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More on Underwater Gliders
ianjk writes "Abcnews.com is reporting on two underwater gliders developed by the University of Washington and Webb Research. Both use very little energy and have quite long ranges (thousands of kilometers). Of course, the US Navy is showing quite an interest in the project." We mentioned these earlier.
Makes snorkeling a whole lot less interesting..
From a technical Navy employee...
You would think that the Navy would be getting all sorts of funding for these types of projects nowadays... but really what's happening is that funding is being diverted to war operations type stuff... so those of us working on new technology for the Navy have gotten huge budget cuts...so don't expect much in the way of cool techie things any time soon.
"If at first you don't succeed, lower your standards."
Have been under study for years- the Mk48 Torpedo is basically a wire-guided drone; it reports information back to the mother sub and can be steered using a joystick.
The USN has been looking into extreme-depth tethered drones- really strange things start happening to sonar and weapons performance at extreme depth.
Of course, this will all come in handy if the USN needs to fight the Third Battle Of the North Atlantic, but for littoral (inshore) warfare, the navy might want to start researching some brown-water navy stuff.
There have been a variety of Navy programs that used trained sea mammals to protect Naval bases, for instance the trained dolphins trained to bump into a VC frogman in Kham Rhan bay, but they never told the dolphins that the bumping hat was an activated mine. Boom!, one less flipper, and one less Charlie.
There are also reports of using sea lions, seals other cetaceans to watch for submersibles and boats, and hit them, forcing a detonation. For instance, Day of the Dolphin is a thinly veiled documentary on teh CIA's attempt to train dolphins to blow up Castro's yacht.
So, with these, everyone will win. The Greenies cute little dolphins don't have to kill, and the US Navy can continue to enforce the Pax Americana, and the rest of the world (except for evildoers) can go about their business, criticizing war mongering Americans, yet profiting from the most peaceful age the world has known since the Roman Empire. We business savvy sorts call that a win-win situation.
Some guy over at kurofivehin, I think he calls himself "UndesirableUsername", said that water transport was The Way Of The Future!
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I wonder how deep these gliders will go? At what depth does the pressure start playing havoc with its sink/swim functions?
:-) but seriously.. I would love to see what kind of data a long term mapping program would compile..
I am really curious as to what we could find if we put a bunch of these in the ocean, and just monitored for objects that don't belong..
the sunken city of atlantis?
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So what happens when the navy's underwater-spy-glider-drones are picked up in a fishing net?
However, because of the density of water, the boyancy is much greater than air. Since this "glider" works on this principal, it should be much easy to worked on a wave/boyancy principal.
I still don't see how it would avoid getting push around by stray currents, etc though. I could see one of these little guys wandering lost and off course at times.
Uhmmm, Yeah. This would be a real dead end, especially if you were to drop thousands of these near a harbour and set them to patrol an area, all without active manpower.
It seems likely that these could evolve into smartmines that will just float around a harbour in predefined locations and patterns. Nobody said that these would be the fastest things in the ocean, but if they have a range of thousands of kilometers, that's also a range of one kilometer a thousand times.
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No That is a good point.. I Agree..Except the viscosity of water is even worse, I think it is 4 or 5 times that of air in this example That is what we are doing in class right now. There is a future in this though, didn't you ever watch Seaquest? Remember Lucas? He had that dolphin craft that went a couple hundred kph..
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This is exactly why water transport is a dead end that has rarely worked in the past.
Most water-based transport has been based on using brute force to displace the water with the object. This, like air to a hot-air balloon, lets the water displace the object. The whole point, had you really read the article, is that the glider is letting the water do all the work.
No very ridiculous. Drag force is typically proportional to the square of the velocity. This thing apparently moves at 1 knot. Reductions in speed save you quite a bit of energy, actually. Viscosity becomes a player at higher speeds.
You only need to look at the lockout on the west coast ports to realize how important water transport is.
Or you might want to read the history of the Phoenicians, Polynesians, or even of Christopher Columbus, all of whom apparently had working water transport, despite your claims.
I realize I may have dreadfully misinterpreted your post, but I can't work out what else you may have meant.
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His bullshit is 100% totally irrelevant in this case anyway, because the gliders aren't for transport, they're for monitoring sea conditions!
Any bright ideas for monitoring deep sea conditions from the air, PhysicsGenius?Great joke! Thanks, I needed a chuckle.
;-) Nicely done.
Energy = work = force times distance. And, in the case of moving through a fluid, force is proportional to the square of the area times the viscosity. Let's say that the square of the area of the glider is 1 unit. And let's say the viscosity of air is 1 and that of water is 2. Then the energy to push the glider through water is twice as high as it would be in air.
Of course, the lift generated is at least proportionally impoved as well (I don't have the equations at hand, so a little handwaiving will have to suffice until someone corrects it with hard facts). A lifting surface generates no lift in a vacuum, thus the need for reaction mass in space. As air thickens, a lifting surface generates more lift, so much so that my plane flies noticably better in the winter than the summer, simply because colder air is generally more dense than warmer air at the same barametric pressure and altitude. This effect should even be more pronounced in even more viscouse, denser fluids, such as water.
Any aerospace engineers or physics students have the equations handy?
This is exactly why water transport is a dead end that has rarely worked in the past.
This was when I finally figured out you were having some fun at our expense.
(To those who don't get it: more than 90% of all goods are transported by water. It is the most effecient means of moving stuff around we humans have yet devised).
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The only "energy" involved in the underwater glider is in shifting ballast and increasing or decreasing buoyancy.
It's an incredibly efficient method of moving stuff, albeit slow.
I'd be interested in seeing what effects various currents might have on possible freight routes using large UW gliders.
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No Way!
C'mon people
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Evil sharks with laser beams attached to their heads!
Heh, really though, why not put the instruments on dolphins. I watched a History Channel program on the Russians strapping surveillance equipment to dolphins and even using radio "mind control" to tell them where to go. Radio controlled dolphins. You'll have an endless supply of them!
Lift and drag are proportional to 1/2*density of fluid*surface area*Velocity squared. (L, D ~ 1/2*rho*S*V^2).
A lifting surface generates no lift in a vacuum, thus the need for reaction mass in space. As air thickens, a lifting surface generates more lift, so much so that my plane flies noticably better in the winter than the summer, simply because colder air is generally more dense than warmer air at the same barametric pressure and altitude.
The effect is much more pronounced in water because of density, not viscosity.
you know, reading articles such as this always leave me with the feeling that we aren't really exploring the use of the seas in future. Almost 70% of the earth is water, but we do not have that much effort or research money in it that we have for space exploration. It's really quite illogical to hope for the stars while ignoring your own backyard. Also considering that pure water is going to be one of the world's biggest problems, we should be paying more attention here.
The energy being used by the glider is harnessed through dropping and rising in relation to the Ocean's surface. It is really not a comparison between Air going gliders and Undersea going gliders, or the effeciencies thereof. It is about utilizing the conditions of the ocean itself as a powersource for a long endurance underwater craft. Its also pretty damn cool!
As for the sea transport bit at the end... While it didn't actually have anything to do with the article, you should probably be aware that most products arrive from overseas on ships- not airplanes. That's why the lockout of the longshoreman on the West Coast last week required Bush II to step in.
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She loves the hot pink underwater glider! It will match all of her outfits, her car, her RV, her house, her guitar, Ken's cardigan and her jetski. I wonder when Presidential Barbie will start bombing Iraq?
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They said the batteres would be LiIon and that the submersible would be comming to surface to communicate, so why not add a couple of solar panels? Im sure it won't bring up the costs significantly. (Heck NASA probably already has a bulk discount on solar panels :) Does the depth and salinity in water affect solar panels; is that why they are refraining from using them?
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Maybe not quite... Rechargeables decay after a while...
It looks like at least some of these designs surface periodically for a GPS fix.
Why not stick a small solar cell on the upper surface? Given the power requirements it shouldn't take too long to recharge. It can probably even recharge a meter or two (or more depending on the water clarity) down from the surface.
retrorocket.o not found, launch anyway?
It is a well documented fact the the countries with a dominant Navy have always been the pwoer house of the world.
.... which is why we keep a dominant Navy. They also make it possible to place embargos into effect!
... why do you think Great Britian was the power house it was back in the day? G.B. is just a small islnad nation, but yet they were the dominant force on this planet for over a century. Why? Their NAVY!!!
There is no way to fly, reload and refuel our (the U.S.) military planes and use them effectively in a war without air craft carriers
As far as history
Keep in mind that there is no way for any Asian or European countries to invade the Americas (if they wanted to) without the use of a Navy. A solid Navy is the key to winning ANY war (without using nukes).
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Charles Eriksen, an oceanography professor and one of the developers of the Seaglider, says that such a propulsion system isn't fast. At best, the glider can make about half a knot -- slightly more than half a mile an hour.
But since it will use only one-half watt of electrical energy to produce that speed, Eriksen says the Seaglider has a range of "thousands of kilometers" and remain in the ocean gather data for much longer.
"We can operate one of these for a year and across whole ocean basins," says Eriksen.
I can picture this thing going for a year...
Some Navy Officer: We've got a special mission for you, we sent out an underwater glider a year ago to collect data on enemy sub movement, we need you to recover the glider.
Navy Seal: Sir yes sir!
*goes into the water, takes 10 steps forward, reaches down, picks up glider*
Navy Seal: Sir I have recovered the glider sir!
The Navy however, has no figher pilot equivalent. The billion dollar war platforms that make up the submarine force are already very unglamorous to work in. The price tag of these ships brings in a whole new player to this battle. Congressmen and women LOVE to see high-priced defense contracts being given to shipyards in their districts.
If these mini-subs are truly effective and the demand for hugely expensive nuclear powered subs begins to drop, it will be interesting to see which senators favor the modernization of our military vs. those who want more pork barrel projects pumping fuel into their local economies.
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Lift and drag are proportional to 1/2*density of fluid*surface area*Velocity squared. (L, D ~ 1/2*rho*S*V^2)
... and we haven't even considered the energy provided by hydro-thermal activity (the oceans have thermals just like the atmosphere does, of course).
Thanks, the days when I had that memorized are long behind me.
The effect is much more pronounced in water because of density, not viscosity.
Oops, I did say viscosity didn't I. Someday I'll actually start proofreading my posts. I meant despite water's viscosity the improvement in lift would be more than enough.
I'm certain the entire post I replied to was tongue-in-cheeck, based on the "water transport will never amount to anything" quip at the end, but the equation you provided underscores how well gliders in water would function
thanks again for the equation.
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And let's say the viscosity of air is 1 and that of water is 2. Then the energy to push the glider through water is twice as high as it would be in air.
That may all be fine and dandy, and you may be correct in the sense that it would take twice the energy to push this object through the water as oposed to through the air. However, there's a gaping hole to your theory:
The fact that the UAV needs to remain IN THE AIR, while the AUV can just FLOAT greatly reduces the amount of energy it will require. And if you create it with blow tanks and other such technology, that would allow it to remain at a certain depth WITHOUT the need to spend ANY energy, making it even more efficient than the UAV.
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..Want to see one swallowed by a whale. Imaging the face on the researcher. Then imagine the face on the whale when this thing expands it's ballast to rise.
Though this would make for an interesting part of ones thesis paper.
I also agree with the earlier poster -- a 1 Knot 'glider' in a 5 knot current sounds only slightly better than a buoy -- but you may be able to use that 1 knot active motion to do things like move cross-current and use different ocean currents to move you around the ocean.
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So someone finally found a use for the Iridium satellites after all!
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Rumour has it that the shark community will be code-naming these gliders:
"Lunch"
So, with these, everyone will win. The Greenies cute little dolphins don't have to kill, and the US Navy can continue to enforce the Pax Americana, and the rest of the world (except for evildoers) can go about their business, criticizing war mongering Americans, yet profiting from the most peaceful age the world has known since the Roman Empire.
Pax Americana?
The most peaceful age the world has known since the Roman Empire?
Sure, If you define it as the state of perpetual war that has existed since the 1930's: our governmentt has been going around the world finding excuses to pick a fight with almost anyone, and the result is large numbers of people in a crazed and desperate enough state of mind to fly a perfectly good airplane into a building full of people, and this is, of course, an age of unprecedented peace among mankind?
Perhaps its due to a preponderance of people who think that naval surveillance drones have something to do with training trusting sea mammals to be suicide bombers...
...if the DEA could use this kind of technology to track all of those 1 a.m. drug running boats from South America.
:)
Good place for funding at least
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But are they ill-tempered, or do they have laser beams attached to their heads?
(sorry)
Wow! The thermal version described in the article is very similar to the "glidoons" proposed in The Inventions of Daedalus a number of years ago. A glidoon is an inflatable glider containing a substance that is gaseous at sea level and condenses in the cold of high altitude. The craft glides up and down without fuel, driven only by the endlessly reversing buoyancy. Exact same principle, and they really did it!
Why wouldn't they use saltwater batteries? Submarines use them. The only thing they need to come up for anymore is food. They can be made on a much smaller scale that would be suitable for this.
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Normally it wouldn't help too much, but given the extremely low power consumption of these devices, even a small number of solar panels could provide quite a bit of run time for a minimal amount of charge time.
Cover 25% of the upper surface of the pictured glider with solar panels and you can probably spend only 30 minutes to charge the thing every few days, or better.
retrorocket.o not found, launch anyway?
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The next step is to combine this with an ability to filter feed on plankton and technology from slugbot for a machine with infinite endurance.
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How do you know? Shark are reported to hit surfboards from time to time, probably not trying to eat the human on top, but a case of mistaken identity. It certainly wouldn't surprise me if these things stop transmitting and turn up with a chunk out of them from time to time. In the deep they would probably be hard to spot, and they wouldn't have smells that a shark would recognize (probably).
err, this isn't just a wargame for the PC. Loads of innocent people are going to die, be made homeless, see their hometowns bombed into rubble and the really evil people will get away. That's why some of us get uptight.
Pax Americana is probably the best we're going to get for a while, but damn, some of you guys treat war like it's a jolly little Victorian English game. Lots of us live in countries where war means enemy tanks rolling down your street in your father's lifetime if not your own.
You make some good points and everybody in Europe knows that the situation we have today is due to the positive intervention (in my opinion) of other countries. A lot of people are very, very grateful, including me.
What's interesting is that I can't tell which country you're writing from based on the statements about your country's foreign policy - I assume USA based on our previous exchange but the points you make could be written by a Canadian, Australian, New Zealander, Indian, Jamaican... these countries and many more sent troops and aid to fight in wars between 1900 -1945. We honour all these countries for their sacrifices.
My key point was that I think a people and their country's attitude to war is profoundly affected by their experience of it. I think that the US (and some other countries) experience of war as something that happens in a remote place is similar to the British experience of war in the 19th Century, rather than the European (and many other countries) experience in the 20th Century. I think it makes a difference that for the USA and some countries, war is still something that is about cheering the boys off to on a foreign front, while life goes on as normal back home. It's telling you note that previous wars you intervened in cost you 'millions of sons' - it only affected young men. For many countries (e.g. Europe), in living memory war has affected *everybody*, war is something that happens in your village. It's about enemy tanks driving down your high street, bombers dropping high explosives on your mother's retirement home, your school being used as a detention centre to accuse your neighbours of being terrorists and acting in the way the victors feel is appropriate. It's about your grandfather surviving in the bombed out rubble of his own home through the middle of the winter with no fuel and little food.
I think that this more direct experience of war makes some countries more reticent about engaging in such an act and gives them a different perspective.