hurdles to overcome, but I am not giving up on it just yet.

Fledi · 2005-08-21 06:42:53

If you accelerate with the track at 7G you still need about 60 km of tracks to get to escape velocity. (edit: this is from LEO to escape velocity)
Such a long structure is very difficult to keep stable in orbit with all the gravitation gradient forces pushing it around.
The recoil is not so much of a problem if you use the rail as an assist for landing i. e. you launch payloads to Earth, which have previously docked at orbital speed, against the orbital path of your rail, so it slows down by 3km/sec and enters the atmosphere at suborbital velocity.

I prefer a rotating tether in orbit to this anyways because it would be way easier to build and maintain as such a long track of electromagnetic accelerators.

As for launching from the ground via magrail, those very high speeds (even way beyond Mach 4) are doable if you run the spaceship in a vacuum tube that ends at high altitude. The track would still have to be very long if you want to reach these speeds however.

The two stage vehicles have the same basic problem as normal rockets, they have to be some 90% fuel in mass (unless you have some advanced scramjet of what I really would like to see some performance data), which limits your structural options.

chat · 2005-08-23 15:36:22

The problem seems to be launching from earth, not the magnetic rail system.

On the moon such a system will achieve escape velocity easily in a km or 2km track with only electrical power.
Maybe the solution is to launch and build everything for space on the moon, even the track and launch vehicle.

Just my thought though
Earth is just to fat.

Dragoneye · 2005-08-24 08:16:40

The problem seems to be launching from earth, not the magnetic rail system.
On the moon such a system will achieve escape velocity easily in a km or 2km track with only electrical power.
Maybe the solution is to launch and build everything for space on the moon, even the track and launch vehicle.
Just my thought though
Earth is just to fat.

I agree for things in space, but we really need something that can easily bring stuff into and out of space with no problems. even if it means distorting gravitational fields...

reddragon · 2005-08-24 10:04:15

we really need something that can easily bring stuff into and out of space with no problems.

Scramjet and space elevator seem like our two best bets to me.

Dragoneye · 2005-08-24 10:39:25

what do you mean by space elevator though? just a huge satelite in space with long cables reaching down to haul something up into space? I was thinking something more along the lines of just making new technology so that we can bypass the bypassing ways of it all....

Grypd · 2005-08-24 13:18:44

If we get a space elevator then there is nothing to stop it being combined with a magnetic launching system. Actually if we have a lift system they will likely be based on magnetic propulsion to move the various cars and if we design it that cars or pallets can be whipped into space then we have a magnetic propulsion system which is long enough and able to send craft to very far places as long as the Earth is in the right place.

John Creighton · 2005-08-24 16:06:20

If we get a space elevator then there is nothing to stop it being combined with a magnetic launching system. Actually if we have a lift system they will likely be based on magnetic propulsion to move the various cars and if we design it that cars or pallets can be whipped into space then we have a magnetic propulsion system which is long enough and able to send craft to very far places as long as the Earth is in the right place.

Looking at this material again, does it have a better electrical conductivity then copper? I know it is stronger. Stronger power lines will have the advantage of surviving better in hurricanes and ice storms. Or even better would be if we could make an RF wave guide out of this material. An RF waveguide would reduce transmission loses significantly allowing better utilization of intermittent sources of power like wind and solar. The stuff is already in a ribbon so if we glue four of them to, wood, plastic or glass and connect them in a square tube

Fledi · 2005-08-24 19:25:46

I wonder how an electrical cable would interact with van Allen Belt radiation and what effect it has to the molecular structure of CNT. Taking a few grams of the material and exposing it to radiation here on Earth would be an interesting project.

chat · 2005-08-25 05:30:50

A space elevator would be the way to go if we are moving mega tons of material into space, but if we are just moving people into space its probably not needed.

With the inner solar system asteroids and comets we should be able to harvest all the fuel and gas we need for more distant ventures, so no need for gigantic fuel transports from earth exist either.
The moon itself might also have all the elements we need to produce fuel.

Right now we are entering an area of nuclear powered ion engines so the fuel and gas requirements in space will be small, mostly needed for manned flight and colonies such as the moon.

I think for the near future we are stuck with chemical launches from earth.

Fledi · 2005-08-25 08:34:46

A space elevator is one of the few options to reduce cost to orbit enough to make it affordable for middle class people to go into space. Only then can a real colonization effort happen on a big scale.

As for how long it will take to improve space transportation enough for this to happen, who knows that? Certainly not within the next 10 years, but even in just 20 years it is not entirely impossible if you are very optimistic.

publiusr · 2005-08-25 12:14:01

Some advancements--but they will still need big rockets to put up the material

http://www.worldchanging.com/archives/003330.html LOOK!
http://physicsweb.org/articles/news/6/4/20
http://www.spacedaily.com/news/nanotech-05zzzg.html
http://www.spectrum.ieee.org/WEBONLY/pu … 5spac.html
www.elevator2010.org/site/index.html
www.liftport.com
http://www.technologyreview.com/read_ar … h=nanotech
http://researchnews.osu.edu/archive/erthboom.htm
http://www.unmannedspaceflight.com/inde … topic=2763

Now--I still think we are a long way from SE--but this will certainly be a useful product.

Very cheap Solar Cells--Graetzel Cells could be a possibility.

redhorizons · 2005-09-30 15:46:40

The LiftPort Group, as sited above, is doing a lot to bring the Space Elevator to reality.
If you combine the lifting potential and effeciency of the SE with system like a rail gun or a tether you could potentially launch 100s of tons of cargo to Luna or Mars for a fraction of the cost of rocket propulsion.
Just fling your cargo containers in the direction you want them to go, add some small rockets for directional control and orbital insertion (Mars missions) and wa la all the stuff you need is ready and waiting when you get there.

publiusr · 2005-10-07 09:30:35

I also like www.launchloop.com

Grypd · 2006-05-22 06:26:56

Launchpoint technologies of California have developed a novel form of rail gun launcher this being in a loop and accelerated by magnetism till up to speed and then fired.

Newscientist Magnetic Sled Could Launch Objects Into Orbit

Jack Chandley · 2006-05-24 09:26:35

Launchpoint technologies of California have developed a novel form of rail gun launcher this being in a loop and accelerated by magnetism till up to speed and then fired.
Newscientist Magnetic Sled Could Launch Objects Into Orbit

Ok, but what about frictional losses due to atmosphere?

Would a release velocity of 10 KPS from an equatorial positioned launch/release facility be sufficient to lob something up to LEO, when accounting the the losses incurred from friction? Also, it not only has to get it to @ 200 mile altitude, but also send it into and orbital inclination, which requires a trajectory taking through yet even more atmosphere. ??

cIclops · 2006-05-24 11:20:10

Launchpoint technologies of California have developed a novel form of rail gun launcher this being in a loop and accelerated by magnetism till up to speed and then fired.

There's no mention of anything having been developed according to their site (last updated July 2005) - only work on "the necessary concepts and technologies" - probably another pure ppt study.

With a recent $100,000 grant awarded from the US Department of Defense Small Business Technology Transfer Program, LaunchPoint engineers are now hard at work on an innovative magnetic space launch system.

New Mars Forums

Announcement

#1 2005-08-18 08:50:34

Re: Magnetic Launching Points

#2 2005-08-18 09:30:51

Re: Magnetic Launching Points

#3 2005-08-18 09:51:20

Re: Magnetic Launching Points

#4 2005-08-18 10:22:38

Re: Magnetic Launching Points

#5 2005-08-18 10:40:03

Re: Magnetic Launching Points

#6 2005-08-18 10:57:02

Re: Magnetic Launching Points

#7 2005-08-18 12:42:52

Re: Magnetic Launching Points

#8 2005-08-18 16:01:27

Re: Magnetic Launching Points

#9 2005-08-20 10:25:33

Re: Magnetic Launching Points

#10 2005-08-21 06:42:53

Re: Magnetic Launching Points

#11 2005-08-23 15:36:22

Re: Magnetic Launching Points

#12 2005-08-24 08:16:40

Re: Magnetic Launching Points

#13 2005-08-24 10:04:15

Re: Magnetic Launching Points

#14 2005-08-24 10:39:25

Re: Magnetic Launching Points

#15 2005-08-24 13:18:44

Re: Magnetic Launching Points

#16 2005-08-24 16:06:20

Re: Magnetic Launching Points

#17 2005-08-24 19:25:46

Re: Magnetic Launching Points

#18 2005-08-25 05:30:50

Re: Magnetic Launching Points

#19 2005-08-25 08:34:46

Re: Magnetic Launching Points

#20 2005-08-25 12:14:01

Re: Magnetic Launching Points

#21 2005-09-30 15:46:40

Re: Magnetic Launching Points

#22 2005-10-07 09:30:35

Re: Magnetic Launching Points

#23 2006-05-22 06:26:56

Re: Magnetic Launching Points

#24 2006-05-24 09:26:35

Re: Magnetic Launching Points

#25 2006-05-24 11:20:10

Re: Magnetic Launching Points

Board footer