CONAG Cruiser Design

Hope you don't me offering an alternative (it may be useless I'm not a nuclear engineer

)
And of yours I like the 2nd Alt most. (I would just lift the GT up 2 decks and maybe split the VLS)
[ img ]

Blackbuck - Is the 57mm not the CIWS ? (on hangar ?)

JSB

Edit after reading the above post not sure my weights will work (reactors to far back).

No. 57mm are a poor excuse for a true CIWS. They fall in-between guns-proper and CIWS and aren't overly amazing at being either. A true CIWS such as RAM would be a much better proposition IMO.

_________________
AU Projects: | Banbha et al. | New England: The Divided States
Blood and Fire

Firstly, thanks to everyone who has replied for all the comments and suggestions!

Blackbuck wrote:

My last concern is the lack of CIWS gun, laser or missile. ESSM is all well and good but if I were building it I'd probably have some sort of close-in systems not least as fail safes against ESSM being taken out of action for whatever reason.

Good point. Any suggestions for a stealthy CIWS mount? I like the concept of lasers, but I'm not entirely convinced the technology is quite there and where there is doubt, I would prefer to go with the "de-risked" option.

acelanceloet wrote:

- it might be an idea to fit AGS-Lite, if shore bombardement is not the main reason of existance for this ship

Shore bombardment is not the primary mission, but it would be useful to have that capacity given that there is sufficient space in the design.

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- I wonder why the Mk 57 PVLS is not used?

Umm...well...I'm not sure! I think I went with the older VLS system purely because I'm more familiar with it.

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- the SPY-3 + VSR have 120 degrees angles instead of the 90 degrees of the SPY-1, so you only need 3 instead of the 4 drawn right now.

Ahhhhhhhh. I wondered about that...

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then, the parts. note that the steam turbines you have used are 1930's vintage, so I would look into newer ones. I have a set of gearing class turbines drawn which are slightly newer (PM me if you want them) but I do not know if it would be more usable.

I used those turbines (in the absence of anything more modern) purely to get a rough sense of the space required. I would definitely by interested to see the Gearing sets though...

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seein the position of the aft turbine room and the electric engine room, I cannot see why you would not pu them in the same room, and maybe even directly couple one of the reactors. by putting the electrical engine to the gearbox you can run both shafts on one reactor or on the gas turbines, or deliver power to the onboard power network (IEP) with an shorter machinery setup.
the post you made later (after I started writing this) fixes that though, but keep it in mind

I'm not sure I follow...I thought one of the main points of an IEP arrangement was to avoid needing complicated mechanical linkages. In fact, I was even thinking about using azipods or fixed pods, but don't know enough about their characteristics in a military design.

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if we go a bit into handwavium, we can say that was the D2G developed further, it would have gotten more power out of the same size. that, and the fact that turbines got better due to computer aided design, we can assume 35000 shp at least, maybe even 40000 from each reactor.

Almost certainly...particularly if you extrapolate from developments in submarine reactors. However, I'd prefer to err on the side of caution!

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a longer waterline might result in a lower required power as well, so I personally think you need the power of the zumwalt as a maximum, not a minimum. (the virginia had enough with the 2 D2G and the ship service generators, of course there was less power required for the systems back then but even so, doubling this amount seems excessive even 50 years later.

My design is roughly the same length as the Virginia, although the beams is greater. It is slightly shorter than Zumwalt, but the beam is slightly less at the waterline so to the length to beam ratio is greater (around 8:1 instead of 7.5:1)

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now, the ship design. you need to look at your mission profile. what speed will you be sailing on most of the time? that is what you optimise the hullform on, and this defines the length (hull speed)
this is reason one why DXGN (virginia) is so much longer then DXG (kidd) (the other is the displacement due to the weight of the reactors) you might end up with a bigger ship then the zumwalt if you want to go 30 knots all the time.

In an ideal world, I would like a ship capable of operating at high sustained speeds but the CONAG system is more suited to a more conventional "cruise and sprint" profile. It all comes down to creating a plausible design with the systems I have some actual knowledge of...otherwise I'm just guessing.

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after you have determined that, the next problem comes alive. on first glance, there are maybe 4 or 5 heavy systems on board: the radars, the VLS, the gun, the reactors and the hull itself, for example. the hull itself has its center of gravity about midships, and you want the weight of your entire ship in about the same place, as that gives you an effective hull form. as the weight of your propulsion system will end up on about 25% of the entire ships weight in this case, and you have very little fluids on board you can stabilise the ship with, this determines the place of the reactors. you can separate them from each other, but the midpoint between them should be about midship.

So...I need to place the reactors around the hull's centre of gravity? Okay...

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the superstructure where your gas turbine is in should not neccecarely be as high as that where the radars are in. hell, those things are light and you can move them around in this case, so you can put them under the helideck if you want.

Where would I place the intakes and exhausts, then? The reason I channelled the uptakes and downtakes through the superstructure is to keep troublesome exhaust gases away from flight operations and/or electronic systems. The alternative is to fit a conventional funnel and split the superstructure into two towers, which is going to lead to extra topweight. I've tried a number of layouts and none really seem to work, to my eye at least.

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note that your freeboard looks quite high. lowering it one deck already gives you one less deck to move the reactor trough. that said, as long as your stability can take it, there is nothing wrong with more freeboard

Actually...my first design had the helideck and hanger one deck lower, but I was concerned that there wasn't enough freeboard then! I was also concerned that a break of deck would make for a weaker hull, so in the end I just added an extra deck.

Weird idea! Don't some of the Russian ships have hatches leading to the reactor compartments? Yes, that does waste some deck space, but if it makes for easier maintenance...

JSB wrote:

Hope you don't me offering an alternative (it may be useless I'm not a nuclear engineer

)

Of course I don't mind! I'm always interested to see how others approach the same problems.

Voila...a reworked version of the preferred design:

[ img ]

I've tried to arrange the reactors (and other heavy equipment) more symmetrically, added PVLS fore and aft and reduced the size of the superstructure. I shall add CIWS to the hangar roof once I choose an appropriate system.

A few questions:

1. Are the GTs too high up?

2. Would there by sufficient space to fit electronic systems (e.g. SATCOM) outboard of the turbine exhausts?

3. Would it be feasible to have each reactor chamber at the bottom of a circular shaft, closed off at the main deck with circular hatches? I realise that cutting big holes in the deck is structurally undesirable, but it would allow for much easier access (even if it does waste space).

- Millennium gets my vote for a gun CIWS, it's bolt-on like Phalanx but does require some third-par direction to be truly effective. 35mm x228 is a beastly round to be spewing out at >1000spm. Failing that, there's always VL-RAM if you're worried about signature.
- I'd still probably put them a deck lower so as to be within the hull proper but that might just be me.
- Plenty of space between the intakes and uptakes for whatever conformal antennae you might have in mind as the ducting obviously goes straight up to avoid presenting a huge IR target side on.
- Not particularly sure as I'm not sure how they went about it IRL

~Mark.

_________________
AU Projects: | Banbha et al. | New England: The Divided States
Blood and Fire

I like the lasts one

,
my only change would be the VLS ( remove the last 2 in forward block to keep reactors/VLS separate)
I would ether go with 4 + 4 or 5 + 5 (with 5th more forward so keep a compartment between reactor/VLS).

JSB

a few notes again:
- IIRC you can directly connect the Mk 57 VLS, and I am at least certain you need far less space between them then you have now (1 pixel should be enough)
- you might be able to use the sizes of the turbines from the county class too, although those have less power. anyways, I will PM you the gearing sets soon, remind me if I don't
- I recommended AGS Lite because it has the same capacity, just lower amounts of ammo, IIRC.
- IEP is an system that refers to having the ships systems and propulsion all connected to one main system. mechanical linkages for multi-engined ships are indeed complicated, but some electrical cross couplings are a lot easier then that, which is basically what I was proposing (but then connected to the IEP)
- I think realism may be better then caution, on this ship, especially on the turbine power which I am certain about that it would end up higher
- again, I think your ship will be bigger then a zumwalt or will lose some systems compared to it, especially if you keep carrying around much of the zumwalts fuel as well.
- on the mission profile, I think it is possible to build a purely nuclear ship of this size with only some generator sets to keep up ship power when at full speed or when in harbour. so I think you should work the other way around, if you want a high sustained speed always, you design a ship around that

that said, CONAG is interesting as it has not been done (much) before.
- you need to place the reactors around the center of bouyancy, actually, which should be below the center of gravity from the entire ship

_________________
Drawings are credited with J.Scholtens
I ask of you to prove me wrong. Not say I am wrong, but prove it, because then I will have learned something new.
Shipbucket Wiki admin

Blackbuck wrote:

I've added a RAM launcher to the hangar roof, but a Millenium Gun would certainly work (and further increase weapon commonality with my air defence frigate).

JSB wrote:

my only change would be the VLS ( remove the last 2 in forward block to keep reactors/VLS separate)

Fair enough...even though the reactor is well inboard, I would have preferred more space between them.

acelanceloet wrote:

- IIRC you can directly connect the Mk 57 VLS, and I am at least certain you need far less space between them then you have now (1 pixel should be enough)

Okay.

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- you might be able to use the sizes of the turbines from the county class too, although those have less power. anyways, I will PM you the gearing sets soon, remind me if I don't

That would be a huge help! I notice that the County Class' turbines are very much smaller...are the ones I'm using too big?

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- I recommended AGS Lite because it has the same capacity, just lower amounts of ammo, IIRC.

I'll take your advice, although I don't think the AGS Lite looks anywhere near as interesting as the real deal!

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- IEP is an system that refers to having the ships systems and propulsion all connected to one main system. mechanical linkages for multi-engined ships are indeed complicated, but some electrical cross couplings are a lot easier then that, which is basically what I was proposing (but then connected to the IEP)

Ah, I see. I imagine there would be some sort of linkage, but I'm not sure how to draw it!

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- I think realism may be better then caution, on this ship, especially on the turbine power which I am certain about that it would end up higher
- again, I think your ship will be bigger then a zumwalt or will lose some systems compared to it, especially if you keep carrying around much of the zumwalts fuel as well.
- on the mission profile, I think it is possible to build a purely nuclear ship of this size with only some generator sets to keep up ship power when at full speed or when in harbour. so I think you should work the other way around, if you want a high sustained speed always, you design a ship around that

that said, CONAG is interesting as it has not been done (much) before.)

If I understand you correctly...you're saying that I don't need the LM2500s for this ship and can manage with the reactors and a few GTG sets. The design does have less than the Zumwalt- only one main gun for example- and if I'm going with the AGS Lite then there will be a further reduction there. Much as I would like to design a larger, faster and more capable ship...I'm not sure I really know where to start with that!

So...taking all these commenst on board, this is my latest layout:

[ img ]

The CONAG layout has been abandoned in favour of pure nuclear propulsion supplemented by a pair of GTGs (I wanted to add a third, but intake and exhaust arrangements make it hard to find the best location). The AGS has been replaced by AGS Lite; the PVLS has been adjusted and the superstructure has been cut down in size.

I've also added access shafts for the reactors- they take up space, but that might prove a worthwhile sacrifice

quite nice! a few things come to mind:
- the aft VLS battery would fit very nicely a bit more forward, on top of the electrical engine room (more next to it, actually) and I would put a third GTG set somewhere under the helideck, exhausting trough the stern. another option would be on top of the turbine rooms
- I would place the GTG amidships one deck lower, clearing some space in the superstructure for computer and CIC equipment.
- I am pondering if it would be an good idea to sacrifice some deck space for an second RAM launcher forward. the RAM is modular enough that you might be able to put it on the deck on top of the reactor, I think?
- the fact that there are acces hatches does not mean the space above it is wasted. you can put storage there, or even systems or crew space...... as long as you can easily remove it when refueled, it works.
- if you lack space, it would make sense to fit at least one electrical engine in the same room as the aft turbine. as the turbines can be placed midships, you might even be able to place both in there (the shape of the underwater hull defines the space so far aft)

_________________
Drawings are credited with J.Scholtens
I ask of you to prove me wrong. Not say I am wrong, but prove it, because then I will have learned something new.
Shipbucket Wiki admin

I have a question ?
How often to you actually need to refuel ? (the SG9 on the Virginia class says 33 years so only once in the ships life ?)

If you are only going to refuel it once in 30+ years does it matter if you need to do a little cutting ? (as long as its not to complicated)

Could you not put say the GTG (in a raft/box) on top of the reactor and crane it off in one piece when it comes time to refuel ?

JSB

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