PLAN Aircraft Carrier programme...(Closed)

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i.e.

Senior Member
Bltizo said:
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.




Couldn't they arrange some of their largest gas turbines with a few diesels to pick up the slack?
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If I can have a ready to go mechanical gear box that can take that kind of power... sure.

ever wonder why chinese naval ships are always CODOG not CODAG?

yeah.

a better way to go would CODAG electric.

Diesel plant is used to power generators which powers the cruise Electric motors... with Geared in gas turbines as boost engines. that would simply the reduction gear box design, just a bit, beacuse you can design a motor that turns at at required low rpm of a prop and the whole thing would be like a gear box for COGAG. but even still the installed power required for Gas turbines would be huge. on the order of >80% of total power output. assume cruise speed is 16-18 kts.

but engineering would be a little simpler.


back in the days of pre-WWI dreadnaight races. US navy adopted coal/oil fire steam turbine plants with a electric drive for their earlier dreadnauhts. Steam Turbines powered a generator, then powered a electric motor at lower RPM to turn props.

basically same thing for Today's QE class except primary source was Steam instead of gas turbines.

westinghouse and GE built them. the reason is because they could not get reliable reduction gear. while RN had no problem because they had a reliable reduction gear. later on ofcourse USN had a reliable reduction gear and that all went away.

but that is toillustrate reduction gear is hard.
 
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chuck731

Banned Idiot
I highly doubt any marine diesel used on a high speed warship would be of the low speed type. Medium speed is more likely for compactness.

Additional advantage of a combined diesel electric and gas electric is the light weight gas turbine can be sited high in the hull or even in the superstructure to avoid routing air ducts deep into the ship.
 
Jeff Head

Jeff Head

General
Registered Member
i.e. said:
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.
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Yes...I know. And yet it is being done.

I believe the Chinese are capable of doing so too.

If they have not mastered it yet...then that does not have to stop them at all. They can certainly use the steam turbine solution which they clearly have already done...which is perfectly fine too.

They have been working fine all over the world for quite some time.

In fact, in terms of training, operations, logisitcs, etc. it is a superior solution for them since they already have one carrier operating that way. But they give up the positive aspects of the gas turbines as well.
 
Jeff Head

Jeff Head

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i.e. said:
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I am not sure if this should be in the amphibious section or carrier section. chinese ship was a LST.
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All discussion regarding the US Navy Ship and PLAN ship incident in the South China Sea has been placed in the US Military News thread and a lot of discussion has occurred over there with it. I moved your post there.

Please continue any discussion regarding that even there.
 
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I

i.e.

Senior Member
Jeff Head said:
Yes...I know. And yet it is being done.

I believe the Chinese are capable of doing so too.

If they have not mastered it yet...then that does not have to stop them at all. They can certainly use the steam turbine solution which they clearly have already done...which is perfectly fine too.

They have been working fine all over the world for quite some time.

In fact, in terms of training, operations, logisitcs, etc. it is a superior solution for them since they already have one carrier operating that way. But they give up the positive aspects of the gas turbines as well.
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Only serious application of CODAG is from germans and it is done in frigates.

a better power option would be this...

4 or 3 shafts instead of 2.

Low speed Marine Diesels for inner pair shafts for economic cruise.
Gas turbines boosters for Outer pairs with electric motors for feathering/drag reduction in cruise.

entire system would be separate. no need for complex reduction gear to combine power on the single shaft. lose a bit economy with the feathering electric motor.

fuel oil has to be seperate bunkerage. light fuel for gas turbines heavy fuel oil for diesels.

or you can convert the gas turbine to burn heavt fuel oil... doable but bit tricky, nasty viscous shit.


kinda like what the interwar german navy had in mind. except the outer shaft pair was intended to powered by steam
 
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latenlazy

Brigadier
Jeff Head said:
I believe that if the turns out to be accurate and they build two hulls, it will be simiar to when they built the two Type 052B vessels, followed by the two Type 052C vessels. They are confidant enough with their design and their shipbuilding capability to do so. Not to mention being confidant enough to man both carriers in a fairly short time frame.

It would not be wasteful at all. Two carriers of very similar design...that represent improvement over the Liaoning, but are basically very similar in overall operation...will provide the PLAN with several key benefits.

1) Similar platforms for each fleet.
2) Huge logistical savings in terms of spare parts, ammunition, etc. for all of the vessels.
3) Huge training savings in being able to train crews that can work on any of the three carriers.
4) A very solid foundation to perfect their operations and policies.

I believe these things are all very desirable for the PLAN and allow them the type of foundation that will make their future progress much more secure, and much less risky. It will also provide them with the largest and most capable carrier force in the world outside of the US Navy.

In that same time frame it is true that the Indian Navy intends to have three carriers...but they will all three be dissimilar and cause the Indian Navy to have a significant logistical issue and training issue that the Chinese will not have. In addition, each of the PLAN carriers will be able to carry more aircraft than the Indian carriers and those aircraft will have greater range and be able to carry more ordinance.

I think the PLAN is embarked on a very significant and well thought out strategy.
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Having one hull take greater risks in its design from the other hull doesn't necessarily negate those advantages.

chuck731 said:
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.
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That's a very interesting point, because there was a rumour a while back that China had purchased designs to the An-225's D-18 engines. There was also another rumour that the core of the WS-10 was being adapted into a gas turbine for ships.
 
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Engineer

Engineer

Major
It would be a pointless endeavor to pursue CODAG arrangement in the present day, as the engines still suffer from efficiency issues when the ship is not operating at design speed. The trend now days is Integrated Electric Propulsion, in which you can turn off engines that you don't need while letting the remaining engines run at maximum efficiency. Also, traditional arrangements require separated engines on top of those for propulsion for providing electrical power. Integrated Electric Propulsion merges the propulsion and electrical generation systems into one thus truly achieving space-saving design. So, my belief is that we won't see a follow on to 001A Class until China achieved success in Integrated Electric Propulsion. That following on class would most likely have a similar power setup as the Queen Elizabeth Class, or perhaps even a dual nuclear-conventional setup.
 
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montyp165

Senior Member
A COGES arrangement (Combined Gas Electric Steam) system would be very good for an IEPS setup, particularly since this arrangement is very thermodynamically efficient, with waste heat from the Gas turbines powering the Steam generation system which simultaneously drives the electric generators.

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