It's time once again for our regular Open Thread. Talk about whatever you want, so long as it isn't Culture War.
The Naval Gazing Discord (link in sidebar) continues to go well, with over two dozen people on it and regular discussion of...a bunch of stuff. I think I'm going to see how it works for a virtual meetup next weekend, 1/28 at 1 PM Central (GMT-6).
Overhauls are Carrier Doom Parts two and three, Missile Guidance and for 2022, The Drone Revolution?* and The Virginia Class.
Comments
How effective would surface-based escort vessels be in protecting convoys from a hypothetical adversary with SSNs? The requirement to "sprint and drift" for effective sonar use seems like it would make it difficult to provide effective coverage of a large convoy.
Alternatively, is that even the right question? Other than the US, high-end navies typically only have a handful of serviceable SSNs. Would they be likely to use them for commerce raiding, or reserve them for more tactical use?
Clearing SSKs out of shallow choke points is a different question.
Could you replace "convoy" with "Marine landing force" to get a more realistic scenario with a higher value target? Although in that case they'd have SSNs of their own as cover.
If the ASW escorts' sprint speed is twice the convoy's average speed of advance, the escorts can spend roughly half their time drifting and still keep up with their charges. (Or if the escorts are at least maintaining steerage way while drifting, they can either drift longer or reduce the top-end sprint speed.) Also, sonar detection ranges can get pretty long once convergence zones start coming into play. One or two drifting ships might be able to cover the approaches to a good-sized convoy for some distance. Also also, if we're talking about the USN running convoys somewhere, we do have other detection assets (Marpats, and undersea sonar networks) specifically to cue friendly ASW assets - and allow vulnerable convoys to be re-routed away from the threat. Finally... even a layered defense will never be perfect - but if there's a shooting war going on, then at some level you just have to accept a certain level of risk.
It could devolve into waiting for a ship to blow up to know where to look.
The ideal would be to have an antineutrino sensor with performance only seen in science fiction on every escort but that probably isn't realistic.
The problem is that while during WW1/2 the speed of the convoy was about 10 knots or less. Currently merchants ships quite often make more than 20 knots, what's make difficult for escort ships to sprint ahead..
@Alex Are you assuming no ASW helicopters aboard the surface vessels? While SSNs are far less vulnerable to aircraft than a 1940s U boat, they don't have a mid Atlantic gap to operate in. Between Helicopters, MPAs and the frigates, approaching to torpedo range would be a serious challenge, and then breaking contact after the attack is your next problem. Having said that, with anti-ship missiles a submarine doesn't have to get that close, so all in all I wouldn't feel confident in the convoy getting through unscathed.
Can't ASW escorts avoid drifting the whole ship by using two towed sonar arrays that take turns drifting behind? E.g. while the FF is moving at the convoy's speed, it reels out the starboard array behind it so that it is essentially motionless and listens effectively, meanwhile reeling in the port array at high speed. When S's cable is fully reeled out, set P adrift listening and reel S in. Probably add lateral movement (eg using fins on the arrays) to avoid fouling.
In any protracted conflict, the US is still going to need to import tons of stuff by sea to keep the economy running. I’m assuming that interrupting this flow of goods would have a high strategic value.
Once the enemy SSN is out in deep water, I don’t think these assets tell us much. We would probably know when e.g. a Chinese SSN left the South China Sea and entered the Pacific, but I’m assuming we’d lose it at that point unless it was actively being followed by another SSN or a surface asset.
Exactly. If only we had some ships that could sprint to 40 knots…
No, I’m actually assuming that the escorts will be frigates or LCS with ASW helicopters. But sonobuoys are a limited resource and you wouldn’t be able to just speculatively drop them for an entire voyage. And jet fuel constraints, crewing needs, and maintenance requirements limit the number of percent of time you’ll be able to have each helicopter in the air. Plus you’ll need to have at least one on standby to take off and go kill a sub if needed.
I’m not sure how much effective coverage MPAs actually provide to detect submerged subs either.
I’m not aware of any existing equipment that enables this.
Steel cables and powered winches exist. What else is needed to enable it?
If it were that easy I assume ASW frigates and destroyers would already be using it, rather than using sprint-and-drift tactics.
Noise from the moving vessel is probably an issue. It would reach the sonar via the tow cable in addition to any sound that travels through the water.
@AlexT, sonar towed arrays are long and heavy, say 800 metres of tow for a 75 metre array. Also somewhat fragile, being packed full of electronics and transmission cable. Reeling an array in or out takes a while because you can't afford to damage the thing.
You need 800 metres of tow cable to get the array away from the noise of the ship itself and to drop below the thermocline layer. Drift speed is say 10 knots, because at higher speeds the cable will oscillate from side to side, lift above the thermocline layer, pick up lots of noise from water rushing past the cable.
If the escort is moving at 30 knots, to keep the towed array at the slower 10 knot speed would mean paying out another 600 odd metres of tow cable every minute of operation. Three kilometres for five minutes. That's a lot of cable to find room for, and a lot of cable to wind in again when you run out and have to start using the other array.
Alexander:
But it still gives an MPA in the area an idea where to drop sonobuoys and the submarine is much slower.
Alex:
The US is big enough to be able to avoid large amounts of imports if necessary though they may need some warning.
But a protracted conflict is likely to result in the US having to supply a lot of weapons to other countries and US forces fighting outside the US.
Alex:
Which would require the escorts to be nuclear powered, unless you consider having them run out of fuel less than half way across acceptable (or have such large fuel tanks there isn't any room for weapons or sensors).
Well, we have LCS, which can sprint at 40 knots. Fuel might be a concern, but we're talking about 40kt sprints here, not sustained pond-crossing at 40kts.
That said, the LCS types gave up way too much to get that sprint speed and are kind of marginal as ASW escorts as a result.
Though I do wonder about some fast-and-cheapish, sensors-mostly platforms for finding the subs and a more conventional medium-speed frigate with the weapons to actually prosecute any contacts found.
Also, given the number of SSNs the US has, could convoys be escorted by a submarine?
Maybe, though at significant cost and sacrifice. It would be much better if we could keep the flow of materials from other countries flowing.
Yeah, it was intended as an LCS joke.
They actually cancelled the LCS ASW modules in 2022 because they couldn’t get the variable-depth sonar working right.
The history of that module is a bit interesting. Originally it was going to be very specialized towards hunting diesel subs in littoral environments. But later in development they decided they wanted more typical deep-water ASW capabilities as well, and redesigned a lot of what was going into it.
Not sure why they had so much trouble getting the towed sonar working. Probably just one of those “If you try to innovate on every single element of your program, you’re going to hit a couple of show-stopping problems somewhere” issues.
Finding the subs is the hard part. Anything that can put a helicopter in the air can handle taking them out.
@Alex @Hugh Fisher
Makes sense. The numbers might be smaller, since the escort could be moving close to convoy speed (that being the whole point). Not impossible, but still weight and space that would presumably be better spent otherwise.
I guess it's hard enough that it's not worth the effort. I.e. the improvement over sprint/drift would be marginal, especially since helos can constantly take readings everywhere.
Aren't the helos supposed to be flying pretty much all the time during an escort run? Does their fuel consumption register when there's a warship sailing at 20kn?
They need a lot of downtime for maintenance, crew rest, etc. You’re also frequently in weather conditions where it’s not safe to fly the helicopter.
It’s a separate fuel tank in the ship. The warship uses diesel, but the helicopter uses jet fuel.
The point stands, I think. When you're designing the ship, you can dedicate some fraction of its tankage to fueling the helicopter. If the helicopter's fuel usage is trivial compared to the ship's, even a small fraction will ensure you never run out of jet fuel.
An Arleigh Burke has a total engine power of 78MW, and the SH-60 Seahawk it carries has a total engine power of 3MW. Engine efficiency is probably similar in both cases, but a Burke escorting 20-knot freighters probably has its engines throttled way down, while a helicopter has to use most of its available power just to stay in the air. Still, I guess there's probably a ~10:1 ratio in fuel use of the two vehicles while in operation. So you want about 10% of your tankage to hold jet fuel if you expect to have a helicopter operating continuously (if that's even practical, maintenance-wise).
(I think a Burke's gas turbine should be able to run on the same fuel as a helicopter anyway, right?)
Maybe, although that runs into the perennial problem with such concepts, where it's really hard to get the submarine to talk to the surface ships it's escorting. I don't know what current doctrine is, but if there's an SSN escort, it's likely to be fairly distant, and more a hunter using the convoy to draw in enemy subs than a traditional escort.
Technically, yes, but in practice the helo is using some form of JP, while the Burke is probably running DFM.
It is worth pointing out that those are both slightly different grades of kerosene. Let me see if I can dig up my Chevron guide to aviation fuel standards.
Both are kerosene blends, but not interchangeable. You could run the Burke's turbines on JP-5/JP-8, but you can't run the helicopters on DFM. In theory you could resolve this by filling the Burke's main tanks with JP, but in practice you'd only do this in an emergency (e.g. a significant local shortage of DFM). DFM is simpler to refine and therefore both cheaper and more plentiful.
Yeah, I am trying to think what would happeen if you had to fuel the helocopter on DFM instead of JP5. (The reveser would, as you say, only be bad for your pocket book)Sadly Chevron let me down. It mostly had info on JP8.
Most of the rules on JP5 are related proformace at atlitude (Iceing wax &c). I don't think it would blow up the turbine (Va or soot). Maybe lubricity or thermal stability problems. I don't think marine engines use fuel for coolant and lubricant the way aircraft engines do.
Gas turbines can run on pretty much anything that burns, but the rest of the engine may not like it, but maybe it'd survive a few flights before you need to replace the engines and there would be an elevated chance of needing to do a single engine landing (or even autorotation).
On the idea of convoys: how would that kind of raiding work nowadays anyway? Subs getting close to use torpedoes, or lobbing ASCMs at medium range after finding the convoy and opening the range?
I suppose that latter would mean that even your ASW frigates need limited area air defense, at least enough to cover the convoy if a sub you kept at arm's length lobs a few YJ-82s from over the horizon. Which I suppose is another strike against LCS as an escort - if an enemy sub does that and the missiles don't lock onto the LCS, their RAM and 57mm mostly can't do anything about it unless the missile overflies them, or nearly so. (I don't know enough about EW here to know if Nulka helps here or not.)
How's the research on synthetizing fuel on board nuclear vessels going?
Given that we are discussing a convoy, it seems to me that fuel capacity simply shouldn't be an issue. Any variant on the theme of "add a low-speed naval oiler", notably "on a tanker that would be a part of the convoy in any case, reserve some capacity for naval (incl. aviation) fuel use, and put a set of unrep equipment on board" would solve the problem without undue cost. The convoy can deliver, say, 1-5% less payload for the same expenditure.
I guess that is the one mission the LCS, sort of, makes sence for: chasing down and machine gunning enemy merchantmen at 40knots.
To answer the bigger question, I think nobody knows. The decisions may not even make any sence. After all, Britain was unable to cut Argentina off from the sea.
I think some advanced ASMs are more expensive than a fully loaded merchantman.
Can a sub get a good enough sonar signature to disambiguate contacts and target missiles from over the horizon?
This is non-trivial, in both equipment and skill set.
It's almost impossible to imagine the US approving rules of engagment that allow surface vessels to "gun enemy merchantment", rather than boarding and seizing them.
On a humorous note, (at least some) investigators for security clearances are now asking about whether the candidate plays War Thunder, because:
Some people can't help themselves. Don't be that guy, though.
@Jade
Aircraft are also a threat, at least anywhere reasonably close to the enemy. You'd definitely want some sort of air defense.
@Basil
That was common in WWII. But that was in the days when you were burning black oil, and the tanker was probably carrying it too. These days, things tend to get refined closer to their destination, but if you had a product tanker carrying DFM or the equivalent, I suppose it could work. It's also less necessary these days because escorts are bigger and longer-ranged.
@ike
Don't know what ASMs this would be. Even LRASM (the most expensive in current US service) is only a couple million each.
https://twitter.com/TheChowderhead/status/1617599107098628097
If you can think of a mission the LCS is better suited to than Commerce Raider, I am all ears : )
More seriously, how many ships does the USN have that are big enough to subdue and man a prize and fight off the air strike it calls down at the same time?
In the extremely unlikely event that a first strike by an enemy power can destroy a large portion of the US Carrier fleet, how fast could the US build extra wartime carriers, by cutting all possible corners and devoting all realistic resources to that?
Looks like during WW2, carriers took around 2 years from laying down to commissioning, could that be achieved again?
@Alex
I will say from personal experience that having people be wrong about stuff you know that's classified is incredibly irritating. Not to excuse what they did, but I can sort of understand it.
Clearing out SSKs and mines from choke points (Persian Gulf, Gulf of Aden, Singapore Strait, Sunda Strait, etc.), if the MCM and ASW modules were ever 100% functional. Unfortunately, the ASW module has been canceled, and it's unclear if or when the MCM module will be fully deployable.
Beyond that, they're basically good for:
It's worth noting that the carriers built during WWII likely wouldn't be adequate to handle the bigger, heavier aircraft we fly today. My guess is that we could probably build something like an Essex-class (a fleet carrier by WWII standards) pretty quickly, but could probably only fly STOVL aircraft (F-35B, USMC AV-8B) from it. Once we add all the bells and whistles required for a CVN, I think you'd hit a lot of logistic, facilities, and expertise constraints that would make it difficult to build many in parallel, and long lead times on individual components would be a problem even if you were only building one ship.
My TL;DR is: I bet we could build things to WWII standards in 2 years, but "minimum viable complexity" has >10xed since then, so it would be really hard to integrate everything in a modern CVN within that window. You'd probably be better off designing a variant of the America-class that uses the interior space for aviation fuel and ordnance rather than marines and vehicles - shipyards could probably churn them out much faster.
At the same time, scaling up aircraft production to have enough carrier air wings would probably be an equally difficult problem, so "# of flattops" might not even be the binding constraint.
It's probably worth pointing out that cranking out CVs in 2 years was considered pretty remarkable even by WW2 standards, so maybe that's not entirely a fair standard of comparison.
It's certainly relevant that the current carrier build rate is meant to indefinitely sustain the industrial base, NOT to get as many hulls out to the fleet as quickly as possible. So it would absolutely be possible to reduce the build time somewhat, perhaps by a year or more. Probably not all the way down to 2 years, though; and before any ramp-up, ample lead time would be required for various subcomponents which are ALSO currently manufactured at a rate optimized to keep the lights on at the factory rather than to maximize production. And of course the current rate of production is only enough to sustain ONE yard with the capacity to build CVNs; building/expanding more drydocks to allow building more ships concurrently would cause even more delays (and drive up costs) for an emergency rebuilding program. But at least that does suggest the Navy could probably regenerate the air wings as fast as, or faster than, it could bring new CVNs into commission.
How much does the N in CVN contribute to the current build times and costs? It certainly makes sense in terms of long-term operational costs, but in extremis, if we needed more flattops, would it be noticeably cheaper to build (updated) Kitty Hawks than Fords?
ike:
They also weren't really trying, refusing to even sink Argentine warships that didn't leave their territorial waters.
Alex:
Yet the US used to torpedo them.
Alex:
Probably big enough to handle small CATOBAR aircraft but as I understand it the Essex class wasn't able to operate the Phantom II.
Jade Nekotenshi:
At the rate they make submarine reactors it may not be a big deal to add a few extra flattop reactors.
@Anonymous
That is sort of my point. It is not really fair to say, "The British Civil Service was uniquely disloyal. Surely, no one else will ever have comparable problems."
I think we still would torpedo them from submarines. Subs and surface vessels have historically been held to different standards on this, mostly because following surface vessel rules of engagement would be suicide for a sub. Ethically, you could argue that there is not a ton of difference, but practically you're pushing up against norms and optics.
Yeah, if we still had e.g. A-7 Corsairs then those could (and did) fly from an Essex-class. But of the USN's existing aircraft inventory, I think the T-45 trainer would be the only aircraft light enough, and it could barely carry any armament even if you added some hardpoints.
I might be overemphasizing the difficulty here - retrofitting a more capable CATOBAR system on an old-ish design might be easier than I expect.
The Charles de Gaulle basically has 2 submarine reactors rather than one big reactor, which has some drawbacks but also saved them a lot of design for a one-off ship.
At the same time, redesigning all the plumbing, equipment, etc. around the reactors would probably be less work than just scaling up the production of the same reactor used in the Ford-class.
Probably not, because almost no one working still has expertise in building the Kitty Hawk, and updating designs, machine tools, etc. is non-trivial. If you want to do something fast, you want to keep the "new stuff"/design phase as minimal as possible, which would basically mean scaling up Ford-class production or doing a minimal modification of the America-class to use the existing production setup and expertise at Ingalls. If you expected the conflict to go on for years, you'd probably do both, and also try to get some additional yards going on the modified America-class as well.
In practice, I'm not sure that we would expect any conflict to last long enough to get new ships in service in time to make a difference. The Navy we have now is probably the Navy we'd have for the duration of the conflict.
The people with the expertise to build and maintain steam plants are also rapidly aging out of the workforce, which would be a special challenge for older designs like the Kitty Hawk. You'd want to use gas turbines, but that has implications for tons of other things (including the CATOBAR system design).
This probably isn't entirely true. The British were able to fly Phantoms off the considerably smaller Hermes with minor restrictions. Some of that was that, IIRC, their Phantoms had better engines, but I suspect that the US didn't want to upgrade its Essexes to handle Phantom for reasons of cost and having enough better carriers around.
Much less of a problem now that most of the bugs are worked out of EMALS. But yeah, I don't think that dropping nuclear power is going to be a win for speed of construction in the short term. It might be in the medium to long term, but I'd generally expect that the extra capability of nuclear is worth it.
The Charles De Gaulle is about the same size as the Essex class (and the America class) and it managed to handle even a Super Hornet (not to mention the smaller Rafales specifically designed for it).
Alex:
I was thinking about increasing production of the larger reactor designed for carriers, not using lots of submarine reactors in each carrier.
Alex:
How long does it take to build civilian ships of that size range?
bean:
They had more than just more powerful engines and even that came at a price.
bean:
Even just the reduction in fuel use may make it worthwhile.
Re: civilian ships, the numbers I saw was 12-16 months for super container ships in the US and 8-10 months in Korea.
Hi guys! Long-time no see, hope you guys are doing well. Grad school sucks, all I can say.
Anyway, I will try to answer some of Alex's questions in the thread above tomorrow. Just wanted to check in!
FXBDM:
That would imply that less than a year is possible, unless there's something about warships that means fitting all the military stuff must take an extra year.
Though the civilian yards have probably got extensive experience building ships quickly and have also likely optimized the design of what they produce to be able to be built fast (would that come at the expense of anything that would matter to the military?).
Unfortunately it's not quite that simple. It is only one factor that the hardware to be assembled is rather more finicky. Another is the problem of "working up" both the ship itself and the larger group it fights as a part of. With most kinds of a civilian ship, you have a tiny crew (behemoth container ships with less than 30 crew total, and that's split over multiple shifts), because the job is relatively simple, and you mostly don't need the specific ship to train people.
With a naval ship designed to be a combatant, things are nowhere near this simple. Perhaps the best way to illustrate this is a historical overview: - Let's start from the ships of the line that functioned straightforwardly, like any other sailing ship plus like any other siege artillery. - Central fire control with spotting was perhaps the first thing that couldn't be practiced anywhere except on a similar warship. Theoretically, ships in a fight were supposed to have little interaction, a battle was supposed to be a number of 1:1 duels in a line. - Torpedoes and submarines and aircraft and radio silence and radar and so on. Land armies don't always get their version of combined arms right, either. - The current new hotness is cooperative engagement capability and it's exactly what it says on the tin. (No, it has nothing to with shipping ...pardon, with romance.) Good luck training it ashore.
"That would imply that less than a year is possible"
I'm not sure it does. In WW2, the average build time for a Liberty Ship was 39 days; for the similarly-sized Cleveland-class CLs it was a bit over a year from keel laying to launching (and several months more to commissioning). So there's not necessarily a strong correlation between the build times of commercial vessels and warships.
Keep in mind that "the military stuff" here isn't just additional equipment (production lines for which would also have to be sped up) that could be dropped into any hull of broadly the right shape, it's very different construction standards - more watertight compartmentalization, damage-resistant structures, provision for damage control, and the like - all of which take longer (and cost more) than a similarly-sized commercial vessel.
You also have to test that everything (both the ship and the equipment onboard) is up to those higher standards. You'd bottleneck there until you can really ramp up the number of test facilities and trained engineers.
In 18 months I'm sure you could put together something that looks like a warship and maybe even functions like one on a good day. The enemy will wait for a bad day and then engage.
Lambert:
But it would also mean that on a good day you'd have an extra ship, maybe that's a worthwhile trade.
"In 18 months I’m sure you could put together something that looks like a warship and maybe even functions like one on a good day. The enemy will wait for a bad day and then engage."
Would the Navy go for that, or would they reinvent the CVE? That is to say, put flat tops and lifts on a few big container ships or tankers and call it a day. By just giving up and building commercial hulls to commercial standards, they might actually be able to get the first examples out in about 18 months - and after the first few examples they could have new ships coming down the ways faster. Of course you'd prefer to keep such ships to fairly benign threat environments as much as possible, doing things like ASW screening and convoy escort where they probably wouldn't need to be able to generate a lot of sorties in a hurry. As a bonus, once the emergency was over it might be possible to convert some of these back to their civilian roles.
That's assuming anybody has much of a shipbuilding industry left after the emergency was over, or any pressing need for large merchant hulls. Because it seems to me that the navy would only embrace something like this in the face of a truly existential threat - and one way or another, that sort of situation probably wouldn't last 18+ months.
From researching this a bit further, it looks like the Wasp class were built in approximately 3 years, laying-down to commission, and they can operate F-35Bs, so presumably you could make something similar (possibly without some of the amphibious assault capabilities, and with more equipment for the planes)
They're pretty slow, though.
@Anonymous
Navies have a well-earned fear of cutting those kind of corners. The number of times it has come back to bite them is very not small. The most prominent recent example is probably Sheffield, but everything from HMS Captain to the various bad experiences with ships built for export argues against it.
@FXBDM
Something like a Wasp but with less amphibious capabilities and more aviation is the America class. America took 5 years, and Tripoli 6. The last Wasp, Makin Island, also took 5, although a certain hurricane had something to do with that. This isn't inevitable, and I'd agree that 3 is definitely possible if we want it, although I'm not sure how much lower we can go without a lot of investment.
@bean
To what extent are ships built for export indicative in this regard? Tinpot dictators mostly get "real" e.g. jet fighters, with only a few corners filed off due to export restrictions, and have bad experiences with them that appear to be due to much more fundamental causes than those corners. If their predecessors in, say, the South American dreadnought arms race had analogous problems, that explains away the hypothesis that anything was wrong with the hardware.
On the other hand, I can fully see the ship incorporating by design what would be called the tooth to tail ratio on land. This is still not an issue with the build quality as such, but a more or less deliberate choice to cram more stuff into the hull than the displacement can reasonably be expected to support.
Ships and aircraft are built rather differently. An exported fighter will generally have slightly different software and maybe an identification light or something. An exported warship is likely to be a custom(ish) design for the people buying it, who are generally much more concerned with visible firepower and much less concerned with everything else than a first-rate navy would be. So you'll get a ship that has a lot of weapons for its displacement, but the enlisted quarters are terrible and there's one diesel generator and no smoke barriers. A lesser version of the same problem showed up on the Type 42, as I mentioned when I wrote about that a while back. I think this is what you were getting at with tooth-to-tail ratio, and I suppose you could frame it that way. My point was mainly that we actually have quite a bit of experience with this, and it's not positive.