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RailgunBy lex, on February 19th, 2009
40 comments to Railgun |
Targets of Opportunityblog advertising is good for you Credo"Sign on, young man, and sail with me. The stature of our homeland is no more than the measure of ourselves. Our job is to keep her free. Our will is to keep the torch of freedom burning for all. To this solemn purpose we call on the young, the brave, the strong, and the free. Heed my call, Come to the sea. Come Sail with me." -- John Paul Jones "Pardon him, Theodotus; he is a barbarian, and thinks that the customs of his tribe and island are the laws of nature" --George Bernard Shaw, "Caesar and Cleopatra" "And those who were seen dancing were thought to be insane by those who could not hear the music."--Friedrich Nietzsche "A kind Providence has placed in our breasts a hatred of the unjust and cruel, in order that we may preserve ourselves from cruelty and injustice. They who bear cruelty, are accomplices in it. The pretended gentleness which excludes that charitable rancour, produces an indifference which is half an approbation. They never will love where they ought to love, who do not hate where they ought to hate."--Edmund Burke “You say that it is your custom to burn widows. Very well. We also have a custom: when men burn a woman alive, we tie a rope around their necks and we hang them. Build your funeral pyre; beside it, my carpenters will build a gallows. You may follow your custom. And then we will follow ours.”--General Sir Charles Napier "Μολὼν λαβέ" -- Leonidas "Blogito Ergo Sum" -- Neptunus Lex Amazon AssociateFor the Effort!Winnar! Subscribe CategoriesPagesTagsacademy
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Is that the same BAE systems of Denver airport luggage mover fame? Oh boy. The navy is in deep, deep doo-doo.
OTOH, with their track record, it’ll mean jobs for a few people for a long time. Redistribute the wealth!
Oz Metal Storm must be a DUD?
http://edition.cnn.com/2003/BUSINESS/06/26/australia.metalstorm/
OR
http://www.youtube.com/watch?v=iX6YvWxtrxw
You can get behind me in line, buddy.
These are interesting to me – first read about them in Heinlein’s 1966 novel “The Moon is a Harsh Mistress” although in that book they were magnetic catapults lobbing stuff up into earth’s gravity well from the moon – but same idea. And I’m sure the idea was around well before he put it into the book.
The next thing I’m wondering about is if we’ll see magnetic cats on carriers or if they wont be ready before everything has gone completely unmanned and they aren’t necessary.
Railguns are mighty interesting. When I was an undergrad, I took a graduate level course on electromechanics from Dr. Bill Weldon, one of the key researchers at the University of Texas Center for Electromechanics. He showed his students solid billets of hardened steel, a foot in diameter and 18 inches long, that had been used as targets for tungsten penetrators fired from a railgun at 4 km/s (about Mach 12). The targets looked like a freeze-frame photo of a bullet passing through air – because that is almost exactly what happened. Since the mechanical properties (strength, ductility, etc) of a material are dependent on the speed of sound of the material, firing a projectile through the material at greater than the speed of sound in that material will cause an object to pass through with dramatically reduced resistance – like a bullet passing through air. When the tungsten projectile passed through the steel billets, it left a wake of shock waves that had melted instantaneously, and then refrozen – it looked just like a freeze-frame photo of a bullet passing through air or water. Amazing. The penetrators weren’t very damaged – since the target material could offer little resistance, only the tip of the penetrator was blunted.
This was 15 years ago, and the research was being performed for the SDIO/BMDO. It’s still ongoing. I found that Dr. Weldon, who is about 5 orders of magnitude smarter than me but who speaks with a small-town Texas drawl, is now doing rail gun research for ONR, and participated in a panel discussion on future naval armaments at the Pentagon a couple of years ago.
He also had developed a machine that could weld drilling pipe almost instantaneously by passing enormous current through it – where there was a joint in the pipe (2 pieces coming together), the increased resistance caused the pipe to fuse, forming a perfect weld. Homopolar welding, it was called. I think it’s being tested on offshore platforms now – the genius of it was that it used some proprietary technologies to make the usually very large homopolar generators much smaller – so you can get tremendous current (millions of amps) from a relatively small source.
http://en.wikipedia.org/wiki/Homopolar_generator
Sorry – engineering geek rant /off.
“I want one.”
“But ossifer,” says Lex, “HR45 didn’t say ANYTHING about rail-guns!”
Lex…you forget you have a real gen-u-ine DD214.
NO TOYS FOR YOU!
(I bet the fee to the BATF will dwarf the ‘stimulus” bill anyhow)
Heck fire, firing a projectile 200 miles has gotta take into effect the old Coriolis force (2 omega sine theta- sorry no Greek characters on keyboard). I saw onena these at NavSea years ago and the “bullet” was a piece of hardened plastic. Pretty humbling to see what it did to airframes and the aluminum that we were building SpruCans and Aegis out of. Now that is technology you can believe in when you see a hole completely thru a hull! At the time the engineer told me one of their chief concerns was the “bullet – anti-bullet” argument. At the time they hadn’t figured out an affordable armor that could be integrated into ships and aircraft without causing huge weight over-runs. So don’t stick something out there you can’t defend against!!
The Battleship mounts a comeback! 200 mile range, Mach 5 impact velocity. Too bad Osama isn’t holed within a couple hundred of the Sea…
Bunker bust this!
I remember film of the experiments back in the 80s for SDI. I wanted one then, and still do. I’m afraid, Lex, the line is pretty long.
JR Peck,
They are already on the boards for the Gerald R. Ford class carriers.
http://www.defenseindustrydaily.com/EMALS-Electro-Magnetic-Launch-for-Carriers-05220/
Let us remember what it took to produce a battleship main gun. Oh yeah, a BATTLESHIP, Turrets, Barbettes, armor, HY80 steel inches thick at a minimum. That whole equal but opposite reaction force that has to be accounted for somewhere in the design. Has anybody seen any sign over the last 40 years that NAVSEA understands the forces involved and will accommodate them in the design of the rail gun shooter? I’m sure they’ll come up with a $12 billion ship that has an absolute upper limit of no more than 400 shots before the ship is a twisted wreck. Not to worry, they’ll also come up with a $40 billion fixit program to make each of them better.
Thanks AW1 – I enjoyed that article. Hard to imagine V-2 without having to clean water brakes. The GlobalSecurity.org article they link also mentions magnetic gear – which is also tough to imagine. On the upside if those people who say magnets are good for you are right, we’ll have some exceptionally healthy ABEs.
Railgun – I wants it!
Electro-Magnetic-Launch-for-Carriers
Hmm, with everybody wearing steel -toed shoes on the flight deck.
We could be seeing the yellow jersey follow the fighter off the bow.
When I was making up loads for the Light Gas Gun at MSFC, we had a German post-doc working on a rail gun in the little room offside the lab. Never got as much velocity as we did with the piston-squeezing and the helium. I did admire the huge bank of very large capacitors, though.
One could do some amazing practical jokes with just one of them. Sadly, by that time I had already decided that I needed to “act normal”, and not get arrested, etc., so I passed on the opportunity.
Oh, BTW, I betcha you could make a gun-assembly plutonium weapon work, if the gun is a light-gas gun.
Be kinda hard to weaponize, I reckon
P.s. Hmm. If you build yer light gas gun plutonium-slug accelerator into a sizable ship, well, you could just steam into a harbor and touch the thing off. A coupla hundred feet would allow you to get some right good velocity on the slug.
From the linked article:
“…and there would likewise be no need for the dangerous chemical propellants (gunpowder) used in today’s cannon…”
Any gun that can toss a projectile 200 miles that arrives at the target still moving at Mach 5+ is going to have some, well, energetic possible failure modes at the launch end.
They just won’t involve burning gun powder.
TANSTAAFL is not just a mild suggestion.
Railguns are an interesting idea, though certainly nothing new. I did a science fair project back in high school making a railgun using common transistors, wire-wrapped iron donuts and a sabot to launch a Q-tip. Punched that Q-tip right through a chunk of plate glass, as a matter of fact, which I’d chosen because glass has a compression strength of nearly 1 million PSI unless there are flaws.
Which, evidently, there were. Because I’m pretty sure I’d done the math right. That wasn’t supposed to happen.
Anyway, interesting properties on a railgun is providing the current necessary for the magnetic field, the electronics fast enough to shut off the magnet your projectile just passed and keep the one it’s approaching on, and how do you handle the electricity you generate in every ferrous material with magnetic fields energizing and collapsing through them? You are, in effect, turning everything made of metal within several feet of that railgun into an electric generator.
God help the sailor nearby with a steel pin in his arm, or his GameBoy.
But it’s a really cool way of making use of that whole E=MV^2 part of Newton’s laws. Notice that mass is pretty well static, but the V part goes up exponentially. Traditionally we’ve packed shells full of HE and made that the payload. Launch them at a high enough velocity and the V part does so much more than the M part there’s no need for explosives.
There is an upper limit to V, however. At about mach 7 the air is a sandpaper, scratching off and burning up the M part of your payload. Terribly embarrassing to launch a shell only to watch it burn up in flight like Skylab on re-entry. Gets ya talked about.
It’s a nifty idea and the natural progression for artillery. It is not, however, without certain inherent constraints that will have to be accounted for when placing it aboard a ship. Made of steel. With folks nearby.
– Max
MaxDamage- Well, I guess I’ll have to step out of the line then, what with all my newly-installed steel hardware in wrist and ankle… *sigh*
SteveH- I’ve been around various acronyms for over 20 yrs now, and I can’t even begin to guess what TANSTAAFL stands for – care to enlighten us?
http://www.all-acronyms.com/TANSTAAFL
“There Ain’t No Such Thing As A Free Lunch”
Get Well Soon MajH!
And the first time I heard TANSTAAFL was “The Moon Is A Harsh Mistress”, by Heinlein. He was right partial to the concept as well
SteveH/
I know they ain’t free–but can’t we get/have some of them things with deferred payments at least? IE, as long as the “bill” doesn’t come due while I’m standing around?
MajHarvey, for shame!!! we’ll chalk it up to “must be the meds talking”…
(for now, take a wee break from ecclesiastical studies and hie thee hither to a book store and grab yerself a copy of “The Moon is a Harsh Mistress” by Rob’t A. Heinlein (scurvy squid that he is))..
…all will be well.
Following one of the links at the defenseindustrydaily.com site (thanks AW1 Tim1) leads to:
http://www.americanheritage.com/articles/magazine/it/2006/4/2006_4_26.shtml
which has the most amazing Hoover cat-shot photo at the beginning.
Larry, not to be picky but that is the strangest F/A18 series S3B Viking I have ever seen (in the caption on the picture of that article).
And Max, about those steel toes? Just think of them as foot warmers on the north sea cruise. Speaking outside my knowledge here, but wouldn’t proper magnetic containment (think Faraday cage) or pole design minimize stray inductance? After all, stray magnetism is wasted energy and the purpose is to put the energy in the projectile, not in the toes, pins, watches, and electronics of the surrounding area.
Max,
I would envision a lot of the surrounding components of any rail gun (or MagCat) to be produced from advanced composites or ceramics. The use of Faraday cage tech, as JoeC mentions, would also be expected to help with shielding.
Of course, using modern ablative technology on the forward section of the projectile would help to minimize any friction problems at high velocity, not unlike what we use to protect nuclear warheads during reentry.
respects,
Huh, JoeC, you mean that’s NOT a supersonic S-3B Block CCXIV with the pointy-nose mod?
FYI: Timberland has been making safety boots with titanium caps that meet or exceed ANSI standards for a few years now. Very light, very nice.
http://www.navweaps.com/Weapons/WNUS_Rail_Gun_pics.htm
some more useful info including some equations for those still carrying their slide rules, and a video for those that aren’t. Now if you can stick a seeker head on to track air targets, oh boy, smart BBs. Neat stuff this.
Navy press release on EMALS:
http://pao.navair.navy.mil/press_releases/index.cfm?fuseaction=home.view&Press_release_id=3790&site_id=6
Interesting thought, rather than build concentric containment of the magnetic field, I wonder if a similar but opposite field could be created to counter the first? Sort of like how active hearing protection works. I’m pretty sure this has been done before using Helmholtz coils.
http://en.wikipedia.org/wiki/Helmholtz_coil
Wiki sure would have saved me a lot of time in the library 20 years ago.
– Max
So, this EMALS thing looks pretty cool as a replacement for the steam catapult, but the big question is: is it really gonna work? How much has been tested so far?
The 5th picture in that article (after the sketch drawing of the catapult workings under deck) is the nose of a Viking so, maybe they were a little excited bout the Hoover and plastered it all round. Can’t say as I blame them, I used to get all excited like around them too!!!
BT: Jimmy T sends.
By coincidence, Galrahn has a new post up about EMALS. He says it doesn’t work:
informationdissemination.blogspot.com/2009/02/and-now-for-really-bad-news.html
Sadly, without details, not much one can tell from his statement. Reminds me of some of the engineers from a certain large defense contractor I work with.
A question for the railgun aficionados: in the railgun shot (G-man’s link above), what caused all the flame/fire trailing the projectile? (I loved the capture of the shockwave ahead of the projectile)
Bad Juju…I’ll take two.
JoeC, rapid oxidation of very small particles of both the target and the projectile that are stripped away by friction and shock. That’s all a flame is, really, and as experiments with flour or iron filings can show, the finer a particle the more rapidly it will oxidize in the presence of heat (which the impact provides a whole lot of).
– Max
@AW1 Tim: Yeah, Lakehurst has had teams aboard working on the EMALS & EAR for a while now. Very interesting technology that I’m looking forward to seeing come to fruition; EMI to A/C systems notwithstanding.
@Larry: Back in a former life we used to recover targets towed behind F-4′s that would survive a CIWS (R2D2) pass, and I always wondered what would allow a projectile to leave its target looking like the projectile had burned its way through. Back then I used to think it was kinetic energy from the expended Uranium rounds, but your explanation makes more sense. A 20mm projectile thwacking a target inside of a mile has to be hoofin’ it at a pretty good fps.
I’m waiting to see more on the Hypersonic croozers that can get to UBL’s cave from a long, long, long way away in 30 minutes.