Werner wrote: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.
You'd be suprised They're not building these ships on a whim...
That's all well and good, but when the ships go to sea in 7 years or so they will be quaint antiques.
I hear the RN is going to upgrade to Windows systems, as the current software is hoplessly outdated. Antique software doesn't really turn in a quaint antique that fast. And it works, sort of.
Too bad the shape of the hull is based on radar signature and not on seakeeping.
Foeth wrote:
Too bad the shape of the hull is based on radar signature and not on seakeeping.
What if I shift to a different frequency? The hull certainly is optimized to perform against a small range of radio frequencies. LIDAR or MASER based devices ought to be able to tell what's there in spite of the hull shape or coatings. A pencil-beam system will reflect something no matter what. Then, you can use interferometric techniques to decide what kind of surface you hit.
How about satellite detection in real-time. The USN has been talking about a "toss-up" satellite launched by an SM-2 which would give you a view of the theatre ahead for several thousand KM. Surely this ship and the water it disturbs cannot be made invisible from a point high overhead.
If an unfriendly power had attempted to impose on America the mediocre educational performance that exists today, we might well have viewed it as an act of war.
Foeth wrote:
Too bad the shape of the hull is based on radar signature and not on seakeeping.
What if I shift to a different frequency? The hull certainly is optimized to perform against a small range of radio frequencies. LIDAR or MASER based devices ought to be able to tell what's there in spite of the hull shape or coatings. A pencil-beam system will reflect something no matter what. Then, you can use interferometric techniques to decide what kind of surface you hit.
How about satellite detection in real-time. The USN has been talking about a "toss-up" satellite launched by an SM-2 which would give you a view of The DDX is clean for the purpose of stealth, if not anything else. So there does not seem to be too many surface imperfection to spoil the stealthiness. The slab sided surfaces are all individually pretty big. the theatre ahead for several thousand KM. Surely this ship and the water it disturbs cannot be made invisible from a point high overhead.
If you try to use Lidar to find a planar optical mirror that's angled away from the detector, Lidar will have hard time finding anything. The size of the beam makes little difference.
The principle behind angling a reflecting plane away from the beam is also employed by shaped stealth technology. This technique would work so long as the dimensions of the reflecting surface is much larger than the wavelength of the beam, and there are no major surface imperfections whose dimensions are similar to or larger than the wavelength of the beam.
The DDX seems to have a clean shape and large flat surface facets. In this case, the only way to clearly defeat its radar stealthiness would be to use a radar (or whatever other similar detector) whose wavelength is similar to or greater than the dimensions of the angled surface of the ship, or at least the dimensions of the biggest major surface imperfections that are exposed to view. Provided the DDX is well built and well designed for stealth purposes, you would need a radar with wavelength on the order of many meters to defeat its large, flat surfaced shape. The only way you can do this would be to use an antenna that is also many meters acorss. This would be hard to do on an tactical aircraft.
Only mirrors in textbooks are that good. In principle, a tiny fraction of the light will be scattered back to the transmitter. In the case of a ship, I imagine a lot will reflect back, particularly as the ship yaws and rolls in the sea. Even were the ship to be non-reflective, the "hole" it leaves in the returned pattern would be distinguishable, especially because an exact frequency of light is involved.
If an unfriendly power had attempted to impose on America the mediocre educational performance that exists today, we might well have viewed it as an act of war.
Werner wrote:Only mirrors in textbooks are that good. In principle, a tiny fraction of the light will be scattered back to the transmitter. In the case of a ship, I imagine a lot will reflect back, particularly as the ship yaws and rolls in the sea. Even were the ship to be non-reflective, the "hole" it leaves in the returned pattern would be distinguishable, especially because an exact frequency of light is involved.
In fact mirrors can easily be made so good you have to use a vast amount of power to get any scatter strong enough for practical detection. It's not practical to us MW lasers for search purposes.
The issue of the hole should be easily fixed by using a few small, carefully designed angle reflectors to fill it in.
Nevertheless, if I recall from my Laser course with I.-S. "Sonny" Jeung, even a laboratory-grade first surface mirror has sufficient bounceback for these purposes. If two Lasers separated by a modest distance are used it will be impossible to mask the ship's location any more than the hole of a doughnut in a hologram.
If you're worried about power, Sonny is currently using a laser to generate the aerospike in a prototype hypersonic jet engine.
If an unfriendly power had attempted to impose on America the mediocre educational performance that exists today, we might well have viewed it as an act of war.
Werner wrote: If two Lasers separated by a modest distance are used it will be impossible to mask the ship's location any more than the hole of a doughnut in a hologram.
If you have reflectors to mimic the natural background scatter, there is no hole to mask.
Werner wrote:
If you're worried about power, Sonny is currently using a laser to generate the aerospike in a prototype hypersonic jet engine.
There are usually enormous gaps between being able to achieve something for one purpose and being able use it in practice for another. The practice of assuming that weapon research PhDs have less insight into the practical engineering issues involved than what can be drawn from vague memory of a off-subject single class does not tend to give good hit rates.
After a scathing review of DDG-1000 in the September issue of The U. S. Naval Institute Proceedings, the only response the ship could gain in her defense in the October issue was penned by the Section Head of the DDG-1000 program. He speaks on and on about the AEGIS and Cooperative Engagement System, which is all well and good considering these systems are common to a large number of hulls, but there is not a word about the ship's "controversial" features such as it's submarine-like hull and extremely low manning, which incidentally means the ship will not have dedicated damage control. The current plan calls for a helo-borne damage control team to chopper out to the ship in the event the enemy or weather do her foul. The author concludes that the unit price of $3 billion and change for the first two ships is well-spent.
I'd rather they buy 1 1/2 carriers with that money. Alternatively, since $4-5 billion will buy a nuclear carrier, I wonder what kind of conventionally powered aircraft carrier could be purchased for $3 billion or less.
Incidentally, since the AEGIS system is a guided missile system based on Radar, any use of the AEGIS is going to pinpoint the "stealthy" ship no matter how carefully her shape and materials have been fashioned. AEGIS is an area defense system that relies on Radar to target the enemy hundreds of miles away and illuminate it for the missile. The cooperative engagement system relies on broadband communications to coordinate task force sensors and weapons. Stealth seems to run counter to the very nature of these weapons.
If an unfriendly power had attempted to impose on America the mediocre educational performance that exists today, we might well have viewed it as an act of war.
G. Shoda wrote:Hope they are doing water tank tests on models. The bow shape looks like it will be susceptible to plunging.
It plunges in the tank so badly the design parameters were re-written to "feature" unmanned weather decks.
What they aren't saying is how wet the flight deck will be during boarding seas or when she is pooped. The tumblehome acts like a ramp to encourage boarding seas.
If an unfriendly power had attempted to impose on America the mediocre educational performance that exists today, we might well have viewed it as an act of war.
G. Shoda wrote:Hope they are doing water tank tests on models. The bow shape looks like it will be susceptible to plunging.
At high speed water will probably pile up onto the bow even in a flat calm sea just like it did on the ram bow of late 19th century armored cruisers.
The entire hull is designed in such a way so that incremental displacement and buoyancy diminishes as draft increases. In other wards, the deeper the ship trims or lists, the less additional correcting moment the hull would be able to offer against further trim or list. This is bad for damage control.
I certainly cannot understand putting a $3 billion ship in the direct line of fire for the enemy. Everyone understands carriers have multiple lines of defense, and the offensive capability is secondary to insuring the task group's survival. This ship, traveling alone, Radar off, sailing directly into the lion's den and firing it's 15.5cm gun on shore targets is inviting disaster.
If an unfriendly power had attempted to impose on America the mediocre educational performance that exists today, we might well have viewed it as an act of war.
The whole thing about the DDX is that it can attack shore and inland from 20 miles out at sea. That is the reason for the two 155mm guns. The long range guided munitions will be able to go further inland than any Iowa's 16 inch shells and far more acuratly. The DDX will also be fitted with the AN/SPY-3 dual phase radar. Its the next step above the AN/SPY-1B/D radars. One band of the radar is a high speed 3D air search radar and the other band is a tracking and illumination radar. The Aegis system has been seriously upgraded from its 1983 configuration. Multiple elements can emit and receive at the same time and many more targets can be engaged than the original sixteen, but the SPY-3 is far more powerful. No AN/SPG-62 illuminators will be required as the SPY-3 will illuminate the target if needed. The project suffers from the typical Rumsfeldian misdirection but I think that once a few get built Congress will be a little more free with the money. 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.
There is a series of articles and commentary in the US Naval Institute Proceedings going back at least to 1998.
Multimode Radar and long range gunfire are good, but once the Radar is turned on the stealth features go out the window. Why compromise the ship so severely for what is obviously a secondary military feature of limited applicability?
On the other hand, take away the stealth requirement and the remaining systems could easily fit into a Burke-class destroyer for a much lower cost.
If an unfriendly power had attempted to impose on America the mediocre educational performance that exists today, we might well have viewed it as an act of war.
But DDX is needed to fill the gap in technology between DDG 51 and the sooner then later CGx project. The systems on DDx are not so much super new, but it is the fact that they all will be in this configuration for the first time. As for the articles in Proceedings, I too have read them and they are all pretty critical of systems, DC, or anything. There are many lesson learned papers that allow naval designers to scale back DC...yes I know there has to be enough people to form a bucket chain we all get it... but it is the overall environment that is adverse to any sort of change(failure.) What can I tell you...to think that every person working on these designs was born just last night is a bit of a misstep, there are plenty of people that are constantly looking over the project and independently looking for issues. I think the design teams need a bit more credit then they are getting right now.
Ben Garbin
Utility Infielder
Brunswick, Me
I can think of no more stirring symbol of man's humanity to man than a fire engine.
~Kurt Vonnegut
The proof is in the pudding. There are too many sad examples lately, like a certain billion dollar super-bomber that loses it's stealthiness if it's skin gets wet; of stealthy fighters that are easy to see with antique Canadian Radars because nobody thought to check it in those wavelengths and so on.
I really don't get the concept of a stealthy ship that advertises it's dual-mode Radar in the next breath. A ship that is going to sail into enemy coastal waters under missile and gun batteries and not have a damage control team....
If an unfriendly power had attempted to impose on America the mediocre educational performance that exists today, we might well have viewed it as an act of war.
They're not building these ships on a whim...
