Medium Carriers

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Based on my research, I think an enlarged, 55,000ton CdG could still do ~26kts without any more reactors. This can be shown a couple of ways:

1. Comparing to CdG
Using Springsharp, a simple but fairly accurate ship simulation tool (www.springsharp.com), the reduction in speed between CdG and a 55,000t "big brother" is ~1kt. This surprisingly low number is because the increase in tonnage is partly compensated by the longer, more hyrodynamically efficient hull.

2. Comparing to CVF
CVF can do 26.3kts (25kts sustained) on 95,000shp. CVF is also a sub-obtimal hull design (because of super-blocks) of significantly larger displacement (65,000t-75,000t) . So it's not inconceivable that a smaller, more efficient 55,000t hull could do 26kts on only 83,000shp.

3.Comparing to CVF "Bravo"
The "Bravo" option for CVF, which was about 55,000t, would have done 25kts on 70,000shp, again with a sub-obtimal hull design. Using SpringSharp and, the speed gain from going from 70,000shp to 83,000shp for a 55,000t displacement hull would be at least 1kt.

So in the end, a 55,000t CdG would probably lose no more than 1kt in speed, which would be more than compensated by the longer 90m catapults. Even if one decided to increase the propulsion by 50% by adding a 3rd nuclear reactor, the extra 41,000shp would only increase speed by 3kts, from ~26kts to ~29kts.

Sounds doable to me....................Regardless, I think France will build a second Carrier sometime over the next next or so.:cool:

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19 years

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I think France will build a second Carrier sometime over the next next or so.:cool:

I cross my fingers, but I won't hold my breath about this... :(
________
Vaporizer volcano

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16 years 8 months

Posts: 65

and with a bigger CdG:rolleyes: ?
enjoy this study
http://i78.servimg.com/u/f78/11/68/74/47/france10.jpg
or
today big aircraft carrier flight deck configuration
http://i78.servimg.com/u/f78/11/68/74/47/carrie11.jpg
medium aircraft carrier configuration (study of 1990's-2000)
http://i78.servimg.com/u/f78/11/68/74/47/cvf-ca10.jpg
medium aircraft carrier study (1970's)
http://i78.servimg.com/u/f78/11/68/74/47/cvv10.jpg
Futur CVN 78 flight deck configuration
http://i78.servimg.com/u/f78/11/68/74/47/cvn-7811.jpg
all modern aircraft carrier of the world:D:D:D:D:D
http://i78.servimg.com/u/f78/11/68/74/47/carrie12.jpg
:D:D:D

In re-reading the thread something jumped out at me regarding this post....

The CVX study was broken up by the USN into three categories of vessels; small (air wing min 40 a/c), medium (air wing min 60 a/c) and large (air wing min 80 a/c). The only qualifiers being that in any size, they had to be able to operate anything in the aviation inventory off the CV's flight deck well into the projected service life of the vessels. The "small" CVX in the CTOL configuration coming out in tonnage in and around the final tonnage of the Midway in the neighborhood of 60,000 with 2 cats, the "medium" about the tonnage of the America at about 80,000 and the "large" going 90,000+.

It's interesting to see how the typing of "medium", and for that matter "light", gets moved about.

ETA....
The "small" CVX
Images posted for fair use...
http://www.fas.org/man/dod-101/sys/ship/docs/cvx-alt/sc4.html

http://www.fas.org/man/dod-101/sys/ship/docs/cvx-alt/5x4iso.jpg

http://www.fas.org/man/dod-101/sys/ship/docs/cvx-alt/5x4top.gif

http://www.fas.org/man/dod-101/sys/ship/docs/cvx-alt/5x4stbd.gif

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From the American point of view, the Nimitz class are no longer 'Super' carriers but 'standard' sized carriers, so that is their baseline intellectually. Also in the CTOL/CATOBAR context, there are minimum requirements in terms of deck size to operate the current generation of aircraft, so these define their view of a 'light' carrier. To be fair anyone planning on entering the carrier club should beware of defining what can be afforded simply by physical size, as steel is still relatively cheap and constiturtes a very small percentage of the overall cost of any modern warship. For example increasing the size of a ship on the drawing board by 10% to 20% may well only increase cost by 1%, as most of the cost of the ship is tied up in expensive radar and weapon systems (eg Aegis, PAAMS etc). HMS Ocean was reported to have cost little more than a type 23 Frigate, mainly because she had only basic self defence weapons and sensors.

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From the American point of view, the Nimitz class are no longer 'Super' carriers but 'standard' sized carriers, so that is their baseline intellectually. Also in the CTOL/CATOBAR context, there are minimum requirements in terms of deck size to operate the current generation of aircraft, so these define their view of a 'light' carrier. To be fair anyone planning on entering the carrier club should beware of defining what can be afforded simply by physical size, as steel is still relatively cheap and constiturtes a very small percentage of the overall cost of any modern warship. For example increasing the size of a ship on the drawing board by 10% to 20% may well only increase cost by 1%, as most of the cost of the ship is tied up in expensive radar and weapon systems (eg Aegis, PAAMS etc). HMS Ocean was reported to have cost little more than a type 23 Frigate, mainly because she had only basic self defence weapons and sensors.

And she only has direct diesel propulsion (no expensive gas turbines or electric motors) and she was largely built to mercantile standards. Furthermore that figure is very misleading as there were huge variations in the costs for the individual Type 23s. HMS Norfolk (first of class) came out at £135.5 million whereas later units drifted between £60 million and £96 million. At least part of the savings came from halving the man hours required by each unit during the production run. By comparison Ocean came out at about £154 million.

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And she only has direct diesel propulsion (no expensive gas turbines or electric motors) and she was largely built to mercantile standards. Furthermore that figure is very misleading as there were huge variations in the costs for the individual Type 23s. HMS Norfolk (first of class) came out at £135.5 million whereas later units drifted between £60 million and £96 million. At least part of the savings came from halving the man hours required by each unit during the production run. By comparison Ocean came out at about £154 million.

Agreed. But the point I was trying to make was that a 20,000 tonne warship was produced for not a great deal more than a 3,000 to 4,000 tonne warship, because the ship's steel is one of the least expensive aspects of the design. This is also a factor in all the current generation of RN warships (eg Type 45, Albion class LPDs, Bay clalss LSDs and CVF) are so much larger than the ships they are/will replace. The extra volume solves many problems such as habitability and installation of equipment at very litle extra cost, and in the case of improved accomodation will go some way to helping recruitment and retention of service personnel.

So when designing a new warship, and ecomomies are required, making the ship smaller is one of the least effective ways of saving money, and in the long run can make the ship near impossible to upgrade and retain in service (eg type 21) thus forcing replacement at an earlier date.

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Agreed. But the point I was trying to make was that a 20,000 tonne warship was produced for not a great deal more than a 3,000 to 4,000 tonne warship, because the ship's steel is one of the least expensive aspects of the design. This is also a factor in all the current generation of RN warships (eg Type 45, Albion class LPDs, Bay clalss LSDs and CVF) are so much larger than the ships they are/will replace. The extra volume solves many problems such as habitability and installation of equipment at very litle extra cost, and in the case of improved accomodation will go some way to helping recruitment and retention of service personnel.

So when designing a new warship, and ecomomies are required, making the ship smaller is one of the least effective ways of saving money, and in the long run can make the ship near impossible to upgrade and retain in service (eg type 21) thus forcing replacement at an earlier date.

Indeed, but it is imperative to remember that RN surface combattants are very high end, the T45 is most complex/sophisticated ship in service today and the one effort to better her on that front has essentially failed (DDG1000) and the same applied to the T23 series in its day. Gas turbines and electric propulsion do not come cheap.;)

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and is only about 16,000t short of a Nimitz.

Don't read anything more sinister into this than amusement. What other conversation could we have where the words 'only' and '16,000 tons' in the same sentence and no one bats an eyelid?!

Al

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Don't read anything more sinister into this than amusement. What other conversation could we have where the words 'only' and '16,000 tons' in the same sentence and no one bats an eyelid?!

Al

Nothing more than a demonstration of the scale of the vessels being discussed, I quite agree however.;)

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Gas turbines and electric propulsion do not come cheap.;)

No, but they need not be frighteningly expensive (see Juan Carlos I propulsion - she is not a very expensive ship) & they can pay for themselves in reduced running costs.

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No, but they need not be frighteningly expensive (see Juan Carlos I propulsion - she is not a very expensive ship) & they can pay for themselves in reduced running costs.

Very true, but the RN format has so far required development money as well.;)

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As far as I can tell, Large commercial diesel engines as fitted to Ocean have similar up front buying costs to Gas Turbines the reals savings come in running and maintenance costs, requiring far fewer engine room personnel to look after them. Hence Super Tankers and other large merchant ships needing only a handful of engineers. Compare Ocean's complement with an Invincible (upon whose hull Ocean's design was based) and the difference is significant. Efforts to keep Oceans costs down at the design and build stage are generally agreed to have gone a little too far, and many of these problems have been remedied now, but the choice of engines was a sound one IMHO.

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As far as I can tell, Large commercial diesel engines as fitted to Ocean have similar up front buying costs to Gas Turbines the reals savings come in running and maintenance costs, requiring far fewer engine room personnel to look after them. Hence Super Tankers and other large merchant ships needing only a handful of engineers. Compare Ocean's complement with an Invincible (upon whose hull Ocean's design was based) and the difference is significant. Efforts to keep Oceans costs down at the design and build stage are generally agreed to have gone a little too far, and many of these problems have been remedied now, but the choice of engines was a sound one IMHO.

I'm sure that I read somewhere that her Crossley Pielstick 16PC2.6 don't lend her the best of peformance.

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I'm sure that I read somewhere that her Crossley Pielstick 16PC2.6 don't lend her the best of peformance.

I was referring to the choice of commercial diesels over Gas Turbines, for the reasons outlined above. If they picked the wrong specific engines for the job, that's another matter. She seems to get from A to B without much fuss though.

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I was referring to the choice of commercial diesels over Gas Turbines, for the reasons outlined above. If they picked the wrong specific engines for the job, that's another matter. She seems to get from A to B without much fuss though.

Totally agree commercial Diesels were the right choice and the chosen ones do get her from point A to B without too much fuss ... just not very quickly.

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Totally agree commercial Diesels were the right choice and the chosen ones do get her from point A to B without too much fuss ... just not very quickly.

Basically chosen for cost, HMS Ocean is the definition of a budget warship. Which really is not an issue as she gets done what is asked of her and is unlikely to be placed in a situation where she needs anything more.

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I'm launching a thread to discuss medium carriers. We tend to focus a lot on individual designs or light STOVL carriers, but there have been quite a few medium carriers post-WWII that are worth comparing. All are pretty sexy designs.

My definition of a medium carrier is one that can operate supersonic conventional jet fighters, with an airwing of 25-50 aircraft (i.e. Colussus & Majestic class don't count). The range of medium carriers goes from HMS Victorious and FS Clemenceau at the small end of the scale to USS Midway and CVF/PA2 at the high end of the scale. Here's a graphical comparison, with some key statistics:

http://i233.photobucket.com/albums/ee106/OPEX-Afghanistan/Carriercomparison.jpg

A superb graphic, thanks v.much for posting this. But I'd include CVF & Midway at the bottom of the Supercarrier group.

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I'm resurrecting this thread to talk about medium carrier air wings, and compare these to USN air wings.

USN CVNs
During Operation Iraqi Freedom (2003), a fairly typical USN airgroup was 12x F-14, 12x F-18E, 24x F-18C, 8x S-3B, 4x E-2C, 4x EA-3B, 2x C-2, 6x helos (on Nimitz). This airgroup was able to sustain ~125 sorties per day for 3 weeks (2 sorties per aircraft per day), so wasn't overcrowded.

Total parking area:15,400m2 (9,400m2 deck parking, 6,000m2 hangar, so a 60-40 split).
Total spotting area for airgroup (wings folded): 11,000m2
--> That gives us a benchmark space utilization rate of 72%

Charles de Gaulle
The maximum airgroup is said to be 32x Rafale, 2x E-2C, 4x helos, though 24x Rafales has also been quoted.

Total parking area: 8,300m2 (4,300m2 deck parking, 4,000m2 hangar). That's a 50-50 split, so the hangar is larger than USN practice.
Total spotting area for airgroup (32 Rafales): 5,800m2 --> 70% space utilisation rate. The 24 Rafale airgroup gives a 54% utilization rate.

CVF CTOL
Total parking area: 12,000m2 (7,300m2 deck parking, 4,700m2 hangar). This brings us back to the 60-40 split that is common USN practice.
Assumming a maximum space utilization rate of 70%, this implies a spotting area of 8,300m2.
--> That's enough for 52x F-35C, 3x E-2C and 6 helos! :eek:

Conclusion
CVF could carry about 75% of a USN CVN's airgroup, and CdG can carry about 50% of a USN CVN's airgroup. The interesting thing is that CVF is about 75% of the displacement of a USN CVN, and CdG is about 45%. This implies that the economies of scale for carriers don't apply as much as they did in the past, or that at the very least medium carriers can be designed with enough internal volume to be as efficient pound per pound as a CVN. ;)

(The caveat is that CVF's fuel & munitions storage isn't sized to cope with such a large airgroup, so isn't entirely true).

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From memory CdG would carry 30+ aircraft only when the majority were SE's. The Rafale is a much larger aircraft, so 24 is probably about right.

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From memory CdG would carry 30+ aircraft only when the majority were SE's. The Rafale is a much larger aircraft, so 24 is probably about right.

I've given this a lot of thought, and everything points to 24 Rafales being an absurdly low number. So if there's any truth to this number, IMHO it must reflect peacetime budgetary constraints and not the way CdG could be operated in wartime, or the way another navy such as the USN would operate her.

USN CVN benchmark
USN CVNs had a 72% space utilization rate during OIF, and achieved very high sustained sortie rates despite this (2x per aircraft for 3 weeks, i.e. 125 sorties per day). USN CVNs in the 1980s and 1990s had even higher space utilization rates, but sortie rates may have been lower. CdG's space utilization rate with 30 Rafales and 2 E-2Cs is 66%. With 24 Rafales this number falls to 54%, which would imply that the French navy doesn't know how to use parking space efficiently.

Clemenceau benchmark
Clemenceau could carry 36 fixed wing of Super Etendard size, despite the fact that her parking space was only 6,800m2 (3,500m2 deck parking + 3,300m2 hangar). CdG has 20-25% more parking space (8,400-8,900m2), which would be enough to carry around 45 Super Etendards.

CdG's design objectives
CdG was designed for an air group of 35-40 aircraft, with F/A-18s providing the fixed wing component. If you take that as meaning 36 F/A-18s and 4 helos, that adds up to 5,300m2. Which in turn translates to about 30 Rafales, 2 E-2Cs and 4 helos.

CdG deck parking analysis
CdG can accomodate 14 Rafales in deck parking without interfering with launch or recovery operations (6 on bow, 8 behind the island), and in a fairly efficient layout for aircraft movements. The hangar can accommodate roughly 18 Rafales and E-2Cs. That's a total of 30 Rafales and 2 E-2Cs

French parliament reports
In 2003, they stated CdG's capacity as 32 Rafale.