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Andy1974

Junior Member
Registered Member
He definitely has a different design than other CCLs have. His might work better.

View attachment 78990
I think this could be improved by adding a volcano like shape to the center of the end cup. It would give the exhaust gas a smoother flow to the outside. A bit like a wine bottle bottom, just push the end cup in towards the nozzle a little.

Mr Kun, feel free to use this idea.
 

BoraTas

Junior Member
Registered Member
The gap between China and Germany in conventional submarine technology has closed. But it could be nice to get German technology on submarine fuel cells - the alternative to the Stirling engine for air independent propulsion. This probably won't be possible given this technology can't really be argued to be dual use, but maybe sometime in the further future... Fuel cells would enable a diesel AIP submarine to stay submerged probably up to 4 weeks, compared to the 2 weeks on an AIP sub using Stirling engines. There are also reports that Germans are getting close to operationalising lithium-ion battery, which is the cutting edge for conventional sub technology, but this is not confirmed.
Who said you China lacked the fuel cell tech :)
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This locomotive uses a 700 kW fuel cell supplied by SPIC Hydrogen Energy Company. For comparison, even the Type 218 has 2 x 120
kW fuel cells.
 

BoraTas

Junior Member
Registered Member
Obviously, nobody can say for sure, because PLAN is very secretive about its submarine schedule. But, looking from the outside in, there are good reasons to maintain both conventional attack submarine and nuclear submarine development. The Wuchang shipyard on the Yangtze (where most of PLAN's conventional subs were built) has recently been expanded, suggesting to wetsern observers of an increase in diesel AIP sub production.

To see why the conventional diesel sub still has its uses, let's take a look at how diesel subs with AIP (because AIP is a basic modern standard) compare versus nuclear subs. I am making a general set of observations that are intended to be true most of the time, and I am not comparing between two specific classes of subs.

Diesel subs with AIP

Pros:

- Very affordable on a per unit basis (e.g. German Type 214 $380 million, Type 39A Yuan class ~$300 million estimated, Soryu class $540 million)
- More stealthy on a short-term or tactical basis. A diesel sub running on its batteries is very silent, and can probably maintain this for the duration of a combat situation. Small hull size also reduces the detection range of enemy active sonars.

Cons:
- Not very stealthy on a sustained basis, because it needs to snorkel every 2-4 weeks, depending on the type of AIP.
- Limited range (constrained by fuel and food supplies, and small storage space)
- Less weapons (due to small hull)
- Less dive depth
- Very slow speed when running on AIP

Nuclear sub:

Pros:

- More stealthy on a long-term sustained basis, because it does not need to surface or snorkel.
- Unlimited range (limited only by food)
- Faster speed (25-30 knots vs. 20 knots for diesel subs)
- More weapons (especially more SLCMs)

Cons:
- Very expensive. A Vriginia class costs approximately $3 billion. Barracuda class costs $2 billion. For the price of one nuclear attack sub, you can produce 5 to 8 competitive diesel AIP subs.
- Maintenance cost if much higher.
- Can't switch off nuclear reactor, which means the reactor cooling pumps will have to keep running. This means a nuclear submarine will always produce a certain level of noise, and usually more than an AIP sub running on its batteries. Technological improvements have reduced the noise level of reactor cooling systems, but nothing beat a diesel sub running slowly on battery power yet.

The diesel AIP sub will still have a role to play in coastal waters or the near seas, where it can return to base or snorkel in relative safety. The diesel sub is also very suited to defensive operations, because it can be prepositioned in the path of advancing enemy fleets and intercept them, which would mitigate the speed disadvantage of the diesel sub. You can also mass produce them, and one nuclear attack sub is not going to defeat 8 AIP subs, in a hypothetical encounter where you don't account for the strategic advantage of the nuclear sub (e.g. in operational range).

The nuclear sub is better suited for distant waters away from home base, for offensive purposes in hostile waters, and for nuclear deterrence.
There are a few wrong points in your comment. A conventional submarine doesn't have to be smaller or have a lesser dive depth. It is just most of them are built that way because great power navies transitioned to nuclear submarines for open ocean missions and other nations lack the need and/or budget for large submarines. A nuclear submarine can be small for example, the NR-1 had a displacement of 400 tons. Likewise, a conventional submarine can be large for example Russia's incoming Seismic Survey sub will have a displacement of 14000 tons.

The dive is the same too. The Type 214 outdives most American nuclear subs with its HY-100 hull. There is nothing constraining weapons storage, food storage and sensor size too. Because these are all dependent on hull size and there is nothing making conventional subs inherently smaller. Conventional subs don't lack range either. The Type 212 has a range of 8000 nm at 8 knots at diesel in addition to a 1250 nm range at 4 knots at AIP fuel despite being small.

What conventional subs lack is high-speed endurance. For example, the Type 212 would run out of diesel fuel in 3600 nm after cruising for 180 hours at its top speed of 20 knots. For battery, this would be less than 7.50 hours. These are my calculations and they don't include propulsive efficiency or engine efficiency changes. For comparison, A nuclear submarine can push 35 knots for 90 days uninterrupted because they have unlimited range. A conventional submarine could have a high top speed (nuclear reactors have a low power density) but the horrible endurance they would have at such speeds makes such a design senseless. Unlimited high-speed endurance gives a nuclear sub a lot of opportunities. It enables offensive chases against surface vessels and allows for efficient ocean patrol. Since detection ranges are limited underwater, speed is extremely important for finding enemies before they find you. It also enables SSBN escort and anti-SSBN missions (though any country engaging in the latter is stup*d and is risking the entire planet, period).

Another advantage of nuclear submarines is they can handle high hotel loads easily, enabling them to run their sensors at higher voltages. Hotel loads are a huge problem for conventional submarines. At 4 knots 3/4ths of the electricity use of the submarine is unrelated to the propulsion. This is why most conventional subs lack desalination facilities and oxygen generators. They would consume too much power. This is also why there were concepts of conventional submarines with small nuclear reactors. The small reactor would generate power for hotel loads and sensors. Just that would quadruple the submarine endurance at 4 knots and would increase the range of sensors. One of such subs was even built (Russian Sarov).

And unfortunately, AIP doesn't solve the problem of snorkeling. AIP subs are ordinary diesel electrics at long missions. German AIP subs have just enough AIP fuel for 8-17 days of operation depending on the speed. 17 days would be for sitting stationary at the seabed and 8 days would be for 6 knots patrol speed. Considering that they have an endurance of 84 days, they would be ordinary diesel-electrics for 67 days at least at a long deployment. The incoming Spanish S-80 Plus tries to improve this by ditching all the diesel fuel and hydrogen tanks and replacing them with ethanol. Ethanol will power both the main piston engines and the fuel cells with the help of a reformer. This will more than double the AIP endurance. AIP systems don't add any high-speed endurance either since all operational systems are limited to a few hundred kilowatts.

Though what I agree with is, conventional submarines are indeed better for near-shore missions. They are both quieter and can be produced in greater numbers and in modern underwater warfare, numbers are very important. 3 diesel-electrics can easily deny more sea area to the enemy than a single nuclear sub. You also don't have to train nuclear technicians/engineers for every submarine. So the summary:

Conventional sub advantages: Silence, cheapness
Nuclear sub advantages: High-speed endurance, not snorkeling, handling hotel loads, unlimited range
Equal points: Possible top speeds (though no conventional sub is designed for this), size, sensor size, food storage, weapons storage, maximum diving depth.
What AIP adds to a conventional sub: Ability to not use the snorkel for 14 days. 28 days if you are using an alcohol reformer. These periods can be longer for a larger conventional sub.

Note: I literally posted most of the information on this topic I digested from different resources in my 20 years of watching the defense industry.
 

Tam

Brigadier
Registered Member
If China is working on Lithium Ion on submarines, I may think that China has gone ahead over the Germans in conventional submarine. China is ahead in Lithium Ion, with only Japan slightly ahead and neck to neck with South Korea. Lithium Ion could be the biggest game changer for conventional submarine technology in decades.
 

5unrise

New Member
Registered Member
There are a few wrong points in your comment. A conventional submarine doesn't have to be smaller or have a lesser dive depth. It is just most of them are built that way because great power navies transitioned to nuclear submarines for open ocean missions and other nations lack the need and/or budget for large submarines. A nuclear submarine can be small for example, the NR-1 had a displacement of 400 tons. Likewise, a conventional submarine can be large for example Russia's incoming Seismic Survey sub will have a displacement of 14000 tons.

The dive is the same too. The Type 214 outdives most American nuclear subs with its HY-100 hull. There is nothing constraining weapons storage, food storage and sensor size too. Because these are all dependent on hull size and there is nothing making conventional subs inherently smaller. Conventional subs don't lack range either. The Type 212 has a range of 8000 nm at 8 knots at diesel in addition to a 1250 nm range at 4 knots at AIP fuel despite being small.

What conventional subs lack is high-speed endurance. For example, the Type 212 would run out of diesel fuel in 3600 nm after cruising for 180 hours at its top speed of 20 knots. For battery, this would be less than 7.50 hours. These are my calculations and they don't include propulsive efficiency or engine efficiency changes. For comparison, A nuclear submarine can push 35 knots for 90 days uninterrupted because they have unlimited range. A conventional submarine could have a high top speed (nuclear reactors have a low power density) but the horrible endurance they would have at such speeds makes such a design senseless. Unlimited high-speed endurance gives a nuclear sub a lot of opportunities. It enables offensive chases against surface vessels and allows for efficient ocean patrol. Since detection ranges are limited underwater, speed is extremely important for finding enemies before they find you. It also enables SSBN escort and anti-SSBN missions (though any country engaging in the latter is stup*d and is risking the entire planet, period).

Another advantage of nuclear submarines is they can handle high hotel loads easily, enabling them to run their sensors at higher voltages. Hotel loads are a huge problem for conventional submarines. At 4 knots 3/4ths of the electricity use of the submarine is unrelated to the propulsion. This is why most conventional subs lack desalination facilities and oxygen generators. They would consume too much power. This is also why there were concepts of conventional submarines with small nuclear reactors. The small reactor would generate power for hotel loads and sensors. Just that would quadruple the submarine endurance at 4 knots and would increase the range of sensors. One of such subs was even built (Russian Sarov).

And unfortunately, AIP doesn't solve the problem of snorkeling. AIP subs are ordinary diesel electrics at long missions. German AIP subs have just enough AIP fuel for 8-17 days of operation depending on the speed. 17 days would be for sitting stationary at the seabed and 8 days would be for 6 knots patrol speed. Considering that they have an endurance of 84 days, they would be ordinary diesel-electrics for 67 days at least at a long deployment. The incoming Spanish S-80 Plus tries to improve this by ditching all the diesel fuel and hydrogen tanks and replacing them with ethanol. Ethanol will power both the main piston engines and the fuel cells with the help of a reformer. This will more than double the AIP endurance. AIP systems don't add any high-speed endurance either since all operational systems are limited to a few hundred kilowatts.

Though what I agree with is, conventional submarines are indeed better for near-shore missions. They are both quieter and can be produced in greater numbers and in modern underwater warfare, numbers are very important. 3 diesel-electrics can easily deny more sea area to the enemy than a single nuclear sub. You also don't have to train nuclear technicians/engineers for every submarine. So the summary:

Conventional sub advantages: Silence, cheapness
Nuclear sub advantages: High-speed endurance, not snorkeling, handling hotel loads, unlimited range
Equal points: Possible top speeds (though no conventional sub is designed for this), size, sensor size, food storage, weapons storage, maximum diving depth.
What AIP adds to a conventional sub: Ability to not use the snorkel for 14 days. 28 days if you are using an alcohol reformer. These periods can be longer for a larger conventional sub.

Note: I literally posted most of the information on this topic I digested from different resources in my 20 years of watching the defense industry.

There is nothing stopping you from building a large conventional submarine, but that statement ignores the fundamental trade-off you face when you have a limited amount of horsepower to work with. A nuclear reactor gives you a far more powerful and sustained propulsion, so the nuclear submarine is better placed to be built larger, and still not sacrifice too much in other areas. You can conceivably make a conventional submarine very large, but probably can't stay submerged for very long (or it will run out of power), and can't move very fast. There is a trade-off to be made between size and other functions for the same average level of horsepower, and my point is that the nuclear sub is much better suited to make that trade-off.

There is a good reason why most nuclear submarines are built to be quite large compared to diesel subs, and, as I said, my observations are general. I don't understand why you are bringing up Russian seismic survey subs, and extremely small outlier nuclear subs, as counters to my general statements about naval submarines. They seem irrelevant to be honest.

Because the nuclear sub can make the trade-off between size and firepower very easily, it can carry a large load of weapons, including 8 or more VLS cells for 32+ cruise missiles. A conventional sub can absolutely do the same, but it has to sacrifice a lot to do so, and that is why the conventional subs are generally not designed that way. Your point about hotel load is obviosly correct, and again this illustrates what you can do with the sustained power output from a nuclear reactor.

You can also put nuclear ballistic missiles on a conventional sub if you want to, for nuclear deterrence purposes, and use that as an example to nit pick at the claim that nuclear subs are better suited for strategic deterrence. There's nothing stopping you, and the North Koreans have done exactly that with the Sinpo class. But that is honestly a bad argument.

Likewise, an implicit point of mine that you have missed is that having greater horsepower in fact allow you to construct the submarine in a way that allows for a deeper dive, with the nuclear submarine again being favoured. The Soviet Sierra II class SSN is built out of titanium, and the Yasen M class is also rumoured to be built of titanium (nobody knows for sure), which not only reduces their magnetic signature, but also allows for a deeper dive depth. If you want to build a conventional submarine to withstand a greater depth, that is totally your choice, but you will be facing much greater constraints and sacrifices to be made.

On AIP - I am adding AIP into the comparison only to make the comparison more balanced, because I am comparing a modern design feature to other modern designs. I just don't want people to zero in on a conventional sub without AIP, and use it to overstate the advantages of a nuclear sub. I am not talking about the cutting edge designs, but I can certainly tell these to you. There are subs without AIP that can actually submerge for longer, given the same power consumption from hotel load and speed. This includes the Japanese Taigei class with lithium ion batteries, that are so good that they have decided to ditch the AIP altogether. Again, adding AIP into the comparison is only to make the comparison more balanced.

I feel you have picked away at certain general claims (e.g. nuclear submarines are larger and can carry more weapons) while ignoring the fundamental reasons why this is true for most cases (nuclear subs have more sustained horsepower than conventional subs, so can afford to be large). My claims are not always true, but there are enough incentives related to engineering and physics that they hold true most of the time. So I will stand by all my statements.
 
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gelgoog

Captain
Registered Member
AFAIK you can't go at high speed on a diesel submarine with a snorkel. 20 knots is basically impossible. It can only do that speed submerged on battery power until the battery runs out. With the snorkel or surfaced I doubt the diesel submarine can do more than 10 knots. Maybe less. A nuclear submarine can do those 20 knots (or more) submerged without range limitation.
 

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