The Future of Current Battleships

Darth Robbhi said:
@Francis Urquhart, while this might sound silly, does a combined gas-turbine/nuke plant make sense at some point?
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There's an engineering problem in that the cost and weight of a nuclear plant isn't directly related to its output. We had that problem with the Tullibee back in the 1950s. So, if one's going to put a nuclear plant in, one might as well get as much ooomph from it as we can. Now, gas turbines would be useful boost but here's the thing. Remember a nuclear plant is just a steam plant with a different source of steam and putting steam and gas turbines together is a match made in hell. It's called COSAG (combined steam and gas) and was used by the British in their Country class destroyers back in the 1950s. HMS Bristol had the same layout and the same issues - ie repeated serious fires. That was bad enough with oil-fired boilers for steam and gas turbines but I'd really not want that risk next to a nuclear reactor.

Captain-General said:
Arguably why not just combined nuclear-diesel? Then you don't have the volumetric waste that is the massive air intakes and uptakes for a gas turbine that are its main weakness. For high speed and economical cruising you use the nuke; for everything else the diesels.
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I've never heard of CONAD being used although the Chinese are reputed to be going that way for their next flight of carriers. The problem is that diesel is really the cruise system so we have two cruise systems and no boost. There's also a problem that steam turbines generate rotational energy while diesels generate reciprocating energy and gearing the two together causes a lot of problems. That's why CODAG (combined diesel and gas) is tending to be dropped these days in favor of CODOG (combined diesel or gas). I don't really see an application for a CONOD plant. That might change with the world shifting over to turbo-electric machinery. There both the reactor/steam turbines and the diesels would be generating electricity.

P.S. isn't that fixed cost per reactor so since we use redundant reactors our modern nukes are really about a $800 M premium on a carrier?
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Actually its per two reactors on a surface ship and one reactor on a submarine (the rafting and silencing on a submarine makes up for the cost saved by a single reactor). All the CVNs have two high-capacity reactors.
 
@Francis Urquhart, this may be another dumb question, but can't a lot of the COSAG issues be solved by using electric motors instead of them being connected to the shafts?

Or, for that matter, could the acceleration issue be resolved by using the reactor to generate electricity, not using the turbines to turn the shaft?
 
One thing I will point out is that unless it changed (which according to my research it hasn't) it is actually black letter law in the US that any 'cruiser' or larger new build ship MUST be nuclear, unless Congress grants an exemption. The Tico's got around that by being, up until the very last moment before commissioning, listed as DDGs.
 
Darth Robbhi said:
@Francis Urquhart, this may be another dumb question, but can't a lot of the COSAG issues be solved by using electric motors instead of them being connected to the shafts?

Or, for that matter, could the acceleration issue be resolved by using the reactor to generate electricity, not using the turbines to turn the shaft?
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To be honest I was just thinking automatically in terms of electric propulsion with any of the generating schemes. Electric Joe won me over on the early 2000s and I never looked back.
 
LordSunhawk said:
One thing I will point out is that unless it changed (which according to my research it hasn't) it is actually black letter law in the US that any 'cruiser' or larger new build ship MUST be nuclear, unless Congress grants an exemption. The Tico's got around that by being, up until the very last moment before commissioning, listed as DDGs.
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This is correct although there is a provision that the Navy may adopt other propulsion solutions provided they provide certification to Congress that it is operationally undesirable for the proposed ship to have nuclear power or that conventional power (these days always gas turbines) offers convincing operational advantages. Convincing as defined by the Navy. These days, the Navy presents its long-term shipbuilding plan to Congress and if they approve it (which they almost always do) then the non-nuclear power exemption (there are no nuclear-powered surface combatants in that plan) is deemed to have been granted. It's worth noting that this nuclear power legislation is never even mentioned in FSAs and the CRS Force Structure Analysis published three days ago..

This is also of course why the Tico replacements are "Future Large Surface Combatants" not "cruisers".
 
Sailor.X said:
Um the youngest Sailors to have served on a Battleship are only 47 years old. We ain't exactly Geriactric.
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That's the youngest, and it's still a huge, huge issue when you're stuck calling back people who have long been retired from service and/or have been promoted way beyond the grades you need.
 
ShadowArxxy said:
That's the youngest, and it's still a huge, huge issue when you're stuck calling back people who have long been retired from service and/or have been promoted way beyond the grades you need.
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Senior Chiefs, Master Chiefs and Chief Warrant Officers still give junior enlisted instructions on how to do things and enough of them are still in. It is sort of in their job description.
 
And how many of them still remember the details of the job they did 20+ years ago? Especially considering that they were probably doing completely different things since, which would contribute to them forgetting what they learned about battleships.
 
PsihoKekec said:
And how many of them still remember the details of the job they did 20+ years ago? Especially considering that they were probably doing completely different things since, which would contribute to them forgetting what they learned about battleships.
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I bet all of them do. I have been out for 24 years and I still know how to parallel a diesel generator. Dude somethings you just don't forget.
 
Darth Robbhi said:
@Francis Urquhart, this may be another dumb question, but can't a lot of the COSAG issues be solved by using electric motors instead of them being connected to the shafts? Or, for that matter, could the acceleration issue be resolved by using the reactor to generate electricity, not using the turbines to turn the shaft?
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IFEP is probably going to be the primary means of drive in future construction and its not restricted just to surface combatants but its already finding its way into fleet auxiliaries and amphibs. The big thing with IFEP is that essentially we are using generators producing current to run electric motors instead of gearing. That's lighter and much more efficient.

To be honest I'm not entirely sure why COSAG worked so badly. I suspect it wasn't so much the configuration of the power train as the situation where we had a steam plant with the gas turbines fitted in around it. The result was probably a very cramped and compromised engine room. I do know that the COSAG ships in the RN had a bad habit of engine room fires and nobody else went that way. The RN went to COGOG with unholy speed. One problem is that a boiler steam plant is happiest using HFO while gas turbines prefer MFO. So one of them is going to be unhappy. I would think that because it was machinery space fires rather than explosions, the boilers had their HFO and the gas turbines had to make do. One can run gas turbines on almost anything hydrocarbony (I saw an M1 Abrams once being started up on paint stripper but that's another story) but performance on substitutes for MFO is degraded.

Using the reactor to generate electricity driving electric motors is probably the way we will end up going. The Ford is a big step in the direction of doing just that. My guess right now is that CVN-82 and CVN-83 will go that way. Getting rid of gearing is a big deal, partly because the gearing is the most over-engineered section of the ship and thus weighs too much, partly because it costs a fortune and partly because a wrench in the wrong place can put a ship down for a year or more.

By the way there are rumors that GE are considering marine-qualifying the LM9000 gas turbine for warship use. Rolls-Royce have already introduced an MT50 gas turbine that equals the LM6000.
 
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Francis Urquhart said:
IFEP is probably going to be the primary means of drive in future construction and its not restricted just to surface combatants but its already finding its way into fleet auxiliaries and amphibs. The big thing with IFEP is that essentially we are using generators producing current to run electric motors instead of gearing. That's lighter and much more efficient.

To be honest I'm not entirely sure why COSAG worked so badly. I suspect it wasn't so much the configuration of the power train as the situation where we had a steam plant with the gas turbines fitted in around it. The result was probably a very cramped and compromised engine room. I do know that the COSAG ships in the RN had a bad habit of engine room fires and nobody else went that way. The RN went to COGOG with unholy speed. One problem is that a boiler steam plant is happiest using HFO while gas turbines prefer MFO. So one of them is going to be unhappy. I would think that because it was machinery space fires rather than explosions, the boilers had their HFO and the gas turbines had to make do. One can run gas turbines on almost anything hydrocarbony (I saw an M1 Abrams once being started up on paint stripper but that's another story) but performance on substitutes for MFO is degraded.

Using the reactor to generate electricity driving electric motors is probably the way we will end up going. The Ford is a big step in the direction of doing just that. My guess right now is that CVN-82 and CVN-83 will go that way. Getting rid of gearing is a big deal, partly because the gearing is the most over-engineered section of the ship and thus weighs too much, partly because it costs a fortune and partly because a wrench in the wrong place can put a ship down for a year or more.

By the way there are rumors that GE are considering marine-qualifying the LM9000 gas turbine for warship use. Rolls-Royce have already introduced an MT50 gas turbine that equals the LM6000.
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Does that mean I get royalties when CONUGTE/COGNUTE gets installed aboard ship?
 
Darth Robbhi said:
Does that mean I get royalties when CONUGTE/COGNUTE gets installed aboard ship?
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You can ask . . . . . . . . . They need a good laugh in Whitehall these days. 😂🤣. You'll get what I got, a nice printed (not even engraved) certificate of merit on fake parchment that you have to frame yourself.
 
Darth Robbhi said:
Can't be any worse than the Marines.
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The Marines don't clash with the paintwork on a CV (the hatch and passageway sizing is a different issue). The Marines do clash with the crew though. I was on a dead dinosaur CV back in the late 1970s and us civilian contractors had to have Marine escort when visiting certain parts of the ship.
 
Francis Urquhart said:
The Marines don't clash with the paintwork on a CV (the hatch and passageway sizing is a different issue). The Marines do clash with the crew though. I was on a dead dinosaur CV back in the late 1970s and us civilian contractors had to have Marine escort when visiting certain parts of the ship.
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I always love that scene when calling the Nimitz to Condition One in The Final Countdown with the ship’s Marine complement running through the chain locker in full battle rattle like their position at stations is to shoot at drifting mines or something. They clearly just wanted in on being Hollywood extras.
 
It's been a long time since I watched that film. I really must see it again. It's probably on Netflix or Google.

There was talk about a sequel that saw another CVN getting involved in the Battle of Midway. It languished in development hell for a few years and then died. A pity that.

Not as one-sided as one might think by the way. Torpedo planes coming in very low and slow were seen as a serious threat right up until the early 1970s.
 
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