CV-18 Fujian/003 CATOBAR carrier thread

[boytoy]

Congrats, you just inented IEPS

Just googled this. So since people are showing pictures of combined gas turbine and diesel electric system. Does this mean 003 is not using a IEPS design? Is there advantages of this over IEPS designs? Or are the tech for IEPS not mature enough yet

 

[boytoy]

Too heavy . Diesel/turbine electric used only if the power is small, or if the weight is not an issue.

What do you mean by this? That the 003 is too heavy? or the full diesel electric generators are too heavy?

 

[Anlsvrthng]

What do you mean by this? That the 003 is too heavy? or the full diesel electric generators are too heavy?

A generator + motor is heavier than a simple transmission.

 

[Intrepid]

Or are the tech for IEPS not mature enough yet

At some point we will see the first aircraft carrier with pods for propulsion. At the moment, the developers do not dare to design this way.

 

[Tetrach]

At some point we will see the first aircraft carrier with pods for propulsion. At the moment, the developers do not dare to design this way.

you already have pods for the (french) Mistral class but it seems it is not that much liked.

 

[Sczepan]

that looks like shafts, not pods

 

[sheogorath]

you already have pods for the (french) Mistral class but it seems it is not that much liked.

Keep in mind that the Mistrals are glorified RO-ROs. They were built to comercial standards, instead of military ones.

 

[nlalyst]

Thanks for the explanation. Why not a full diesel electric power system where propeller is only powered by electric motors? This would eliminate need for gear boxes used by the gas turbine. You can put the generators in the center of the ship, and route power to the motors near the propellers. No need for long shaft, which increases both space efficiency and power efficiency.

Good question. USS Langley, the first aircraft carrier the US built and commissioned had electric drive. This was a conversion from a 1910s electric drive collier. At that time reduction gear drives were not yet mature enough and the USN experimented both with electric and geared drives. Simultaneously, in the 1910s, the US built 6 battleships with electric drives (turbo-electric propulsion). The USN seemed rather satisfied with the arrangement, and proceeded to build 2 fleet carriers (45,000t) with electric drive. It had plans to build six largest ever battleships at the time (48,000t) in 1920, also with turbo-electric propulsion. However, the Washington Naval Treaty smashed those plans.

The main argument against turbo-electric propulsion that I could find cited is excessive weight. Nonetheless, the US launched roughly 120 destroyers with turbo-electric propulsion in just 2 years (1943-1944).

Congrats, you just inented IEPS

No, such arrangement doesn't have to be IEPS.

 

[Anlsvrthng]

Good question. USS Langley, the first aircraft carrier the US built and commissioned had electric drive. This was a conversion from a 1910s electric drive collier. At that time reduction gear drives were not yet mature enough and the USN experimented both with electric and geared drives. Simultaneously, in the 1910s, the US built 6 battleships with electric drives (turbo-electric propulsion). The USN seemed rather satisfied with the arrangement, and proceeded to build 2 fleet carriers (45,000t) with electric drive. It had plans to build six largest ever battleships at the time (48,000t) in 1920, also with turbo-electric propulsion. However, the Washington Naval Treaty smashed those plans.

The main argument against turbo-electric propulsion that I could find cited is excessive weight. Nonetheless, the US launched roughly 120 destroyers with turbo-electric propulsion in just 2 years (1943-1944).


No, such arrangement doesn't have to be IEPS.

The problem of long shafts bit overblown.

They are not that heavy ,they need to be only hollow tubes.

Issue is simple, the ship has a cost ,weight limit, and a desired maximum speed, and the electric propulsion usually has inferior characteristic if all three considered compared to direct geared drive.

 

[nlalyst]

The problem of long shafts bit overblown.

They are not that heavy ,they need to be only hollow tubes.

The USN selected electric drive in the 1910s because it was the more mature reduction technology. The Washington Naval Treaty of 1922 substantially limited the max displacement of capital ships. The extra weight of electric drive together with the maturation of reduction gears made them the inferior solution.

Those 120 escort destroyers built in 1943-1944 used electric drive because the gear manufacturing capacity was insufficient to keep up with demand.

Issue is simple, the ship has a cost ,weight limit, and a desired maximum speed, and the electric propulsion usually has inferior characteristic if all three considered compared to direct geared drive.

True, but those are not the only relevant parameters for a warship. In no particular priority: survivability, acoustics, fuel economy are three parameters where electric propulsion typically has the advantage.