Next Generation DDG and FFG thread (after 055, 052D, 054B)

antiterror13

Brigadier
If they use the 40 MW gas turbines, they could make a CODAG configuration with one 40 MW boost turbine, and two of those 7 MW diesels.

This could be used in a new DDG to replace Type 052. I still expect Type 054B frigates to be built but that weapon configuration is underwhelmimg.

For redundancy reason, I think the 40MW version is for bigger warship with 2 or 3 units of them. I think 2 unit of gas turbine is more desirable than only 1
 

ACuriousPLAFan

Brigadier
Registered Member
If they use the 40 MW gas turbines, they could make a CODAG configuration with one 40 MW boost turbine, and two of those 7 MW diesels.

This could be used in a new DDG to replace Type 052. I still expect Type 054B frigates to be built but that weapon configuration is underwhelmimg.
For redundancy reason, I think the 40MW version is for bigger warship with 2 or 3 units of them. I think 2 unit of gas turbine is more desirable than only 1

Just to clarify some things:

For FFGs, having only one medium/high-power marine gas turbine engine is sufficient for CODOG or CODAG propulsion systems. No FFGs need to travel in the high-30s of knots or even 40+ knots of speeds.

(A side note: The Talwar and Nilgiri FFGs (with 2x LM2500 gas turbines per ship) are odd cases which should not be emulated, given the fact where China already has superior options in both gas turbine and diesel/diesel-electric engine domains.)

Meanwhile, for DDGs and CGs, having more than one medium/high-power gas turbine engines is a definite must. Otherwise, there wouldn't be enough power to propel the warships at their required speeds.



Additional mentions:

Back when the 055 DDG's design was finalized, the CGT-25M is the highest power marine gas turbine engine available to the designers. That's why the 055 DDGs needs 4 of them to achieve the necessary speeds (at dash).

But now, with more powerful marine gas turbine engine options becoming available (e.g. CGT-30M, CGT-40M, CGT-50M, QC400 and QC500) alongside technological advancements in marine propulsion systems (e.g. electric motors and IEPS), reducing the number of gas turbine engines per ship becomes the viable path in order to free up more hull spaces for other purposes. This means that going forward, only two medium/high-power marine gas turbine engines would be sufficient for PLAN DDGs and CGs.
 
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gelgoog

Lieutenant General
Registered Member
Larger gas turbines are more compact per unit of power and one gas turbine has less parts than two. This means one large gas turbine will be cheaper to manufacture and easier to maintain than two smaller ones.

Modern frigate designs like FREMM and Mogami all seem to be moving this way. The only reason it did not happen with destroyers is lack of engines with enough power.

There is no point in having redundancy on the boost engines since if any of them fails you won't operate at peak velocity. The redundancy is important for the smaller cruise engines.
 

taxiya

Brigadier
Registered Member
Larger gas turbines are more compact per unit of power and one gas turbine has less parts than two. This means one large gas turbine will be cheaper to manufacture and easier to maintain than two smaller ones.

Modern frigate designs like FREMM and Mogami all seem to be moving this way. The only reason it did not happen with destroyers is lack of engines with enough power.

There is no point in having redundancy on the boost engines since if any of them fails you won't operate at peak velocity. The redundancy is important for the smaller cruise engines.
One large GT solution does not consider the optimal distribution of power demand. Warships need many power levels for various work loads. Type 45's broken-down was due to precisely this reason, GT was too powerful and diesels were too low causing GT to be used more often than expected.

I would not use ships of other navy as a standard to argue for PLAN because those ships may be designed to spend more time in low speed and power even in their combat mode while the single powerful GT is only used for a dash. They could be designed for survilance role. PLAN's frigate may be required to be more active such as defending CV or LHD/LHA. Different profile need different power plant arrangement.

According to a study by Naval Engineering University, the desired power plant composition for a IEPS 4500t frigate is 21MW, 5-8MW and 1-2MW. The total installed power is 42MW. It is made up of two 21MW GT and couple of medium and small GTs (can be diesels too) It's conventional counterpart also demands similar power composition.

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