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Concordat posted:I'm just under the impression that intercepting ballistic missiles is really, really hard. Even with super fast projectiles. The Sprint missile goes about as fast as railgun projectiles, doesn't it? poo poo, they're looking at using precision guided hyper velocity shells fired out of 155mm cannons to do missile defense. If this works, it is a massive money-saver for point defense vs firing THAAD or Patriot interceptors.
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Jul 14, 2016 22:22
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xthetenth posted:Does a 9X have that much range when coming from a stationary ground platform? You can look at the MICA which exists in both air-launched and VL versions. Service range is up to 50 km for air-launched, up to 20 km for truck-or-ship-launched.  
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Jul 14, 2016 22:57
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Concordat posted:I'm just under the impression that intercepting ballistic missiles is really, really hard. Even with super fast projectiles. The Sprint missile goes about as fast as railgun projectiles, doesn't it? In the same ballpark, since we're talking hypersonic speeds. But computers and tracking are a bit more advanced than they were in the 1960s. Not saying it's easy, but it's a solvable problem.
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Jul 14, 2016 23:07
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MrYenko posted:A conventional rifle/cannon cartridge is somewhere between the two. The impulse is strongest at ignition, and tapers off as the projectile moves down the barrel, since the volume available for the gun gas to expand into is growing. With a rail gun, it is a constant acceleration, all the way down the barrel. (Though I'm sure you can fiddle with that and adjust acceleration rated along the barrel if you wanted to.) I really doubt it's constant acceleration. The acceleration is fundamentally the interaction between the current passing through the armature and the magnetic field created by the passage of that current, so acceleration is only going to be constant if current is constant. Capacitors don't discharge linearly, the exact falloff depents on the time constant for that cap but it's a logarithmic falloff, not linear at all; if they were doing something like starting to discharge the cap in a secondary circuit and then shunting the output to the projectile when the cap is in the more linear portion of its discharge cycle, okay, but there's no reason I can think of that they'd want to do that. Then there are second order effects, as arcing occurs and changes the resistance across the armature. If you were using a big magnetohomopolar generator or something like that, you could get a more linear current flow but I don't think that's what that Navy gun uses.
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Jul 14, 2016 23:14
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Godholio posted:In the same ballpark, since we're talking hypersonic speeds. But computers and tracking are a bit more advanced than they were in the 1960s. Not saying it's easy, but it's a solvable problem. You also probably wouldn't only be using one projectile. To get into full blown air defense capable you would want multiple projectiles, which means either figuring out how to do very rapid fire, how to fire multiple projectiles at once, or just stacking a bunch of barrels together. Think more hypersonic shotgun than hypersonic rifle. THen you have to think about what your intercept rate is, which means different things depending on what you want it to do. Not every system has to knock down everything all the time. Say it's only 30%. That's not ideal if you're parking one in Tel Aviv to keep mortars out of people's backyards, but it's a pretty good start if you want to put a few hundred of them in the suburbs of Seoul to blunt the effect of a N. Korean rocket artillery barrage. Cyrano4747 fucked around with this message at 23:22 on Jul 14, 2016 |
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Jul 14, 2016 23:17
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Cyrano4747 posted:but it's a pretty good start if you want to put a few hundred of them in the suburbs of Seoul to blunt the effect of a N. Korean rocket artillery barrage. Best Pink Floyd Laser Light show ever.
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Jul 14, 2016 23:19
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Cyrano4747 posted:You also probably wouldn't only be using one projectile. To get into full blown air defense capable you would want multiple projectiles, which means either figuring out how to do very rapid fire, how to fire multiple projectiles at once, or just stacking a bunch of barrels together. Think more hypersonic shotgun than hypersonic rifle. I agree completely, but we were talking about intercepting ballistic missiles. Those attacks are generally not as saturating as tube or rocket artillery.
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Jul 14, 2016 23:23
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Slamburger posted:I thought conventional bullets accelerated the entire time they were in the barrel, hence why adding barrel length (up to a limit) increases muzzle velocity. Losing acceleration isn't loosing speed! You can still accelerate, just less than before. Say your speed goes from 0 to 100 to 180. At first, you accelerated by 100, then you accelerated only by 80, that's a loss of acceleration (20 less than before), but still an increase in speed.
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Jul 14, 2016 23:25
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Koesj posted:The most impressive part is where it was wholly written by a goon and still it's pretty great. this is a really good short story, you all should read it Mazz posted:Also this crazy poo poo by Boeing, basically slapping everything they can onto an Avenger turret: lol this was my GI Joe-esque vehicle I mentioned earlier
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Jul 15, 2016 01:31
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iyaayas01 posted:lol this was my GI Joe-esque vehicle I mentioned earlier 
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Jul 15, 2016 01:35
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Phanatic posted:I really doubt it's constant acceleration. Those are some mighty fine hairs you're splitting. Yes, possibly whole nanoseconds are elapsing between periods of acceleration.
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Jul 15, 2016 01:41
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YYOOOOOOOOO JOOOOOOOOOEE it's pretty stupid that they're putting it on a truck though, needs to be on some impractically high mounted tracked vehicle for the best GI Joe effect
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Jul 15, 2016 01:52
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Murgos posted:Those are some mighty fine hairs you're splitting. Yes, possibly whole nanoseconds are elapsing between periods of acceleration. I'm not sure you get my meaning. You fire a conventional bullet, acceleration initially builds as the powder starts to combust but peaks rapidly and falls off as the bullet travels down the barrel, because the propellant gases are expanding and cooling and generating less pressure. Chamber pressure looks like this:  And acceleration is going to follow along with that chamber pressure. You fire a railgun by discharing a capacitor bank, the acceleration peaks rapidly and falls off as the capacitor discharges. Capacitors charge/discharge on a log curve, it looks like this:  Current through the projectile will go as the discharge voltage, acceleration will go as current. It's not splitting hairs if the point made was "With a rail gun, it is a constant acceleration, all the way down the barrel." It's not, it's no more constant than the acceleration of a conventional bullet. I don't know where you got me saying that there are periods of acceleration and spots between them where time's elapsing. Phanatic fucked around with this message at 02:20 on Jul 15, 2016 |
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Jul 15, 2016 02:14
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I've never understood why the key for smart ABM isn't super small nukes. Not the 5 kiloton to 1 megaton yields of old, but rather ones with something like .01 kiloton yields. I know adding a warhead creates political and treaty concerns and higher cost as well as adds a layer of PAL complexity, but it'd make a near-miss still a kill, either by explosive effect or neutron flux. In a mass exchange, no level of ABM is going to stop even 10% of your incoming, but against a North Korean missile which surely won't have quasiballistic or course-changing abilities, it'd be almost a guaranteed intercept, and a nuclear detonation, even a .01 kiloton one, would be enough to destroy and render harmless a chemical or biological payload as well. The ABM Treaty is already toast, so why not?
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Jul 15, 2016 02:26
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Is the whole capacitor bank discharging at once? It seems like you'd want to stagger it to keep the acceleration up. Edit: I think those warheads would be seen as highly destabilizing.
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Jul 15, 2016 02:30
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Godholio posted:Is the whole capacitor bank discharging at once? It seems like you'd want to stagger it to keep the acceleration up. I believe the whole reason something like a coilgun works to get such crazy speeds is that you basically activate one set of magnets ahead of the projectile, pulling it forward, then you deactivate them and activate the next set of magnets to pull it even more. A railgun works by having positively and negatively charged rails and running a current through them, which creates a magnetic field behind the projectile that pushes it out.
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Jul 15, 2016 02:56
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BIG HEADLINE posted:I've never understood why the key for smart ABM isn't super small nukes. Not the 5 kiloton to 1 megaton yields of old, but rather ones with something like .01 kiloton yields. I know adding a warhead creates political and treaty concerns and higher cost as well as adds a layer of PAL complexity, but it'd make a near-miss still a kill, either by explosive effect or neutron flux. In a mass exchange, no level of ABM is going to stop even 10% of your incoming, but against a North Korean missile which surely won't have quasiballistic or course-changing abilities, it'd be almost a guaranteed intercept, and a nuclear detonation, even a .01 kiloton one, would be enough to destroy and render harmless a chemical or biological payload as well. You'd also be EMP'ing your own country / theatre of operations.
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Jul 15, 2016 03:10
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Godholio posted:Is the whole capacitor bank discharging at once? It seems like you'd want to stagger it to keep the acceleration up. What you want is to maximize current. The acceleration doesn't arise from current directly; the current creates a magnetic field and the interaction of that field and the current is what generates the Lorenz force on the projectile. I mean, you could stagger discharges of multiple capacitors to keep the current flow through the projectile more constant, but if you could do that you could *not* do that, and dump more current and achieve higher acceleration. You're trying to maximize muzzle energy, I'm not sure why you'd even bother trying to keep acceleration constant if it doesn't get you any more muzzle energy than starting at a higher acceleration and settling for the same average acceleration. chitoryu12 posted:I believe the whole reason something like a coilgun works to get such crazy speeds is that you basically activate one set of magnets ahead of the projectile, pulling it forward, then you deactivate them and activate the next set of magnets to pull it even more. A railgun works by having positively and negatively charged rails and running a current through them, which creates a magnetic field behind the projectile that pushes it out. Mostly right. The only bit that's wrong is that the magnetic field doesn't push on the projectile; if it did, you'd need a ferromagnetic projectile, but a railgun only needs a conductive one. The force accelerating the projectile is the Lorenz force arising from the *interaction* of the electric and magnetic fields. It's also trying to separate the rails from one another, which is why a railgun needs to be much more structurally robust than a coilgun. Phanatic fucked around with this message at 04:06 on Jul 15, 2016 |
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Jul 15, 2016 03:16
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That Works posted:You'd also be EMP'ing your own country / theatre of operations.
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Jul 15, 2016 03:42
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hobbesmaster posted:I was thinking more from a technical standpoint but point taken. One reason for not using Standard Missiles is the booster stage. SM-2 and SM-6 both have a booster stage. That works over water, where 99% of the time there's nothing for that stage to land on. Over land, that becomes a much dicer proposition. If you look at the S-300 / 400 family, those missiles are huge and don't have boosters. About ADATs, I read somewhere that it's command guidance, via laser grid, made the system practically immune to ECM. I think StarStreak uses a similar command guided launcher. If the US gets back into SHORAD in a big way, expect that the missiles will tend more towards that command guided system and less towards active homing. That type of guidance will be attractive in a high ECM / Cyber environment.
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Jul 15, 2016 04:22
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iyaayas01 posted:this is a really good short story, you all should read it And wash it down with a nice cold draft of http://www.drabblecast.org/2013/12/06/drabblecast-305-testimony-emergency-session-naval-cephalopod-command/
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Jul 15, 2016 05:58
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Already linked a few pages back.
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Jul 15, 2016 06:20
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BIG HEADLINE posted:I've never understood why the key for smart ABM isn't super small nukes. Not the 5 kiloton to 1 megaton yields of old, but rather ones with something like .01 kiloton yields. I know adding a warhead creates political and treaty concerns and higher cost as well as adds a layer of PAL complexity, but it'd make a near-miss still a kill, either by explosive effect or neutron flux. In a mass exchange, no level of ABM is going to stop even 10% of your incoming, but against a North Korean missile which surely won't have quasiballistic or course-changing abilities, it'd be almost a guaranteed intercept, and a nuclear detonation, even a .01 kiloton one, would be enough to destroy and render harmless a chemical or biological payload as well. At very low yield radiation effects are more prominent than blast or flash. Nuclear weapons don't scale down as well as conventional bombs.
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Jul 15, 2016 07:36
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Squid story was amazing. e: And Colder War was really really good. Reminded me of both http://www.scp-wiki.net/transcript-of-meeting-june-2-1972 and https://www.fanfiction.net/s/11780793/1/The-Legacy-of-the-Prophets Loel fucked around with this message at 11:02 on Jul 15, 2016 |
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Jul 15, 2016 10:32
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Loel posted:Squid story was amazing. Semi related: http://www.scp-wiki.net/transcript-of-telephone-conversation-august-9-1991 BIG HEADLINE fucked around with this message at 11:37 on Jul 15, 2016 |
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Jul 15, 2016 11:34
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Godholio posted:Why's it wishful thinking? If your projectile has the speed to intercept the target, the rest is just math. Slamburger posted:I thought conventional bullets accelerated the entire time they were in the barrel, hence why adding barrel length (up to a limit) increases muzzle velocity. I mean the phrase "moments after the gunpowder ignites" is extremely vague in this context but the point of the author seems to imply the bullet slows in the barrel in contrast to a railgun.
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Jul 15, 2016 11:43
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Koesj posted:The most impressive part is where it was wholly written by a goon and still it's pretty great. Loel posted:Squid story was amazing. BIG HEADLINE posted:Semi related: http://www.scp-wiki.net/transcript-of-telephone-conversation-august-9-1991 Quoted for in-flight reading
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Jul 15, 2016 15:02
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You're gonna get off that flight in one hell of a mind state unless you also have like a couple Spongebob episodes queued up.
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Jul 15, 2016 15:43
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Sperglord posted:One reason for not using Standard Missiles is the booster stage. SM-2 and SM-6 both have a booster stage. That works over water, where 99% of the time there's nothing for that stage to land on. Over land, that becomes a much dicer proposition. Just have Space-X design them and land in the local Walmart parking lot.
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Jul 15, 2016 16:10
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or just have your C-RAM shoot down the booster stage after it's done, what could go wrong 
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Jul 15, 2016 16:45
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Sperglord posted:One reason for not using Standard Missiles is the booster stage. SM-2 and SM-6 both have a booster stage. That works over water, where 99% of the time there's nothing for that stage to land on. Over land, that becomes a much dicer proposition. Doesn't seem to have stopped Aegis ashore.
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Jul 15, 2016 20:52
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TCD posted:Doesn't seem to have stopped Aegis ashore. True, though Aegis Ashore is a fixed site operating against a generally well known threat path. A mobile air defense is different. I suspect another reason is just climate control / transport resiliency.
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Jul 15, 2016 21:01
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Looks like there is military coup happening in Turkey right now.
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Jul 15, 2016 21:08
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Back Hack posted:Looks like there is military coup happening in Turkey right now. Woah what? Links? Where is this happening? I don't see mention of this anywhere.
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Jul 15, 2016 21:10
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Saint Celestine posted:Woah what? Links? Where is this happening? I don't see mention of this anywhere. http://www.telegraph.co.uk/news/2016/07/15/turkey-low-flying-jets-and-gunfire-heard-in-ankara1/ https://twitter.com/Mr_Ghostly/status/754040955532038144?ref_src=twsrc%5Etfw
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Jul 15, 2016 21:12
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It's fairly official that poo poo's going down now https://twitter.com/DailySabah/status/754045090998390784 not as much news about exactly what's going on though.
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Jul 15, 2016 21:13
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https://twitter.com/CNNTURK_ENG/status/754040048908197888 Tanks on the roads, low flying jets over Akara. That sort of thing.
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Jul 15, 2016 21:13
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Saint Celestine posted:Woah what? Links? Where is this happening? I don't see mention of this anywhere. Tweets about it are popping up everywhere right now, news sites are just now starting to cover it. Can't really link anything since I'm on my phone.
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Jul 15, 2016 21:15
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iyaayas01 posted:YYOOOOOOOOO JOOOOOOOOOEE Maybe it's a turret that swings down from a helicopter? Make it look sorta like a Blackhawk except with a twin tail and the passenger cabin is the turret's stowed area
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Jul 15, 2016 21:20
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Social media has been shut down in Turkey now. ALthough instagram was still up!
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Jul 15, 2016 21:21
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