Electromagnetic railgun as launcher

[Carreidas 160]

Not sure if I've seen this covered here before. The gun in the link can put 32MJ of kinetic energy into a bullet, giving a theoretical 2kg projectile a muzzle velocity of ~5.5km/s. That's more than halfway to orbit.

You're going to have a hard time getting it to 9km/s (needed to overcome delta v losses), deal with shockwave, friction, acceleration, thrusters etc. but I can see 1kg satellite "bullets" coming out of this.

Why not point it upward and shoot out a multitude of small deep space probes (provided you can get the 11.2+ km/s for escape velocity)?

To minimize air drag, why not put this thing high on a mountain near the equator (Atacama desert)?

Any thoughts on what it takes to make this gun an orbital launcher? I know about the Babylon Gun, HARP, QuickLaunch etc. but electric seems the way to go for now...

[kirghizstan]

awesome weapon, but 2 issues?

how would you power it in the locations you are proposing?

could a satellite take the g's this thing would impose on them?

[Carreidas 160]

awesome weapon, but 2 issues?

how would you power it in the locations you are proposing?

could a satellite take the g's this thing would impose on them?

Yes, I was wondering that myself. The issue is not power generation (32MJe = 8.9 kWh = peanuts for a diesel aggregator, could even be solar powered) but rapid discharge from capacitors into the gun.

As for g forces, http://www.gforces.net/a-discussion-on-typical-examples.html notes that "Rating of electronics built into military artillery shells, g forces equal to 15,500 g" so I'm not too worried about that. Biggest worry is having a propulsion system (for orbital manoevres) that can withstand 1000g.

Alternative is to stretch the barrel. The navy wants to put these things on ships, limiting their size, but for space launch a long barrel shouldn't be a problem.

[IRobot]

I remember a guy that had that idea some 30 years ago, a massive cannon that eventually would put small sats in orbit. Then he got involved with Saddam Hussein in a project of a very large cannon.

I think it was called Babylon...

[Carreidas 160]

I remember a guy that had that idea some 30 years ago, a massive cannon that eventually would put small sats in orbit. Then he got involved with Saddam Hussein in a project of a very large cannon.

I think it was called Babylon...

He eventually got killed, presumably by Mossad. Rule #1 in rocketry, don't get involved with shady regimes...

[Crispy]

Not sure if I've seen this covered here before.

Then you haven't been looking very hard!

http://forum.nasaspaceflight.com/index.php?topic=24115.0
http://forum.nasaspaceflight.com/index.php?topic=20383.0
http://forum.nasaspaceflight.com/index.php?topic=27421.0
http://forum.nasaspaceflight.com/index.php?topic=29458.0
http://forum.nasaspaceflight.com/index.php?topic=11909.0
http://forum.nasaspaceflight.com/index.php?topic=20098.0
http://forum.nasaspaceflight.com/index.php?topic=21730.0

I'll save you the bother of reading them. The idea is a dead end.

[Carreidas 160]

Not sure if I've seen this covered here before.

Then you haven't been looking very hard!

http://forum.nasaspaceflight.com/index.php?topic=24115.0
http://forum.nasaspaceflight.com/index.php?topic=20383.0
http://forum.nasaspaceflight.com/index.php?topic=27421.0
http://forum.nasaspaceflight.com/index.php?topic=29458.0
http://forum.nasaspaceflight.com/index.php?topic=11909.0
http://forum.nasaspaceflight.com/index.php?topic=20098.0
http://forum.nasaspaceflight.com/index.php?topic=21730.0

I'll save you the bother of reading them. The idea is a dead end.

Woops, call me lazy I wish the search function on NSF worked a bit better...

[edit] Actually, how is it a dead end? This gun shoots bullets at +5km/s. Haven't seen that in the threads above. Actual bullets instead of PPT presentations.

[JohnFornaro]

Nice railgun video.  Unfortunately, they shot a hole thru their logo!  Maybe next time, they won't put the logo right in front of the barrel.  Free advice.  I'm full of it.

could a satellite take the g's this thing would impose on them?

"Rating of electronics built into military artillery shells, g forces equal to 15,500 g" so I'm not too worried about that. ... Alternative is to stretch the barrel. The navy wants to put these things on ships, limiting their size, but for space launch a long barrel shouldn't be a problem.

Sure, the electronics could withstand those recoil forces.  But could the satellite?

As to the length of the barrel, it is associated with mass, so a long barrel indeed would be a problem.

I remember a guy that had that idea some 30 years ago, a massive cannon that eventually would put small sats in orbit. Then he got involved with Saddam Hussein...

Didn't that guy have his name legally changed to Gerard Incorrect?

As to having covered this topic before, I'd like to announce that I have re-invented the wheel.

[DMeader]

"Rating of electronics built into military artillery shells, g forces equal to 15,500 g" so I'm not too worried about that.

That's fine if you want to put an artillery shell into orbit. Show me a traveling-wave-tube amp (common satellite component) that can take 15K g.

[Carreidas 160]

"Rating of electronics built into military artillery shells, g forces equal to 15,500 g" so I'm not too worried about that.

That's fine if you want to put an artillery shell into orbit. Show me a traveling-wave-tube amp (common satellite component) that can take 15K g.

Miniaturization has come a long way. Is such an amp required or can it be substituted by a more hardy instrument? Note that 15k g is quite high, I think 1000g is more likely...

My biggest concern is finding thrusters that can take 1000g of load. In any event you'll need 2-3 km/s delta-v to circularize the orbit, which is about 1/3 of total mass for a 300s Isp engine.

[DarkenedOne]

Crispy was right that the idea has been proposed before.  I do not believe the idea is a dead end like he says.  The idea has a great deal of potential.

The only real problem is what application will it serve.  Sensitive equipment and people cannot survive such high G forces.  Essentially the technology is limited to launching materials that can with stand the G force.  Materials like fuel, water, oxygen, propellant, and some components.   

[ARD]

It does appear that only bulk components could take the acceleration.  As for how those payloads can be put into an orbit...

Suppose the cannon were to put its payload into a high-apogee sub-orbital trajectory.  Could a pre-deployed (by rocket) space tug then intercept the payload and circularize its orbit?  If one launches loads of propellant for delivery to a depot, one can refuel the tug with gun-launched propellant.

[go4mars]

I personally don't expect railguns to take much to orbit in my lifetime.  One exception would be for shipping very large volumes of raw metal up to a large orbital construction facility (a longshot for my lifetime) and I still wouldn't expect to see that unless someone makes a materials science breakthrough.  Like inexpensive diamond supports for a really long railgun (muzzle of it above 60 km altitude or so).  Reusable rockets seem like a better path in general.  I think most of its application will be for moving things around in space and some military applications. 

[Tass]

Like inexpensive diamond supports for a really long railgun (muzzle of it above 60 km altitude or so).

Diamond? Why diamond? There are way stronger and less brittle materials available even now. Don't confuse hardness with strength.

[hydra9]

If you used that NAVY rail gun on the Moon at the lunar equator then you could launch 10 of the 18 kilogram aluminum projectiles per minute at a speed of 2.5km/s (close to delta-v for Earth-Moon L1 and  L2 from the lunar surface). A space catcher located at L1 could capture the objects. 

So in theory, such a device could place 26 tonnes of aluminum at L1 per day or close to 9500 tonnes to L1 a year. Of course, you'd have to manufacture the aluminum projectiles from the lunar regolith. But aluminum would be valuable in its own right for the manufacture of space mirrors for solar power satellites or for interplanetary light sails or even for simply mass shielding space stations and interplanetary spacecraft against radiation and micrometeorites.

 Whether the aluminum projectiles could also carry other payloads such as lunar regolith or lunar ice would be interesting. Even if an aluminum projectile could only carry 10% of its weight as payload, that could mean that one such device could transport nearly 1000 tonnes of ice or regolith to L1 per year for water, air, and rocket fuel. Such lunar resources accumulated at L1 might dramatically reduce the cost of space travel between LEO and L1 and L1 and the lunar surface and back.

Marcel F. Williams
 

[93143]

Diamond? Why diamond? There are way stronger and less brittle materials available even now. Don't confuse hardness with strength.

Actually, hardness correlates quite nicely with strength.  Diamond is incredibly strong.  What you want is toughness, which is often negatively correlated with hardness/strength.

[ChileVerde]

Miniaturization has come a long way. Is such an amp required or can it be substituted by a more hardy instrument? Note that 15k g is quite high, I think 1000g is more likely...

Back around 1994, I sat in on a meeting at Livermore on their SHARP light-gas gun(*) that they were proposing for orbital launch of bulk materials.  Since the projectile couldn't be totally dumb if it were to get into LEO, the question of how many g electronics could handle came up. The answer was that 30k g was in hand and demonstrated and they didn't see much in the way of getting up to 100k g if that were needed. Obviously, they were talking about specially designed solid state devices.

(*) What they really wanted was a light-gas gun in which the hydrogen would be heated really hot by a pebble-bed nuclear reactor.  Alas, such was not to be.

[RobLynn]

Any launcher which has significant barrel erosion (like rail guns and conventional rifled guns) seems like a pretty bad idea as refurbishment costs are likely to be high.

Likewise requiring the use of extremely expensive high voltage pulsed power supplies seems like a really bad idea.  Scaling the payload up to useful sizes becomes insanely expensive.

Rail guns have historically also had a lot of problems getting to velocities over 5-6km/s.

Gas guns come with their own problems, including massive pressure vessels at high temperatures and fast acting valves, though still a lot cheaper than rail guns, and potential for near-zero wear. Quicklaunch has a proposal for a gas gun launch system that looks pretty good (far better than railgun):
http://quicklaunchinc.com/
Their idea of submerging the tube in the ocean seems excellent, as probably allows them to sit on equator and with a little turning of tube fire projectiles into any orbit.  The Marianas trench could allow launch tubes up to 15-20km long at 45-30° angles above horizontal for lower accelerations (might also be suitable for kicking a human carrying craft up to 2-3km/s)


Ram accelerators seem like they might be as good or better than gas guns.  They are probably the most easily scalable solution and a many kilometers long 2-3m diameter launcher could probably be built for a few billions.   Barrel is non-contact with projectile, and like gas guns they are able to accelerate projectiles to orbital velocities.  The barrels are relatively simple and low pressure - and so can be made out of cheapest available steel with relatively crude finish and fabrication methods, they can also be very long to reduce acceleration requirements.  No large pressure vessels required, very brief peak temperatures and the projectiles don't have to withstand enormous currents either.

[JohnFornaro]

If you used that NAVY rail gun on the Moon at the lunar equator then you could launch 10 of the 18 kilogram aluminum projectiles per minute at a speed of 2.5km/s (close to delta-v for Earth-Moon L1 and  L2 from the lunar surface). A space catcher located at L1 could capture the objects.

Great.  Now what do I do with this material?  Before they knew how to efficiently mine Al, it was as valuable as gold, and rarer, I think.  The cost of this material as described, amortiing the costs of the gun and catcher, would be higher than sending the material up on an F-9.

The larger picture I keep getting at is mission prioritization.  Someday, in the far far distant future, there might be a railgun and the necessary infrastructure supported by a thriving economy.  But that will not happen unless the earlier steps are taken.  And tbe earlier steps won't be taken if effort is spent working on these currently unrealistic and functionally useless conjectures.

[StraumliBlight]

Moonshot Space [Dec 1]

And not in short, we’re developing a kinetic electromagnetic space launch system, designed for small and medium payloads of resources and equipment.
The system uses electromagnetic acceleration to propel payloads to hypersonic velocities, creating a cleaner, faster, and far more scalable path to space.

Built for high availability and extreme cost-efficiency, complementing, rather than competing with traditional rockets. While rockets launch satellites and astronauts, Moonshot specializes in direct in-orbit delivery of the resources that satellites, space stations, and in-space infrastructure rely on.

https://www.moonshot.space/

Electromagnetic launch co Moonshot Space raises $12m [Dec 1]

Moonshot Space focuses on an innovative space launch vehicle that does not use rocket propulsion as is customary at NASA or SpaceX, but rather inertial force alone, based solely on electricity. It is a powerful electromagnetic accelerator, built to launch objects to hypersonic speeds of up to 8 kilometers per second (28,800 km/h), in a short time and using only electricity.

Using induction, the launcher hovers on a railway track that juts into the sky, in a manner reminiscent of a monorail, and detaches the spacecraft at top speed to altitude. Due to the fact that launch rockets are not involved, and the spacecraft does not need to carry fuel for this purpose, objects can be launched more easily and make more intelligent use of inertial force, as well as freeing up more space for payload - the rule of thumb says that any rocket launched into space can only carry 4% of its weight as payload. From the moment that launched capsule passes the speed threshold of 2.5 kilometers per second, it will reach an orbit around the earth.

[...]

Moonshot Space has signed initial agreements with companies in the field of logistics and space refueling, including Italy’s D-Orbit and US firm Orbit Fab.

The company is focusing on building a prototype - a scaled-down model that will travel on a track of only a few dozen meters, which will also be used by Israeli defense companies in testing aircraft and hypersonic systems. The accelerator is expected to accelerate objects to speeds of 6 times the speed of sound (7,200 km/h).