# How much will a naval railgun improve a ship's performance? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [June 1, 2017, 8:52am UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825 "2017-06-01T08:52:14Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![dude\_robert](https://avatars.discourse-cdn.com/v4/letter/d/8e7dd6/32.png) [@dude\_robert](https://boards.straightdope.com/u/dude_robert)\ **Post date:** [June 1, 2017, 8:52am UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/1 "2017-06-01T08:52:14Z")
So what will these guns be used for mostly? I heard they have longer range and are slightly cheaper than more expensive cannons like the AGS LRLAP, but what do you think? Other: What is the “damage” of those railguns? Does it just make a small hole in the other ship’s hull? How well would a upgraded Arleigh Burke (for example) with a railgun and no missiles do against another Burke with missiles? How well would it do against a Burke with 2 AGS guns with the LRLAP ammunition and no missiles on either side? Would these standard railgun rounds be able to penetrate a large battleship’s armour? ---
**Author:** ![dude\_robert](https://avatars.discourse-cdn.com/v4/letter/d/8e7dd6/32.png) [@dude\_robert](https://boards.straightdope.com/u/dude_robert)\ **Post date:** [June 1, 2017, 9:49am UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/2 "2017-06-01T09:49:29Z")
Oddly enough, this post hasn’t yet appeared in the IMHO forum. I’m just bumping it to see if that will resolve the issue. ---
**Author:** ![Tranquilis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tranquilis/32/3639_2.png) [@Tranquilis](https://boards.straightdope.com/u/Tranquilis)\ **Post date:** [June 1, 2017, 7:44pm UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/3 "2017-06-01T19:44:43Z")
Oh, they’re a bit more than “longer ranged.” Like 100+ miles, vs. the more common 13-15 miles now possible from the commonly-used gun/munition combinations currently used. Solid shot aren’t cheap, but they’re a lot less expensive (and more reliable) than chemical warhead shells - They have no moving parts, and are essentially machined hunks of alloy. Still not pocket change because “high-tolerance machined alloy.” 7 seconds to the horizon is VASTLY more fast that current munitions. There are multiple reasons ship-to-ship cannon fire misses at anything over short range, and that’s because the target _moves_ between the time you fire and the time the shell arrives - Good prediction computers help a lot there, but reducing the time available for errors to accumulate is always a massive bonus to accuracy. In fact, the speed of the current prototype rail guns (Mach 7+) is so fast that the shells are credible antiaircraft weapons even without fragmentation warheads. If they manage to perfect fragmentation warheads (and I can guarantee they’re working on it!), the cost per shell goes up, but the lethality expands exponentially. The kinetic energy transfer on a hit is _violent_: [clouds of burning metal fragments, secondary fragmentation, shock damage](https://youtu.be/O2QqOvFMG_A), and more. Plus you can count on this happening in multiple compartments and spaces - It may not be as physically impressive as a bomb, but systems & mission kill will do the job just fine. Missiles and gun systems are complementary. One is _relatively_ short range, fast-response, and cheap. The other is slower, longer-ranged, and expensive. Everyone is fascinated with the old battleships and their armor, but big==bigger target; armor is obsolete with the advent of aerial combat aviation. Railguns will only add to that, though it’s really not a question that will ever come up in the real world. ---
**Author:** ![Tranquilis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tranquilis/32/3639_2.png) [@Tranquilis](https://boards.straightdope.com/u/Tranquilis)\ **Post date:** [June 1, 2017, 7:47pm UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/4 "2017-06-01T19:47:35Z")
Oh, and there’s a safety/capacity bonus: No propellant charges, so magazines are VASTLY more safe, and you can stack a lot more rounds in the same space, or the same number of rounds in a much smaller space. ---
**Author:** ![Chimera](https://avatars.discourse-cdn.com/v4/letter/c/8e8cbc/32.png) [@Chimera](https://boards.straightdope.com/u/Chimera)\ **Post date:** [June 1, 2017, 9:17pm UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/5 "2017-06-01T21:17:19Z")
Let’s look at an Arleigh Burke class Destroyer, since it seems to be the standard comparison model. Installed power: 3 × Allison AG9140 Generators (2,500 kW each, 440 V) Propulsion: 4 × General Electric LM2500 gas turbines each generating 26,250 bhp (19,570 kW);[4] So we have 7.5mw of generator power and 79mw of turbine propulsion. Now I’m sure they’re not set up for it, but assuming they modify future ships (and best bet is entirely new design to handle it), that is quite sufficient power for multiple railguns, a few lasers, and a little left over for radar, equipment and some propulsion. You’d probably want to build in a couple of MWh of battery storage too, so you’re not slowing to charge your weapons. So you’re replacing an ammo locker full of explosive shells and short ranged missiles for a flammable battery pack and a bunch of inert ammo. ---
**Author:** ![mixdenny](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mixdenny/32/2962_2.png) [@mixdenny](https://boards.straightdope.com/u/mixdenny)\ **Post date:** [June 1, 2017, 11:22pm UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/6 "2017-06-01T23:22:46Z")
I dunno, the last I heard they currently throw a 50-70 lb projectile at a 20-25% increase in velocity over similar sized conventional rounds. Nice, but nothing really revolutionary. And power requirements increase exponentially. Dennis ---
**Author:** ![dude\_robert](https://avatars.discourse-cdn.com/v4/letter/d/8e7dd6/32.png) [@dude\_robert](https://boards.straightdope.com/u/dude_robert)\ **Post date:** [June 2, 2017, 12:29am UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/7 "2017-06-02T00:29:40Z")
But what will the shell actually damage the ship with, other than just putting a perfectly smooth but tiny hole in the hull and maybe coming out the other end and imbedding itself into a fishing boat? ---
**Author:** ![Chimera](https://avatars.discourse-cdn.com/v4/letter/c/8e8cbc/32.png) [@Chimera](https://boards.straightdope.com/u/Chimera)\ **Post date:** [June 2, 2017, 12:49am UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/8 "2017-06-02T00:49:19Z")
> [@mixdenny](#): > > I dunno, the last I heard they currently throw a 50-70 lb projectile at a 20-25% increase in velocity over similar sized conventional rounds. Nice, but nothing really revolutionary. And power requirements increase exponentially. > > Dennis 75mm L/40 (M3/M6) Muzzle Velocity: 618 m/s (2,030 ft/s) (2224 km/h) Railgun 8,600 km/h So almost 4 times faster. ---
**Author:** ![drewder](https://avatars.discourse-cdn.com/v4/letter/d/57b2e6/32.png) [@drewder](https://boards.straightdope.com/u/drewder)\ **Post date:** [June 2, 2017, 12:55am UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/9 "2017-06-02T00:55:08Z")
Being able to shoot incoming artillery and rockets out of the sky is a big plus. Sent from my SM-G955U using Tapatalk ---
**Author:** ![Chimera](https://avatars.discourse-cdn.com/v4/letter/c/8e8cbc/32.png) [@Chimera](https://boards.straightdope.com/u/Chimera)\ **Post date:** [June 2, 2017, 1:01am UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/10 "2017-06-02T01:01:07Z")
> [@dude\_robert](#): > > But what will the shell actually damage the ship with, other than just putting a perfectly smooth but tiny hole in the hull and maybe coming out the other end and imbedding itself into a fishing boat? At these speeds and energies, the metal is going to flow away from the impact like water. Besides the fact that 100 miles is over the horizon and it won’t be coming at them straight on, but on a more ballistic course. So even if it punched cleanly through the metal, the moment the shell hits the water, bye bye. (hitting water at high speed is kind of like running into solid rock) ---
**Author:** ![Okrahoma](https://avatars.discourse-cdn.com/v4/letter/o/90db22/32.png) [@Okrahoma](https://boards.straightdope.com/u/Okrahoma)\ **Post date:** [June 2, 2017, 2:00am UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/11 "2017-06-02T02:00:54Z")
> [@dude\_robert](#): > > But what will the shell actually damage the ship with, other than just putting a perfectly smooth but tiny hole in the hull and maybe coming out the other end and imbedding itself into a fishing boat? In the video, the shell separated itself into shrapnel immediately before impact. That would probably transfer most of the kinetic energy into the explosion. ---
**Author:** ![Chimera](https://avatars.discourse-cdn.com/v4/letter/c/8e8cbc/32.png) [@Chimera](https://boards.straightdope.com/u/Chimera)\ **Post date:** [June 2, 2017, 2:09am UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/12 "2017-06-02T02:09:59Z")
[Rail gun in action](https://www.youtube.com/watch?v=uH9dWhrqIpQ) ---
**Author:** ![Projammer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/projammer/32/559_2.png) [@Projammer](https://boards.straightdope.com/u/Projammer)\ **Post date:** [June 2, 2017, 2:18am UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/13 "2017-06-02T02:18:37Z")
> [@dude\_robert](#): > > But what will the shell actually damage the ship with, other than just putting a perfectly smooth but tiny hole in the hull and maybe coming out the other end and imbedding itself into a fishing boat? More than making holes, it’s going to fill every compartment it passes through with shrapnel and/or plasma. ---
**Author:** ![Projammer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/projammer/32/559_2.png) [@Projammer](https://boards.straightdope.com/u/Projammer)\ **Post date:** [June 2, 2017, 2:25am UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/14 "2017-06-02T02:25:52Z")
Something occurs to me about targeting ships beyond the horizon. Since the projectile is purely ballistic, is it possible for the target to be below the flight path necessary to clear the horizon? If you have to discharge the projectile slower for it to fall enough to hit the target, how much energy are you losing in the v[SUP]2[/SUP] part of the equation? ---
**Author:** ![Okrahoma](https://avatars.discourse-cdn.com/v4/letter/o/90db22/32.png) [@Okrahoma](https://boards.straightdope.com/u/Okrahoma)\ **Post date:** [June 2, 2017, 2:43am UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/15 "2017-06-02T02:43:51Z")
> [@Projammer](#): > > Something occurs to me about targeting ships beyond the horizon. Since the projectile is purely ballistic, is it possible for the target to be below the flight path necessary to clear the horizon? If you have to discharge the projectile slower for it to fall enough to hit the target, how much energy are you losing in the v[SUP]2[/SUP] part of the equation? Wouldn’t the projectile speed have to be above escape velocity for your scenario to occur? ---
**Author:** ![Projammer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/projammer/32/559_2.png) [@Projammer](https://boards.straightdope.com/u/Projammer)\ **Post date:** [June 2, 2017, 2:46am UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/16 "2017-06-02T02:46:36Z")
Dunno. It’s been too many decades since high school and college physics. But I believe there are a couple of rocket surgeon members here. ---
**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\ **Post date:** [June 2, 2017, 3:30am UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/17 "2017-06-02T03:30:34Z")
> [@Chimera](#): > > 75mm L/40 (M3/M6) Muzzle Velocity: 618 m/s (2,030 ft/s) (2224 km/h) > > Railgun 8,600 km/h > > So almost 4 times faster. With 8x the energy. > [@Chimera](#): > > At these speeds and energies, the metal is going to flow away from the impact like water. Water the temperature and consistency of molten steel traveling at the speed of sound. ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [June 2, 2017, 3:32am UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/18 "2017-06-02T03:32:42Z")
I am not a rocket surgeon member but I know some things. If a shell fired _horizontal_ is going so fast that its rate of fall due to gravity matches the curvature of the Earth, it is in orbit. That’s what an orbit is. To achieve that, something has to be going around about 7.9km/sec Based on a figure given above, the railgun is only achieving 2.38km/sec, so this isn’t a concern. ---
**Author:** ![Tranquilis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tranquilis/32/3639_2.png) [@Tranquilis](https://boards.straightdope.com/u/Tranquilis)\ **Post date:** [June 2, 2017, 4:07pm UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/19 "2017-06-02T16:07:27Z")
> [@Okrahoma](#): > > In the video, the shell separated itself into shrapnel immediately before impact. That would probably transfer most of the kinetic energy into the explosion. A point here: That was one of two projectile types shown - the first was a solid penetrator, the second was the fragmenting projectile. If you look at the linked video, the first projectile hits the rack of steel sheets, and the slow-motion portion show the cloud of glowing fragments and plasma in the first two cells, then each remaining cell gets additional bursts of plasma at the point of penetration, then there’s a final burst of flame briefly visible in the trap structure. That fragmentation and plasma represents an extreme fire hazard, as well as secondary missile hazzards. The first two spaces, in a real ship, would’ve been wrecked AND on fire. Additional spaces beyong would merely be on fire. Not mentioning any equipment that might be struck. ---
**Author:** ![Projammer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/projammer/32/559_2.png) [@Projammer](https://boards.straightdope.com/u/Projammer)\ **Post date:** [June 2, 2017, 9:18pm UTC](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825/20 "2017-06-02T21:18:34Z")
> [@Princhester](#): > > I am not a rocket surgeon member but I know some things. If a shell fired _horizontal_ is going so fast that its rate of fall due to gravity matches the curvature of the Earth, it is in orbit. That’s what an orbit is. To achieve that, something has to be going around about 7.9km/sec > > Based on a figure given above, the railgun is only achieving 2.38km/sec, so this isn’t a concern. That sounds right. So to hit a target beyond the horizon we’d have to ‘lob’ the projectile onto it anyway. At least until we hit the 7.9km/sec number and it just follows the curve. 🙂 [Next page](https://boards.straightdope.com/t/how-much-will-a-naval-railgun-improve-a-ships-performance/787825.md?page=2)