The Ship Model Forum

Actually both the CGN and CG versions look like well balanced designs, top job!! :thumbs_up_1: :thumbs_up_1:

Cheers Bruce

She looks good with turbines too....

this is for seasick and anyone else wanting conventional power for their strike cruiser. I must say, it goes against every bone in my body haha, but it does look pretty cool. Since this is my world, her plants will consist of four LM-6000's.

Hope you all like, and as usual, I would love to get feed back

PS just to toot my own horn I have to say, I think its pretty cool that I got the "heat signature" from the stacks in the pic

Fair seas
Joe

[url=http://s996.photobucket.com/user/sabotage181/media/roughcsg.jpg.html][img]http://i996.photobucket.com/albums/af89/sabotage181/roughcsg.jpg[/img][/url]

Seasick, You just repeated verbatim what I said durring my oral board for my SW haha

Dave, good to hear from you. That is strange about the CVN's not having a way to make emergency steam. The Virginia had and emegency boiler (you can see that exhaust stacks directlly under the 48 platform) you think the CVN's would have it.

I envision CSGN as being all electric. I have encorporated 4 emergency gas-turbine generators because of this. this baby will definatly be able to get out of dodge with the nuke plants down

The only time I would ever do a combined nuclear and conventional plant is for emergency propulsion. I have seen in person a 90,000 ton CVN stuck at the pier for 4 days in the event of nuclear contamination, because it could not get its reactors up to turn its screws. This is unacceptable. There is no reason not have an LM-2500 in two of the four or even each of the drive trains so they could light off and turn a screw(s). The ship with over 3,000 crew would have a few GSEs added to it, but the ship would be able to make way with both reactors down.

I was shocked and disappointed to learn through experience that our CVNs cannot make way without a reactor being up.

The problems with nuclear are mostly economic. Nuclear has a high manning requirement compared to normal steam, gas turbines, and diesels. Nuclear has a larger foot print than the others (amount of space and weight/displacement needed).

The nuclear reactor is a boiler. The heat is provided by the radioactive decay of Uranium-235 in the fuel cores. Since no oxidation reaction is needed this makes nuclear ideal for submarines. The heat from the decay passes through the walls of the core into water vessels surrounding them. The heat boils the water into steam which moves through pipes to the heat exchanger where the steam pipes come into contact with pipes with water in them. The steam pipes boil the water in the secondary pipes which turn to steam and are fed to steam turbines. The pipes that carried the steam to the heat exchanger carry the residual steam/hot water to the condenser where it is cooled to liquid water and fed back to the reactors. The steam after it passes through the turbines enters a condenser that returns it to liquid form and sends it back to the heat exchange to be boiled again.

The combined nuclear and steam system on the Soviet Kirov class didn't work very well and is unlikely ever to be repeated again by anyone, well maybe North Korea.

ok, first of all CSGN-138 will not be a (primarily) shore bombardment ship. That's my BBRGN you're thinking of. CSGN-138, with her 8 inch Mk-71 could be used for this mission if needed. In a low threat area. Much like to USS Virginia was called for shore bombardment in Lebanon in the 80's .

Secondly, the rail guns on my BBRGN would have a range of at least 50 miles and up to 200 and more, so she wont be in danger of getting hit from shore. She will be laying well offshore shelling the crap out of whatever :)

In my world fossil fuel has become prohibitively expensive (it's a stretch of the imagination I realize....) so I'm opting for nuclear power. I even have a nuclear frigate on the drawing board....AKA...in my mind :)

As far as the most efficient use of power, I'm definitely not an engineer so I'll leave those debates up to you all, And I will highly enjoy reading your thoughts on the subject. Just know I'm all for the nuk's :) if you like a CONAG or even full Gas-turbine, then I have no problems with you envisioning them that way. Hell, I may even draw CSGN-138 with exhaust stacks just to see how it looks.

I am enjoying all your comments. Please keep them comming

My plan is to ditch nuclear entirely. If a ship provides fire support for forces ashore, nuclear is a liability. Plunging fire from counter battery guns penetrating the reactor housing would cause an emergency while a round punching a hole in a gas turbine or a diesel would cause considerably less damage.

My idea is to use an integrated system. On a ship the size of the CSG-138 the full electrical load for weapons, hotel, and cruising speed can be provided by diesel alternators. To go full power on propulsion the MT30 or LM2500+G4 would be brought on line to provide the electric motors with a power on a secondary bus. If you want to go the route of having the gas turbines turn screws via reduction gears I believe that works just as well. I'm not enamored with nuclear power for surfaces forces other than for CVN.

Side Question:
USS Makin Island has one set of screws on reduction gears connected to the LM2500+ and a set of electric motors run form the IPS?

[quote="Seasick"]150 megawatts might be a conservative estimate. No Navy has adopted the LM6000 for service on combat vessels, rather its being used mostly for offshore drilling platforms. The GE LM2500+G4 or the Rolls Royce MT-30 are, probably, your best options for turbines for peak power, a base of your electric demand can be supplied by diesel alternators. 8,000 kilowatt alternators are available so if you have eight on board (not difficult) that will provide up to 64 Megawatts. In general they are more fuel efficient than the gas turbines and since you'll need a constant flow of electric they are a good option. The rest of your capacity can come from 4 MT-30.[/quote]
I am not following you.

You are suggesting basing the ship power plant size on peak demand, current naval engineering theory is not to do this with an integrated propulsion system.

Eight GTGs plus nuclear propulsion is excessive. My example was comparing a conventional plant to a conventional IPS plant.

Also, the issue of armor, damage and nuclear power brings up some additional points:

1) Armor, does nothing to stop damage from electrical overloads, particularly nothing to protect sensitive 400 hz electronics.

2) Armor does not stop other types of damage like shock or vibration from affecting the reactors.

3) The up front capital spent on fueling the reactor is a sunk cost - if loose the ship, you loose decades of fuel with the ship.

150 megawatts might be a conservative estimate. No Navy has adopted the LM6000 for service on combat vessels, rather its being used mostly for offshore drilling platforms. The GE LM2500+G4 or the Rolls Royce MT-30 are, probably, your best options for turbines for peak power, a base of your electric demand can be supplied by diesel alternators. 8,000 kilowatt alternators are available so if you have eight on board (not difficult) that will provide up to 64 Megawatts. In general they are more fuel efficient than the gas turbines and since you'll need a constant flow of electric they are a good option. The rest of your capacity can come from 4 MT-30.

The latest generation of Russian anti-ship missile is the P-800 Oniks (Onyx) (SS-N-26) which has replaced the earlier P-270 Moskit (SS-N-22 Sunburn) and P-700 Granit (SS-N-19 Shipwreck). Flies fast and low and you'll need to heavily armor your reactor and heat exchanger against it you go nuclear. One option is too increase your draught so that the entire reactor system is below the water line but that can slow your ship down and require more energy.

[quote="CSGN138"]
Busto, what would be the benefit of having a cogatunuc plant. I'm thinking if you go nuke you don't need a tanker. Would there be a worthwhile benefit in combining? Didn't the Ruskies do that with Kirov and didn't like the end result?[/quote]
The issue is efficiency and flexibility in sizing the ship’s power plant. Long answer follows below.

Before the demand for powerful air-search-radar systems like Aegis, a ship’s propulsion power requirements dwarfed it’s electrical power requirements and life was easy. A ship was designed with a maximum design speed, which in turn drove the power plant required. Electrical power generation was easy too: you simply totaled the peak demand of all electrical loads, calculated any reserve margin (think battle damage), and this determined the number and size of generators.

Typically two, sometimes three gas or steam turbines, diesel engines, motors, etc. were coupled to each reduction gear/shaft. This ensured that the crew could tailor power output to power demand so the ship operated close to optimal fuel efficiency. This is as big a deal for nuclear as for conventional power plants. This was done by selected the number of shafts and prime movers running. As an example CG-47 with two shafts and four GTGs, has a number of options to satisfy slow and medium speed operations.

However, this happy situation changed as power demands from radars and other systems grew, and now very high power active phased arrays, directed energy weapons, rail guns etc. are expected to grow a warship’s electrical demands to as much as 50-100% of it’s propulsion demands. This makes Integrated Power Systems very attractive – not only can you trade complicated, expensive, noisy reduction gears for quiet, efficient motors; architects can distribute the generators throughout the hull, re-adjust shafts, and enjoy a host of benefits. Even the greater displacement demanded by heavy electric motors has the benefit of allowing the weight to be restored lower in the hull to offset topside weight. However, the problem of sizing the propulsion plant is now much more complicated.

Consider a 21st century replacement for the CG-47: using high power active phased arrays, directed energy weapons, rail guns etc. the ship might need as much as 200,000 SHP for it’s power plant - really 149 megawatts. The designer might chose three LM6000s and 3 smaller GTGs. This would be an incredibly flexible and resilient power plant; that could run efficiently across the power spectrum. Now substitute two nuclear power plants, and you can see that your ship is likely to spend decades with two massive power plants operating running at a small fraction of rated capacity. That is a recipe for incredibly low efficiency.

Adding more generators to your power plants is the way to go, but four (or more) nuclear reactors is likely to be cost prohibitive. Ergo the gas turbine generator as a solution.

[quote="Busto963"][quote="CSGN138"]I'm thinking two aircraft carrier sized plants, as the rail guns require a lot of power. [/quote]I missed this point.

Why not a combined nuclear and gas turbine propulsion system driving electric generators? The extra power will only be needed for a fraction the time when actually firing the rail gun. Even slowing down and diverting power to weapons over propulsion is likely to be entirely satisfactory as no amount of propulsion is going to outrun an missile or other airframe.[/quote]

Busto, what would be the benefit of having a cogatunuc plant. I'm thinking if you go nuke you don't need a tanker. Would there be a worthwhile benefit in combining? Didn't the Ruskies do that with Kirov and didn't like the end result?

[quote="Sciquest2525"]I wonder if Ruevan Leopold's strike cruiser Mk 2, the variant design featuring a below decks hanger and capacity for 18 AV-8As would be viable for a strike cruiser.
I note that CSGN Mk 2s would have featured all the armament you want for your design in missile launchers and even add a second Mk 71 gun and have had armor to boot.
Reuvan Leopold ship would have qualified as a true hybrid.
The book. The Hybrid Ship argued that today's hybrid would be viable using STOVL strike fighters and heavy missile armaments and enabled independant operations like cruisers of old.
Is there a place for hybrid missile/STOVL aircraft with AMDR radar suite?[/quote]

Actually, if you look at my CSGN final thread, there is one on there with F-35's

Also your comment about adding a second mk 71 confuses me because there are two already depicted in the image

[quote="CSGN138"]I'm thinking two aircraft carrier sized plants, as the rail guns require a lot of power. [/quote]I missed this point.

Why not a combined nuclear and gas turbine propulsion system driving electric generators? The extra power will only be needed for a fraction the time when actually firing the rail gun. Even slowing down and diverting power to weapons over propulsion is likely to be entirely satisfactory as no amount of propulsion is going to outrun an missile or other airframe.

I wonder if Ruevan Leopold's strike cruiser Mk 2, the variant design featuring a below decks hanger and capacity for 18 AV-8As would be viable for a strike cruiser.
I note that CSGN Mk 2s would have featured all the armament you want for your design in missile launchers and even add a second Mk 71 gun and have had armor to boot.
Reuvan Leopold ship would have qualified as a true hybrid.
The book. The Hybrid Ship argued that today's hybrid would be viable using STOVL strike fighters and heavy missile armaments and enabled independant operations like cruisers of old.
Is there a place for hybrid missile/STOVL aircraft with AMDR radar suite?

No Drawings as of yet, but here is a little artical if you would like

http://www.gizmag.com/us-navy-second-railgun-prototype/24521/

[quote="CSGN138"]Here is my BBRGN. I am very excited about this ship. I've been reading up on rail guns and it is some very promising technology. [/quote]
This should make a very nice model.

Do you have any drawings for the rail guns?

Here is my BBRGN. I am very excited about this ship. I've been reading up on rail guns and it is some very promising technology. Muzzle velocities of up to 20,000 fps. As an ex-fc I can really appreciate that number, because it makes a fire control solution extremely reliable. The farther out you go the less reliable it becomes, but think about that number. Say a missile is out at 40 miles, inbound on your ship (ill have to get the calculator out for this part, brb) that's 211,200 feet. at 20,000 fps it'll take roughly 10 seconds for your projectile to get there and kill it. That's a lot of time for the missile to make a course change and screw your fire control solution, but as most asm's are on a bee-line course for their target, at that range anyway, its pretty easy to put that projectile where that missile is going to be in ten seconds. In addition, with the right power supply the cyclic rate of the rail gun is going to be a lot faster than a gas operated cannon, so with the right setup this system would be like a CIWS system only at 40 miles out. I'm excited about this stuff and I'm thinking of making an AAW frigate armed with rail guns only. An attack sub nuc power plant should provide plenty of power for it.

Anyway this is my BBRGN for now. It's very rough, but as I progress I will update this image

I'm thinking two aircraft carrier sized plants, as the rail guns require a lot of power. The sensors are not set in stone yet. For now I am trying the SPS-48 on for size. Any AAW capabilities will be purely defensive. This ships primary mission will be shore bombardment and ASuW.

Again, any comments, suggestions or criticisms gladly taken

[img]http://i996.photobucket.com/albums/af89/sabotage181/BBRGN.jpg[/img]

OH nice Tim, I had not heard of this. thank you. And so Cliff, to answer your question about harpoons, they are augmented with the LRASM

LRASM will take care of the ASM role - they go in the VLS so don't worry about that.