“Some people call it super gun. I’m OK with that,”
July 10, 2014 4:39 PM Subscribe
The U.S. Navy has just unveiled two rail-gun prototypes that it will be testing in 2016. [video]
Capable of firing a comparatively inexpensive $25,000 kinetic projectile at speeds between 4,500 mph to 5,600 mph over a hundred and ten miles. The guns use energy from the ship itself, and to fire, produce a force that could propel an entire freight train through a wall at 100 miles per hour.
Railguns have long been the stuff of science fiction stories, but there have been amature builds over the years.
Capable of firing a comparatively inexpensive $25,000 kinetic projectile at speeds between 4,500 mph to 5,600 mph over a hundred and ten miles. The guns use energy from the ship itself, and to fire, produce a force that could propel an entire freight train through a wall at 100 miles per hour.
Railguns have long been the stuff of science fiction stories, but there have been amature builds over the years.
One of the current problems is the barrel wears out very quickly, which is much more expensive to replace. Still a demonstration and proof of concept.
posted by stbalbach at 4:48 PM on July 10, 2014
posted by stbalbach at 4:48 PM on July 10, 2014
Do we know if it actually works? I mean obviously they've fired it, but have they actually been able to shoot something out of the sky?
posted by dejah420 at 4:51 PM on July 10, 2014
posted by dejah420 at 4:51 PM on July 10, 2014
Probably a good weapon to protect Seoul from North Korea artillery?
posted by surplus at 4:55 PM on July 10, 2014
posted by surplus at 4:55 PM on July 10, 2014
I couldn't find anything that suggested that they had used it successfully that way, which, I suppose, could mean that it's classified, but I figured it more likely that the person talking about how we were going to use it was providing a bit of marketing.
The fire control to make this projectile hit that target is probably going to be a whole separate project for the Navy, but I thought that just the facts about the pure energy that these produce was interesting enough.
posted by quin at 4:57 PM on July 10, 2014 [1 favorite]
The fire control to make this projectile hit that target is probably going to be a whole separate project for the Navy, but I thought that just the facts about the pure energy that these produce was interesting enough.
posted by quin at 4:57 PM on July 10, 2014 [1 favorite]
I would think it would be almost IMPOSSIBLE to aim a small projectile (with no guidance capability), going Mach 7.5, from a moving ship in rocking waves, at a missile doing Mach 2-4, which may be maneuvering slightly due to air currents or programming.
I'm assuming the projectile costs $25K because the specifications have to be SOOOO perfect....not because it has any guidance capability.
In the end, I'm betting "operational by 2018" is about 5-10 years off the mark.
posted by whatgorilla at 5:01 PM on July 10, 2014
I'm assuming the projectile costs $25K because the specifications have to be SOOOO perfect....not because it has any guidance capability.
In the end, I'm betting "operational by 2018" is about 5-10 years off the mark.
posted by whatgorilla at 5:01 PM on July 10, 2014
How would you aim it? It's huge!
posted by Uncle Grumpy at 5:02 PM on July 10, 2014
posted by Uncle Grumpy at 5:02 PM on July 10, 2014
“This will give us an advantage over our adversaries and our partner’s adversaries that want to do some damage to our country, our security.”
Well, it's about damn time we had a military advantage. Finally.
posted by orme at 5:04 PM on July 10, 2014 [25 favorites]
Well, it's about damn time we had a military advantage. Finally.
posted by orme at 5:04 PM on July 10, 2014 [25 favorites]
Great quote from the video linked by stbalbach:
"[...] won't replace missiles, but the cost is about a fraction of the money."
About? Really?
posted by Verg at 5:06 PM on July 10, 2014 [11 favorites]
"[...] won't replace missiles, but the cost is about a fraction of the money."
About? Really?
posted by Verg at 5:06 PM on July 10, 2014 [11 favorites]
"It can shoot down ballistic missiles, it can shoot down very advanced cruise missiles, it can shoot down fast moving aircraft, it's extremely safe."
Well, not safe for the people in the aircraft, but YMMV.
posted by Joey Michaels at 5:07 PM on July 10, 2014 [3 favorites]
Well, not safe for the people in the aircraft, but YMMV.
posted by Joey Michaels at 5:07 PM on July 10, 2014 [3 favorites]
Well, a Patriot missile costs about $2.5M a pop, but the guidance and support structure is fairly cheap comparatively speaking. Even the newer TOW anti-tank missiles are about $60K and Javelins are $80K, so $25K is peanuts after you pay for the actual gun and barrels.
posted by whatgorilla at 5:12 PM on July 10, 2014 [1 favorite]
posted by whatgorilla at 5:12 PM on July 10, 2014 [1 favorite]
The sabot makes sense, and it looks like they are giving it a chemical kick.
posted by poe at 5:13 PM on July 10, 2014
posted by poe at 5:13 PM on July 10, 2014
how would that work?
If it hits the mortar, the mortar explodes before landing on the city?
So, if it can be aimed via an Aegis-like system, then maybe?
posted by surplus at 5:14 PM on July 10, 2014
If it hits the mortar, the mortar explodes before landing on the city?
So, if it can be aimed via an Aegis-like system, then maybe?
posted by surplus at 5:14 PM on July 10, 2014
Great quote from the video linked by stbalbach:
"[...] won't replace missiles, but the cost is about a fraction of the money."
About? Really?
Hah. Great catch.
posted by clockzero at 5:15 PM on July 10, 2014 [1 favorite]
"[...] won't replace missiles, but the cost is about a fraction of the money."
About? Really?
Hah. Great catch.
posted by clockzero at 5:15 PM on July 10, 2014 [1 favorite]
"Probably a good weapon to protect Seoul from North Korea artillery?"
-- if you had an aiming system that could detect incoming NK artillery shells, plot their trajectory, aim the rail gun, and get off a shot, you could theoretically shoot down their artillery (which supposedly NK has a ton of, hidden in the mountains along the border--and evidently they can reach Seoul). I'd think it would take a 155mm shell about 3-4 minutes to reach Seoul, 35 miles away.....so that's a lot of time to shoot it down.
posted by whatgorilla at 5:19 PM on July 10, 2014 [1 favorite]
-- if you had an aiming system that could detect incoming NK artillery shells, plot their trajectory, aim the rail gun, and get off a shot, you could theoretically shoot down their artillery (which supposedly NK has a ton of, hidden in the mountains along the border--and evidently they can reach Seoul). I'd think it would take a 155mm shell about 3-4 minutes to reach Seoul, 35 miles away.....so that's a lot of time to shoot it down.
posted by whatgorilla at 5:19 PM on July 10, 2014 [1 favorite]
It's actually a percentage of the cost, but they didn't want to confuse people with a lot of technical jargon, so - "about a fraction."
Also, "It can even go over 110 miles to support our Marines and soliders on the ground." Those soliders need all the help they can get.
posted by Kirth Gerson at 5:20 PM on July 10, 2014
Also, "It can even go over 110 miles to support our Marines and soliders on the ground." Those soliders need all the help they can get.
posted by Kirth Gerson at 5:20 PM on July 10, 2014
I'd rather have an A-10 giving me support than someone shooting danger close to me from 100 miles away. Of course, $25K is only 250rds from an A-10, though that will do an awful lot of damage (unless the marines need support attacking something with 10ft thick steel walls or something).
posted by whatgorilla at 5:23 PM on July 10, 2014 [2 favorites]
posted by whatgorilla at 5:23 PM on July 10, 2014 [2 favorites]
It won't be operational until the projectile cost is big enough to blow holes in a peace dividend (if peace should ever break out).
posted by srboisvert at 5:37 PM on July 10, 2014 [1 favorite]
posted by srboisvert at 5:37 PM on July 10, 2014 [1 favorite]
Waiting for the unveiling of the prototype portal gun.
posted by Wolfdog at 5:38 PM on July 10, 2014 [1 favorite]
posted by Wolfdog at 5:38 PM on July 10, 2014 [1 favorite]
I would think it would be almost IMPOSSIBLE to aim a small projectile (with no guidance capability), going Mach 7.5, from a moving ship in rocking waves, at a missile doing Mach 2-4, which may be maneuvering slightly due to air currents or programming.
Watch videos of modern tanks in action. The main gun can hold steady on a target even while driving by it sideways, over rough terrain. The tank is going up and down every which way with the terrain, and the barrel of the gun is rock solid. We already have this; it's not a stretch to adapt it to railguns on a ship.
posted by xedrik at 5:39 PM on July 10, 2014 [4 favorites]
Watch videos of modern tanks in action. The main gun can hold steady on a target even while driving by it sideways, over rough terrain. The tank is going up and down every which way with the terrain, and the barrel of the gun is rock solid. We already have this; it's not a stretch to adapt it to railguns on a ship.
posted by xedrik at 5:39 PM on July 10, 2014 [4 favorites]
I'd prefer the money be spent on designing a light rail gun that could implant mass transit in crowded and congested cities from over 100 miles away. That would be handy.
posted by GenjiandProust at 5:42 PM on July 10, 2014 [34 favorites]
posted by GenjiandProust at 5:42 PM on July 10, 2014 [34 favorites]
Well, that's my commuting problem solved.
posted by arcticseal at 5:43 PM on July 10, 2014 [1 favorite]
posted by arcticseal at 5:43 PM on July 10, 2014 [1 favorite]
I thought the tricky bit of shooting down missiles with previous systems was hitting the, relatively, small and fast moving target. Has that been overcome?
posted by calamari kid at 5:45 PM on July 10, 2014
posted by calamari kid at 5:45 PM on July 10, 2014
Sigh. If only we'd use this technology for space exploration, but it seems we only wish to listen to Reason.
posted by sourwookie at 5:54 PM on July 10, 2014 [7 favorites]
posted by sourwookie at 5:54 PM on July 10, 2014 [7 favorites]
This is a very complicated way to blow up a few Somali speed boats.
posted by humanfont at 6:00 PM on July 10, 2014 [4 favorites]
posted by humanfont at 6:00 PM on July 10, 2014 [4 favorites]
Jesus, $25,000 per shot. I have no idea how to follow that sentence with anything that isn't a really angry derail.
posted by middleclasstool at 6:12 PM on July 10, 2014 [3 favorites]
posted by middleclasstool at 6:12 PM on July 10, 2014 [3 favorites]
First rail gun, next Gundams. Don't worry, space isn't too far away.
posted by Atreides at 6:13 PM on July 10, 2014 [1 favorite]
posted by Atreides at 6:13 PM on July 10, 2014 [1 favorite]
What is the power required per shot? Recharge time? The article mentions putting these on cruisers and destroyers. How are these conventionally powered ships going to generate that much electricity? The US no longer has any nuclear cruisers, remember.
And, as mentioned above, I'm not even touching the targeting issues.
posted by InsertNiftyNameHere at 6:15 PM on July 10, 2014
And, as mentioned above, I'm not even touching the targeting issues.
posted by InsertNiftyNameHere at 6:15 PM on July 10, 2014
Prepare to fire the wave motion gun.
posted by LastOfHisKind at 6:19 PM on July 10, 2014 [2 favorites]
posted by LastOfHisKind at 6:19 PM on July 10, 2014 [2 favorites]
HOLY SHIT MY DAD MADE METAFILTER
THESE ARE HIS GUNS
posted by robocop is bleeding at 6:30 PM on July 10, 2014 [41 favorites]
THESE ARE HIS GUNS
posted by robocop is bleeding at 6:30 PM on July 10, 2014 [41 favorites]
I'm really happy to see this go off. Growing up, we went from the lightning gun, to Reagan Star Wars space guns, to plasma guns, to rail guns. I tried to talk him into doing an AMA, but realized I'd need to be there to translate Mechwarrior-to-English for him.
posted by robocop is bleeding at 6:39 PM on July 10, 2014 [1 favorite]
posted by robocop is bleeding at 6:39 PM on July 10, 2014 [1 favorite]
His dad makes railguns, and his son is excited about him being on Metafilter.
Kids....
posted by dglynn at 6:39 PM on July 10, 2014 [10 favorites]
Kids....
posted by dglynn at 6:39 PM on July 10, 2014 [10 favorites]
The fact I have not made a device capable of leveling a hardened bunker is a constant source of disappointment at Thanksgiving dinner. "I'm not like you, Dad!" I sob as I pick out meat bits from my hair. "Maybe the Turklerometer is the best I can do! Why can't you be happy for me??!!" I then wail and try to storm out through the turkey-shaped hole in the wall.
posted by robocop is bleeding at 6:43 PM on July 10, 2014 [37 favorites]
posted by robocop is bleeding at 6:43 PM on July 10, 2014 [37 favorites]
I looked up the speed of the Iron Dome's Tamir interceptor missile, and allegedly it peaks at Mach 2.2. If a railgun can fire a projectile at Mach 7.5, the speed difference may be enough to compensate for the lack of flight control.
posted by rosswald at 6:49 PM on July 10, 2014
posted by rosswald at 6:49 PM on July 10, 2014
"Reason", aka, "Ultima Ratio Regum".
(i did an image search for "reason railgun" and it mostly showed me scantily-clad anime schoolgirls. No idea what's up with that)
posted by sourwookie at 7:03 PM on July 10, 2014 [2 favorites]
(i did an image search for "reason railgun" and it mostly showed me scantily-clad anime schoolgirls. No idea what's up with that)
posted by sourwookie at 7:03 PM on July 10, 2014 [2 favorites]
The idea of a superweapon as ultimate deterrent goes back ages. (One of the best books on the topic: War Stars: The Superweapon and the American Imagination by H. Bruce Franklin)
Given the state of affairs, I'm pretty sure it will never work as advertised, but it will make a neat hole in a thing.
posted by fifteen schnitzengruben is my limit at 7:06 PM on July 10, 2014
Given the state of affairs, I'm pretty sure it will never work as advertised, but it will make a neat hole in a thing.
posted by fifteen schnitzengruben is my limit at 7:06 PM on July 10, 2014
Having been a kid during the Reagan Star Wars/SDI late-stage Cold War era, there's a part of my brain that's all IT'S HAPPENING
posted by the painkiller at 7:16 PM on July 10, 2014 [1 favorite]
posted by the painkiller at 7:16 PM on July 10, 2014 [1 favorite]
His dad makes railguns, and I'm excited to find out they made a live-action Space Battleship Yamato movie.
posted by straight at 7:42 PM on July 10, 2014 [3 favorites]
posted by straight at 7:42 PM on July 10, 2014 [3 favorites]
How are these conventionally powered ships going to generate that much electricity?
Most modern naval ships have hybrid propulsion. Big turbine generators creating electricity to power electric motors.
So probably you'd need to slow the ship down and max out the generators, putting the power into the firing system, if you wanted to put as many rounds downrange as quickly as you could.
posted by Kadin2048 at 7:47 PM on July 10, 2014 [2 favorites]
Most modern naval ships have hybrid propulsion. Big turbine generators creating electricity to power electric motors.
So probably you'd need to slow the ship down and max out the generators, putting the power into the firing system, if you wanted to put as many rounds downrange as quickly as you could.
posted by Kadin2048 at 7:47 PM on July 10, 2014 [2 favorites]
But the missiles it could potentially replace, while slower, are semi-autonomous after launch: capable of tracking and steering themselves after the moving targets. The Patriot missiles for instance used neural networks (as I understand it) to hunt down their fast moving targets. The railgun, though super fast, is ballistic once launched - isn't it? That would seem to make it unlikely that it could take out an incoming missile until it was very close.
posted by NailsTheCat at 7:51 PM on July 10, 2014
posted by NailsTheCat at 7:51 PM on July 10, 2014
No reason (aside from making it withstand the initial hard acceleration) why you can't launch something like a missile out of a gun tube. You get longer range because you aren't burning up onboard fuel just to accelerate from a standing start.
The US Navy experimented with a naval artillery / missile hybrid for the DD-X program. Originally it was designed to be fired directly upwards from the ship, with the rounds then maneuvering independently to their targets. No gun turrets required. It was eventually dropped from the DD-X but for reasons of cost, not because it was inherently unfeasible.
posted by Kadin2048 at 8:09 PM on July 10, 2014
The US Navy experimented with a naval artillery / missile hybrid for the DD-X program. Originally it was designed to be fired directly upwards from the ship, with the rounds then maneuvering independently to their targets. No gun turrets required. It was eventually dropped from the DD-X but for reasons of cost, not because it was inherently unfeasible.
posted by Kadin2048 at 8:09 PM on July 10, 2014
Maybe it is the teenage boy in me, but anytime I can fire a projectile at 7.5 mach then make it explode, I am pretty amazed.
posted by 724A at 8:20 PM on July 10, 2014
posted by 724A at 8:20 PM on July 10, 2014
Prepare to fire the wave motion gun.
The grizzled captain in that video has mastered the art of sitting rigidly while staring forward.
posted by cosmic.osmo at 8:28 PM on July 10, 2014
The grizzled captain in that video has mastered the art of sitting rigidly while staring forward.
posted by cosmic.osmo at 8:28 PM on July 10, 2014
No reason (aside from making it withstand the initial hard acceleration) why you can't launch something like a missile out of a gun tube.
That's a good point. Indeed, it may not need propellant at all: just the 'smarts' to find the target and standard (albeit hypersonic) control surfaces to steer.
posted by NailsTheCat at 8:30 PM on July 10, 2014
That's a good point. Indeed, it may not need propellant at all: just the 'smarts' to find the target and standard (albeit hypersonic) control surfaces to steer.
posted by NailsTheCat at 8:30 PM on July 10, 2014
No reason (aside from making it withstand the initial hard acceleration) why you can't launch something like a missile out of a gun tube.
Normally I wouldn't worry about magnetic fields affecting internal electronics, (and the projectile in a rail-gun is not driven by magnetic field) but at the scale of current shorting here, I assume there are some big electromagnetic effects and it may be the case that internal electronics would tap some of the magnetic field and fry themselves.
Clockwork guidance system? :-)
posted by anonymisc at 8:39 PM on July 10, 2014
Normally I wouldn't worry about magnetic fields affecting internal electronics, (and the projectile in a rail-gun is not driven by magnetic field) but at the scale of current shorting here, I assume there are some big electromagnetic effects and it may be the case that internal electronics would tap some of the magnetic field and fry themselves.
Clockwork guidance system? :-)
posted by anonymisc at 8:39 PM on July 10, 2014
How would you aim it? It's huge!
Actually it looks kinda small for naval artillery to me.
it looks like they are giving it a chemical kick
Stuff I'd seen elsewhere said the explosion from the barrel is plasma from the rails ablating. I've seen stuff saying that they use either chemical propellant or a gauss gun to shoot the round into the railgun proper because meow meow physics meow.
posted by ROU_Xenophobe at 8:42 PM on July 10, 2014 [4 favorites]
Actually it looks kinda small for naval artillery to me.
it looks like they are giving it a chemical kick
Stuff I'd seen elsewhere said the explosion from the barrel is plasma from the rails ablating. I've seen stuff saying that they use either chemical propellant or a gauss gun to shoot the round into the railgun proper because meow meow physics meow.
posted by ROU_Xenophobe at 8:42 PM on July 10, 2014 [4 favorites]
they use either chemical propellant or a gauss gun to shoot the round into the railgun proper because meow meow physics meow.
...otherwise the current would instantly weld the projectile to the rails, and/or then proceed to vaporize the metal...
...which is not the desired outcome
:-)
posted by anonymisc at 8:46 PM on July 10, 2014 [5 favorites]
...otherwise the current would instantly weld the projectile to the rails, and/or then proceed to vaporize the metal...
...which is not the desired outcome
:-)
posted by anonymisc at 8:46 PM on July 10, 2014 [5 favorites]
According to the Wikipedia page about railguns, the magnetic field is about 10 Tesla, more than enough to take out all but the most carefully constructed of electronics devices... that coupled with the insane amount of heat and acceleration involved lead me to conclude that the projectile is just there for its inertia.
posted by MikeWarot at 9:07 PM on July 10, 2014
posted by MikeWarot at 9:07 PM on July 10, 2014
Indeed, it may not need propellant at all: just the 'smarts' to find the target and standard (albeit hypersonic) control surfaces to steer.
Indeed.
Making electronics withstand 10T of flux is a pretty interesting challenge, though. I'd imagine that would be...unpleasant... on a GPS antenna.
posted by Kadin2048 at 9:16 PM on July 10, 2014
Indeed.
Making electronics withstand 10T of flux is a pretty interesting challenge, though. I'd imagine that would be...unpleasant... on a GPS antenna.
posted by Kadin2048 at 9:16 PM on July 10, 2014
GPS probably wouldn't do you much good at these speeds. It hits its target in a little over a minute (if it is 100 miles away).
posted by eye of newt at 10:43 PM on July 10, 2014
posted by eye of newt at 10:43 PM on July 10, 2014
I wanted to build an electromagnetic rail gun so bad as a teenager, so this makes me happy.
posted by ob1quixote at 12:06 AM on July 11, 2014
posted by ob1quixote at 12:06 AM on July 11, 2014
Look - unless it produces a spiral trail from the projectile everyone involved is wasting their time.
posted by GallonOfAlan at 12:36 AM on July 11, 2014 [3 favorites]
posted by GallonOfAlan at 12:36 AM on July 11, 2014 [3 favorites]
Not dirigible mounted and no props to Gibson. Your rail gun is invalid.
posted by digitalprimate at 12:43 AM on July 11, 2014
posted by digitalprimate at 12:43 AM on July 11, 2014
This is perfectly calculated to split my personality between the one that thinks more big guns are the last thing we need and the one that thinks this is way cool.
posted by Segundus at 1:36 AM on July 11, 2014 [3 favorites]
posted by Segundus at 1:36 AM on July 11, 2014 [3 favorites]
> Making electronics withstand 10T of flux is a pretty interesting challenge, though.
Use old-fashioned hand wiring and tubes rather than integrated circuits.
It severely limits circuit complexity, of course.
posted by ardgedee at 4:26 AM on July 11, 2014
Use old-fashioned hand wiring and tubes rather than integrated circuits.
It severely limits circuit complexity, of course.
posted by ardgedee at 4:26 AM on July 11, 2014
Railguns and laser canon will be deployed before the end of the decade, and probably fired in anger not long after. It's the end of air superiority fighters. Hell, it's probably the end of chemical artillery (rockets and missiles included.)
It does create an interesting new "anti-railgun railgun" windmill to tilt at. Satellite Defense is going to be A Thing, and it will be impossible for a while. Good news for private space contractors - lots of business sending up new birds to replace the ones shot down in various border skirmishes.
posted by Slap*Happy at 5:11 AM on July 11, 2014
It does create an interesting new "anti-railgun railgun" windmill to tilt at. Satellite Defense is going to be A Thing, and it will be impossible for a while. Good news for private space contractors - lots of business sending up new birds to replace the ones shot down in various border skirmishes.
posted by Slap*Happy at 5:11 AM on July 11, 2014
I love military hardware. I'm not so fond of the applications, but the hardware is just fantastic. It is designed, to ridiculously exacting specifications, to do one particular task extremely well. Better, it occasionally has use outside the killing people and blowing stuff up fields!
Besides, railguns are a nifty technology.
@sourwookie, probably you got the scantily clad schoolgirls because there's an anime titled "A Certain Scientific Railgun" that apparently involves scantily clad schoolgirls (though apparently not railguns in anything but a very loose sense).
posted by sotonohito at 6:18 AM on July 11, 2014
Besides, railguns are a nifty technology.
@sourwookie, probably you got the scantily clad schoolgirls because there's an anime titled "A Certain Scientific Railgun" that apparently involves scantily clad schoolgirls (though apparently not railguns in anything but a very loose sense).
posted by sotonohito at 6:18 AM on July 11, 2014
I wonder if the anti-missile angle is posited on some kinda flak approach where the projectile itself fragments, or its a very tough envelope that falls apart after firing, throwing up a debris field?
posted by Mister_A at 7:09 AM on July 11, 2014
posted by Mister_A at 7:09 AM on July 11, 2014
I would think it would be almost IMPOSSIBLE to aim a small projectile (with no guidance capability), going Mach 7.5, from a moving ship in rocking waves, at a missile doing Mach 2-4, which may be maneuvering slightly due to air currents or programming.
Arstechnica did a write up on fire control computers. Highly interesting reading, especially if you've ever done enough mechanical and electrical engineering math to understand the symmetry between the two fields.
Needless to say, the ballistic aiming problem has been long solved.
posted by Pogo_Fuzzybutt at 7:49 AM on July 11, 2014
Arstechnica did a write up on fire control computers. Highly interesting reading, especially if you've ever done enough mechanical and electrical engineering math to understand the symmetry between the two fields.
Needless to say, the ballistic aiming problem has been long solved.
posted by Pogo_Fuzzybutt at 7:49 AM on July 11, 2014
10T of flux would do bad things even to mechanical computers, unless they were built entirely using plastic or something. You'd have eddy currents strong enough to weld the parts together, I suspect. Something entirely optical would work, I suppose.
The only interesting solution I could come up with was put all the electronics inside a Mu-metal capsule to shield it from the field, with all electrical connections physically air-gapped from the sensors and stuff outside the capsule with strong dielectrics that you remove mechanically when the sabot discards. Wouldn't give you a lot of time to power everything on and start working, though.
I am now curious how those GPS-guided Excalibur shells get a satellite lock during their brief flight downrange. I wonder if the GPS receiver needs to be "primed" before firing so that it doesn't have to do a complete cold-start. I've never seen a receiver do a complete cold-start in less than about a minute, even the really high-end surveying receivers. That's a pretty good trick the more I think about it.
posted by Kadin2048 at 9:38 AM on July 11, 2014 [1 favorite]
The only interesting solution I could come up with was put all the electronics inside a Mu-metal capsule to shield it from the field, with all electrical connections physically air-gapped from the sensors and stuff outside the capsule with strong dielectrics that you remove mechanically when the sabot discards. Wouldn't give you a lot of time to power everything on and start working, though.
I am now curious how those GPS-guided Excalibur shells get a satellite lock during their brief flight downrange. I wonder if the GPS receiver needs to be "primed" before firing so that it doesn't have to do a complete cold-start. I've never seen a receiver do a complete cold-start in less than about a minute, even the really high-end surveying receivers. That's a pretty good trick the more I think about it.
posted by Kadin2048 at 9:38 AM on July 11, 2014 [1 favorite]
Use old-fashioned hand wiring and tubes rather than integrated circuits.
I'd think that would make the problem worse - then not only are you dealing with tubes that are directly affected by external magnetic fields, and cannot withstand acceleration without disintegrating, but also analogue circuitry where any kind of precision comes from minimizing all the electromagnetically induced current slopping around everywhere, not cranking it up to eleven million.
Perhaps a mechanical solution? If an unwired chip can survive (and even that might be a lot to ask), perhaps the circuitry can be mechanically connected after launch? Coils are broken until after the fields die down, etc. It'd blow that $25,000 budget like... well like a rail gun, and I wouldn't want to be in charge of reliability...
posted by anonymisc at 9:49 AM on July 11, 2014
I'd think that would make the problem worse - then not only are you dealing with tubes that are directly affected by external magnetic fields, and cannot withstand acceleration without disintegrating, but also analogue circuitry where any kind of precision comes from minimizing all the electromagnetically induced current slopping around everywhere, not cranking it up to eleven million.
Perhaps a mechanical solution? If an unwired chip can survive (and even that might be a lot to ask), perhaps the circuitry can be mechanically connected after launch? Coils are broken until after the fields die down, etc. It'd blow that $25,000 budget like... well like a rail gun, and I wouldn't want to be in charge of reliability...
posted by anonymisc at 9:49 AM on July 11, 2014
HOLY SHIT MY DAD MADE METAFILTER
THESE ARE HIS GUNS
Note to self: don't get into any heated arguments with robocop is bleeding.
posted by yoink at 10:15 AM on July 11, 2014 [1 favorite]
THESE ARE HIS GUNS
Note to self: don't get into any heated arguments with robocop is bleeding.
posted by yoink at 10:15 AM on July 11, 2014 [1 favorite]
I am now curious how those GPS-guided Excalibur shells get a satellite lock during their brief flight downrange. I wonder if the GPS receiver needs to be "primed" before firing so that it doesn't have to do a complete cold-start.
Almost certainly. Most GPS startup time consists of waiting to receive initialization data from the satellites at 50 bits per second. If you already have that data from a different source, then you don't have to wait and can get a fix right away. Cell phones already do this with with aGPS.
posted by cosmic.osmo at 2:04 PM on July 11, 2014
Almost certainly. Most GPS startup time consists of waiting to receive initialization data from the satellites at 50 bits per second. If you already have that data from a different source, then you don't have to wait and can get a fix right away. Cell phones already do this with with aGPS.
posted by cosmic.osmo at 2:04 PM on July 11, 2014
GPS-guided Excalibur
The M982 needs to have guidance because it is not purely ballistic - it uses fins to increase range. This rail gun is purely ballistic and fire control in those situations is a well understood science.
That said, as you point out, there isn't any real chance for guidance aboard the projectile so, the error bound on fire control will be as good as it gets. Although, I suspect for a munition like this, the error bound will be some approximation the effect radius, so it might not matter much.
posted by Pogo_Fuzzybutt at 2:14 PM on July 11, 2014
The M982 needs to have guidance because it is not purely ballistic - it uses fins to increase range. This rail gun is purely ballistic and fire control in those situations is a well understood science.
That said, as you point out, there isn't any real chance for guidance aboard the projectile so, the error bound on fire control will be as good as it gets. Although, I suspect for a munition like this, the error bound will be some approximation the effect radius, so it might not matter much.
posted by Pogo_Fuzzybutt at 2:14 PM on July 11, 2014
I'm not a physicist or engineer, but it seems like even a near miss of a projectile doing Mach 7.5 would be enough to seriously disrupt a missile or artillery shell going Mach 4. I don't know that you'd want to be anywhere close to underneath the intersection, but that probably applies on a direct hit, too.
posted by Caduceus at 4:02 PM on July 11, 2014
posted by Caduceus at 4:02 PM on July 11, 2014
Someone uptopic was apparently outraged that this would cost $25K to fire, but aren't other munitions of comparable destructive yield significantly more expensive?
posted by uberchet at 5:23 PM on July 11, 2014
posted by uberchet at 5:23 PM on July 11, 2014
"it's not a stretch to adapt it to railguns on a ship."
--I'll check out the article on ballistic aiming, but comparing a tank shooting at non-moving targets (or those going a maximum of 50mph), is a lot different than those going over Mach 2 with a projectile going over Mach 7.5. All a ballistic missile has to do is have a program that moves it in a random direction by 5ft every 15-20 seconds and this thing can't hit it.
posted by whatgorilla at 10:21 AM on July 12, 2014
--I'll check out the article on ballistic aiming, but comparing a tank shooting at non-moving targets (or those going a maximum of 50mph), is a lot different than those going over Mach 2 with a projectile going over Mach 7.5. All a ballistic missile has to do is have a program that moves it in a random direction by 5ft every 15-20 seconds and this thing can't hit it.
posted by whatgorilla at 10:21 AM on July 12, 2014
I thought this was really cool until I realized the distance the projectile will travel if it missed its target.
Over the ocean it is less likely to hit something important, like friendliest, over land, not so much.
posted by Gadgetenvy at 10:59 AM on July 13, 2014
Over the ocean it is less likely to hit something important, like friendliest, over land, not so much.
posted by Gadgetenvy at 10:59 AM on July 13, 2014
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posted by stbalbach at 4:45 PM on July 10, 2014