6 ms·

The concept is the same for any projectile weapon: I'm going to convert stored energy into kinetic energy. Bow and arrow? Stored energy in the bow turned into

by mabbo 7y ago

The concept is the same for any projectile weapon: I'm going to convert stored energy into kinetic energy. Bow and arrow? Stored energy in the bow turned into kinetic energy in the arrow. Handgun/cannon/musket? Stored chemical energy in some compound, quickly converted into kinetic energy in the bullet via exploding. A rail gun isn't much different- it's just a different means to store the energy (in electrical storage) and a different means to apply the energy to the projectile (magnets). The real problem is that these two changes require a lot of overhead in terms of gear to make it work. It's only worthwhile to do it if you intend to really, really add a lot of kinetic energy to something. It's the same reason the electric car has taken 100 years to finally be worthwhile- chemical energy is much more dense and easy to convert into kinetic energy. Battery tech is only now catching up to the point that it's worth doing.

steve19 7y ago
You put it well. The problem of of putting energy into projectiles caused a move from kenetic to chemical weapons (missiles). But delivering chemicals to a target is expensive and at some point scaling it up becomes politically dangerous (you cannot just lauch even a conventional icbm without all sorts of risks). Scaling up kenetic weapons ended up with huge battleship guns that did almost as much damage to the ship itself as the target (OK, a bit of an overstatement but I doubt any of those sailors left the navy with hearing intact). They were slow to fire, extremely heavy, and required a lot of dangerous chemicals to be stored. One mistake and the ship would blow up. This allows deep penetrating weapons containing huge amounts of energy to pierce bunkers from way over the horizon. This is the kind of weapon the Navy will want if the Korean peninsula ever heats up to a boil. Edit: I suspect I am being downvoted because I am discussing weapon systems. There is a difference between advocating for weapons/war and discussing them. It is better weapons are discussed in the open, than developed in secret where the public cannot weigh in. Truly horrifying things are born in the dark.
- killjoywashere 7y ago
  Point of order in the definitions here: an explosive projectile is still a kinetic weapon and is not NOT a chemical weapon. A chemical weapon causes chemistry to happen in/on the target: mustard gas, VX nerve gas, etc. This is not my opinion. This is widely accepted and a matter of many international treaties.
  - ses1984 7y ago
    I think kinetic or chemical refers to the type of energy that puts the project in motion, from something like a bowstring to rocket propellant.
    - killjoywashere 7y ago
      I fully understand what OP was trying to say. The problem is words. You can think whatever you want. If you want to deal with other people in a shared reality and influence the arc of history, I suggest learning to identify, adopt, and use rigorously defined words as intended, wherever possible, because that frees up your very limited intellectual capabilities to focus on the things you actually want to change.
      - deleted 7y ago
        [deleted]
      - homonculus1 7y ago
        This is pedantry. OP's context was clear, and a comment thread on HN is not "the arc of history".
- PopeDotNinja 7y ago
  > ...huge battleship guns ... were slow to fire ... I was curious about how fast battleships could actually fire, so I googled around and found a couple stats. On an Iowa class battleship: - Armed with nine 16"/50 caliber Mark 7 guns [1] - Each 16" gun is quoted as having a firing rate of 2 rounds per minute [2] - Each shell weighed between 1900lbs / 865kg and 2700lbs / 1225kg pounds [3] So math says 2 rounds/minute * 9 guns is 18 shells/minute. That is 34_200 lbs (18 * 1900) and 48_200 lbs (18 * 2700) of ordinance per minute. I would not want to be on the receiving end of that! EDIT: fixed some numbers I goofed after @CapricornNoble was kind enough to point them out. Thanks! [1] https://en.wikipedia.org/wiki/Iowa-class_battleship#Main_battery https://en.wikipedia.org/wiki/Iowa-class_battleship#Main_bat... [2] https://en.wikipedia.org/wiki/16%22/50_caliber_Mark_7_gun#Service_history https://en.wikipedia.org/wiki/16%22/50_caliber_Mark_7_gun#Se... [3] https://www.cs.mcgill.ca/~rwest/wikispeedia/wpcd/wp/i/Iowa_class_battleship.htm https://www.cs.mcgill.ca/~rwest/wikispeedia/wpcd/wp/i/Iowa_c...
  - steve19 7y ago
    Interesting but I don't think that's sustained fire. You see crazy him rpm for firearms. The rate of fire is restricted by the magazine size (ship guns do have magazines) and how fast the gun can cool. The US Army changed the barrel of the M4 Carbine (automatic rifle) after some troops during a sustained defense of some hill had barrels failing after glowing white hot. Machine guns often have barrels that can be replaced during prolonged engagements. A hot naval gun could detonate the charge if it overheats. It has happened although I don't remember how long ago.
    - PopeDotNinja 7y ago
      Good point. I removed the reference to sustained fire. Still a lot of ordinance for the receiving end to dodge! The dent those guns put in the water when firing is mind boggling to me => http://i.imgur.com/5aKQulg.jpg http://i.imgur.com/5aKQulg.jpg
    - dredmorbius 7y ago
      The Maxim gun (1880s - WWI-era) and M1917 Browning machine gun machine guns were water-cooled. Barrel heating is indeed a problem.
- Balgair 7y ago
  One important difference is heat management. Electric weapons are super neat. Their specs can put the projectile very kenetic, they can uitilize more exotic energy sources, etc. However, in terms of a man portable gun, they just really don't have the specs needed. Sure, we can make them more ruggeded and more effective at lower KE output. But a major issue for a man portable gun is heat. Heat causes expansions and affects ductility, ductility and expansion cause jams. Jams mean you're dead. It turns out that the brass cartridge is really really good at getting hot and then taking that heat with it as it is ejected. The HK-G11 is a good example of the issues that the lack of heat ejection can cause [0]. As we do not have super-conducting materials that can be man portable and at room temperature, there is significant heat build up in the copper rails of the rail gun. With catridges you can throw that heat away easily, with rails, you have to have a cooling system in them to continue to use the gun. Either that or you have to stop the warfighter from using the gun until it cools. This, especially when lives are on the line, is non ideal. Hence, railguns are mostly used in much larger applications like ships. There you can have the cooling equipment to keep the gun functional and operating and you can use the ocean as a heat sink. Your heat issues are still present though. More exotic materials than cooper are used for the rails, things that need to be at LN2 temperatures. But on a ship, you have the room and weight to carry the LN2 cooling equipment. Currently, railgun tech is still being developed. Reliability is a big issue, one that was solved in chemically launched projectiles through decades of tial and error. Rail guns are likewise going to need those decades of learning to occur. [0] https://www.youtube.com/watch?v=QGKcvM2Hh4g https://www.youtube.com/watch?v=QGKcvM2Hh4g
  - petra 7y ago
    We have much better engineering tools today, so why would it take decades ?
    - Balgair 7y ago
      The weapons we have today are very well engineered (cheap, reliable, understood tolerances/ranges, etc). As such, where railgun tech will be used is in limited cases as compared to the well developed cheamically launched projectiles. That means that there are less cases where the railgun can be used and then learned from. Especially with weapons, you need real life testing in order to understand the engineering issues, as lab testing is generally forbidden due to loss of human life. Hunting deer and boars will only give you so much. Fortunately, we humans don't go to War too often these days (though this is very debatable to a lot of real people). Unfortunately for railgun engineers, that means there is not a lot of real world testing in the panic that is a battle.
dghughes 7y ago
Rail guns will be powerful but powerful chemical energy LASER weapons will be frightening without projectiles, instant, no recoil, fast aim.
ChuckMcM 7y ago
I don't disagree, at 100,000 feet all weapons are mass gets propelled by force, where I part ways with you is here: "A rail gun isn't much different" While I completely agree that in concept rail gun isn't different, making one is extremely different. That is why I would have little trouble making a bow and arrow over the weekend that would serve as a respectable weapon[1], but I would not be able to create a similarly lethal rail gun[2]. Reducing the theory to practice is neither straight forward nor obvious. People have been trying to build them for 100 years after all and we're only now seeing some that come close to being competitive with other weapon systems. What I'm saying is that your "overhead in terms of gear to make it work" covers for a whole crapload of technology and engineering. What I hear when you dismiss this technology is a lack of appreciation for what is involved, it sounds to me like someone saying "Making an atom bomb is pretty simple right, simply hold a super-critical mass of fissile material really tightly until you've achieved the desired number of fission events. Right?" But you can't pick up two 4 lb pieces of plutonium and bang them together like a couple of rocks and expect to get a bomb event (although you will die). There is nothing "simple" about it, even if the concept is easy to express. [1] In part because we learned how to make bows in Boy Scouts and I spent a summer doing a survival course where I had the opportunity to build one for my final. [2] Even though I'm a classically trained EE, understand the theory, have experience in switching fairly high currents from my Battlebot experiences and a fairly complete EE lab at my disposal.
- mabbo 7y ago
  Oh, we're definitely in agreement- conceptually the same, implementation details of a few orders of magnitude different. Mostly I was replying to the idea that "hey, we've known how to do this for 100 years". Sure we have- conceptually. We knew that batteries/electricity + magnets could implement the same pattern as "chemicals exploding". But we sure as heck didn't know how to make it practical. That's why it's 100 years later and very few of us have either electric cars or rail guns.
Retric 7y ago
It’s not just about more kinetic energy, a larger shell gets you that. Higher speed projectiles means longer distances which saves missiles which are extremely expensive and you only carry so many of them. Rail guns can be powered by IC engines saving you carrying oxidizer around which is really heavy and dangerous. Many ships where destroyed when their gunpowder magazines detonated, sometimes outside of battle. Rail guns can also be powered by Nuclear which is extremely compelling of your ship is already going to have a Nuclear Reactor.
walrus01 7y ago
> It's the same reason the electric car has taken 100 years to finally be worthwhile- chemical energy is much more dense and easy to convert into kinetic energy. no kidding, and that's understating it. Look at the kilojoules (or watt-hours) per kilogram in one litre of diesel versus one kilogram of lithium ion batteries, or one volumetric litre of li ion batteries. It's significantly greater.

by mabbo 7y ago

steve19 7y ago

You put it well. The problem of of putting energy into projectiles caused a move from kenetic to chemical weapons (missiles). But delivering chemicals to a target is expensive and at some point scaling it up becomes politically dangerous (you cannot just lauch even a conventional icbm without all sorts of risks). Scaling up kenetic weapons ended up with huge battleship guns that did almost as much damage to the ship itself as the target (OK, a bit of an overstatement but I doubt any of those sailors left the navy with hearing intact). They were slow to fire, extremely heavy, and required a lot of dangerous chemicals to be stored. One mistake and the ship would blow up. This allows deep penetrating weapons containing huge amounts of energy to pierce bunkers from way over the horizon. This is the kind of weapon the Navy will want if the Korean peninsula ever heats up to a boil. Edit: I suspect I am being downvoted because I am discussing weapon systems. There is a difference between advocating for weapons/war and discussing them. It is better weapons are discussed in the open, than developed in secret where the public cannot weigh in. Truly horrifying things are born in the dark.

killjoywashere 7y ago
Point of order in the definitions here: an explosive projectile is still a kinetic weapon and is not NOT a chemical weapon. A chemical weapon causes chemistry to happen in/on the target: mustard gas, VX nerve gas, etc. This is not my opinion. This is widely accepted and a matter of many international treaties.
- ses1984 7y ago
  I think kinetic or chemical refers to the type of energy that puts the project in motion, from something like a bowstring to rocket propellant.
  - killjoywashere 7y ago
    I fully understand what OP was trying to say. The problem is words. You can think whatever you want. If you want to deal with other people in a shared reality and influence the arc of history, I suggest learning to identify, adopt, and use rigorously defined words as intended, wherever possible, because that frees up your very limited intellectual capabilities to focus on the things you actually want to change.
    - deleted 7y ago
      [deleted]
    - homonculus1 7y ago
      This is pedantry. OP's context was clear, and a comment thread on HN is not "the arc of history".
PopeDotNinja 7y ago
> ...huge battleship guns ... were slow to fire ... I was curious about how fast battleships could actually fire, so I googled around and found a couple stats. On an Iowa class battleship: - Armed with nine 16"/50 caliber Mark 7 guns [1] - Each 16" gun is quoted as having a firing rate of 2 rounds per minute [2] - Each shell weighed between 1900lbs / 865kg and 2700lbs / 1225kg pounds [3] So math says 2 rounds/minute * 9 guns is 18 shells/minute. That is 34_200 lbs (18 * 1900) and 48_200 lbs (18 * 2700) of ordinance per minute. I would not want to be on the receiving end of that! EDIT: fixed some numbers I goofed after @CapricornNoble was kind enough to point them out. Thanks! [1] https://en.wikipedia.org/wiki/Iowa-class_battleship#Main_battery https://en.wikipedia.org/wiki/Iowa-class_battleship#Main_bat... [2] https://en.wikipedia.org/wiki/16%22/50_caliber_Mark_7_gun#Service_history https://en.wikipedia.org/wiki/16%22/50_caliber_Mark_7_gun#Se... [3] https://www.cs.mcgill.ca/~rwest/wikispeedia/wpcd/wp/i/Iowa_class_battleship.htm https://www.cs.mcgill.ca/~rwest/wikispeedia/wpcd/wp/i/Iowa_c...
- steve19 7y ago
  Interesting but I don't think that's sustained fire. You see crazy him rpm for firearms. The rate of fire is restricted by the magazine size (ship guns do have magazines) and how fast the gun can cool. The US Army changed the barrel of the M4 Carbine (automatic rifle) after some troops during a sustained defense of some hill had barrels failing after glowing white hot. Machine guns often have barrels that can be replaced during prolonged engagements. A hot naval gun could detonate the charge if it overheats. It has happened although I don't remember how long ago.
  - PopeDotNinja 7y ago
    Good point. I removed the reference to sustained fire. Still a lot of ordinance for the receiving end to dodge! The dent those guns put in the water when firing is mind boggling to me => http://i.imgur.com/5aKQulg.jpg http://i.imgur.com/5aKQulg.jpg
  - dredmorbius 7y ago
    The Maxim gun (1880s - WWI-era) and M1917 Browning machine gun machine guns were water-cooled. Barrel heating is indeed a problem.
Balgair 7y ago
One important difference is heat management. Electric weapons are super neat. Their specs can put the projectile very kenetic, they can uitilize more exotic energy sources, etc. However, in terms of a man portable gun, they just really don't have the specs needed. Sure, we can make them more ruggeded and more effective at lower KE output. But a major issue for a man portable gun is heat. Heat causes expansions and affects ductility, ductility and expansion cause jams. Jams mean you're dead. It turns out that the brass cartridge is really really good at getting hot and then taking that heat with it as it is ejected. The HK-G11 is a good example of the issues that the lack of heat ejection can cause [0]. As we do not have super-conducting materials that can be man portable and at room temperature, there is significant heat build up in the copper rails of the rail gun. With catridges you can throw that heat away easily, with rails, you have to have a cooling system in them to continue to use the gun. Either that or you have to stop the warfighter from using the gun until it cools. This, especially when lives are on the line, is non ideal. Hence, railguns are mostly used in much larger applications like ships. There you can have the cooling equipment to keep the gun functional and operating and you can use the ocean as a heat sink. Your heat issues are still present though. More exotic materials than cooper are used for the rails, things that need to be at LN2 temperatures. But on a ship, you have the room and weight to carry the LN2 cooling equipment. Currently, railgun tech is still being developed. Reliability is a big issue, one that was solved in chemically launched projectiles through decades of tial and error. Rail guns are likewise going to need those decades of learning to occur. [0] https://www.youtube.com/watch?v=QGKcvM2Hh4g https://www.youtube.com/watch?v=QGKcvM2Hh4g
- petra 7y ago
  We have much better engineering tools today, so why would it take decades ?
  - Balgair 7y ago
    The weapons we have today are very well engineered (cheap, reliable, understood tolerances/ranges, etc). As such, where railgun tech will be used is in limited cases as compared to the well developed cheamically launched projectiles. That means that there are less cases where the railgun can be used and then learned from. Especially with weapons, you need real life testing in order to understand the engineering issues, as lab testing is generally forbidden due to loss of human life. Hunting deer and boars will only give you so much. Fortunately, we humans don't go to War too often these days (though this is very debatable to a lot of real people). Unfortunately for railgun engineers, that means there is not a lot of real world testing in the panic that is a battle.

dghughes 7y ago

Rail guns will be powerful but powerful chemical energy LASER weapons will be frightening without projectiles, instant, no recoil, fast aim.

ChuckMcM 7y ago

I don't disagree, at 100,000 feet all weapons are mass gets propelled by force, where I part ways with you is here: "A rail gun isn't much different" While I completely agree that in concept rail gun isn't different, making one is extremely different. That is why I would have little trouble making a bow and arrow over the weekend that would serve as a respectable weapon[1], but I would not be able to create a similarly lethal rail gun[2]. Reducing the theory to practice is neither straight forward nor obvious. People have been trying to build them for 100 years after all and we're only now seeing some that come close to being competitive with other weapon systems. What I'm saying is that your "overhead in terms of gear to make it work" covers for a whole crapload of technology and engineering. What I hear when you dismiss this technology is a lack of appreciation for what is involved, it sounds to me like someone saying "Making an atom bomb is pretty simple right, simply hold a super-critical mass of fissile material really tightly until you've achieved the desired number of fission events. Right?" But you can't pick up two 4 lb pieces of plutonium and bang them together like a couple of rocks and expect to get a bomb event (although you will die). There is nothing "simple" about it, even if the concept is easy to express. [1] In part because we learned how to make bows in Boy Scouts and I spent a summer doing a survival course where I had the opportunity to build one for my final. [2] Even though I'm a classically trained EE, understand the theory, have experience in switching fairly high currents from my Battlebot experiences and a fairly complete EE lab at my disposal.

mabbo 7y ago
Oh, we're definitely in agreement- conceptually the same, implementation details of a few orders of magnitude different. Mostly I was replying to the idea that "hey, we've known how to do this for 100 years". Sure we have- conceptually. We knew that batteries/electricity + magnets could implement the same pattern as "chemicals exploding". But we sure as heck didn't know how to make it practical. That's why it's 100 years later and very few of us have either electric cars or rail guns.

Retric 7y ago

It’s not just about more kinetic energy, a larger shell gets you that. Higher speed projectiles means longer distances which saves missiles which are extremely expensive and you only carry so many of them. Rail guns can be powered by IC engines saving you carrying oxidizer around which is really heavy and dangerous. Many ships where destroyed when their gunpowder magazines detonated, sometimes outside of battle. Rail guns can also be powered by Nuclear which is extremely compelling of your ship is already going to have a Nuclear Reactor.

walrus01 7y ago

> It's the same reason the electric car has taken 100 years to finally be worthwhile- chemical energy is much more dense and easy to convert into kinetic energy. no kidding, and that's understating it. Look at the kilojoules (or watt-hours) per kilogram in one litre of diesel versus one kilogram of lithium ion batteries, or one volumetric litre of li ion batteries. It's significantly greater.