These things seem pretty high tech. Is the US messing around with this stuff as well?
http://www.chinfo.navy.mil/navpalib/factfile/ships/ship-sea.html
Anything other than that, I dunno.
In the book Skunk Works Ben R Rich (head of the works for a time) talks, IIRC, about trying to get the Navy interested in stealth - including for subs - to no avail. There’s a piece on the “Sea Shadow” that bernse’s link shows and the political waters it foundered in
Do the Swedish ships offer any advantage? If not, what was the point, they look cool?
I think they mentioned a slightly reduced radar signature.
IIRC the periscope on a sub is ‘stealthed’ (shape and material) to make it harder to pick up on radar when it pops out of the water. As to why you’d want to bother stealthing the rest of a sub I can’t imagine…it IS stealthy (underwater where it stays all the time anyway).
Why would an ASW ship need to be stealthed? It is either part of a battle group most of which will show-up just fine on radar and its target (a submarine) woudn’t be fooled by it anyway as it would track the ship from noise emissions. Same goes for its mine-sweeping purpose…mines don’t track with radar either.
Seems like a waste of time to me for this ship at least.
Maybe there are materials or shapes that could better defeat active measures, like sonar or magnetic anomoly detectors, rather than things that just make the sub quieter.
I’m just guessin’, mind you.
Hah, I canoed past one of them last week 
I can see 3 Swedish subs right now for that matter.
Stealth my ass…
Interestingly, when I was there just now, the top English searches were Visby, Navy and Submarine. Behold the combined power of Fark and the SDMB.
This is the makers site afaik.
http://www.kockums.se/SurfaceVessels/visby.html
http://www.kockums.se/AboutKockums/navalstealthmain.html
There is some more relating to stealth technologies for surface and submarine vehicles. Boyo Jim, they mention demagnetsing the vehicles with a counteractive magnetic field and that both the geometry and materials used for the hulls have sonar deflecting properties. They also mention radar absorbant material and selective frequency surfaces for covering antennae.
Mmmmm Seaquest…
I seem to remember the periscope thing too, but the stealth the Skunk Works people were trying to push was against sonar rather than radar - somewhere else in the book he talks about bats flying into the planes stored in the hangers because they can’t “see” them -the shaping of the surfaces worked at a wide range of frequencies.
Thinking about it, I wonder if Rich rubbished the Navy’s reluctance a bit too glibbly - the shapes in the early days of the technology were very angular because the computers could only process 2D shapes,so the fighters looked like origami - later more powerful computers and better algorithms allowed for 3D surfaces as in the bomber.
The sub -as presented to the Navy - was of the early “folded paper” design and had spectacular sonar performance - but thinking about it, if some really odd-shaped angular shape is moving at any speed through water I would expect it to generate its own noise that could be picked up.
I personally think the PT boat of WW2 fame is as stealthy as you need to get.
There will be no ship to ship fighting any more anyway.
Not so. If you can stealth a ship it could be worthwhile. Most ships these days will be taken out by a missile and antiship missiles are radar guided (torpedo being a distant second and naval cannons probably close to zero). First you have the plane searching for a target with radar and once locked up the missile takes over and guides with radar. No stealth yet is 100% invisible to radar but what it does do is decrease the distance before a targeting radar can get a lock. This allows the surface ship more time to respond at the very least and if you could cloak an aircraft carrier (the primo target if it’s available) and make it look smaller on radar the aircraft or missile may choose a different ship to strike in the battlegroup. Not good for those on the ‘lesser’ ship but in the calculus of war better a destroyer gets nailed than an aircraft carrier.
I still don’t see the point of cloaking an ASW/minesweeper ship though. It’s not that the cloaking hurts but why go to the effort and expense for that sort of ship? If you’re going to bother at all I’d think there’d be some better choices than that.
[QUOTE]
*Originally posted by Whack-a-Mole *
Depends , personally the swedes may want it because they want to control the baltic sea , plus do reconasaince missions ,if their airforce all of sudden disapears, shadow big taskforces for follow on strikes.
Then again , it could just be keeping up with the jones.
Declan
The US Navy is interested in stealth… My outfit works very hard to reduce radar cross section, sound, heat emissions, rf emissions, etc. In addition to that, there are newer ships in the works with a new generation of these technologies. One example: DD(X).
The Visby is not primarily an ASW ship though. It is also a missile carrier (according to the site the Swedish navy version carries 8 RBS15 SSMs).
For smaller nations (like Sweden) it is often neccessary to have ships capable of handling multiple tasks because we cannot afford to have specialized ships for every task. So the Visby must be able to handle Anti-shipping duties, Air Defence, ASW recon etc.
The Swedish Navy is also quite small and, it certainly has no Task Forces the way the US Navy has, so a fairly small stealthed vessel may be quite ideal for our needs.
The manufacturer, Kockums, also produces submarines that from what I have read are considered to be among the best conventional submarines in the world.
I believe they recently sold some to Australia.
Touching on stealth and submarines for a second, let me ask a stupid question here.
In The Hunt for Red October, they mention the “Catapillar” drive, which I assumed is was some sort of water jet or something. Could something like that be feasable and are there any other completely radical sub designs out there that could work?
The technical term is magnetohydrodynamic propulsion, or MHD propulsion. It basically uses water as part of a linear motor. In a normal motor, you pass current through a wire and apply a magnetic field to it, and the wire moves. (Faraday’s Law, I think.) In MHD propulsion, you pass electric current through water and apply a magnetic field. The water moves through the engine smoothly and out the back. The caveat is that seawater isn’t a very good conductor (compared to copper) so there’s a lot of power loss there. You also need an extremely powerful magnetic field, preferably generated by a superconducting magnet.
There was a lot of talk about this technology in the early 90s. I believe the US navy has/had a test vehicle, and there was also a Japanese industrial consortium which built an experimental ship. You can see a photo at the top of this page - it’s 100 ft long and achieved a top speed of 8 knots. I haven’t heard much about it since then, at least not in the popular press. (I don’t have any inside information)
I would imagine that an extremely powerful magnetic field would be easy to detect, so there goes your stealth, right?
It all depends what sensors the other side use. It would be stealthy enough for sonar, for example, assuming it’s quieter than a conventional propellor design.
But there are ASW aircraft that use Magnetic Anomoly Detectors (MAD), and I imagine such a system would spike pretty well on there sensors. Who knows, maybe it would be such a huge magnetic target that it couldn’t be localized? But I doubt it.
I heard second hand , maybe from a P-3 operator that the mad array or boom was only good for a hundred feet.
Declan