CV-18 Fujian/003 CATOBAR carrier thread

Blitzo

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Actually, depending on


actually, look up hydrodynamic hull speed.

Depending on whether the ship’s previous top speed was its hydrodynamic hull speed, it is paradoxically very possible for that same ship to become capable of slighter higher top speed with same engine power if you keep the same, beam, draft, and accept a slight increase in displacement to add a few percent to its length.

It is a trade off between increasing frictional drag of a longer resulting from greater wetted area, and the effect of a longer hull increasing the speed at which the wave drag increases exponentially.

I am aware of that particular relationship.

Yet the fact that they chose not to pursue a slightly longer ship (assuming that they could maintain an equal or greater speed while retaining the same propulsion), suggests to me that there must be a significant reason for it.

Of the various possibilities, like cost, design limitations, and limitations of technology, the most likely is probably technology, and of technology, I think the most likely domain is overwhelmingly propulsion.

I have a few questions about them, is there any relationship between deck space and displacement?
The deck space of 003 is close to the Ford, so is their displacement also close?
View attachment 74219

There isn't a universally applicable relationship between flight deck area and displacement.

Close is relative. Is within 10,000-15,000 tons close?
One only needs to see the difference in displacement between Kitty Hawk class and Nimitz/Ford despite relative closeness in key dimensions.
An additional 10m of length, with different propulsion, can certainly add up, especially if the waterline beam is also wider by even only 0.5m.
 

Blitzo

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To illustrate the way in which an additional 10-15m in the flight deck bow could enable a fourth catapult on the waist, see this very spur of the moment, casual modification of that previous line comparison:

The lengthening of the bow lets you put the bow catapults and JBDs correspondingly more forward, it allows you to then angle them slightly more to the starboard side -- meaning not only is your port bow JBD no longer infringing on the angled runway, but it also gives you more clearance from the angled runway to emplace a second waist catapult (in green) that is starboard relative to the existing waist catapult.


Of course, this is very quick and dirty and not meant to be exhaustive, more for demonstrative purposes.

Untitled.jpg
 

gelgoog

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No Chinese surface combatants use gas turbines of the type and scale that would be needed for a carrier of this size.
There will be no commonality available.
More importantly, CV-16/17 already use steam turbines. Future CVNs will also use steam turbines as part of their propulsion package.
It makes no sense for 003 (even assuming multiple such ships are built), as another aircraft carrier, to adopt a wholly different type of propulsion that has no commonality with either CV-16/17, or future CVNs.
The use of gas turbines in the QEs makes sense for the RN. They do not plan on building anymore carriers for many decades, beyond their two QE class they have. Whatever type of propulsion they choose for them do not have to consider commonalities of technology base and logistics with the rest of their carrier fleet because they will not have any other carriers to begin with.
The PLAN do not have that luxury

I will add that originally the plan was to use steam catapults instead of EMALS. The steam boilers made a lot more sense with that consideration. Also, the QE class uses 36MW gas turbines. The Chinese Navy gas turbines used in the destroyers have 28MW power. Then you also have to consider the Type 003 is larger than the QE class. It makes a lot more sense just to continue using the boilers and then switch to nuclear I think.
 

Richard Santos

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I will add that originally the plan was to use steam catapults instead of EMALS. The steam boilers made a lot more sense with that consideration. Also, the QE class uses 36MW gas turbines. The Chinese Navy gas turbines used in the destroyers have 28MW power. Then you also have to consider the Type 003 is larger than the QE class. It makes a lot more sense just to continue using the boilers and then switch to nuclear I think.
That said, not all else is equal in real life operations.

I wouldn't be surprised -- in fact tbh I expect it -- if the eventual CVN has four catapults rather than three.


As for "why" 003 has three catapults rather than four -- imo, aside from the topic of power generation and storing etc, there is also the matter of deck space.

If we look at the way in which the catapults and launch positions/JBDs on US carriers (e.g.: Ford, Nimitz etc) are arranged, the two waist catapults have their "end positions" well to the port side and a little bit aft of the bow/port launch position to provide sufficient clearance.
As far as 003 is concerned, adding in another waist catapult (likely it would have to be a "starboard" waist catapult, given the configuration of the current waist catapult) would provide insufficient clearance from the bow/port catapult.

Part of this is just because of the bow flight deck configuration and geometry.
However, the easiest solution to this, would be if the bow flight deck was another 10-15m longer, which would allow the bow catapults/launch positions/JBDs to correspondingly move "forwards" by another 10-15m relative to the waist catapults launch positions (which would remain fixed), as well as allowing the bow JBDs to be forward relative to the bow aircraft elevator which in turn enables both of the bow catapults/launch positions/JBDs to correspondingly be "tilted" slightly to the starboard side (which cannot be done at this stage because to the starboard of the starboard/bow JBD is the bow aircraft elevator. All that in turn will enable the addition of an additional starboard waist catapult with sufficient clearance.

This comparison of 003's general configuration and that of Ford is pretty illustrative, and the aforementioned changes I described for 003 (lengthening the bow flight deck by 10-15m, repositioning of the bow catapults/JBDs to the starboard a bit in front of the bow aircraft elevator, and subsequent addition of a starboard waist catapult) would basically result it looking like the flight deck and catapult configuration of Ford/Nimitz.

View attachment 74218

I don’t think 003 we’re given only three catapults because the Chinese couldn’t find any space for the fourth. Very likely the rate at which launchers can be conducted I was determined to have maxed out at Three catapults because of the Choreograph movements of different aircraft elevator and hanger, these movements would have been carefully games out when the carrier was designed.

And also possibly The limit in the electric generating plant capacity causes the maximum launch rate to be attained with 3 catapults.
 

Kejora

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I found this article by Minnie Chan from 2017
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This old illustration still refers the new carrier as Type 002. Although they got the 003's island design and Shandong's length wrong they got 003's measurement right.
8decdd62-bed9-11e7-b942-6d23cbdef96a_image_hires_194219.jpg
 

lgnxz

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I used 82m for the drydock width.
Lol ok how do you get that number in the first place? This is also contradicting your own statement since you make your own guesstimation then rather than others' line is not completely parallel or whatever. And no, the drydock width is actually known and it isn't 82m. Should've realize that way earlier that your measurement is really off with how low the length of the ship is.
The image could likely suffer from shear and horizontal and vertical pixels may not have equal dimensions.
Or that your estimation is just wrong. Different people measuring different picture that I post earlier has managed to get an estimation that are really close to each other.
 

nlalyst

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Lol ok how do you get that number in the first place? This is also contradicting your own statement since you make your own guesstimation then rather than others' line is not completely parallel or whatever. And no, the drydock width is actually known and it isn't 82m. Should've realize that way earlier that your measurement is really off with how low the length of the ship is.
I got it from @Totoro 's original photo, by placing a line at a slightly different angle and at slightly different endpoints. The contrast, especially on the starboard size is very low and just a 3px difference in placement will net the difference between mine and his measurement. In my opinion, the red line he drew to measure the drydock width does not look right. It is too short, and his pixel size is larger than it should be.

For the new measurement that I posted, I used the 82m figure @Bltizo provided as the known width, based on contractor data. According to you, what should be the width?

Finally, the pixels need not have the same dimensions in the vertical and horizontal dimension. If you look again at @Totoro analysis you will see that his pixel sizes are all over the place depending on which object he used as a yardstick and the direction. Also, his dry dock length differs from Horobeyo's (353.85m vs 355m), which tells me that at least one of those is an estimate.
Or that your estimation is just wrong. Different people measuring different picture that I post earlier has managed to get an estimation that are really close to each other.
Could be. If you do the measurement yourself, you will notice that each time you get a slightly different result. If one is to be pedantic, he should repeat the measurement 10 times and report a statistic.
 
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