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Science

Faster Than Supersonic Travel - Underwater 219

Posted by Hemos from the gimme dept.
waimate writes "This fascinating article describes a scheme devised by the Soviet Union for superfast underwater travel - faster than Concorde. The idea is to use Cavitation - an effect usually the enemy of marine architects, and turn it to an advantage, creating vessels (initially torpedoes) encased in a bubble of vacuum and powered by rockets. All under the water. Watch out for that mullet !"
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Faster Than Supersonic Travel - Underwater More

Faster Than Supersonic Travel - Underwater

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  • Re:Stealth this is not -- more like murder (Score:1)

    by Anonymous Coward
    Incidentally, being hit at close range by a supersonic shock in air will kill a human. So you can imagine what this will do. Both v_c and isothermal compressibility are much higher for water.

  • Re:How well does it scale? (Score:1)

    by Anonymous Coward
    I think he means when corporations buy patents and then not use them or let anyone else use them just so they won't have competition. Take my 14 year-old Kuschall manual wheelchair. It has a revolutionary folding mechanism that no other wheelchair used and won't use again until the patent expires. Everest & Jennings (which is bankrupt now) bought the designs from the Swedish wheelchair maker just to keep others from using that mechanism. It's now the year 2000 and all the foldable manual chair makers still use the same folding mechanism that's been in use for over 50 years. I just bought a new Invacare brand lightweight manual chair and it too uses the ancient folding design. Wow, that's great progress and we owe it all to corporations. If a device to remove hydrogen from gasoline didn't exist, all the oil companies would buy out any technology advancements in fuel cells to slow down progress. I am glad using gasoline in a fuel cell doesn't polute as burning it does. At least that's something.
  • Hmmm I think this could probabely cause another problem, but probabely I am wrong. You can't just travel trough water, the water must be moved somewhere. When you travel at such high speed the water must be moved somewhere very fast and water isn't very much compressable. So when one of these power submarines get near a shore they could produce some sort of artificial tsunamis.
    The shockwave effect is much stronger in liquid than in air. I once saw someone first shoot a Bullet into an empty Barrel and a water filled Barrel. The empty Barrel just got a small hole, but the filled Barrel was completely blown apart.

    - Yasa

  • Wow? Are you psychic? (Score:1)

    by Anonymous Coward
    Either you know a hell of a lot more about this than given in the relatively short blurb of the story, or you've gotta be psychic.

    After all, you, SOMEHOW know that this thing will have to give a sufficient shockwave to kill the 'billions' of fishes, without knowing how strong the shockwave is, how fast it dissipates in water, and what animals will be affected (and how).

    (Just as a random question, how many bacteria, birds, floating spiders, plants, etc, are killed in every shuttle launch. You're psychic ass MUST be able to answer this.)

    You're either psychic, or spouting bullshit. Which one is it?

  • Re:What about airplanes & birds. :) (Score:1)

    by Anonymous Coward
    Why not just send a few of those torpedoes through first? That should clear things out...
  • Fluids are fluids, but some fluids support the weight of vehicles better :)
  • I remember stories about farmers complaining that their cows gave sour milk because of being exposed to the sonic booms -

    if it ain't broke, then fix it 'till it is!
  • No, it was a caterpillar drive.

    And the big flaw in the technology (besides the extremely low speed), is that a magnet of the size required to do the job would create one -hell- of a blip on magnetic sensors. Such sensors are used to detect the disturbances in the magnetic fields of the Earth caused by extremely large ships.

    So basically, even if they can't hear you...they still know where you are.


    ---
  • any form of combustion forms nitrous oxides as a result. jet engines iirc are more notiorious than most (there being no particularly good way to tack a catalytic converter on the back of a jet engine, for rather obvious reasons) nitrous oxides are one of the many gases that are, or were at one time, suspected of being unfriendly to the ozone. while this is a minor issue for normal airliners, it is a much more hotly debated issue for the concorde (and any other high altitude jet aircraft) as they fly in the altitude range where these ozone depleting gases can do the most damage.

    so yes, it's basically just a function of it's burning fuel, except that it's burning fuel at the altitude where it could potentially be most hazardous. i don't recall if this was ever proven or not, however.
  • "who wants to sit in a craft as it is fired from a gun, or risk getting stranded in the middle of the ocean if it slows down too much?"

    This has to be one of the stupidest things I've read in a scientific article. HELLO!!!

    Think about airplanes. Hey, what happens if *they* slow down too much? Ever heard of stall speed? Hey, if this sucker slows down, and loses it's ability to supercavitate, as long as it doesn't hit too much turbulence, then at least with a minimum of equipment it'd simply maintain ballast or float up. Beats dropping into the ocean from 30,000 feet in that Concorde!

    And if someone mentions the fact that going that fast is dangerous due to turbulence, go look up what happened on the first dozen or so style of planes when they went supersonic. If the leading and trailing edges are incorrectly engineered, they create 'ripples' of compression and vapors that can develop un-equal forces on the plane's control surfaces, literally throwing it into a spin or ripping it into pieces. It's an engineering issue, sure, but so was Mach in the air.

    I have read articles by 'experts' of the time saying man would never go above 50 miles an hour in an open vehicle as the 'air pressure' would prevent him from breathing. *sheesh*
  • That huge cost difference is due to the price of fuel for the Concorde. During design, they didn't expect the oil crises of the 70's, nor how much fuel the final aircraft was going to consume for how little payload/few passengers it can carry.

    The environmental stuff you are talking about was no minor thing...the noise of the aircraft is tremendous even at slow speeds. (You have to remember, by the time that the Concorde could actually do commercial service (1976 or so) Boeing had already given up on making its own supersonic aircraft.) So the Concorde was prohibited to come into the US, at the request of communities surrounding the airports. I forgot how they fixed that problem, I think it was some sorta special agreement that allowed more routes to Europe for US based carriers.
  • Actually, I would think at these speeds, a dolphin, or whale, or any large mammal for that matter, as well as debris, pieces of shell, metal, etc. would be catastophic for the "Sub". Moving at that speed, a small piece of metal, relatively stationary compared to the "sub" would destroy the sub if it somehow was forced into the bubble, however, most surrounding creatures shouldn't effect it, seeing as the force on the outside of the bubble should literlly clear away anything in it's path.
  • Imagine flying around on supercavitating, underwater "jetskis". What fun! Quick, to the patent office!
  • I assume if you've got a propulsion powerful enough to push that much water out of the way, lift is the least of your worries. Just angle the jet downward a bit. I imagine you could do that by modifying the shape or attitude of the tip of the craft. Still, the article mentioned wings (only the tips of which would be touching water) as a method of steering so they could use that for lift as well. I guess this is simpler than steering with the tip because of the enormous preassure on it.
    --
  • Strikes me that if you drive into anything that collapses (or even significantly wobbles) your cava-bubble, you're going to plough into plain ordinary water at supersonic speed, and decelerate pretty sharpish. Even assuming the hull doesn't smash into confetti, the passengers will be salsa on the forward bulkhead.
  • They're already doing things to help create the shock wave in front of the craft. Basically it involves shooting a stream of plasma ahead of the cone. Plasma super-heats the air, causes a shockwave, shockwave creates a "hole" of low-pressure for the craft to pass through. Nose cone still critical though. :)
  • If such a rocket could be built, it would seem to me that using it to either

    1) move stuff up to space

    or

    2) move stuff around the planet, via a nice high (ballastic) trajectory

    would be a much more worthwhile use of it.

  • Another prime example of vapourware. The russians are just making this all up so to shake up the commercial underwater travel industry. They are learning these tactics from Microsoft.

    "I can only show you Linux... you're the one who has to read the man pages."

  • I'd be willing to bet that they have a good handle on how light is refracted by sea water and can compensate for it. Otherwise, all you'd have to do is fire one round, watch how far it misses by, and then compensate with a second round. Easy.
  • I don't think so, otherwise they would've been able to reach their destination in mere hours instead of the damn long time it took them.

    ---
  • The other problem is that if it ever drops below its critical speed, there's no reasonable way for a vessel to reinitialize its cavitation drive.

    Float to the surface, and start up those rockets. Keep flying/bouncing until there is speed enough, then dive.

  • And if there was any doubt of where you were ... well you just runied it 'cause Shkval can't be used in a dog leg attack. Kind of like pinning a big Hear I am tag on your head.

    These things move faster than the speed of sound in water. So sonar & similiar eqipment can't see an incoming shkval at all before it hits.

    Taking a look at the trail after being hit may not be that interesting.

  • Interesting - I think the only way it could be done in air (that you are suggesting that is) is to have the bubble be a pure vaccum so there is now drag. But I guess you hadn't thought of the fact that a pure vaccuum provides no lift. So you need air. This is not the same as underwater, in this case, since they are being launched and just going and going - under water you can have the same bouyancy as the surrounding material, which is tough in a plane. So the only feasible way would be to somehow launch a craft at such high speeds that the lack of lift would not matter - and this is essentially putting the craft into orbit. And I still don't know how you would get a pure and complete vaccuum around the craft.
  • That is true, but it still does not explain what the surrounding medium would be - a pure vaccuum? Or something else? The reason bubbles hold underwate is because if the internal surface tension on the barrier between the water and the air pulled out of the water. Last time I checked, there was not much tension on the surface of a vaccuum. In fact, the Van-der-Waals force between molecules of air is so much less than that of water that I doubt any type of bubble like that could hold unless you created a traditional bubble - with a medium that holds together on the boundary (the skin of a soap bubble, the soap itself).
    But it's all speculation anyway - without a good flight plan they're screwed from the start.
  • Dude, try thinking. The water is vaporized. If you do it in air, you "vaporize the air?" No, it's already a vapor - so use a vacuum smart guy.
  • This sounds like a really cool technology - however it has quite a ways to go before it might be considered for commercial use. As people already have mentioned (I'm sure) the environmental impact might be significant due to the great speed. Also, any number of things could cause the vaccuum around the vessel to dissipate (watch out for the seaweed) and drag the ship down. But these bubbles have very interesting physical properties. not just the bubbles to encapsulate the ship, but just bubbles in general (in a liquid, that is). Their ill effects were obviously noted when props on ships started to corrode and such. Also, when electroforming, bubbles can help agitate the solution for quicker ion dispersion, but if the bubbles are near the surface being electroformed then the bubbles cause disuniformity.
    Anyway, bubbles are just fun. Expecially Soap bubbles.

  • re entry (Score:1)

    by CR0 ( 22574 )
    i am not a areospace engineer in anyway, but can't this technology be used to help spacecraft on re-entry? if we only had to worry about the nose burning up, that would seem to be a lot easier.

  • I don't think these are going to disappear beneath the sea. Even a conventional torpedo leaves a bubble trail. Imagine the bubble trail left by such a craft.

    ----------------------------------------------
  • I do see some problems with it replacing airlines. Although 30 minutes from Minneapolis to Florida would be nice to achieve, I suspect people near the surface of the Mississippi River would not be particularly fond of the technology.
  • It may have not been clear in the movie, but the book explained it was more of an electromagnetic jet. Water traveling through a tube was accelerated by magnetic fields, moving the submarine much more quietly than allowed by propellers. Silence is loved by, well, the silent service.
  • With directional propulsion, it'll turn faster & brake faster out of harms way than most aircrafts.

    I see. In the future, the "fasten seatbelts" sign will mean dolphins ahead instead of a thunderstorm.

    I wonder what the effect on the passengers on a craft like this will be when they are exposed to several Gs.
  • Assuming supersonic travel underwater produces the same kind of shock waves ("sonic booms") that air travel does, damage to the hearing of marine mammals could be extensive.

    Not to forget that underwater shockwaves are a lot more powerful than those in air. I'd expect that a supersonic underwater veichle(sp?) would have a nice large death-zone.

  • Navigation & Environmental Damage (Score:2)

    by Anonymous Coward

    Two things:

    1. For navigation/obstacle avoidance underwater, radar is useless, since radio waves just don't propagate far enough. Which leaves sonar. But if you're travelling faster than sound, you'll overtake obstacles before the sonar does. So what else is there?

    2. Assuming supersonic travel underwater produces the same kind of shock waves ("sonic booms") that air travel does, damage to the hearing of marine mammals could be extensive. There is already evidence that military sonar causes such damage. This could be much worse.

  • You realize that sound travels faster underwater than it does in the air. So which speed of sound is it?
  • I can't believe I wasted all that mental horsepower arguing with a crank the other day...you're pretty good at pulling meaningless equations out of your ass, huh?

    OK., here's the laymans' explanation, broken down into small words so you can understand it. You are not "pushing aside" water. You are moving inside a layer of water that is moving inside another layer of water, etc, etc. The principal behind this method of reducing drag in a fluid environment is called "laminar flow". Do a little basic research before tossing out the equations, huh?

    SoupIsGood Food

  • It's not that simple. You get most
    of that energy back. The stuff closing
    in behind you can push you forwards,
    (and it's not that simple either).

    You could use a similar calculation and
    prove that tuna couldn't swim that
    fast without an onboard nuclear reactor.
    But they do, and you don't need a geiger
    counter in a sushi restaurant.
  • Whales have exactly the same ear setup as any other mammal - an aural canal, ear drum, 3 inner ear bones and a cochlea. Toothed whales however pick up sound mainly through their jawbones which transmit directly to the cochlea.

    What you are 'thinking' of is the spermaceti organ of the sperm whale - it is not thought that this has anything to do with hearing but it might be an acoustic lens used in the emitting half of the sonar system, or a buoyancy regulator.

    BTW, TinMan00, if you are going to correct someone, especially in the rather graceless way you did rgmoore, it is advisable to check facts first.

    Nick

  • If density is what matters, then the speed of sound through trolls should be much faster still..

    Cheers,
    Ben
  • The should just mount a giantic spear on the front of it as they go. Free fish and blubber for everyone at the end of every trip!
  • I think the problem with spacecraft reentry is that you must get rid of a huge amount of kinetic energy, the difference between orbital velocity and a reasonable velocity in the atmosphere. You want to convert kinetic energy to thermal energy at a rate slow enough that the spacecraft doesn't burn up.
  • In other words same problems as with modern aviation (most modern planes are incapable of flying with all of their engines shut). So the solution is well known - do not stop.
  • Plus, it would be the first vehicle that travels underwater and flies.

    There is a list of about 10-20 successful prototypes of such vehicles. One of them was actually tested in broad daylight in the middle of SF bay in the 80-ties.

    They all have been heavily unsuccessful so far, but this makes them actually a fully viable idea.

  • No, you dumb ass. Sound travels faster through water. Sound travels as a compression wave, a compression wave can travel faster through a denser substance. Sound travels very rapidly through a solid piece of steel.

    Take a physics class.

    LK
  • Wow. Don't have a cow man.

    You are confusing capitalism with IP. IP very rarely results in "superior" science. Most of the time it doesn't even result in fair competition. Indeed, IP's sole purpose is to prevent competition by granting time-limited monopolies (although even the time-limited part is under fire). IP law, in fact, has much more in common with socialism than capitalism - it attempts to solve the "common good" problem in a completely anti-competitive way. Just because corporations like it doesn't make it Capitalism(TM).

    Unfortunately, in the science game, IP is generally quite useless, and growing steadily more problematic. Corporations depend on IP not to spur innovation, but to play patent portfilio games. Drug companies use branding as an excuse to hold patients hostage, and to prevent generic equivalents to their over-priced wares. Bio-tech companies use it to guarantee they "own" the genes they "discover".

    Every year we grow less dependant on wealth generated from distributing limited goods "fairly". Information starts to look less and less like a limited good (despite corporations antiquated whinings - funny how much they love socialism when they can't make money in a truly free market). Sooner or later this house of cards is going to collapse, and people like you will be left wondering how it all worked in the first place.
  • hmm well it would have to be a higher frequency than the speed you were travelling, and hopefully it won't work nearly as poorly, since I've seen deer "trapped" in between the effective range of those stupid whistles
    (for those of you who have no idea of deer whistles are.. my apologies)
  • mulletsgalore.com [mulletsgalore.com]

    hairstyle of the gods!

  • The noise level is huge. I know New York kicked up a stink. I remember being at Heathrow and watching Concorde takeoff a few times... it drowned out even nearer 747-400s easily. It's a loud SOB.
  • Now this water has to be pushed at around 340 m/s too

    The water doesn't have to be pushed at the same speed as the vessel. If the submarine were completely flat and sufficiently large in the front, then yes, it would need to push the water in front of it like a bulldozer, requiring an unfeasible amount of power. But water flows around a submarine or torpedo -- not in front of it -- and one that is designed with a minimum of drag (for this very reason) should leave the water it moves through relatively still.

    Cheers,
    IT
  • The US has neutron bombs. Russia has neutron bombs. China has [go.com] neutron bombs, having stolen the plans from the US. Pakistan has [nwsource.com] neutron bombs if it wants them. India probably has [timesofindia.com] neutron bombs. The information is out there, and eager nations with a rudimentary level of manufacturing infrastructure and raw materials can build what they want.

    Weapons aren't inherently "defensive" or "offensive". They only kill or maim people. "Offensive" and "defensive" are just a measure of political justification and the history behind intentions to kill or maim people.
  • Nitrous oxide is a greenhouse gas. Don't think environmentalists don't know it.
  • Well, I got me an AE degree too; such vehicles exist already --they are called wave-riders, riding the shockwave their blunt body is creating. Look at a buncha X Planes, and most significantly the X-33.

    Also, all modern ICBM designs induce shock waves at their nose to push air aside and reduce overheating of the rocket body --at some point in the Cold War that was such a huge breakthrough that the US had fake, wooden, sharp noses attached over the blunt noses when moving the ICBMs around...

    engineers never lie; we just approximate the truth.
  • Hear, hear, you're right on the money... this thing is totally unfeasible commercially at least. Plus, to add to your comments: I doubt they can get SONAR to work at all, at least from a supersonic version. It being faster than sound coming from the SONAR and all :-)...

    engineers never lie; we just approximate the truth.
  • I'm feeling even lazier than usual, so I'll be brief:

    Underwater rail guns?
  • Not likely. Despite appearences, jet airplanes are actually extremely efficient (for long hauls -- across the oceans and whatnot)... Like, on par with trains (on a Joule / Person*mile rating). While a supercavitating submarine may be orders of magnitude more efficient than a standard sub, it is still more drag than a 747 at 35,000 ft.

    One technical problem they didn't even address is heat dissipation. Rocket propulsion releases huge ammounts of heat. A traditional sub has excellent cooling by virtue of being entirely enclosed in water. The pressure in such a cavity will be the vapor pressure of water at edge of the bubble. Since sea water is cold, this will be fairly low, so they can't dissipate heat very quickly. Of course, they can conduct it to the nose, which will have water contact, but that will be quite a challenge.

    Bottom line, I think this will have a huge impact for naval warfare, and has several potential commercial applications (underwater exploration and science), but not likely to be used as mass transit.
  • The shuttle's solid rocket boosters basically use thermite: aluminum mixed with ammonium perchlorate if I remember correctly, with a poylmer stabilizer to control the burn rate. The result is aluminum oxide plus other stuff. Aluminum is a toxic chemical if it gets into your system.
  • Sonic booms do not break windows at cruise altitude. If you hit Mach 1 at 2,000 feet perhaps, but if you're going that fast at that altitude a couple windows don't matter because you're probably spiralling into the ground.

    They just don't fly supersonic over well-populated areas because of regulations concerning noise. It would drive people nuts. (Not to mention leading to overpopulation. Old study showed that sonic booms were directly linked to a 8% unplanned pregnancy jump in some small British burg affected by the Concorde. Men, draw your own concusions. ;)
  • nope, go read the article and no biscuit for you. They are actually referring to submarine vehicles exceeding the speed of sound _in water_ (speeds they refer to include 1.5 km/s and 2.5 km/s). Now that's fast. Of course, this is all very theoretical anyway.
  • A 20,000 HP whale would be cool, but I'd imagine it could also do better than 30 knots. Unfortunately, your calculations need some basis in reality before they make any sort of reasonable approximation (even with a fudge factor of 100x).

    Well if you take that "huge" fudge factor, that would mean that your record-braking blue whale has a 200 HP power. This is the same as a sports car. I think a blue whale can be much more powerful than that. Hey, a blue whale is probably thousands of times more powerful than a human being (it can weight 200 tons, ~2000 times more than a human being). It's really really strong!

    Also, consider how much power it takes to bring a plane to supersonic speeds and try to imagine that water is about a thousand times heavier than air. It might work for a small torpedo, but not for a submarine.

    So I still maintain that my calculations are correct within my 100 fudge factor... So instead of arguing that you don't like the final number, it'd be very pleased if you can point specific errors I made.
  • Having done some fluid dynamics before, I know that it's far from being that simple. What I'm trying to do is find an order of magnitude. But the fact remains: the Bernouilli equation tells you that drag is proportionnal to the square of the speed. Also, the power is the drag times the speed, so the power is proportionnal to the third power of the speed. It's *roughly* the same as for airplanes, except that the density of water is more than 1000 times that of air (at high altitude).

    As for getting back energy, it won't happen, since the back of the submarine is in low-pressure vapour, this actually adds to the drag.
  • The principal behind this method of reducing drag in a fluid environment is called "laminar flow".

    I know what laminar flow is. However, The flow from such a submarine would be turbulent, not laminar. Let's look at Reynolds number:

    R = L*V*rho/mu = 10 m * 300 m/s * 1000 kg/m3 / .01 P = 3,4 x 10^9. IIRC laminar flow ends around 1000, the this flow is turbulent. An object moving at that speed in air will cause a lot of turbulence. Also, the ration between the density and viscosity is higher in water that air, thus at equal speed the Reynods in water will be higher.

    As for the "pushing water aside" analogy, you can take Bernouilli's equation with F = .5 * K * rho * v^2 and you will end up with the exact same result for the power (with K=1).

    Now, instead of calling names, I'd be very interrested in having a *technical* discussion with you.
  • 2.5 GW is probably achievable with a rocket propulsion over a very short period of time, such as the one required for a torpedo (in ten seconds it can to 3 km). However, this is different for a submarine, which needs to be able to cruise at that speed. The submarine will have at least 100 times the drag and will need to keep that speed for at least several minutes, if not hours to be useful. In terms of total energy, there's about a factor of 1000 between the torpedo and the submarine.
  • Well, if you consider the problem of bringing a load of 50 tons to 500 km of altitude (ie into orbit) in only one second, you get:
    P = 9.8 m/s2 * 50,000 kg * 500,000 m / 1 s = 250 GW.

    This means that the rockets of the submarine would be enough to bring the said submarine into orbit in only 1 second! I doubt such a rocket exists.
  • While a agree that water doesn't have to be pushed at 340 m/s (I'm only roughly approximating), it still has to be pushed aside quite fast in order to produce supercavitation. Remember that the nose is flat, which is not the most hydrodynamic shape. Even if you consider a drag coefficient of .2 (it's probably above that), you get 50 GW power to drive the sub.
  • Can you explain the objections to the Concorde? I'm not familiar with them. How does it degrade the ozone layer? Or is this just a function of its burning fuel?
  • Actually it doesnt matter how much lift youre creating, how much lift does the body of a Delta rocket create? Just abut nil, and really, if youre gong fast enough, the cavitation itself could create lift, just as there are now designs for lifting body, this could be lifting cavitation, the problem is youd have to shape the cavitation somewhat so as to create the most lift, but id imagine fins or bumps on the nose cone could shape the flow to some extent.

  • Well I'd like to ask your opinion about breaking the speed of light. After all people were convinced of not being able to break the sound barrier in the past ...

    You are right - it is an engineering issue. So you should pay attention to the numbers. If neither you nor they have numbers, then this engineering issue is just not addressed. Not amount of examples or counterexamples beats a quantifiable number - even if it was just a handwaving guesstimate.

  • It seems like at very high speeds it might be difficult to navigate around obstacles under water.
    As mentioned in the article, it's a bit worse than that. They're hoping to find some way to steer the thing. Forget navigating, at the moment it travels a straight-line course. The other problem is that if it ever drops below its critical speed, there's no reasonable way for a vessel to reinitialize its cavitation drive. Once up to speed, you're fine. Drop below that speed, and the drag shoots way up, and you need a specialized launcher to get yourself into the cavitation regime again.
  • If this thing can only go in a straight line, wouldn't the earth's curvature result in this thing shooting out of the ocean and becoming an uncontrollable ICBM?
  • Creating a vaccuum, and flying around at mach 1.x. Yay. We can kill dolphins with ease. Either bludgeon them or suck them into your supersonic wake for a few hundred miles. Thank you, Russia!

  • As a couple of people pointed out, sound travels faster in water, and as a general rule, faster in denser material.

    To make sense of it, remember that sound is a vibration. Now, if you hit a brick, how fast is the hit transmitted? Likewise, if you hit the air, how fast is the hit transmitted? Finally, if you hit a vacuum, no hit is transmitted, making the speed of sound in a vacuum infinitely slow.

  • Unfortunately, this isn't a joke. Scientists are already starting to see some quite nasty effects of very loud underwater sounds on whales and dolphins. There was, for instance, a recent mass beaching incident in which loud sounds deafening the whales was implicated; they were showing classic signs like ruptured eardrums. This is particularly nasty because whales and dolphins depend so heavily on sound for navigation.

  • It seems like at very high speeds it might be difficult to navigate around obstacles under water. They might just happen to crash into say a whale, debris, seaweed, etc...
    Sounds like a cool technology though.
  • Well, when the military wants a weapon, i don't think they give too much thought to the environment.
    Just look at nukes!
  • This will give dolphins a HELL of a headache...

    1st post!
  • " ... Ladies and gentleman. In the event we lose cabin pressure, 75 pound SCUBA tanks will drop from the ceiling above you. Place the mask securely on your face, slip into your wet suit, and pull the straps to tighten. Your seat cushion may also be used as a floatation device..."



    -- "Computer Literacy? You mean my computer is supposed to read?"
  • Speed of sound in air ~340 m/s Speed of sound in water ~1500 m/s Speed of sound in Steel ~5900 m/s So if you were travelling at 2500 m/s then even without the cavitation that will prevent usefulness of SONAR you'd still be blind - you'd get to your target before it's imaged. Of course if you start pinging earlier and use prior pulses, add predicitive software, or rely on your target not moving much between launch and impact it's feasible. It's useful for torpedoes, useless for manned travel.

  • Is it just me, or every major technological and scientific development during the last 60 years is related to military research? Nuclear power, electronics, Internet, and now, supersonic underwater traveling

    Switching to the subject, there is a very serious problem: the supersonic submarine (SSS) will be totally blind. The only scanner type that works underwater, the sonar, uses sound waves, so it is as fast as sound. The vehicle is supersonic, so it will bypass its own signals. Even if it knew what it was running into, there would have been no way of steering it away to safety

    Looking at the positive [development] aspects, they could build in-water tunnels (like a pipe that goes INSIDE the ocean). This pipe would not let whales in, and that would also solve the guidance problem.

  • If I understand the article correctly, there will be no sound in the bubble. Why? Well, if the craft causes cavitation, then the bubble will essentially be a vaccuum. Sound cannot travel through a vaccuum. The only 2 possibilties would be if the exhaust from the rockets creates pressure within the cavity, or atomized water droplets might cause a sort of an atmosphere, particularly if they are friction heated into steam. The article didn't really describe that much the exact properties of the cavity, but in theory, the physical properties of cavitation create a vaccuum. Because the craft is underwater, air will never be exposed to it, and a normal atmosphere as we know it cannot exist. As I'm sure that the exact properties of this technoligy will remain secret for some time to come, we might just have to wait and see. Also, if the craft is traveling at super-sonic speeds, any sound should be left behind, and even though it could be transmitted through the water back to the front of the vessel (wich is contacting the water), the craft would be going too fast for the sound to "catch up" to the nose of the craft. Where the sound might stay is in the bubbles left behind the craft from the rockets. For those who don't believe me, tie an M-80 to a rock and drop it in a few feet of water. You will hear a low noise when the munition detonates, and a very loud noise a second later when the bubble reaches the surface and opens. It's a very cool effect. The concern I have is that sound travels faster underwater than it does at normal atmospheric densities, and for much longer distances. What affect will an underwater sonic boom have on wildlife and small surface craft? I for one wouldn't want to be in a small boat above one of these things.
  • I looked at the article but didn't see an acutal 'speed' listed. Since soundtravels faster in water is it breaking the speed of sound relative to water?
  • (1) Hello, it's blind. How the heck is it going to see where it's going? Navy ships' passive sonar capability is seriously reduced at speed because of the noise being produced by the ship going through the water (and the increased noise of the ship's machinery). Active sonar? Well, that *might* help a little, but echo from active sonar has to be heard too (see above).

    obviously, you'd put the eyes in orbit.

    (2) Most of the marine life (including seaweed, etc) stays relatively close to the surface. Great, you say -- make the thing travel deeper to avoid skewering whales, etc. Well, that'd be nice, but it's a *lot* harder to cavitate at depth due to the increased pressure (and reduced temperature) -- and the relationship is not a proportional one. Besides being harder to cavitate in the first place, it'd be harder to maintain the bubble around the vehicle (because sea pressure would be trying to collapse it).

    a compromise depth of around 40m should do the trick.

    (3) Even if you could see where you were going, how would you turn? Control surfaces on the vessel wouldn't do anything because they're in a bubble. Change the direction of the rocket? Kill the bubble.

    I imagine there will be traditional, subsonic propulsion systems for the harbor, otherwise, it is a straight shot across an ocean.

    (4) Rockets aren't exactly green machines either. Pump our oceans full of chemicals? I don't think so.

    The rockets work on powdered aluminum. so there will be an increase of aluminum oxide in the oceans, which isn't going to be much consiedring the VOLUME of the ocean. Besides, there's the potential of magnetic, nuclear and even engines external to the cava-bubble(tm)

    (5) The speed required to maintain a cava-bubble (tm) around a large commercial vessel would be MUCH greater than that required to create/maintain a bubble around a small object like a bullet or a torpedo.

    and so the engines would have to unleash more force? I don't see the problem here..

    (6) Revisiting the "can't see" issue a bit -- assuming they *could* get active sonar to work from within a noisy bubble, what kind of range/warning is it going to give at those speeds? Ever drive really fast at night? Headlights don't give you a whole lot of reaction time, do they? This situation would be much worse.

    Revisiting the "eyes in orbit" solution, You'd also have marked lanes under water, and numerous turn-off/breaking lanes to divert the vehicle from collisions. Or, you might have a few accidents per decade, as there isn't much activity at >30m beneath the surface.

    (7) This is currently being used for non-manned things that we don't care about. They either run into something or blow up or whatever. Great. Ever wonder what the stopping experience is going to be like for humans? Think about it -- the speed creates the "bubble" which eliminates the drag. Okay, we reach our destination, start to slow down -- bubble collapses -- but guess what, we're still going pretty fast -- now we have a ton of drag slammed onto us. And people whine about a airliner slowing down after a landing. :o)

    retractible drag surface fins and maybe 'artificial cavitation' obtained by millions of small bubbles released out of the skin through tens of thousands of small pores designed to reduce drag during transition between speeds.

    (8) Cost? Well, I dare say it'd be a heck of a lot more costly than the Concorde.

    cost is defined by demand. also, the concorde is too noisy in the air, while this would be more or less quiet.

    (9) If people are interested in travelling on submarines, why don't we have commercial submarines now?

    There is NO current, practical use for a traditional submarine in commercial travel applications. however, 1 hour to Calais from New York is a monumental increase in travel speeds. I know what I'd choose. have you ever spent 12+hours trying to get to London from the US? I have. The choice is obvious, and that makes it all the much more desirable.

    It sure is easy to tear stuff down, isn't it? Next time, maybe you could use that awesome imagination to try and *solve* some problems, instead of just pointing them out.

    This pessimism doesn't exactly make you wise, just clever...


    :)Fudboy
  • Since the principle is to vaporize the water in order to create the bubble... instead of doing it by accelerating the projectile to a super high speed in order to create a low pressure zone, and thereby encourage the water to vaporize, what if you heated the nose of the projectile to vaporize the water? Would this reduce the initial speed needed to create the bubble?

    Just a thought.

  • More on the Russian Rocket Torpedo (Score:3)

    by CrusadeR ( 555 ) on Sunday July 23, 2000 @09:37AM (#911956) Homepage
    The technology mentioned in the article was developed for the "Shkval" rocket torpedo (image [milparade.com]), which was originally (according to intelligence analysis at the time) intended as a "revenge" weapon: the Russian boat in question would fire it back down the bearing a Western (or PLA-N I guess) submarine had already fired upon the Russian boat from. Since it travelled at around 200 knots (which is absolutely insane for even a torpedo) and was armed with a nuclear warhead, it probably had a fair chance of producing the desired datum even without a guidance system.

    More recently [milparade.ru] (spring of 98 or so), the Russians tested a conventionally-armed version, which they could get away with by adding a guidance system to the weapon. Given that the Russian sub fleet barely puts to sea anymore, I have no idea if this is actually in service or not.

  • Re:Somebody has way too much time on their hands.. (Score:3)

    by locust ( 6639 ) on Sunday July 23, 2000 @03:28PM (#911957)
    obviously, you'd put the eyes in orbit.

    How do you plan to track targets such as whales or icebergs from orbit? Do you plan to catch and mark everything that swims so that you can avoid it? Remeber the higher your speed the smaller the thing has to be to put you into a world of hurt. Even if you mark lanes, you still have the problem that some aminals are going to change depth on you regardless of what you do. You also have the problem of fishermen who will go where ever the fsck they want and fish whatever the fsck they want, and damn your super sonic craft.

    as there isn't much activity at >30m beneath the surface.

    Plankton are the microscopic animals that for the base of the oceanic food chain. I don't think they will survive the shockwave the craft will produce. Some marine biologist correct me here. Which brings to mind the question of what effect the shockwave will have on the hulls of existing (and especially aging) ships?

    cost is defined by demand. also, the concorde is too noisy in the air, while this would be more or less quiet.

    What is more annoying the sound of the concord or the sound a thousand environmentalists? More to the point what will the craft sound like underwater. Someone has already raised the point of deafening sonar.

    There is NO current, practical use for a traditional submarine in commercial travel applications. however, 1 hour to Calais from New York is a monumental increase in travel speeds. I know what I'd choose. have you ever spent 12+hours trying to get to London from the US? I have.

    After all the waiting for sea lanes to clear, the travel into warmer waters to avoid other obsticles, and the constant battle with environmentalists who will inist you are killing everything in the water (wait until you see that first picture of a dead dolphin, its what did in the drag-net fisherment), it will still be cheaper and faster to fly. Besides, a goose will get sucked into a jet engine and appear on the menu for the next flight, a whale will get all the passengers killed.

    --locust

  • Some clarifications (Score:3)

    by craw ( 6958 ) on Sunday July 23, 2000 @03:53PM (#911958) Homepage
    Instead of replying to individual comments, I'll put all my stuff here. The speed of sound in an object is a equal to sqrt( E / rho ) where E is the Young's modulus (think stiffness) and rho is the density of the material. For liquids (no shear stress) E reduces to the bulk modulus (1/compressibility). Hence, speed does not increase because density increases.

    It will be extremely difficult to have an operational sonar with a superfast platform. Anybody read Tom Clancy? Remember how he mentions that subs go acoustically blind if they go too fast. Here's a simple underwater (not air) acoustic lesson. A decibel (dB) is defined as 20 log10( P/Po ) with respect to a microPascal (uPa) at 1 m distance. There are additional rules that apply for the frequency content (1 Hz bandwidth) and signal duration (1 sec), but I'll neglect this for simplicity. P is the pressure of the signal, and Po is the reference pressure (1 uPa). 10^5 uPa = 1 dyne/(cm^2) = 10^-6 atmosphere. Hence 1 atmosphere = 10^11 uPa = 20*11 dB = 220 dB.

    Now consider geometrical spreading loss. For distances under 10 km, we have spherical loss = 20 log10(D/1m), where D is distance in meters. So for 10m there is a 20dB loss, for 100m there is a 40dB loss, for 1km a 60dB loss.

    Put it all together. A good active sonar will put out a 235dB signal. If it travels 50 m out and 50 m back, and if the target is a perfect reflector, and if there is no absorption loss, then the received signal is 195dB=10^-1.25 atmospheres. I would guess that the pressure fluctuations by a superfast system will easily exceed this value. And note, I have chosen to use very conservative numbers.

    There is no hard scientific evidence that Navy sonars harm mysticetes (baleen whales), odontocetes (dolphins), or pinnapeds (seals). In terms of physical damage to their hearing mechanisms, the animal would have to be very close. Suppose 1 atm fluctuations are deadly (this is a very conservative value), then the animal would have to be less than 10 m away from a 235dB source. Now if we are talking about long-term hearing loss, then we also need to consider other, more continuous noise sources in the water; namely shipping noise.

    Final notes: the dB reference pressure is different for underwater versus air. The dB's I talk about are peak-to-peak dB's. You need to factor in frequency bandwidth and time duration if you want to convert to watts.

  • Re:Hunt for Red October (Score:3)

    by GW Hayduke ( 19878 ) on Sunday July 23, 2000 @09:24AM (#911959)
    Actually that was the "caterpillar drive" which was supposedly capable of near-silent propulsion.
    An interesting site for submarine technology, etc.. is over at http://www.pbs.org/wgbh/nova/subsecrets/ [pbs.org]

  • Comment removed (Score:3)

    by account_deleted ( 4530225 ) on Sunday July 23, 2000 @03:00PM (#911960)
    Comment removed based on user account deletion

  • Re:Quick calculation (Score:3)

    by costas ( 38724 ) on Sunday July 23, 2000 @11:07AM (#911961) Homepage
    Nit to pick: I doubt they're considering 340m/s as Mach 1. Underwater, that's probably gonna be closer to 1.5 Km/s --speed of sound changing with medium density and all that...

    engineers never lie; we just approximate the truth.

  • Re:How well does it scale? (Score:3)

    by Gurlia ( 110988 ) on Sunday July 23, 2000 @10:40AM (#911962)
    I only hope humanity doesn't get screwed out of useful tech by corporations traping this in useless IP barriers.

    Umm... have you realized that the car you drive every day, the water and electrical supply you use every day, the trains and airplanes and all the other forms of public transportation, and even the computer you use, are built by corporations who "trap" technology in what you call "IP barriers"?? Thanks to these evil, evil, corporations, we actually don't have to scavenge for loose bits of scrap metal from the junkyard in order to built an "open-source" car, an "open-source" aircraft, an "open-source" electrical supply!! Surely those corporations are Satan himself!

    Man, talk about Slashdot dogma. I'm sure happy Linux isn't invented by a frog-in-the-well like you, otherwise today we'll still be suffering under the tyranny of crappy M$ junkware. It's rabid, brain-washed zealots like this that make Open Source so repulsive to businesses who could make major contributions, that make people think Open Source supporters are just a bunch of disgruntled college students. That make employers cringe when their IT staff suggests to switch to Linux or BSD. That make newbies want to stay with Windows 'cos they're constantly despised by so-called "Linux experts" who think they're so darn smart even though they don't even know what Open Source is really about.

    How many on the "Open Source bandwagon" are the shouters and cheerers, and how many actually know what it's about?! If you want to advocate your anti-corporation garbage, please at least don't call it "Open Source".

    (Yeah, mod me down. Thanks for reinforcing blind Slashdot dogma. I have enough karma to burn. I just hope somebody reads this and wakes up, before it disappears into the recesses of Troll -1.)


    ---

  • Re:Somebody has way too much time on their hands.. (Score:3)

    by Maurice ( 114520 ) on Sunday July 23, 2000 @12:08PM (#911963)
    (4) Rockets aren't exactly green machines either. Pump our oceans full of chemicals? I don't think so.

    Big rockets are usually powered by liquid hydrogen and oxygen. The end result is water. Smaller ones may use RP1 (kerosene) and liquid oxyden but the end result of this is still water, plus carbon dioxide. None of these are toxic. Solid fuel boosters usually use some sort of nitrogen compound and the end result is some sort of nitogen oxide, which is also non-toxic (mostly that is, some particular compounds of N and O are called laughing gas IIRC and they make you errr, happy when you inhale).
    In general most chemical rocket boosters are quite environmentally friendly.

  • Hmm... (Score:3)

    by milkman1 ( 139222 ) on Sunday July 23, 2000 @09:40AM (#911964)
    This article would seem to suggest that:
    1) This tech. will allow us to go faster than the Concord.
    2) That this would be a viable intercontinental transport system.

    It would seem to me that there are many forms of (air) transport faster than the Concord (SR-71 Blackbird, rocket powered vehicals.) However we don't use these for transportation. I seriously doubt that a rocket powered craft is going to cost less to fuel than even the SR-71, much less the Concord.
    Considering the small number of people that can even afford to fly the Concord, I doubt that this plan will have much viability outside the military.

  • Re:Somebody has way too much time on their hands.. (Score:3)

    by buback ( 144189 ) on Sunday July 23, 2000 @11:31AM (#911965)
    your just Pessimists. if we'd of listined to you we'd have never faked landing on the moon!

  • what about environmental issues? (Score:3)

    by Gnaythan1 ( 214245 ) on Sunday July 23, 2000 @09:58AM (#911966)
    seems a supersonic airplane would just shatter a few windows... but a supersonic sub would send shockwaves that would kill a hell of a lot of fish... anybody looked into that?

  • Re:It'll never happen (Score:4)

    by Chris Johnson ( 580 ) on Sunday July 23, 2000 @01:29PM (#911967) Homepage Journal
    Oh, by all means. Nobody seems to be taking into consideration how efficient water is for wave transmission. Ever heard of the Yangtze River Dolphin? It's an endangered species (not sure of its current status) in a very busy river. Douglas Adams wrote a book about endangered creatures called 'Last Chance To See', one of which was the Yangtze River Dolphin. One problem of the dolphin's was the amount of background noise in the river from just plain old outboard motors- lots of them- interfering with the dolphin's echolocation, its sonar. Douglas Adams tried to check out what noises were in the river, and put a hydrophone into the water (a waterproof mike), expecting to hear something like New York City rush hour, only with outboard motors...

    Water is a very efficient transmitter of soundwaves. Adams heard no outboard motors, no dolphins- nothing but a continuous, ceaseless, raging white noise so intense no information could be heard from it at all. All those outboard motors echoed and echoed until the river was one unbearable shriek of sound...

    Now. How much louder than a cheap outboard motor is a rocketpowered submarine creating a cavitation bubble so great that a _ship_ fits inside it?

    This might work as a military weapon where you don't give much of a damn what else you hit, but use as sea transportation will, surprisingly quickly, leave _no_ form of sonar available for anybody. Not whales, not fish, not oil tankers. I'm not sure how many of these subs it would take but you have to understand how incredibly 'live' water is- sound does not propagate like it does in air. The ambient noise level will simply rise and rise until you can't use sonar for anything anymore- by which time of course, huge amounts of the sea's ecosystem will be hosed, which could also be considered a Bad Thing. That _is_ where the earth gets most of its oxygen y'know ;P

  • 250 GigaWatts: Time Travel? (Score:4)

    by IntelliTubbie ( 29947 ) on Sunday July 23, 2000 @11:16AM (#911968)
    Combining the two results gives us 250 GW of power required to move our submarine.

    Wow, and it only takes 1.28 GW to travel through time! That is, if you can find an engine powerful enough to accelerate you to 88 mph. Doc, look out!

    Cheers,
    IT

  • US Navy Too! (Score:4)

    by superid ( 46543 ) on Sunday July 23, 2000 @09:19AM (#911969) Homepage
    The US Navy has been researching this technology for quite a while as well. See this article [navy.mil] from 1998.

  • Quick calculation (Score:4)

    by jmv ( 93421 ) on Sunday July 23, 2000 @09:52AM (#911970) Homepage
    Consider a "small" submarine with a radius of 2m, going at a speed of 340 m/s (Mach 1 at sea level). The amount of water this submarine has to push aside is pi*(2m)^2*340m/s = 4300 m3/s

    That's 4300 tons of water per seconds. Now this water has to be pushed at around 340 m/s too, which corresponds to a kinetic energy of 58000 kJ/ton of water. Combining the two results gives us 250 GW of power required to move our submarine.

    This calculation is very approximate, but it still gives an order of magnitude. Even if I'm 100 times over, it still means thousands of megawatts, the power of a big nuclear plant. This is why I doubt we'll see a supersonic submarine soon.

  • Screw Underwater (Score:4)

    by cybercuzco ( 100904 ) on Sunday July 23, 2000 @09:29AM (#911971) Homepage Journal
    The real question is can this be done in air? One of the big problems supersonic vehicles have is shockwaves and heating on leading edges, now while getting my Aerospace engineering degree i had to take a fluid dynamics course or two, and the gist of it is that fluids are fluids and both air and water are fluids. If you can create a blunt nosed craft that can reach high speeds with low drag, this can be an amazing breakthrough for air and spaceflight. it certainly has piques my curiosity and ill be following devlopments closely.

  • Stealth this is not -- more like murder (Score:5)

    by Morgaine ( 4316 ) on Sunday July 23, 2000 @10:30AM (#911972)
    Any living organism caught by the shock front from this thing is going to be jelly. A megawatts drive underwater would translate directly into millions or billions of fish dead on each trip, and probably several boats and human lives lost as well for good measure.

    Someone's got to be kidding.

  • Somebody has way too much time on their hands... (Score:5)

    by CyberPup ( 87109 ) on Sunday July 23, 2000 @10:48AM (#911973)
    Sheesh, give a little techno-babble to a reporter and he has everyone dreaming about daily bullet trips across the Atlantic. Gimme a break.

    This technology is fairly reasonable for what it's being used for (blind, dumb, fast, small things).

    It won't scale to large vehicles, and most reasonable humans have an aversion to travelling in blind, dumb, fast things anyway.

    Here's a short list of "strikes against it" that immediately come to mind:

    (1) Hello, it's blind. How the heck is it going to see where it's going? Navy ships' passive sonar capability is seriously reduced at speed because of the noise being produced by the ship going through the water (and the increased noise of the ship's machinery). Active sonar? Well, that *might* help a little, but echo from active sonar has to be heard too (see above).

    (2) Most of the marine life (including seaweed, etc) stays relatively close to the surface. Great, you say -- make the thing travel deeper to avoid skewering whales, etc. Well, that'd be nice, but it's a *lot* harder to cavitate at depth due to the increased pressure (and reduced temperature) -- and the relationship is not a proportional one. Besides being harder to cavitate in the first place, it'd be harder to maintain the bubble around the vehicle (because sea pressure would be trying to collapse it).

    (3) Even if you could see where you were going, how would you turn? Control surfaces on the vessel wouldn't do anything because they're in a bubble. Change the direction of the rocket? Kill the bubble.

    (4) Rockets aren't exactly green machines either. Pump our oceans full of chemicals? I don't think so.

    (5) The speed required to maintain a cava-bubble (tm) around a large commercial vessel would be MUCH greater than that required to create/maintain a bubble around a small object like a bullet or a torpedo.

    (6) Revisiting the "can't see" issue a bit -- assuming they *could* get active sonar to work from within a noisy bubble, what kind of range/warning is it going to give at those speeds? Ever drive really fast at night? Headlights don't give you a whole lot of reaction time, do they? This situation would be much worse.

    (7) This is currently being used for non-manned things that we don't care about. They either run into something or blow up or whatever. Great. Ever wonder what the stopping experience is going to be like for humans? Think about it -- the speed creates the "bubble" which eliminates the drag. Okay, we reach our destination, start to slow down -- bubble collapses -- but guess what, we're still going pretty fast -- now we have a ton of drag slammed onto us. And people whine about a airliner slowing down after a landing. :o)

    (8) Cost? Well, I dare say it'd be a heck of a lot more costly than the Concorde.

    (9) If people are interested in travelling on submarines, why don't we have commercial submarines now?

    -- CP (Who, by the way, spent several years on submarines; and spent three years teaching Heat Transfer & Fluid Flow)

  • It'll never happen (Score:5)

    by John Jorsett ( 171560 ) on Sunday July 23, 2000 @10:36AM (#911974)
    Environmentalists have conniptions over sonar discombobulating whales migration patterns and maybe even deafening them. They also accuse the supersonic Concorde of contributing to the degradation of the ozone layer. Now combine the two in the form of supersonic underwater travel and you may as well just paint the target on your back for Greenpeace. Had this emerged before environmentalism took such a hold, maybe it would continue to be used, but attempting to introduce it today just isn't going to fly. And I hate to say it, but just maybe that would be a good thing for once.

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