Using Railguns To Send Supplies Into Space

[Photon Guy]

What would be the practicality of using railguns to send supplies into space? The way a railgun works is by using magnets to propel objects at really high speeds so a railgun would no doubt be able to propel a spacecraft at escape velocity and by doing so, it would eliminate the need of fuel to launch spacecraft into space. Such spacecraft would have to be unmanned as the acceleration of a railgun would be too much for people to withstand, they would be squashed like pancakes, but I see no reason why supplies couldn't be sent that way. So the idea is that spacecraft containing supplies could be launched into space and then retrieved by personnel on the ISS, Im wondering how that would work. 

[Moontanman]

10 minutes ago, Photon Guy said:

What would be the practicality of using railguns to send supplies into space? The way a railgun works is by using magnets to propel objects at really high speeds so a railgun would no doubt be able to propel a spacecraft at escape velocity and by doing so, it would eliminate the need of fuel to launch spacecraft into space. Such spacecraft would have to be unmanned as the acceleration of a railgun would be too much for people to withstand, they would be squashed like pancakes, but I see no reason why supplies couldn't be sent that way. So the idea is that spacecraft containing supplies could be launched into space and then retrieved by personnel on the ISS, Im wondering how that would work. 

IMHO the main problem of using rail guns to send objects to space would be the enormous friction with the earth's atmosphere. Any object so accelerated would become white hot and evaporate much like a meteor does when it enters the Earth's atmosphere.  Then you would have to include engines to allow the object or package to maneuver to the space station.

This would be much easier to do if you were launching package from an airless body like the moon.    

[Phi for All]

Which supplies can withstand human-squashing forces?

[Moontanman]

44 minutes ago, Phi for All said:

Which supplies can withstand human-squashing forces?

Pemmican? I've seen proposals for doing this and the g forces and the friction would be "difficult" to engineer a solution to these problems from the surface of the Earth. Maybe not impossible but once you compare it to a meteor entering the Earth's atmosphere it makes the problem look insurmountable... of course you could use it to turn mixed vegetables into chunky salsa. 

I may have overstated this a bit, in my mind i was thinking of the spin launch vehicle,  https://www.spinlaunch.com/ not an electromagnetic launch but the g  forces would be very similar and the friction equally enormous. 

[Photon Guy]

4 hours ago, Moontanman said:

IMHO the main problem of using rail guns to send objects to space would be the enormous friction with the earth's atmosphere. Any object so accelerated would become white hot and evaporate much like a meteor does when it enters the Earth's atmosphere.  Then you would have to include engines to allow the object or package to maneuver to the space station.

You have that same problem with friction and the heat it generates with any sort of spacecraft that reaches escape velocity. Conventional spacecraft are made to withstand the friction and heat with special heat shielding. A spacecraft sent into space by a railgun could have that same sort of shielding, and it could have cooling systems too. Yes it would need some engines and fuel to maneuver to the station as you point out but not the tremendous fuel that you need to reach escape velocity the way conventional spacecraft do as the railgun would take care of that. 

4 hours ago, Moontanman said:

This would be much easier to do if you were launching package from an airless body like the moon.    

But we don't send supplies from the moon to the ISS, we send it from Earth to the ISS. I suppose we could set up a moon base and start mining the moon and producing supplies on the moon that way, but that's a long way off. 

4 hours ago, Phi for All said:

Which supplies can withstand human-squashing forces?

Lots of supplies. Water for instance. And food that you don't mind having squashed. Food remains edible when it's squashed. 

[Moontanman]

2 hours ago, Photon Guy said:

You have that same problem with friction and the heat it generates with any sort of spacecraft that reaches escape velocity. Conventional spacecraft are made to withstand the friction and heat with special heat shielding. A spacecraft sent into space by a railgun could have that same sort of shielding, and it could have cooling systems too. Yes it would need some engines and fuel to maneuver to the station as you point out but not the tremendous fuel that you need to reach escape velocity the way conventional spacecraft do as the railgun would take care of that. 

Not true, conventional spacecraft start out slow and by the time they reach orbital speed they are in very thin air to no air and little to no friction. Starting out at faster than orbital speed at ground level means you get lit up by friction immediately. Much like a meteor hitting the atmosphere at 25,000 mph, the gs aren't the worst of it. Being heated to beyond the melting point of nearly every material almost instantly would be a big hurdle to get past.   

2 hours ago, Photon Guy said:

But we don't send supplies from the moon to the ISS, we send it from Earth to the ISS. I suppose we could set up a moon base and start mining the moon and producing supplies on the moon that way, but that's a long way off

Reality what a concept. I was simply stating that this would work much better from an airless body like the moon than the deep gravity well and atmosphere of the Earth. 

2 hours ago, Photon Guy said:

Lots of supplies. Water for instance. And food that you don't mind having squashed. Food remains edible when it's squashed. 

Very true but just how many gs and how fast would a rail gun package have to accelerate to before leaving the gun, the muzzle velocity of this gun would have to be outrageous! Would that acceleration interfere with the electronic and mechanical parts of the package? The rail gun thing is very cool but can you really accelerate a reasonable sized package to orbit, remember you would have to start out quite a bit faster than orbital velocity to get to orbit from the Earth's surface due to friction. 

[TheVat]

7 hours ago, Phi for All said:

Which supplies can withstand human-squashing forces?

Pancakes, of course.  Or maybe just send up batter mix.  

One could send up people, if the capsule were filled with water, and passengers floated in it, properly suited.  

[Moontanman]

3 minutes ago, TheVat said:

Pancakes, of course.  Or maybe just send up batter mix.  

One could send up people, if the capsule were filled with water, and passengers floated in it, properly suited.  

Hmmm, I wonder just how much acceleration a human can tolerate while being supported by water.

  

[TheVat]

I've looked into this elsewhere.  Apparently one can go beyond 20 Gs, if liquid breathing systems are used (like the perfluorocarbon goop Ed Harris breathes in The Abyss.)  Here's a clip from wikipedia....

Liquid immersion provides a way to reduce the physical stress of G forces. Forces applied to fluids are distributed as omnidirectional pressures. Because liquids cannot be practically compressed, they do not change density under high acceleration such as performed in aerial maneuvers or space travel. A person immersed in liquid of the same density as tissue has acceleration forces distributed around the body, rather than applied at a single point such as a seat or harness straps. This principle is used in a new type of G-suit called the Libelle G-suit, which allows aircraft pilots to remain conscious and functioning at more than 10g acceleration by surrounding them with water in a rigid suit.^[57]

Acceleration protection by liquid immersion is limited by the differential density of body tissues and immersion fluid, limiting the utility of this method to about 15g to 20g.^[58] Extending acceleration protection beyond 20g requires filling the lungs with fluid of density similar to water. An astronaut totally immersed in liquid, with liquid inside all body cavities, will feel little effect from extreme G forces because the forces on a liquid are distributed equally, and in all directions simultaneously. However effects will be felt because of density differences between different body tissues, so an upper acceleration limit still exists.

[Moontanman]

1 hour ago, TheVat said:

I've looked into this elsewhere.  Apparently one can go beyond 20 Gs, if liquid breathing systems are used (like the perfluorocarbon goop Ed Harris breathes in The Abyss.)  Here's a clip from wikipedia....

Liquid immersion provides a way to reduce the physical stress of G forces. Forces applied to fluids are distributed as omnidirectional pressures. Because liquids cannot be practically compressed, they do not change density under high acceleration such as performed in aerial maneuvers or space travel. A person immersed in liquid of the same density as tissue has acceleration forces distributed around the body, rather than applied at a single point such as a seat or harness straps. This principle is used in a new type of G-suit called the Libelle G-suit, which allows aircraft pilots to remain conscious and functioning at more than 10g acceleration by surrounding them with water in a rigid suit.^[57]

Acceleration protection by liquid immersion is limited by the differential density of body tissues and immersion fluid, limiting the utility of this method to about 15g to 20g.^[58] Extending acceleration protection beyond 20g requires filling the lungs with fluid of density similar to water. An astronaut totally immersed in liquid, with liquid inside all body cavities, will feel little effect from extreme G forces because the forces on a liquid are distributed equally, and in all directions simultaneously. However effects will be felt because of density differences between different body tissues, so an upper acceleration limit still exists.

Very cool, I've learned something new. 

[Photon Guy]

12 hours ago, Moontanman said:

 Starting out at faster than orbital speed at ground level means you get lit up by friction immediately. Much like a meteor hitting the atmosphere at 25,000 mph, the gs aren't the worst of it. Being heated to beyond the melting point of nearly every material almost instantly would be a big hurdle to get past.   

Some meteors do manage to land without burning up, they're called meteorites, so that goes to show it is possible for an object to pass through the earth's atmosphere at such incredible speeds without burning up. A spacecraft launched by a railgun could have special heat shielding as well as cooling systems. The heat shielding might have to be better than the shielding used now but it could be done. That plus good cooling systems might be adequate to protect against the heat and friction. Also, the spacecraft doesn't have to be launched at ground level. It could be launched from on top of a tall structure or you could even have a railgun with a long enough barrel that by the time it exits the muzzle its well above ground level. A longer railgun could also allow for a more gradual acceleration which would be desirable. 

12 hours ago, Moontanman said:

Very true but just how many gs and how fast would a rail gun package have to accelerate to before leaving the gun, the muzzle velocity of this gun would have to be outrageous! Would that acceleration interfere with the electronic and mechanical parts of the package? The rail gun thing is very cool but can you really accelerate a reasonable sized package to orbit, remember you would have to start out quite a bit faster than orbital velocity to get to orbit from the Earth's surface due to friction. 

The escape velocity on Earth is 24923 MPH so it's about the same speed as meteors hitting the earth's atmosphere that you mentioned. The problems of friction and heat could be solved by what I mentioned above. And also if you launch from a higher altitude the escape velocity is lower so that is another advantage of doing that. The idea of using railguns is to cut fuel costs and the spacecraft being sent by such means would weigh far less because they wouldn't have to lug around all that fuel that would otherwise be used if you were to try to get to orbit the old fashioned way. 

[TheVat]

8 minutes ago, Photon Guy said:

The escape velocity on Earth is 24923 MPH so it's about the same speed as meteors hitting the earth's atmosphere that you mentioned.

Just a reminder - rockets would usually go to an orbital position rather than directly leaving Earth.  Velocity for LEO is around 7.8 km/sec, or 17000 mph.  This would be somewhat easier to implement with the railgun.  And, as you mentioned, having the barrel end at high altitude would help with the frictional challenges.  A tall mountain (especially near the equator, where aiming east would add the maximum earth's rotational velocity) would be a useful support, perhaps.  

[Moontanman]

2 hours ago, Photon Guy said:

Some meteors do manage to land without burning up, they're called meteorites, so that goes to show it is possible for an object to pass through the earth's atmosphere at such incredible speeds without burning up.

Yes, very large meteors manage to land via stripping off speed via burning off much of their material due to "friction" most objects simply burn up before they hit the ground. Spacecraft get by with using the atmosphere to slow down by not plunging uncontrolled into the atmosphere and by taking a path that allows the frictional heat to be bleed off slowly via a shallow angle not by an immediate steep plunge into the atmosphere.  

 

2 hours ago, Photon Guy said:

A spacecraft launched by a railgun could have special heat shielding as well as cooling systems.

Cooling systems? A cooling system that can handle 100s of gs? Yes the heat shielding will have to be quite special I am sure. 

2 hours ago, Photon Guy said:

The heat shielding might have to be better than the shielding used now but it could be done.

Yes, I am sure it could be done, but at what cost? 

2 hours ago, Photon Guy said:

That plus good cooling systems might be adequate to protect against the heat and friction.

Yes very good cooling systems, if there any chance you could elaborate on these special/good systems you keep mentioning? 

2 hours ago, Photon Guy said:

Also, the spacecraft doesn't have to be launched at ground level. It could be launched from on top of a tall structure or you could even have a railgun with a long enough barrel that by the time it exits the muzzle its well above ground level. A longer railgun could also allow for a more gradual acceleration which would be desirable. 

You do realize the gun's breach would still be at ground level and the barrel would still be full of air that the projectile would have to move out of the way, think friction, you would get no benefit from raising the muzzle above the thickest part of the air since this would not change the problem of the package having to fight through the air in the barrel.  in fact the rail guns I have seen illustrations of didn't even have barrels, do they have barrels/muzzles? 

2 hours ago, Photon Guy said:

The escape velocity on Earth is 24923 MPH so it's about the same speed as meteors hitting the earth's atmosphere that you mentioned. The problems of friction and heat could be solved by what I mentioned above.

Magic would do the trick as well I am sure. 

2 hours ago, Photon Guy said:

And also if you launch from a higher altitude the escape velocity is lower so that is another advantage of doing that.

How high would the gun have to be to take advantage of this lower escape velocity? How much difference in escape velocity would you get by launching from an altitude of five miles? 

2 hours ago, Photon Guy said:

The idea of using railguns is to cut fuel costs and the spacecraft being sent by such means would weigh far less because they wouldn't have to lug around all that fuel that would otherwise be used if you were to try to get to orbit the old fashioned way. 

So you would just have to lug a rail gun to high altitude and all the fuel it takes to lug the rail gun up to high altitude? 

Edited January 30 by Moontanman
spelling

[Photon Guy]

On 1/30/2024 at 9:54 AM, TheVat said:

Just a reminder - rockets would usually go to an orbital position rather than directly leaving Earth.  Velocity for LEO is around 7.8 km/sec, or 17000 mph.  This would be somewhat easier to implement with the railgun.  And, as you mentioned, having the barrel end at high altitude would help with the frictional challenges.  A tall mountain (especially near the equator, where aiming east would add the maximum earth's rotational velocity) would be a useful support, perhaps.  

Good point. To send supplies to the ISS you would only need to reach a velocity of 17000, perhaps less if you're firing from a high altitude, so friction would be less of a problem than if you were firing at escape velocity. The atmosphere is significantly thinner at the peak of Mount Everest than it is at sea level so at such an altitude friction is less of a problem. 

On 1/30/2024 at 11:43 AM, Moontanman said:

Yes, very large meteors manage to land via stripping off speed via burning off much of their material due to "friction" most objects simply burn up before they hit the ground. Spacecraft get by with using the atmosphere to slow down by not plunging uncontrolled into the atmosphere and by taking a path that allows the frictional heat to be bleed off slowly via a shallow angle not by an immediate steep plunge into the atmosphere.  

 

Cooling systems? A cooling system that can handle 100s of gs? Yes the heat shielding will have to be quite special I am sure. 

You might not need to subject your craft to such extreme Gs if you have a railgun with a very long barrel so that acceleration is much more gradual but that it still reaches the desired velocity by the time it leaves the muzzle. Also as TheVat pointed out, you wouldn't need your craft to reach escape velocity as orbital velocity is much lower. 

On 1/30/2024 at 11:43 AM, Moontanman said:

Yes, I am sure it could be done, but at what cost? 

Yes very good cooling systems, if there any chance you could elaborate on these special/good systems you keep mentioning? 

That would be an engineering project to design such systems but we're not talking about launching people. A good mechanical system should be able to withstand more Gs than a person. And as I mentioned above, you might not need to subject the system to such extreme Gs. 

On 1/30/2024 at 11:43 AM, Moontanman said:

You do realize the gun's breach would still be at ground level and the barrel would still be full of air that the projectile would have to move out of the way, think friction, you would get no benefit from raising the muzzle above the thickest part of the air since this would not change the problem of the package having to fight through the air in the barrel. 

The railgun could be designed so that there's a vacuum in the barrel. The muzzle could be closed, opening only when the craft exits it. 

On 1/30/2024 at 11:43 AM, Moontanman said:

in fact the rail guns I have seen illustrations of didn't even have barrels, do they have barrels/muzzles? 

The railgun I've seen pictures of have barrels. 

On 1/30/2024 at 11:43 AM, Moontanman said:

How high would the gun have to be to take advantage of this lower escape velocity? How much difference in escape velocity would you get by launching from an altitude of five miles? 

So you would just have to lug a rail gun to high altitude and all the fuel it takes to lug the rail gun up to high altitude? 

You could have the railgun permanently stationed at a higher altitude, it could be built on top of a platform or as TheVat said you might be able to use a mountain for support. Crafts containing supplies to be sent into space could be brought up to the railgun by elevator. 

[swansont]

3 hours ago, Photon Guy said:

To send supplies to the ISS you would only need to reach a velocity of 17000, perhaps less if you're firing from a high altitude, so friction would be less of a problem than if you were firing at escape velocity. The atmosphere is significantly thinner at the peak of Mount Everest than it is at sea level so at such an altitude friction is less of a problem. 

Getting to that elevation is somewhat of a problem, unless you think sherpas can haul everything up. And “significantly thinner” is still significant; it’s about a third of an atmosphere. 

[Endy0816]

@Photon Guy

A variation on the concept I've seen that bypasses the atmosphere issue, was to have a continual stream of projectiles keeping aloft their own vacuum tube. Would require constant energy to maintain though.

Edited February 1 by Endy0816

[Photon Guy]

On 1/31/2024 at 6:51 PM, swansont said:

Getting to that elevation is somewhat of a problem, unless you think sherpas can haul everything up.

Mount Mckinley is about two thirds the height of Mount Everest so we could use the peak of the mountain to mount the railgun and we could build an elevator in the mountain. 

On 1/31/2024 at 6:51 PM, swansont said:

And “significantly thinner” is still significant; it’s about a third of an atmosphere. 

And one third of the atmosphere would greatly reduce friction. 

[swansont]

1 minute ago, Photon Guy said:

Mount Mckinley is about two thirds the height of Mount Everest so we could use the peak of the mountain to mount the railgun and we could build an elevator in the mountain. 

Are you prepared to discuss the engineering difficulties of this? If not, you're just offering science fiction.

1 minute ago, Photon Guy said:

And one third of the atmosphere would greatly reduce friction. 

The devil's in the details, which you are not presenting.

[npts2020]

17 hours ago, swansont said:

Are you prepared to discuss the engineering difficulties of this? If not, you're just offering science fiction.

IMO the engineering difficulties would not be as great as the political and financial ones. Near as I can tell, the main engineering difficulties are related to scale and the fact that it has not been done before.