DD(x) wowee!!

[Werner]

LPI Radars use agile frequency transmitters to shift up and down the spectrum so that no pulse exists at a particular frequency long enough to trigger the RWR. SPY-3 is a conventional X-band Radar, and it serves as a target illuminator, which has to transmit on a predictable frequency so the missiles can track the designated target.

[Walt]

The Chinese will have it knocked off in 2-3 years at a fraction of the cost.

In all seriousness, a local shipyard here in Shanghai is about to commission several of the PLN's stealthy FAC triamarans. You can see both vessles in their new cammo paint schemes as you drive over the north end of yard on the Xupu Bridge.

http://www.strategypage.com/military_ph ... ealth.aspx

Their plan to focus on smaller missile carrying fast attack craft & ultra quiet diesel subs could well put a serious bottleneck to any plans the US has towards projecting power in the region during a conflict.

I seriously doubt Taiwan is the real answer these are coming online since China has far more larger designs on ensuring "their" sea lanes remain uninterupted. Considering their fleets ruled the oceans 600 years ago, they may just have the rights to feel this way again. Should be an interesting time to come..

Chuck [/url]

Yeh we know that China has stole some plueprints etc. for this ship and other excellent stealth technoligy but now they can't find them

[Guest]

which has to transmit on a predictable frequency so the missiles can track the designated target.

Not really. The frequency shifts doesn't have to be random. It can be algorithmic to allow a frequency agile seeker to home in on it provided the seeker has access to the same algorithm or input. Such frequency agility in a radar would remains unpredictable to an hostile RWR that is not privy to the algorithm, and would therefore continue to defeat to RWR.

[Guest]

Indeed, if the missile use semi-active TVM guidance, the very same controller that gives radar illuminator frequency agility can also control the missile seeker. One does not even have to duplicate the frequency controler it in the missile.

[Werner]

AEgis and SM-2 are not TVM. They are descendents of beam-riders who eventually obtained their own active Radars. As it is, the missile is guided onto the initial course by beam riding, then receives guidance updates once or twice in flight to guide it into the "basket" where it turns on it's own Radar. SM-3 and SM-6 have a secondary IR tracking ability.

If you look at an AEgis ship you can see the separate Mk-99 guidance antennae which bring the missile onto it's base course before shifting control to the SPY antenna.

[Robin]

AEgis and SM-2 are not TVM. They are descendents of beam-riders who eventually obtained their own active Radars. As it is, the missile is guided onto the initial course by beam riding, then receives guidance updates once or twice in flight to guide it into the "basket" where it turns on it's own Radar. SM-3 and SM-6 have a secondary IR tracking ability.

If you look at an AEgis ship you can see the separate Mk-99 guidance antennae which bring the missile onto it's base course before shifting control to the SPY antenna.

Werner,

Sorry but no the missile doesn't ride a beam on initial course it receives all that from the radar and mid course guidance updates. The Mk-99 are used to illumate the target for the last 10 - 6 seconds before target impact.

[Seasick]

Aegis and SM-2MR

The USN hasn't used beam riding missiles since the mid 1970s. The current Aegis system uses a differnet mechanism:
1. The AN/SPY-1 radar acquires the target and tracks it.
2. The Mk99 system programs the auto-pilot on the SM-2MR missile to fly to the target.
3. The Missile is launched.
4. The AN/SPY-1 is still tracking the target and provides updates on its heading and range.
5. The Mk99 uploads course corrections to the missile until the missile is around 10 seconds from intercept.
6. The Mk99 turns the AN/SPG-62 and illuminates the target.
7. The missile picks up the illumination and steers into the target.
6A. The SM-2MR Block IIIB missile has an option for terminal IR homing. Most of the USN's inventory of SM-2MR block IIIA or IIIB with some Block III. The current plan is to upgrade the remaining block III and IIIA to IIIB standard.

There has never been a beam-riding standard missile. Beam riding Terrier was phased out in the mid 1960s and replaced with homing-Terrier which required the AN/SPG-55 radar rather than the earlier AN/SPQ-5 radar for illumination.

[Guest]

There has never been a beam-riding standard missile. Beam riding Terrier was phased out in the mid 1960s and replaced with homing-Terrier which required the AN/SPG-55 radar rather than the earlier AN/SPQ-5 radar for illumination.

But the beam riding Terriers were the linear antecedents of the Standard series Missiles. So Werner was not wrong.

[Gone Asiatic]

The day of menacing gun boats is over, people are most afraid of what they can't see these days. UAV, supersonic missiles, and jet fighters are the three biggest menaces these days.

Add submarines to the front of your list.

http://www.youtube.com/watch?v=RV8MF-440xg

[gs]

Whole idea is flawed. What you want is an inexpensive nimble & expendible platform (trimarans, perhaps) to go into harm's way. Something like the WWII landing craft with rocket launchers.

The DDX is nothing but a space aged battleship. It will be a sitting duck to a land based Excorcet.

[Guest]

Disagree. Assuming our forces would not be so constituted from now on so as to be suitable for counter insurgency only, and that big power politics and war preparation will continue to be a cornerstone of our military planning, then going the Small and economic ships route will merely serve to reduces the gap that our big power opponents will have to bridge.

People keep looking at numerous occurrence of counterinsurgency operations and argue our forces should be skewed to fight the most probably battle. This is stupid. As a big power surrounded by two oceans we will never fall because we got our asses kicked in a counterinsurgency operation. We could fall, however, if we loose a big war with a big power. We should never sacrifice the gap between us and our peer power competitors in order to make ourselves look better in what are, in the final analysis, less consequential coin operations.

[Mark Petersen]

IMO what the USN and the RN should be looking at is a commercial hull with a good turn of speed if required and good endurance to allow tifor operational flexibility. And the hull is the basis of the ship class. The hull would be adaptable to different mission requirements by swapping out standard size modules that could carry ASW gear, SAMs, gunfire support or even ABMs*. In addition the vessels should have low manning requirements. With secure com links would it be possible to have the trained SAM or ASW techs sitting in a nice warm dry building at Norfork, San Diego or Great Lakes for that matter rather than having the the vessel being required to provide berthing space, provisioning etc. That way the actual crew requirements would only need to the people needed to operate the ship and the command group. That said it doesn't mean the ship if operating as a specialzed platform it needs to be defenseless aqainst all other threats. A base line missile defense and gun system should be included in the standard design. But the idea of sending something with the capabilities of an Arleigh Burke or better into coastal waters to do trade sanction duty is stupid. maybe the Arsenal Ship wasn't such a bad idea in the first place. Just my $.02 as a taxpayer. I want value for my money.

*Sea Fighter perhaps

[Dave Wooley]

What I think is utterly absurd is the sacrifice of ship qualities to attain "stealth", when it is obvious to any serious student of physics that the inevitable progress in computing power or signal strength will render these features obsolete almost immediately.

Werner could you explain? I understood that no matter what the signal strength angling the sides of the structure of the vessel will deflect the radiated energy of radar, so the return image seen on the radar display is considerably reduced. Your statement assumes that progress in detection is not matched by progress in concealment.
Dave Wooley

[Werner]

Simple reflection of the hull is only one way to "see" an object in this way. Another way would be to process the returned signal looking for units of information moving "coherently". For example, the disturbed water through which the hull is moving will provide a substantial reflection, and the peak of this signal (say the curl 1/3 the way down the hull) will have a coherent movement at some regular speed.

In the battles up "The Slot" during 1942-3, the enemy's destroyers were frequently not seen until they turned to engage with torpedoes. Then their bow waves were spotted in the gloom as they turned. The ship's paint must have been sufficient camouflage, but no paint would cover the disturbed water beyond the ship's hull.

An expert in communications has shown the B-2 can be detected by monitoring the disturbances in cell phone carrier signals it causes as it moves across the active network. Tens of billions in investment defeated by the unintended influences on a system which did not even exist when the B-2 was designed.

[Foeth]

For example, the disturbed water through which the hull is moving will provide a substantial reflection, and the peak of this signal (say the curl 1/3 the way down the hull) will have a coherent movement at some regular speed.

As will all waves traveling at sea. Plus, you have to be willing to point a radar in a general direction. Not sure if that is such a good idea against an opponent you haven't found yet. The rest is anecdotically interesting.

[Dave Wooley]

Simple reflection of the hull is only one way to "see" an object in this way. Another way would be to process the returned signal looking for units of information moving "coherently". For example, the disturbed water through which the hull is moving will provide a substantial reflection, and the peak of this signal (say the curl 1/3 the way down the hull) will have a coherent movement at some regular speed.

In the battles up "The Slot" during 1942-3, the enemy's destroyers were frequently not seen until they turned to engage with torpedoes. Then their bow waves were spotted in the gloom as they turned. The ship's paint must have been sufficient camouflage, but no paint would cover the disturbed water beyond the ship's hull.

An expert in communications has shown the B-2 can be detected by monitoring the disturbances in cell phone carrier signals it causes as it moves across the active network. Tens of billions in investment defeated by the unintended influences on a system which did not even exist when the B-2 was designed.

It was said that during the war in the Balkans the Serb AA defence downed an F117 because during the bombing of Belgrade air disturbance was detectable by sophisticated Russian air defence radar. However the air defence was ready and waiting. As Foeth has said first you have to be aware that there is a warship in the area for your radar to focus on. Even the best of radar waves can be deflected by the expedient of altering the shape of the vessel. There are of course other forms of detection IR and residual noise which is probably a more lightly method in detection than radar. Regarding bow wave disturbance even that can be reduced considerably by using wave-piecing bows. Of course there is no such thing as being invisible, that�s for science fiction but the chances are you wont know your enemy is there until he lets you know first by then its probably to late.
Dave Wooley

[orangebarrelman]

<clip>

An expert in communications has shown the B-2 can be detected by monitoring the disturbances in cell phone carrier signals it causes as it moves across the active network. Tens of billions in investment defeated by the unintended influences on a system which did not even exist when the B-2 was designed.

Sounds like the way Star Fleet blockaded the Romulan resupply ships during the Klingon Civil War during The Next Generation, with taceon beams....

[Guest]

All Werner is saying is it can not be counted on to make one's assets effectively invisible. Granted. But that does not significantly reduce the value of stealth. There are many grades of visibility. Just by reducing your visibility to the point where, in a tactical situation, your enemy would have a fussier picture of your disposition than you have of his is enough. Achieving that would justify stealth. If that's achieved, stealth is valuable. If you can make the enemy's picture even fuzzier by being totally invincible, that's a bonus.

[Werner]

Just at the conclusion of the Cold War Soviet Mathematics researchers published a series of papers on techniques for the detection of submarines from space. They were able to detect deeply submerged submarines using the internal waves generated by the submarine which were observable as coherent millimeter-sized changes of the surface patterns above the submarine. Such patterns can be programmed to "leap out" of a large area scan when the signal processor has the correct parameters. I would say the issue of scanning for a "stealthy" ship could use similar techniques, but it is probably easier in reality because it is effectively impossible to make a material which has low reflectivity to all frequencies of the electromagnetic spectrum at once.

[Guest]

Just at the conclusion of the Cold War Soviet Mathematics researchers published a series of papers on techniques for the detection of submarines from space. .

Conveniently Soviet Union's applied military research and development establishment collapsed immediately afterwards, thus sparing these high spiritied mathematicians of any need to temper their claims with with real life experimentation.