PLAN Aircraft Carrier programme...(Closed)

Bltizo said:

At the very least we should agree that retaining steam boilers in the new carriers is ridiculous.


The chinese shipbuilding has mastered gas turbines and fitting a few QC-280s together will easily propel a Liaoning+ sized carrier. We've heard them make a breakthrough in IEPS too, and it would be within the bounds of imagination for at least one if not both to feature such a propulsion driven by proven gas turbines.


You know, I find parallels between liaoning and the plan purchase of sovremennies.
The sovremenny was the most powerful destroyer that PLAN had at the time of its arrival. Observers could have been forgiven for thinking new PLAN destroyer designs may simply seek to emulate it. Clearly that wasn't what happened.

The PLAN knew what capabilities it wanted, they recognised the sovremremennies shortcomings, especially in propulsion and set about building ships that were much more modern and western than Russian.
I expect a similar case for carrier development. We may very well see similarities between liaoning and the first indigenous carriers in terms of ski jump, but I'd be surprised if there weren't major changes in hangar, elevator, island, deck space, propulsion. The fact is, the admiral kuznetsov class is hardly a competitive carrier design compared to western carriers and it gets many small things wrong. Part of it was soviet doctrine, part of it was probably soviet design


But the PLAN has had years if not decades to study the kind of flattop they want, and are probably the worlds biggest fan of the USN. I expect them to make the best of the ski jump configuration if that is what they end up fielding on their first indigenous carriers. It will be an interesting ship for sure.

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On the contrary, it makes a lot of sense for the Chinese to keep using steam turbines for their indigenous carriers.

1. A 60,000 ton carrier will need well in excess of 200MW of shaft power to reach speeds normally seen in carriers (32 knots)

2. The largest marine gas turbines the Chinese ever used is 25Mw. To propel a carrier will call for an unwieldy arrangement of 8 or more such units. Gas turbines are compact, but it's associated air ducts are space consuming. Having large number of gas turbine units and their associated air ducts complicate internal layout and weaken damage control.

3. High power Marine gas turbines are a relatively low volume business, it is unlikely one could spend the money needed to develop a dedicated marine gas turbine and have that pay. Which is why high power marine turbines are usually adaptations of aircraft turbines. There is no known Chinese aircraft turbine large enough to be adaptable to development into marine gas turbine of over 20-25Mw.

4. The advantages of gas turbine over steam turbine is minimum for a carrier.

5. Afaik, china has not yet produced a large domestic gas turbine for electric power generation. There is great advantage to using gas turbine for power generation, especially for a country eager to reduce smog and cut down on green house gas emission. This further suggests gas turbine technologies Is not fully mature in china.

chuck731 said:

On the contrary, it makes a lot of sense for the Chinese to keep using steam turbines for their indigenous carriers.

1. A 60,000 ton carrier will need well in excess of 200MW of shaft power to reach speeds normally seen in carriers (32 knots)

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Not necessarily. The Nimitz class carriers displace 100,000 tons and their reactors supply a total of 194Mw of power.

chuck731 said:

2. The largest marine gas turbines the Chinese ever used is 25Mw. To propel a carrier will call for an unwieldy arrangement of 8 or more such units.

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They would probably not use a straight gas turbine system. Few of the larger vessels (LPD, LHD/A, CV, etc) using gas turbins do.

I believe that the Gas Turbines on the Type 052C/D destroyers, the QC-280 gas turbines, are the largest the PLAN has in use at this time for naval vessels. They use two per vessel. They generate 28 MW each...but that is splitting hairs.

The diesel engines that they use on the much larger Type 071 LPD are the Shaanxi 16 PC2.6 V400 diesel engines, which generate 35.32 Mw. They use four for the LPD.

By comparison, the US , on it's 45,000 ton USS America, uses two GE LM-2500+ engines. Each of these engines produce 28.6 MW. In order to gain sufficient power, the LHA also uses six 4 Mw diesel engines. This produces over 50Mw for each shaft for that Hybrid electric propulsion system.

My guess is, that the PLAN would do something similar if they wanted to power larger vessels using Gas Turbines. This would mean a CODOG (Combined Diesel or Gas) or a CODAG (combined Diesel and Gas) propulsion system.

If they used a pair of QC-280s, mated to a 16 PC2.6 v400 diesel, they could produce over 182 Mw for their carrier. As stated, the US Nimitz class scarriers, at 100,000 tons, have 194 Mw of power available.

Chuck731 said:

High power Marine gas turbines are a relatively low volume business, it is unlikely one could spend the money needed to develop a dedicated marine gas turbine and have that pay. Which is why high power marine turbines are usually adaptations of aircraft turbines. There is no known Chinese aircraft turbine large enough to be adaptable to development into marine gas turbine of over 20-25Mw.

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As stated, the PLAN would not go straight gas turbines, they would probably use a hybrid system.

A good example of a similarly sized carrier doing this is the the UK's Queen Elizabeth class. They will use two of what are probably the best naval gas turbines on the planet, the Rolls-Royce MT-30 which produce a whopping 36Mw of power each. But they then couple those with four Wartsila diesel engines two at 9 Mw and the other two at 11Mw. They add two ConverTeam 20Mw induction engines and end up with 152 Mw of power for their carrier.

Now, the PLAN may well decide to stick with the current type propuslion system that the Liaonling has. I am just pointing out that they could indeed modernize that powerplant if they choose to do so. Since they have capable enough gas turbine and diesel engines, I think there is a very good chance that they will either use a CODOG or CODAG system to make it happen.

That's a good point, They would more likely opt for a combined diesel and gas turbine arrangement if they use gas turbine at all.

Scyth said:

I don't think that catapults will be built into the ski-jump. At least not on the new carriers. Technically, it may be feasable, but for an aircraft carrier design, you usually choose either the ski-jump or the catapult. Having both is unnecessarily complicated. If you already got working catapult technology, I don't see the added value of a ski-jump.

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The fact that something hasn't been done before doesn't mean it's a bad idea. It is not at all complicated to have a bend EM cat. The speed at which the aircraft have to be delivered at the end of the cat is lower than with a straight cat so its length can be less. That means that less deck area will have to be cleared, from where aircraft will have to be respotted when aircraft are to be launched, saving work for the deck crew. On the other hand you do not need the aft take off position now available on Liaoning and Adm K. Fighters might be launched without using AB, saving fuel and time. The result is a more efficient carrier with a smaller crew.

delft said:

The fact that something hasn't been done before doesn't mean it's a bad idea. It is not at all complicated to have a bend EM cat. The speed at which the aircraft have to be delivered at the end of the cat is lower than with a straight cat so its length can be less...

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This discussion has been replayed several times on SD in the past. Our most experienced aircaft carrier members, who have lived and worked on carriers for well over 20 years, and those who have been involved in various carrier sub-system design, all agree that while such a thing could be done, that is is very unlikely that it will be done.

There is simply no real need for it.

It would add a signficant degree of complication and machinary to an otherwise straight forward ski jump design that is working very well in the STOBAR configuration.

It would add another type of catapult that would have to be learned, matinained, and operated in addition to catapult designs that themselves already work fine.

It would certainly not be used to eliminate the waist launch position in any case. That position provides important flexibility and redundancy.

Anyhow, as I said, this discussion and debate has gone on several different times and always ends up at the same place. Could be done, but probably will not be done.

Until we get actual news that someone is actually preparing to do it, lets' just leave it at that.

Otherwise we will fill up our PLAN Carrier News thread with a lot of OT debate about something that isn't PLAN Carrier News at all...just long debates about conjecture.

My suggestion would be, that if members have a serious desire to continue to discuss this idea in detail, start a seperate thread about it specifically in the Member's Club Room. Perhaps, a "Carrier Ski Jump Catapult Discussion," or something like that.

chuck731 said:

On the contrary, it makes a lot of sense for the Chinese to keep using steam turbines for their indigenous carriers.

1. A 60,000 ton carrier will need well in excess of 200MW of shaft power to reach speeds normally seen in carriers (32 knots)

2. The largest marine gas turbines the Chinese ever used is 25Mw. To propel a carrier will call for an unwieldy arrangement of 8 or more such units. Gas turbines are compact, but it's associated air ducts are space consuming. Having large number of gas turbine units and their associated air ducts complicate internal layout and weaken damage control.

3. High power Marine gas turbines are a relatively low volume business, it is unlikely one could spend the money needed to develop a dedicated marine gas turbine and have that pay. Which is why high power marine turbines are usually adaptations of aircraft turbines. There is no known Chinese aircraft turbine large enough to be adaptable to development into marine gas turbine of over 20-25Mw.

4. The advantages of gas turbine over steam turbine is minimum for a carrier.

5. Afaik, china has not yet produced a large domestic gas turbine for electric power generation. There is great advantage to using gas turbine for power generation, especially for a country eager to reduce smog and cut down on green house gas emission. This further suggests gas turbine technologies Is not fully mature in china.

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Like Jeff said, the QC-280 generates 28MW each, and all new destroyers in the last few years feature them.

Now, that's probably not enough for a straight COGAG arrangement in a ship of that size, however linking it with some diesels should be enough as suggested. If their IEPS really has made a breakthrough, they could integrate their diesels and gas turbines in such a way similar to the QE class.


In any case, I will be immensely surprised if they decide to go for steam turbines. The drawbacks of using such an obsoleted design are many. And the chinese shipyars haven't produced a large military steam turbine vessel since the 051C, and may arguably be less familiar with steam turbines than diesel and/or gas propulsion (inexperience is another major reason why I doubt they'd use steam turbines: it simply looks like a riskier option, not to mention inferior performing)

Bltizo said:

The drawbacks of using such an obsoleted design are many. And the chinese shipyars haven't produced a large military steam turbine vessel since the 051C, and may arguably be less familiar with steam turbines than diesel and/or gas propulsion (inexperience is another major reason why I doubt they'd use steam turbines: it simply looks like a riskier option, not to mention inferior performing)

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who built and installed the units on the Liaoning?

you are aware that china has three companies that are the biggest builders of power generation Steam turbines in the world, right?

Steam turbines has thermal efficiency approaching that best of Gas Turbines.

yes it is maintenance heavy and bulky and needs quite a bit of work up from cold. But what choice does china have? It just does not have a gas turbine of a that size right now.

i.e. said:

But what choice does china have? It just does not have a gas turbine of a that size right now.

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As stated...CODAG.

Using a combination of two groupings of the following:

2 x QS-280 turbines (2x28 Mw=56 Mw)
1 x Shaanxi 16 PC2.6 V400 engine (1x35.3 Mw=35.3 Mw)

Would give them 91.3 Mw per group or a total of 182.6 Mw which would be more than enough to drive the carrier.

Either that, or something like it.

This is what the UK is doing for its new Queen Elizabeth carriers (70,000 tons) using the Rolls-Royce MT-30 turbines, and what the US is doing for its America class LHA (45,000 tons) using the General Electric LM-2500+ turbines.

i.e. said:

who built and installed the units on the Liaoning?

you are aware that china has three companies that are the biggest builders of power generation Steam turbines in the world, right?

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That is... An excellent point. I can't believe I forgot that the carrier actually lacked engines when it arrived in china so of course they'd be installed by the chinese.

Steam turbines has thermal efficiency approaching that best of Gas Turbines.

yes it is maintenance heavy and bulky and needs quite a bit of work up from cold. But what choice does china have? It just does not have a gas turbine of a that size right now.

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Couldn't they arrange some of their largest gas turbines with a few diesels to pick up the slack?

Jeff Head said:

As stated...CODAG.

Using a combination of two groupings of the following:

2 x QS-280 turbines (2x28 Mw=56 Mw)
1 x Shaanxi 16 PC2.6 V400 engine (1x35.3 Mw=35.3 Mw)

Would give them 91.3 Mw per group or a total of 182.6 Mw which would be more than enough to drive the carrier.

Either that, or something like it.

This is what the UK is doing for its new Queen Elizabeth carriers (70,000 tons) using the Rolls-Royce MT-30 turbines, and what the US is doing for its America class LHA (45,000 tons) using the General Electric LM-2500+ turbines.

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the hard part of CODAG is in the "A"

the gear box that connects those two,... gearing a set of high speed gas turbine with a Low speed (60 rpm ish) low speed commercial marine diesel will be an insane technical challenge.

if you can design a low speed marine desiel that can reverse and stop a Low speed marine diesel in 10 secs and drive it up to max power in reverse in no time. then I am all for it.