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Faster Than Supersonic Travel - Underwater
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 !"
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?
You should never take life too seriously - You'll never get out of it alive.
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.
http://rareformnewmedia.com/
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
-- "It's a sad day for American capitalism when a man can't fly a midget on a kite over Central Park" - Jim Moran
If density is what matters, then the speed of sound through trolls should be much faster still..
Cheers,
Ben
My usual seat in the cluetrain is at A HREF="http://pub4.ezboard.com/biwethey.ht
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.
Mea navis aericumbens anguillis abundat
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.
Baker's Law: Misery no longer loves company. Nowadays it insists on it
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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.
Baker's Law: Misery no longer loves company. Nowadays it insists on it
http://www.sigsegv.cx/
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
"Hi. This is my friend, Jack Shit, and you don't know him." - Lord Kano
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)
-- Life: Hate the Game... Love the cereal
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.
Open Source. Closed Minds. We are Slashdot.
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
Power corrupts. PowerPoint corrupts absolutely.
The US has neutron bombs. Russia has neutron bombs. China has neutron bombs, having stolen the plans from the US. Pakistan has neutron bombs if it wants them. India probably has 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.
"If one is really a superior person, the fact is likely to leak out without too much assistance" -- John Andrew Holmes
Nitrous oxide is a greenhouse gas. Don't think environmentalists don't know it.
"If one is really a superior person, the fact is likely to leak out without too much assistance" -- John Andrew Holmes
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?
MSK
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.
www.eFax.com are spammers
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.
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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.
Opus: the Swiss army knife of audio codec
The principal behind this method of reducing drag in a fluid environment is called "laminar flow".
.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.
.5 * K * rho * v^2 and you will end up with the exact same result for the power (with K=1).
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 /
As for the "pushing water aside" analogy, you can take Bernouilli's equation with F =
Now, instead of calling names, I'd be very interrested in having a *technical* discussion with you.
Opus: the Swiss army knife of audio codec
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.
Opus: the Swiss army knife of audio codec
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.
Opus: the Swiss army knife of audio codec
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.
Opus: the Swiss army knife of audio codec
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?
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.
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!
Pax Digitalia
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.
For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
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.
There's no point in questioning authority if you aren't going to listen to the answers.
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?"
The face of a child can say it all, especially the mouth part of the face.
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.
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).
:o)
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.
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
:)Fudboy
I guess I'm only a Fudboy, looking for that real Transmeta
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.
The technology mentioned in the article was developed for the "Shkval" rocket torpedo (image), 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 (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.
:wq
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
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.
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/
-- Life: Hate the Game... Love the cereal
How quickly does the object slow down once the bubble collapses? Say you fire a .270 or a 30-06 rifle into water, it nearly stops after going in 1 meter. Either of these 2 rounds fire between 2200 and 3200 feet/second, depending on how much/type of powder, and the weight of the bullet. So, at a minimum, the bullet goes from 2200 fps to 0 in a split second because there's no bubble around it. When the bubble collapses on your manned vehicle, will it slow down just as fast? If so, the people inside are going to be goopy mess of blood, flesh and bones stuck in the nose of the vehicle. So they're going to have to fire the vehicle from some sort of large gun into the water to get the bubble to form, and then at the end of the trip, the bubble will collapse and the vehicle will go from over the speed of sound to relatively nothing in under a second. The chances of this actually working are nearly zero, why don't they just shoot travelers in the head before they get on the thing. What happens if they hit a whale or a stray mine left over from wwII? The thing will mostly be unsteerable, and any change in direction will take several tens of miles or the bubble will collapse. I admit, it's a cool concept, but I'll let them make a few mistakes before I ever get on one.
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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.
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.)
---
mikre he sophia he tou Mikrosophou.
(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.
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.
your just Pessimists. if we'd of listined to you we'd have never faked landing on the moon!
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?
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
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
Power corrupts. PowerPoint corrupts absolutely.
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.
Opus: the Swiss army knife of audio codec
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.
"The question of whether machines can think is no more interesting than [] whether submarines can swim" - Dijkstra
Sheesh, give a little techno-babble to a reporter and he has everyone dreaming about daily bullet trips across the Atlantic. Gimme a break.
:o)
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.
(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)
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.