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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 !"
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.
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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.