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The Jet Fighter Laser Cannon
fahrbot-bot sends in a Register piece about DARPA issuing the penultimate contract for what is intended to be a jet-mounted laser cannon. The Reg outdoes itself in a BOTEC involving downsizing to shark scale. "The US military will shortly issue a brace of contracts for 'refrigerator sized' laser blaster cannons. One of the deals will see a full-power ground prototype built which will be the final stage prior to America's first raygun-equipped jet fighter. ... If it scales down far enough, this would seem to put handheld HELL-guns within an order of magnitude of the striking power offered by conventional small-arms. A 9mm pistol bullet has about 750 joules muzzle energy: a 5kg portable HELL-ray weapon would put out this much energy in a blast less than a second long. ... A dolphin can carry a human being weighing up to 100kg along for a ride. A thoroughbred shark in good training can surely match this. Thus, we seem to be looking at practicable head-[laser] output in the 20-kilowatt range."
Ok, I see the obligatory "sharks" tag, but what about the "pewpewpew" tag?
When I read the summary I wondered if they'd be putting one of those on flying robot drones and then I realized that yes, it's 2009 and we live in the fucking future.
In Capitalist America, bank robs you!
Really? Compare the USP and the Glock pistols in Counter-Strike - which one does more damage?
Which is exactly the sense in which it is used here, as is indicated by the language from TFA quoted in TFS: "the final stage prior to America's first raygun-equipped jet fighter."
So, in the series in which the last (or "ultimate") stage is the contract for a laser-armed jet fighter, the contract for the ground-based prototype is the second to last (or "penultimate") stage.
So, great job of knowing what "penultimate" means, but next time work on reading and understanding the post in which it is used before accusing someone of using it wrong.
the knife:
http://www.youtube.com/watch?v=cudCajMNRM0&feature=player_embedded
The Kruger Dunning explains most post on
Then I take it GNU renders you apoplectic.
Protoplasm. Quiet Protoplasm. I like quiet protoplasm.
Yeah, the Air Marshals use the .357 SIG, as does the Secret Service. The Coast Guard adopted it as well. I believe the FBI is still using the .40 S&W but I could be mistaken.
The 9mm is a joke. It's even worse for the military because they aren't allowed to use expanding ammunition. Buddy of mine who deployed in Iraq tells a story of an insurgent whom wasn't stopped in spite of the fact that he had absorbed no less than six center of mass hits from the M9. Makes you question the wisdom of the military abandoning the Model 1911, doesn't it?
I want peace on earth and goodwill toward man.
We are the United States Government! We don't do that sort of thing.
One of the deals will see a full-power ground prototype built which will be the final stage prior to America's first raygun-equipped jet fighter.
This prototype is second to last(penultimate) contract in this project. The last one (or ultimate) will be for the actual jet. The use is valid.
Give me Classic Slashdot or give me death!
It begs the question of why people use big sounding words and phrases they obviously don't understand. It literally makes my head explode.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
I would like an elegant weapon from an more civilized age.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
How can you guys deflect protons when you're being so negative?
-- John Truong
The fluorescence/phosphorescence was the most interesting thing to me. They're the same effect but different phenomena: you hit something really hard with a bunch of UV, and the surface -- the stuff that didn't get ablated -- is now covered in molecules with electrons blown up into higher orbitals. The ones that fall down immediately (within nanoseconds) are what produce fluorescence. The ones that have absorbed enough energy that they're in an orbital/spin combination that won't allow them to directly drop down to their original orbital, take a long time before they can do something like electron tunnelling to return to their orbital -- where by 'long time' I mean from a millisecond up to maybe six hours. So that's where you get actual glow-in-the-dark. I could put a notecard up in the beam and trigger a shot, and there'd be a nice yellow glow off the piece of paper for maybe half a second, and then the paper itself would be a moderate brown color. Next shot and it'd be gone. The individual shots were on the order of a microsecond long.
Interesting factoid that I wish I didn't know: fluorine gas smells somewhat like Elmer's Glue. Deep UV lasers often use fluorine as an excimer and when you have to replace the cavity mirrors, no matter how many times you purge it with argon, there's still some fluorine in there when you finally open it up. Gack *cough*.
Nostalgia's not what it used to be.
Michelangelo: I've got it! I've got it! We'll call it "The Last But One Supper"!
Pope: What?
Michelangelo: Well there must have been one, if there was a last supper there must have been a one before that, so this, is the "Penultimate Supper"! The Bible doesn't say how many people were there now, does it?
Pope: No, but...
Michelangelo: Well there you are, then!
Pope: Look! The last supper is a significant event in the life of our Lord, the penultimate supper was not! Even if they had a conjurer and a mariachi band. Now, a last supper I commissioned from you, and a last supper I want! With twelve disciples and one Christ!
Michelangelo: One?!
The enemies of Democracy are
Expanding rounds are forbidden from being used in war by the Hague Convention of 1899. Full metal jacket rounds may be better at penatrating armor, but the real reason they are used is because using expanding ammunition (in war) is a war crime.
[the relevant section of the treaty]
"linux is just DOS with a UNIX like syntax" -- Galactic Dominator (944134)
As for the size of the wound, that depends on how tightly you focus the beam.
There are limits to that. The divergence of the beam depends upon the size of the optics. For a man portable weapon system, I'd guess 10 cm is about the maximum optics diameter that would be useful. Assuming a wavelength of 1 micron, 10 cm gives a divergence of 1e-5 radians, so at 100 meters you could focus to a 2 cm diameter spot for an irradiance of 240 watts per square cm. At 1000 meters you're up to a 20cm spot for a fairly insignificant irradiance of 2.4 watts per square cm. If you want something useful at a kilometer, it's not going to be man portable.
Lets put that into terms every slashdotter will understand. Remember your 5 cm diameter magnifying glass and its 20cm focal length? It projected an image of the sun 1.7 mm in diameter with an irradiance of 122 watts per square centimeter, almost exactly half of our laser gun at 100 meters, and 50 times larger than our gun at 1000 meters.
So now, lets build a magnifying glass to match our laser gun. We want a 2 cm diameter spot, so we'll need a longer focal length, by the ratio of 20/1.7, which turns out to be 235 cm. We'll also need 750 watts of sunlight or 0.53 square meters of collecting area. That means a lens 82 cm in diameter. Feel free to build one and put a steak in the focus for one second. Please post your results to slashdot. I personally doubt that a second in that spot would be fatal to a human, but it would hurt a hell of a lot.
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All it would have to do is heat up the fuel tanks to combustion. It may not even have to do that, the thermals on jet fighter engines are insane. The exhaust leaves at far greater than the melting temperature of the alloy the engines are made out of. Therefore all sorts of tricks like laminar airflow cooling are used. However, an external source of heat into the system could totally mess up those cooling techniques...