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The Military

The Jet Fighter Laser Cannon 464

Posted by kdawson
from the back-of-the-shark-calculation dept.
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."
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The Jet Fighter Laser Cannon

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  • Tags (Score:5, Funny)

    by Shadyman (939863) on Tuesday November 17, 2009 @06:12PM (#30135966) Homepage
    Ok, I see the obligatory "sharks" tag, but what about the "pewpewpew" tag?
  • 9mm? (Score:3, Funny)

    by Shakrai (717556) on Tuesday November 17, 2009 @06:13PM (#30135982) Journal

    Why not compare it to a real handgun caliber [wikipedia.org]? ;)

    • Re:9mm? (Score:4, Informative)

      by TheKidWho (705796) on Tuesday November 17, 2009 @06:22PM (#30136090)

      Fail.

      From you're own link, the bullet performance shows 702J as the highest energy output.

      • by TheKidWho (705796)

        You're/your before I get castrated by the grammar Nazis.

    • I prefer a pistol grip on a shortened 12 gauge with buckshot myself.
      • by Shakrai (717556)

        Well yeah, but those are rather hard to wear on your person when you visit the grocery store ;)

  • The Future (Score:5, Funny)

    by colmore (56499) on Tuesday November 17, 2009 @06:20PM (#30136068) Journal

    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.

    • Re:The Future (Score:4, Informative)

      by evanbd (210358) on Tuesday November 17, 2009 @06:31PM (#30136246)

      Give credit [xkcd.com] where credit is due.

      We live in a world where there are actual fleets of robot assassins patrolling the skies. At some point there, we left the present and entered the future."

      • by Virak (897071)

        That line bears only the most vague resemblance to his post. This is not the patent system. Credit is not due just because someone else came up with a similar idea before you.

    • Something went wrong with the future.
      We crossed into a time-line where there are no flying cars. Who's going to go back in time and fix this?

      • Re: (Score:3, Insightful)

        by Chris Mattern (191822)

        Flying cars had (and have) two basic flaws that prevent their implementation:

        a) Controlling a vehicle in three dimensions takes more skill than the average person has. Remember the last idiot you saw on the road? Which would have been today if you've driven today, by the way. Now imagine him *flying*.

        b) a vehicle that generally operates with the ground 500 or 1000 feet below it needs better reliability than can be obtained with the way the average car is maintained. Doubly so when you remember you not o

        • Re: (Score:3, Interesting)

          by EdIII (1114411) *

          Basically we can boil your argument down to "people are too fucking cheap and stupid".

          I totally agree. If it were not for concerns about government totalitarianism I would wholly support a 100% public transportation system in which only licensed, heavily regulated, and *REGULARLY TESTED* operators could use any transportation equipment in a public space.

          The average person just does not have the responsibility and skill to be operating motor vehicles next to other average people. The real problem is that y

  • Effect on humans? (Score:3, Interesting)

    by Singularity42 (1658297) * on Tuesday November 17, 2009 @06:26PM (#30136158)

    I've never heard an analysis of effects on humans. Bullets are good a disrupting tissue, often causing death. A laser might deliver a cauterized burn, or blindness if in the right spot.

    • Re: (Score:2, Funny)

      by mujadaddy (1238164)
      I take it you're volunteering.
    • Re: (Score:3, Informative)

      A laser might deliver a cauterized burn, or blindness if in the right spot.

      Blinding weapons are a violation of the Geneva Conventions (Protocol IV, if I recall correctly - and no, the USA isn't a signatory to Protocol IV last I looked).

      • Re: (Score:3, Informative)

        by Stray7Xi (698337)

        Blinding weapons are a violation of the Geneva Conventions (Protocol IV, if I recall correctly - and no, the USA isn't a signatory to Protocol IV last I looked).

        Weapons designed to blind are a violation. Weapons that may inadvertently cause blindness are acceptable. Just about every weapon we have can cause blindness. I suspect this weapon will be designed to burn a hole into their head rather then blind.

        But Law of War also says you limit collateral damage. Will diffuse reflections from these lasers cause collateral blindness. When dealing with highpower lasers in a dynamic environment, there's really no predicting where reflections might end up.

      • Re: (Score:3, Informative)

        by c6gunner (950153)

        Blinding weapons are a violation of the Geneva Conventions (Protocol IV, if I recall correctly - and no, the USA isn't a signatory to Protocol IV last I looked).

        And?

        Weapons designed for the purpose of blinding people would violate the convention. Weapons designed to kill people which may, on occasion, blind someone, are perfectly legal. Soldiers get blinded by bullet fragments and shrapnel too, you know.

    • Re:Effect on humans? (Score:5, Interesting)

      by smellsofbikes (890263) on Tuesday November 17, 2009 @08:07PM (#30137536) Journal
      I can tell you from personal experience that high power lasers cause cauterized burns (in fact, if it's a big enough UV laser you get to watch your skin glow briefly: everything fluoresces and phosphoresces if you hit it with enough photons, I think) and causes blindness. Weird corollary: visible lasers are the nasty ones because they blow holes in the back of your eye, where we can't fix things. Most of the visible-wavelength laser PhD's I've worked with have had partial blindness in some area because they've cooked their retinas. However, IR and UV lasers, while seemingly more dangerous (because you can't see them and don't know you're being hit until it hurts/your vision goes fuzzy) are actually nicer since they primarily bake the front part of the eye, and we can repair that, either with corneal transplants or new intraocular lens implants. One of the PhD's I was working with on a massive UV laser had given himself DIY laser keratotomy: he'd flattened one cornea when a laser discharged a single pulse while his right eye was in the beampath. (It was one hell of a laser: we'd warm it up in the morning using a brick, because they're cheap and *anything* in front of a kilowatt laser is disposable so you might as well go with cheap.)

      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*.

  • Mirrors (Score:3, Funny)

    by HEbGb (6544) on Tuesday November 17, 2009 @06:27PM (#30136170)

    Time to get into the mirror business! It's a lot easier to deflect protons than bullets, I'll tell you that.

  • HELL = "High Energy Liquid Laser"

    "LASER" = Light Amplification by Stimulated Emission of Radiation. It strikes me as wrong to use the first letter of an acronym as the last letter of another acronym.

    It should be HELLASER = High Energy Liquid Light Amplification by Stimulated Emision of Radiation.

  • ...a brace of contracts...

    I get lost with all the legal verbiage.

    • by Zordak (123132)
      I'm even a lawyer, and I've never heard anybody say "a brace of contracts." I've heard "a brace of pistols," and I think Samwise caught a "brace of conies" in The Two Towers, but I would just say "two contracts." Still, at least the guy posting the story used "penultimate" right.
  • over one second? (Score:4, Interesting)

    by painandgreed (692585) on Tuesday November 17, 2009 @06:30PM (#30136220)
    We've been down this way back during the star wars days and trying to shoot down missiles. Any sort of energy that is released in the term of a second or so is useless against anything but stationary targets where you can assume you will hit the same point for that entire second. Bullets on the other hand expend their energy in a range of ten thousandths of a second. Until lasers or other beam weapons can deliver enough energy in a short enough amount of time similar to a bullet or supersonic missile, they simply will not make good weapons. Just make your missiles spin and any energy hitting them will be over a very large area. Similarly, the energy given for a 9mm hitting a human target that is moving around will be affected less than the firer of a 9mm who will probably absorb that energy over a shorter time and less area due to recoil.
    • It might depend a bit on your objectives. If you want to spread terror by setting fire to (say) Baghdad then cruising around the sky with a laser might be more efficient than dropping bombs all over the place.

    • by CannonballHead (842625) on Tuesday November 17, 2009 @06:49PM (#30136522)

      But you can keep a laser focused on something a lot easier. Light moves a whole lot faster than a supersonic missile. If you think of it as a "photon machine gun," it's a lot easier to keep the "bullets" hitting the target when your bullets fire rather rapidly and can move at the speed of light. One second of laser-shining-on-a-moving-object can't be TOO hard.

      • by v1 (525388)

        tho especially considering the criticality of weight, it's a lot easier to coat a missile with chrome than armor plating.

        One would assume that all ICBMs around the world are either already chromed or can be retrofitted very easily should the laser tech become more mainstream.

    • by T Murphy (1054674)
      I don't doubt the engineers involved see the glaring problems that need to be fixed before this can be deployed, but if DARPA thinks they've got the potential to produce the real deal they'd do well to throw money at this project to speed development.

      In any case, these lasers just have to replace some roles for more expendable munitions, assuming firing the laser is significantly cheaper than dropping a bomb or firing a smart missile.
  • Obligatory (Score:2, Funny)

    by Dripdry (1062282)

    Val Kilmer seen running around MIT hollering with joy.

    • Re: (Score:3, Informative)

      by DragonWriter (970822)

      Val Kilmer seen running around MIT hollering with joy.

      "Pacific Tech" from Real Genius was modelled on (very closely, in many areas) Caltech, not MIT.

  • Does firing a laser bring recoil opposite the laser's direction with the energy equal to that in the laser, the way firing a bullet does?

    • Does firing a laser bring recoil opposite the laser's direction with the energy equal to that in the laser, the way firing a bullet does?

      Yes, but not enough to notice. In theory a laser can be used as a rocket drive, as can my LED torch. Just not a very good rocket.

      • by Doc Ruby (173196)

        If the recoil has the energy of the projected laser but in the opposite direction, the way a bullet gun's recoil does, how is it not enough to notice? The lasers in this article, including the hypothesized portable version, pack quite a wallop.

        • Re: (Score:3, Informative)

          by MichaelSmith (789609)

          If the recoil has the energy of the projected laser but in the opposite direction, the way a bullet gun's recoil does, how is it not enough to notice? The lasers in this article, including the hypothesized portable version, pack quite a wallop.

          The recoil has the momentum of the projected laser. Photons, like atoms, have mass-energy which, along with velocity determines momentum. But a lot of energy gives very little mass. So photons have a lot of velocity (C) and hardly any mass, so they have hardly any momentum for a lot of energy.

          The atoms in normal rocket exhaust have less velocity but heaps more mass-energy, most of which is just dead weight.

          • by Doc Ruby (173196)

            Right - momentum is equal in trajectory and recoil, not energy. There's not a lot of momentum in even a high powered laser beam compared to the inertia of the laser machine firing it, absorbing the recoil.

        • by volsung (378)
          Because recoil due to conservation of momentum, not conservation of energy. The "projectiles" (ok, summing over many, many projectiles with the laser) leave with the same kinetic energy, but the rest mass of the photon is zero. Since we're dealing with photons, we would really need to do the math with conservation of relativistic 4-momentum to get the right answer. (Newtonian conservation of momentum says there would be no recoil at all from a laser, but that's not quite true. It's just really, really t
        • Re: (Score:2, Informative)

          by XSpud (801834)
          The recoil doesn't have the same energy, but it will have the same momentum.
      • by jpmorgan (517966)
        Photons have no rest mass; they have a very high energy:momentum ratio. So yes, there is some recoil, but it's insignificant.
    • Think about how a gun works - you are accelerating a substantial mass (bullet). With a laser, you are accelerating photons which have almost no mass, so even though the same amount of energy is involved you have far less recoil.

    • by v1 (525388)

      Does firing a laser bring recoil opposite the laser's direction with the energy equal to that in the laser, the way firing a bullet does?

      Most of the energy of a laser is in the heat, and very little in the mass of the photons being fired. Bullets work the other way, their energy is almost all in the mass, and very little in their heat.

      So lasers have almost zero recoil.

      That being said, the kinetic (mass) energy of a bullet is basically converted to heat when it hits, and it can be considered to burn/melt th

  • Wake me when they make a {voice=Arnold}"phased plasma rifle in the 40 watt range" {/voice}

    • I think we are way beyond 40 watts now.

    • 40 watt? So basically, you want a flashlight.

  • It seems to me that 750 joules of kinetic energy in a bullet would do a lot more damage to a target than 750 joules of electromagnetic energy. A laser can only burn through tissue, and that'll always take longer than a metal slug takes to penetrate, given the same amount of energy, right?

    • by geekoid (135745)

      no.
      It depends on the lengths of time the 750 is delivered

      "A laser can only burn through tissue,"
      I don't know why you think that, for 400 bucks you can buy a LASER that cuts metal.

    • by esampson (223745) on Tuesday November 17, 2009 @07:39PM (#30137188) Homepage

      Yes and no. The amount of energy isn't a terrible base line of comparison if you are doing "apples to apples". There are really 3 factors involved; the energy, how rapidly and efficiently the energy is transferred to the target and over how much area. Sunlight is a pretty good way of illustrating this. In full sunlight you can assume that 1 square foot (30cm x 30cm) receives about 100 watts of energy. Since 1 Joule is 1 watt per second that means that in about 7.5 seconds an area roughly the size of your chest would receive about as much energy as a 9mm bullet.

      Obviously this has practically no effect on you. However take a magnifying glass a bit over 1 foot across (32 cm) and focus all of the energy into a spot a little under 1/3 of an inch (9 mm) across and all of a sudden you're causing some serious skin trauma. Likewise if the sun were suddenly 7.5 times brighter you would start to peel and blister in a hurry. Combine all the light of 7.5 seconds into a circle 1/3 of an inch across and apply it all in 1/100th of a second and you'll inflict some real damage.

      Unfortunately the laser in their example delivers all its energy about 100 times slower than that. There's also a question of how big the target spot is and of course the fact that just the color of the target can cause a substantial amount of the energy to be reflected (substantial in this case being perhaps a few hundred Joules). So while the total amount of energy isn't a terrible way to compare them that does assume that the beam is focused relatively tightly (probably a safe assumption) and delivers the energy as a sudden single shot (which it clearly doesn't). As it is the comparison is less "apples to apples" and more "apples to orangutans".

  • by Anonymous Coward

    All you'd need is a large spinning mirror and you could vaporize a human target from space. Better go make sure someone didn't steal Kents tracking system.

    Plus sharks with FRICKIN LAZER BEAMS attached to their heads?

    I like the first movie better.

  • OK, so 702 joules sounds impressive. It is, but only for mechanical energy. Those same 702 joules only heat 10 mL of water 17'C (30'F). Not even enough for a burn! But maybe enough to blind.
  • From TFA:

    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.

    Since 9mm guns tend to be pistols they weigh a lot less than 5kg (11 lbs.). Most semi-automatic pistols are also capable of accurately firing 3-4 rounds per second and as has already been men

  • by 140Mandak262Jamuna (970587) on Tuesday November 17, 2009 @07:09PM (#30136806) Journal
    I would like an elegant weapon from an more civilized age.
  • How did we get sharks to fly at jet speeds? with a laser on them?

  • by Jackie_Chan_Fan (730745) on Tuesday November 17, 2009 @09:16PM (#30138172)

    A dolphin with a laser taped to its head, nailed to an airplane?!!

    THIS IS MADNESS!

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