Slashdot Mirror
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.
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.
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.
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.
--
E_NOSIG
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).
The Future of Human Evolution: Autonomy
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.
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.
If brevity is the soul of wit, then how does one explain Twitter?
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?
The same reason you don't have solar cells on your car or on your laptop. They simply don't generate nearly enough energy to be worthwhile.
Does the depth and salinity in water affect solar panels; is that why they are refraining from using them?
This is not an issue - they can simply be covered with something transparent.
Tor
Actually, US armed forces and the CIA has been using Iridium satellites for all kinds of stuff since they were launched.
Tor
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.
I prefer a void in conversation to a vacuous one.