CV-18 Fujian/003 CATOBAR carrier thread

[Anlsvrthng]

Very strange conclusion from you. Here is the USN data of their catapult.

Other drawbacks to the steam catapult include a high volume of 1133 m3, and a weight of 486 metric tons.
While the EMALS' figure is less than 425 and 225 repectively.

If you have a car that keeps breaking down, I wonder how could you make it more robust and reliable by patching it with more metal.

EMALS's initial problem is not going to be solved by making it larger and heavier. It will be either working or breaking within its current dimension.

This data omit the mass and volume of generators, that is +200 ish tons . To justify the EMALS they changed everything that they can to electrical ones, including lifts example.

Without the EMALS there is no real reason to have 200+MVA generator capacity/


Interesting, have you ever saw the difference between a fail safe and a non fail safe system ?
You can take example the breaking system of cars. Or the steering.
Both of them has built in redundancies, that increase the cost, mass and volume (example the breaking/steering needs mechanical connection only for redundancy ).

Or the spare wheel in the car consume space, require tools and increase the mass of wheel hub due to the required roadside disassembly requirements.

You can omit the spare wheel, use single 2" nut on each wheel and save money, space, mass. and have bad day if you need to replace the wheel roadside.

And it doesn't cover basic engineering changes, like how to make impossible to fall metal swarf into the linear motor. By adding extra cover, split the motor into two like the steam catapult, with extra mass and volume. Example. Or how to make/adjust the installation to be serviceable on sea, what additional equipment required on board with space and mass to store it and so on.

 

[latenlazy]

This data omit the mass and volume of generators, that is +200 ish tons . To justify the EMALS they changed everything that they can to electrical ones, including lifts example.

Without the EMALS there is no real reason to have 200+MVA generator capacity/


Interesting, have you ever saw the difference between a fail safe and a non fail safe system ?
You can take example the breaking system of cars. Or the steering.
Both of them has built in redundancies, that increase the cost, mass and volume (example the breaking/steering needs mechanical connection only for redundancy ).

Or the spare wheel in the car consume space, require tools and increase the mass of wheel hub due to the required roadside disassembly requirements.

You can omit the spare wheel, use single 2" nut on each wheel and save money, space, mass. and have bad day if you need to replace the wheel roadside.

And it doesn't cover basic engineering changes, like how to make impossible to fall metal swarf into the linear motor. By adding extra cover, split the motor into two like the steam catapult, with extra mass and volume. Example. Or how to make/adjust the installation to be serviceable on sea, what additional equipment required on board with space and mass to store it and so on.

Bringing up the generators is a bit of an odd point...given that it’s not like carriers don’t need massive generators to power all their other subsystems even if they don’t have EMALS. While EMALS does probably require larger generators, it doesn’t need a host of steam generation and fluidic systems to power steam catapults. If we’re going to talk about tradeoffs between the systems it makes no sense to nitpick individual items when what matters is the sum cost-benefit comparisons of the whole system.

It’s also not like steam driven systems don’t have their own maintenance challenges. You’re not strapping on extra motors for the catapults as extra weight so much as swapping them out for all the heavy mechanical machinery and pipes that are needed to make such catapults work. Electrical systems maintenance and repair can of course be a nightmare if you end up not building those considerations into your design, but the same is true for mechanical systems, and arguably it’s much easier to design service friendly electrical systems than mechanical systems.

I think using the Ford class as the benchmark for what to expect with EMALS reliability is frankly a bit of a flawed argument. Nothing says that the Ford class is the standard bearer for what to expect with an EMALS system that’s designed and built well. We’ve seen plenty of examples where US weapons programs have led to headaches not because they’re essential properties of the technology but because of program mismanagement.

 

[silentlurker]

Very strange conclusion from you. Here is the USN data of their catapult.

Other drawbacks to the steam catapult include a high volume of 1133 m3, and a weight of 486 metric tons.
While the EMALS' figure is less than 425 and 225 repectively.

If you have a car that keeps breaking down, I wonder how could you make it more robust and reliable by patching it with more metal.

EMALS's initial problem is not going to be solved by making it larger and heavier. It will be either working or breaking within its current dimension.

Wasn't the whole issue with Ford that the catapults were too interconnected and had shared systems instead of individual ones?

 

[latenlazy]

Wasn't the whole issue with Ford that the catapults were too interconnected and had shared systems instead of individual ones?

Yes. It was a poor system design. My suspicion is that they didn’t properly define their requirements, or did sufficient design review over how their requirements were implemented.

 

[Anlsvrthng]

Bringing up the generators is a bit of an odd point...given that it’s not like carriers don’t need massive generators to power all their other subsystems even if they don’t have EMALS. While EMALS does probably require larger generators, it doesn’t need a host of steam generation and fluidic systems to power steam catapults. If we’re going to talk about tradeoffs between the systems it makes no sense to nitpick individual items when what matters is the sum cost-benefit comparisons of the whole system.

It’s also not like steam driven systems don’t have their own maintenance challenges. You’re not strapping on extra motors for the catapults as extra weight so much as swapping them out for all the heavy mechanical machinery and pipes that are needed to make such catapults work. Electrical systems maintenance and repair can of course be a nightmare if you end up not building those considerations into your design, but the same is true for mechanical systems, and arguably it’s much easier to design service friendly electrical systems than mechanical systems.

I think using the Ford class as the benchmark for what to expect with EMALS reliability is frankly a bit of a flawed argument. Nothing says that the Ford class is the standard bearer for what to expect with an EMALS system that’s designed and built well. We’ve seen plenty of examples where US weapons programs have led to headaches not because they’re essential properties of the technology but because of program mismanagement.

Again, this is nothing emotional argument, but simple cold head engineering assessment.

Given two system, with known whole cost, mass, volume and maturity , decision is which one is the best to install.

I saw many example for emotion/interest/carrier based procurement when a mid level manager sold same new thingy from catalogue as "revolutionary" to help his/her carrier , and it failed by the same way as observed in the case of Ford.

Let see:
1. EMALS needs lot of electricity, with redundancy
2. It needs big and heavy generators, way more than the power requirements of the ship
3. They start to switch everything to electrical
4. They have a ship with overall inferior performance compared to the baseline requirements, due to underestimated maturing times, lack of onshore test and so on.

Wasn't the whole issue with Ford that the catapults were too interconnected and had shared systems instead of individual ones?

That part of the issue, if the interconnection deducted it still has four times higher failure rate than the matured steam design.

 

[Intrepid]

Even a steam powered ship will have electricity. But future ships will not have steam. So it is better to chose EMALS as standard.

 

[nlalyst]

Bringing up the generators is a bit of an odd point...given that it’s not like carriers don’t need massive generators to power all their other subsystems even if they don’t have EMALS. While EMALS does probably require larger generators, it doesn’t need a host of steam generation and fluidic systems to power steam catapults. If we’re going to talk about tradeoffs between the systems it makes no sense to nitpick individual items when what matters is the sum cost-benefit comparisons of the whole system.

It's not nitpicking. The power requirements of EMALS are substantial and easily exceed the 64MW of power generation available on the Nimitz class ships. Depending on the source, the Ford class is said to have 2.5x or 3x the electrical power generation of the Nimitz: 160MW-192MW. Therefore, it is only fair to include the weight of additional turbine generators.

Even a steam powered ship will have electricity. But future ships will not have steam. So it is better to chose EMALS as standard.

Steam is a given on a nuclear powered ship and I think most of us agree that will be the propulsion type of choice for future PLAN carriers.

 

[latenlazy]

It's not nitpicking. The power requirements of EMALS are substantial and easily exceed the 64MW of power generation available on the Nimitz class ships. Depending on the source, the Ford class is said to have 2.5x or 3x the electrical power generation of the Nimitz: 160MW-192MW. Therefore, it is only fair to include the weight of additional turbine generators.

Steam is a given on a nuclear powered ship and I think most of us agree that will be the propulsion type of choice for future PLAN carriers.

You’re missing my actual main point, which is about not nitpicking components of a system to determine net tradeoffs.

Again, this is nothing emotional argument, but simple cold head engineering assessment.

Given two system, with known whole cost, mass, volume and maturity , decision is which one is the best to install.

I saw many example for emotion/interest/carrier based procurement when a mid level manager sold same new thingy from catalogue as "revolutionary" to help his/her carrier , and it failed by the same way as observed in the case of Ford.

Let see:
1. EMALS needs lot of electricity, with redundancy
2. It needs big and heavy generators, way more than the power requirements of the ship
3. They start to switch everything to electrical
4. They have a ship with overall inferior performance compared to the baseline requirements, due to underestimated maturing times, lack of onshore test and so on.


That part of the issue, if the interconnection deducted it still has four times higher failure rate than the matured steam design.

You seem to be operating under the assumption that steam designs don’t have points of failures or their own shortcomings.

It’s true that the engineering tradeoff equation is not an emotional determination, but you seem to be *assuming* what the determinant items are, as if the designers and procurers of these systems aren’t doing those assessments themselves.

 

[Intrepid]

Steam is a given on a nuclear powered ship and I think most of us agree that will be the propulsion type of choice for future PLAN carriers.

But not on smaler units with helicopters and drones, that need EMAILs, too.

I think, there is a civil option of use for EMAILs, so the developing costs will be paid back more than once, to bring eVTOLs with less intern use of electric power into the air.

 

[Anlsvrthng]

It’s true that the engineering tradeoff equation is not an emotional determination, but you seem to be *assuming* what the determinant items are, as if the designers and procurers of these systems aren’t doing those assessments themselves.

I am not assuming this, several high ranking USA representative , reports and the observation of the cost overruns showing that the "the designers and procurers of these systems aren’t doing those assessments themselves".

So it is more of a fact : )