back to article New laser raygun tech: Our sharks kick the tyres

Raygun fans will be overjoyed today to hear that a major problem of energy weapons - the fact that they tend to be hugely more devastating to themselves and their users than they are to their targets - may soon be solved. No, really. Even the very latest laser and high-powered microwave weapons have beam efficiencies well …

COMMENTS

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  1. Rob 30
    Boffin

    only just up to the job

    presumably they could use several of them to enable firing longer bursts?

    1. Olafthemighty
      Boffin

      Wait, what?

      Dude, these things weigh 35 kilos apiece - how many do you think a shark (bear in mind it's already carrying a head-mounted frikkin' laser cannon) can reasonably carry while still being able to operate usefully?

      1. TeeCee Gold badge

        Re: Wait, what?

        So you're going to need to genetically engineer giant sharks to fit lasers to.

        I don't see that being a problem for any evil genius worth his salt.

  2. Anonymous Coward
    Thumb Up

    Excellent...

    Thank you Lewis, for as usual you provide us with respite from the abysmal standard of journalism found elsewhere on the site. And I approve highly of your jocular musings.

    Keep up the good work, soldier!

  3. Trevor 10
    Black Helicopters

    $20 Says

    $20 says the wax-type material is actually just wax but with a really high price tag.

    1. Wommit
      Paris Hilton

      Wrong!

      Keep up the good work, sailor.

      There, fixed it for you.

  4. Disco-Legend-Zeke

    No, Mr. Bond, I Don't...

    ...expect you to talk, I expect you to die.

    1. Fluffykins Silver badge

      But

      I'm going to wax lyrical first

  5. lglethal Silver badge
    Pint

    Lewis Thank You!!

    Thank you Lewis for putting this tricky scientific jargon in to language that we, the common would-be-supervillian, can understand!

    Your a credit to your profession! Here's a pint on the house/secret volcanic island lair...

  6. lawndart
    Headmaster

    HTML no, only text plain, mmmm.

    Piscine? Selachimorphine, surely?

  7. Gordon is not a Moron
    Terminator

    Now if they were reallllly clever

    they turn the heat energy back into power to help keep the ray gun firing, and make the whole thing relatively efficent.

    1. Chris Miller
      Boffin

      You've heard of the second law?

      If someone points out to you that your pet theory of the universe is in disagreement with Maxwell's equations — then so much the worse for Maxwell's equations. If it is found to be contradicted by observation — well, these experimentalists do bungle things sometimes. But if your theory is found to be against the second law of thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation.

      Sir Arthur Stanley Eddington, The Nature of the Physical World (1915), chapter 4

      1. sT0rNG b4R3 duRiD

        @Chris Miller

        A cryptic reply, it would seem.

        What are you implying exactly, pray tell, my good sir?

    2. Flocke Kroes Silver badge

      Lasers not that hot

      http://en.wikipedia.org/wiki/Carnot's_theorem_(thermodynamics)

      To turn heat into electricity you need a source of heat and a source of cold. The more extreme the better because the best possible efficiency is:

      1 - Tcold/Thot [temperatures in Kelvin, which is centigrade+273]

      At present, politicians like killing people in hot countries, so pretend Tcold 27°C (300K). I am not sure what the operating temperature of a solid state laser is, but mil spec is 125°C (398K). That gives a theoretical best possible figure of 25% efficient. Getting 12% of the power needed to run a 50% efficient laser is not worth lugging around something bigger and more complicated than the generator providing the other 88%. (You cannot have the heat from the generator - it must be at a low temperature already because the generator is near the limit of efficiency.)

      Remember the entire point of the article was that it is difficult to dump 100kW into air. Computers dump heat into air by raising its temperature. You want a large difference in temperature to reduce the amount air whistling through the fans. For a generator running on waste heat, you want to maximise the amount of air screaming through your cooling turbines to avoid increasing Tcold. You also have the same problem on the hot side - you have to run the lasers just short of melting point and pump coolant through them very hard so the coolant is not much colder than the laser and you get a useful Thot at the generator.

      1. Nexox Enigma

        Entropy!

        Simply put:

        The wax stores what is referred to as 'low grade' heat energy, which, by definition, isn't very useful, and won't give you a large enough difference in temperature to run an efficient thermal cycle, which is how you to convert it to mechanical or electrical energy. The best you'd probably end up with is a few percent conversion efficiency at the cost of large, heavy, and expensive equipment.

        It could, however, be used for heating or possibly cooking. So now at least the shark tank water is warm, to avoid your captors going into shock before they get torn limb from limb by teeth and high energy weaponry.

  8. This post has been deleted by its author

  9. Flocke Kroes Silver badge

    Sharks rarely fly

    The reason why sharks are the carrier of choice for lasers is they normally swim in the sea - which is a much easier place to dump heat than the air. Dumping 100kW into sea water requires about 1L/s of water going through the heat exchanger. (You could use less, but then you risk scolding a shark armed with a big laser.) To fire your 100kW laser continuously, you need to pump over 600kW of fuel into an engine to get 200kW of electricity to the laser. As well as dumping 100kW of heat from your laser, you also have to dump 400kW from the generator.

    Even so, the real challenge is fitting your shark with a generator:

    http://www.jobsite-generators.com/multiquip_standby_generator_mqp200iv.html

    http://en.wikipedia.org/wiki/Great_white_shark

    http://en.wikipedia.org/wiki/Whale_shark

    Fitting a 3 ton generator onto a 2 ton great white shark is going to sink the shark. Perhaps a 21 ton whale shark could carry the kit, but they are filter feeders. They lack the 'I am going to bite off your torso' image that people expect from a shark guarding an evil super-villain's base.

  10. Dazed and Confused

    Swimming pools

    But if you've got a handy swimming pool you can dump vast qualities of energy into there and turn the whole thing into a hot tub.

    1. Santa from Exeter
      Headmaster

      Pedantic, moi?

      (You could use less, but then you risk scolding a shark armed with a big laser.)

      Images of Sister Mary saying "Naughty shark, write out 100 times 'I will not attempt to singe Mother Superior with my head-laser'"!

    2. Mike Richards

      Or...

      ...shark fin soup with extra meaty chunks.

    3. Anonymous Coward
      Anonymous Coward

      Maybe not an idiot

      But perhaps he also had a taste for shark's fin soup?

  11. I ain't Spartacus Gold badge

    Admit it!

    They've just invented a big lava lamp!

    I'd buy a lava lamp that could also kill intruders at 20 paces. I'm not so sure about the 40 seconds running limit until it explodes, showering your disco lounge with 30 kilos of boiling wax though...

    There wouldn't even be time to finish your Campari and soda - and the only music quick enough to finish before your lava-lamp-of-death goes nuclear is going to be punk, which rather puts the dampeners on the romantic mood - almost as much as being showered in molten wax and flying glass.

    Oh well, back to the drawing board.

  12. Anonymous Coward
    Anonymous Coward

    Liquid cooling...

    Surely sharks have the advantage that they can simply heat the pool?

    40Kw into a swimming pool isn't going to make a sauna.

  13. Scott Wheeler
    Boffin

    Ok, I'll bite

    Can anyone explain why this is difficult?

    Consider a (largish) 130bhp motorcycle - this has a peak power output of 100kW. It also has an efficiency somewhat south of 25%, so about 300kW thermal output. On a full-bore launch, the rider is dumping the power into the oil-cooled clutch, starting at the full 100kW, and declining to zero as the bike starts rolling and the rider stops slipping the clutch. Additionally a proportion of the thermal output has to be dissipated through the engine's liquid or air cooling system (the remainder leaving via the exhaust gas). Such a bike can usually sustain a steady state cruise at max power for several minutes: the clutch isn't a consideration here, but it still has to dissipate 300kW (thermal load, via cooling system and exhaust) plus 100kW (aerodynamic drag, and thermal loss from transmission).

    Am I missing something obvious?

    1. Anonymous Bastard
      Flame

      Or perhaps you just need more wax

      A LOT more wax...

      http://www.glow.co.uk/acatalog/COLOSSAL-LAVA-LAMP.html

      (Flames for obvious reasons)

    2. Ru
      Boffin

      Re: Can anyone explain why this is difficult?

      The key thing is that a large proportion of the heat generated in an internal combustion engine is going to be lost via its exhaust. A car engine might only need to shift ~20kw of heat via its cooling systems. It is possible to have an open cycle laser, but a device that chucks out very hot, very toxic clouds of gas is commonly known as a 'chemical weapon' and would be frowned upon.

      Next, vehicle design takes advantage of forward movement through air to provide a fair bit of cooling. Static or slow-moving laser emplacements don't have this luxury. Try running an engine hard on a stationary vehicle and see what happens.

      Engines can also run quite warm and are generally made of quite robust components, whereas lasers like to run cool to prevent degradation of the beam or damage to delicate optical bits.

      There are probably other issues regarding energy densities making it harder to cool smaller components generating the same amount of heat energy before they toast themselves, but I don't know enough about the workings of a chemical laser to comment on that. I shall leave it as an exercise to the reader ;-)

    3. Rogerborg

      Correction

      "[A 130bph] bike can usually sustain a steady state cruise at max power for several minutes"

      Nah, most sports bikes will run out of fuel well before that, and in any case the distance to journey termination is strictly limited by the next bend, tree, pothole or the natural predator of bikes, a BMW X5 helmed by a peroxide blonde on her mobile.

      1. John Smith 19 Gold badge
        Happy

        @Rogerborg

        "a BMW X5 helmed by a peroxide blonde on her mobile."

        Careful. I think that might be viewed as a slur against non-blonde women.

        You don't want to feel the wrath of the Moderatrix?

  14. Thomas 4
    Boffin

    A note of caution about water as a heat sink

    Many sharks are only found within certain temperature ranges and that the pool is like to be pr-warmed anyway to suit the shark's metabolism. As for the solution to this issue, the article mentions that heat build up only becomes a major problem is the super-villan waffles on at length about his plans. The simple remedy is to have said shark carved up the super-villan with aforementioned skull-ray, thus allowing the plot to move forward and scoring points with the whole "ironic death" thing.

  15. Mike Richards

    Having trouble visualising this one

    I'm fine with the quantum hijinks, but I need more details about the scantily-clad women - preferably in the form of photos (with or without their Eee netbooks) bonus points will be awarded for going the extra mile and providing their phone numbers.

    1. Anonymous Coward
      Anonymous Coward

      Sorry, you'll have to send a telegram

      For those suffering an imagination failure:

      http://myweb.tiscali.co.uk/zhochaka/Pictures2/SnatchVixen1.jpg

  16. Anonymous Coward
    Anonymous Coward

    Dear Mr Page

    ..have you ever heard of the term "evaporation" ??

    Water is particularly good at absorbing heat while evaporating: 2.2 MegaJoule per Liter (yeah, that's a French-Euro-Communist unit of volume, ya know).

    http://en.wikipedia.org/wiki/Enthalpy_of_vaporization

    I admit that you might need a refrigerator-type heat-pump to cool your laser, because it might not allow for 373 Kelvins (or 100 degrees in French-Euro-Communist units of temperature).

    Early engines (steam or internal combustion) use(d) this principles very effectively. Also machine guns.

    You could also collect soldiers/airmen/seamen piss and excrement and use the H20 of that as a coolant.

  17. Baskitcaise

    Reg Units?

    Are we talking tea-light values here or the whole contents of Madame Tussauds?

    For example:

    To shoot 3 beflippered spies takes 20 Tea-lights

    Or

    To shoot 3 beflippered spies takes one Demis Roussos

    ?

  18. Anonymous Coward
    Grenade

    ba

    Forget the sharks, mount all the crap you need on some monster tank or robot, can anyone say mechwarrior?

    but seriously, how long does it take to actual course 9mm like damage, mobile foot soldiers are unlikely to stand around too long whilst getting shot at by regular weapons. I have no idea of the technical side to these things but if you had to choose between smaller laser based weapons that may be slower than convential weapons or some form of weapons platform that can dump a shed load more energy in to something for those "quick" shots i think id rather the later.

  19. E 2

    Wouldn't the shark be...

    threatening to ravish the scantily clad table-mounted female side kick? And how would a shark do that anyway?

  20. Baldy
    Alien

    heatsinks

    Hey - aren't these the heatsinks that you mount in the Mechwarrior games?

  21. Tom Chiverton 1
    FAIL

    Umm

    So, exactly the same as what was on the lunar rovers then. Progress eh ?

  22. Jeff Cook
    Coffee/keyboard

    You're missing the obvious way to re-use the energy released as heat

    Hook it up to a sterling engine to recycle some of the heat energy and help power the laser after you've fired it a couple of times. Granted I'm in IT and completely unfettered with any engineering/physics know-how but sounds like it would work...

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