CG(X)/CGN(X)

From the looks of what I've found so far, sometime around last July, the Navy split on the design for the CG(X). They have been directed to develop a nuclear powered cruiser, as well as the next generation cruiser (CG-21). Instead of using one hull to do both, the design group have come up with two hulls. They've been pretty tight lipped about both, but this is what has been come up with so far.

Hull 1 will be a 14,000 ton "escort" cruiser, based on the DDG-1000 Zumwalt hull form. These would go out with the carriers and protect the battlegroups.

Hull 2, would be a 20-25,000 tonner, using a nuclear powerplant. It would be a missile defense hull, and mount KEI interceptors. The hull would have to be much larger, because switching to a KEI missile would cost them 6 VLS cells per missile. It's a 40 inch diameter by 39 foot tall missile, where the SM-3 is 21 inches by 21 feet tall.

There are two schools of thought for the powerplant. One would have them take the same reactor as used in the Seawolf, and mount two in the hull. The other school of thought has them taking a carrier reactor and chopping it in half. This would give them plenty of power for radars and other sensors, as well as to fire the missiles.

The Navy won't discuss any plans for either hull, but it APPEARS they will build 14 of the CG(X) hulls, and 5 of the CGN(X) hulls.

Under pressure from the Navy to develop a new cruiser based on the DDG 1000 Zumwalt-class hull form, and from Congress to incorporate nuclear power, a group of analysts working on the next big surface combatant may recommend two different ships to form the CG(X) program.

One ship would be a 14,000-ton derivative of the DDG 1000, an “escort cruiser,” to protect aircraft carrier strike groups. The vessel would keep the tumblehome hull of the DDG 1000 and its gas turbine power plant.

The other new cruiser would be a much larger, 25,000-ton nuclear-powered ship with a more conventional flared bow, optimized for the ballistic missile defense (BMD) mission.

www.navytimes.com...

[edit on 2/23/2008 by Zaphod58]

Zaphod58,

ARe they serious about this??

I saw the last generation of nuclear cruisers under construction.
The last of these was CGN 41..the USS Arkansas.

To my knowlege there is only one yard in this country which can currently handle such a nuclear construction task. No other yard currently has the facilities or category of nuclear license to handle such a nuclear contract...nor would other yards even want to take on such a task.

Gas turbine Naval cruisers or frigates are currently built in Bath, Maine and Pascogula, Mississippi yards. They could easily handle the non nuclear type construction.

Only Northrop Grumman Newport News has such a nuclear license and the facilities to currently handle such a job.

Until I read your post here I had no idea that this was even under consideration.

Thanks for the post,
Orangetom

As of about the middle of last year they were serious about it. Everything I've found so far backs it up. They have been directed to look into a nuclear powered cruiser. It's the only thing that would have enough power to operate sensors AND fire the KEV that's under development. The gas turbine doesn't even come close. From what I've read about the KEV it's a real beast.

Why develop a new KE Delivery system and a new, larger hull? It was Kruschev that liked quantity, not quality. I don't want to ride that pig.

If they're bent on a CGN... why not go with the lighter hull, fewer missiles and only one reactor?

We had the technology for this in the 70's!
en.wikipedia.org...

Think of what we've learned about naval reactors since then, as well as how to use it effectively in surface units.

I don't know, I'm just trying to lend support to the "fast and nimble" school of thought.

I DO know that my opinion on this board won't make a lick of difference in what the ultimate build configuration ends up to be.
Nice find Zaphod58.

I have had a very hard time finding information on the new KEV interceptor, but from the little I HAVE found it appears that it will be a true ICBM interceptor, as opposed to the SM-3. That means big, and fast. The range guesstimates on it are also very large. They want to be able to kill an ICBM in any stage of flight, including boost.

Edit to add: By using the wide diameter missile they are talking about, the ship firing only has to be with 1000 kilometers of the launch site to be able to hit an ICBM in the boost phase. They're talking about missiles capable of 6.5 kilometers per SECOND.


[edit on 2/24/2008 by Zaphod58]

There was an article in this months Popular Science about these future ships for the US Navy, and apparently they are still planned. Very interesting concept. The introduction of a Destroyer meant to pound shores for amphibious landings and Nuclear Cruisers that also act as a launching platform for UCAV's. Very interesting concepts with the use of one hull for both the Zumwalt-Class and teh CGX to cut costs for the 313 ship navy plan.

Warships of Tomorrow

The Navy was mandated to build nuclear ships by the 2008 Defense Authorization Bill. They have to do it.

SEC. 1012

a) Integrated Nuclear Power Systems- It is the policy of the United States to construct the major combatant vessels of the strike forces of the United States Navy, including all new classes of such vessels, with integrated nuclear power systems.

(b) Requirement to Request Nuclear Vessels- If a request is submitted to Congress in the budget for a fiscal year for construction of a new class of major combatant vessel for the strike forces of the United States, the request shall be for such a vessel with an integrated nuclear power system, unless the Secretary of Defense submits with the request a notification to Congress that the inclusion of an integrated nuclear power system in such vessel is not in the national interest.

(c) Definitions- In this section:

(1) MAJOR COMBATANT VESSELS OF THE STRIKE FORCES OF THE UNITED STATES NAVY- The term `major combatant vessels of the strike forces of the United States Navy' means the following:

(A) Submarines.

(B) Aircraft carriers.

(C) Cruisers, battleships, or other large surface combatants whose primary mission includes protection of carrier strike groups, expeditionary strike groups, and vessels comprising a sea base.

(2) INTEGRATED NUCLEAR POWER SYSTEM- The term `integrated nuclear power system' means a ship engineering system that uses a naval nuclear reactor as its energy source and generates sufficient electric energy to provide power to the ship's electrical loads, including its combat systems and propulsion motors.

Yep, that is correct, by law the Navy is directed to use nuclear power for all it's major combat vessels.

Due to the increasing cost of diesel, nuclear is now cheaper over the service life of a typical Navy vessel than conventional fuel.

At the same price or cheaper, nuclear gives many tactical advantages: effectively unlimited range, major space savings, diminished replenishment requirements.

I am curious whether they are going to go direct drive or electric drive?
I suspect electric in keeping with the "electric ship" concept.

[edit on 2/27/08 by xmotex]

Originally posted by xmotex
I am curious whether they are going to go direct drive or electric drive?
I suspect electric in keeping with the "electric ship" concept.

The last subparagraph of that section I posted indicates a strong suggestion that electric propulsion be used. Given that DDG-1000 is electric propulsion, CGN(X) going electric is not a huge technological leap.

I am not so sure that electric drive can provide the raw brute force that a nuclear propulsion system does making steam for a steam main propulsion turbine. Even with variable pitch propellors to tweak out the last bit of force from the RPM provided by electric drive. I think steam main engines are more powerful and have a higher top end.

What steam engines are not ...is as simple a set up as electric drive.
They tend to need more support systems...condensate returns. alot of lube oil systems..coolers...condensors air ejectors..et al. Also a complex system to maintain a sufficient amount of demineralized water by way of a distiller plant...in addition to water for hotel services. This can also be done with a high capacity revese osmosis system.
Nonetheless ..steam main engines need alot of support systems...thus meaning training for the crews to run and maintain them.

Electric drive has come along way no doubt. It is just that if you look at the specs...most electric drive engines have a lower top end than steam main engines.

No doubt that steam generators can provide the watts of electricity needed for the new electronic systems. There are a whole new generation of generators available than were twenty years ago.

Gas turbine engines are very fast on these FFG type cruisers or Frigates ...whatever they are calling them. They are coupled to a shaft with a variable pitch propellor. Also the propellors are very oversized for these ships compared to older generations of cruisers. THese ships can flat out move when needed. What these ships are not at speed is fuel effecient. They go through alot of JP5 fuel. THey must often pull up to an aircraft carrier or a oiler to take on fuel.
I suspect that long term this is the drawback which is steering the Navy back to nuclear propulsion.

My question for those of you in the know..is how much speed can these new electric main engines give to a fully loaded cruiser?? Anyone up to this?? Remember...the cruisers need to be able to keep up with the carriers under way. THey are part of the protective screen.

Thanks,
Orangetom

[edit on 28-2-2008 by orangetom1999]

reply to post by orangetom1999


I guess the question would be whether there's room in an LPD hull to fit two double the propulsion motors of a DDG. Go from 2 screws to 4 to move the extra 10,000 (roughly) tons. I honestly don't know how that would work. The other question is what reactor plant to go with. Modify an existing sub design, develop a new destroyer/cruiser design or dust off the old cruiser designs and try to freshen those designs up a bit. There are a lot of hurdles to clear for a new CGN program, especially in a time when every other new development shipbuilding program is under intense scrutiny for cost and schedule.

Remember an electric motor delivers 100% of it''s torque from 0RPM up.

So I think electric might offer an acceleration advantage.

IIRC it takes nuclear vessels a little while to get "up to speed" even if their top speeds are high. I have been led to believe one of the reasons the USN went to gas turbines (actually CODOG) is the extremely rapid acceleration they offer.

If a nuclear-electric system can confer all the advantages of nuclear with the acceleration advantages of gas turbines, it will be a winner...

reply to post by xmotex


A BIG advantage of gas turbines that nuclear-electric still will not be able to counter is the ability to go from pierside, shutdown to underway and heading to a hotspot in a matter of hours, not days. Once on station, that advantage is nullified, but still in an emergent situation having a nuclear vessel shutdown pierside means that vessel can't exactly scurry out of harm's way or even hurry to lend aid to another area/asset.