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Subject: Most Efficient Carrier Size
Roman    3/2/2004 12:57:47 PM
It is often said that the bigger the Aircraft Carrier the more efficient it is, but I suspect that only works up to a point and in any case it may be preferable to have more smaller hulls to be able to deploy them in more places simultaneously. So what is the most efficient size of an Aircraft Carrier? Do you think Aircraft Carriers larger than the Nimitz would see further gains in efficiency?
 
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Librarian    RE:Area of improvement - hull speed   2/11/2005 2:14:23 PM
"Why don't navies simply build ships with greater length to width ratios to take advantage of this?" They do where possible. Look at the length to width ratio of the New Jersey class Battleships. However, it is not always possible. A narrower ship is less able to handle rough seas. Therefore, there is a trade-off made between narrowness for speed and width for stability. In addition, for ships like carriers, one consideration is the need to maximise the size of the flight deck. Given the size of aircraft relative to ships (planes aren't that small compared to a ship), there has to be a lot of width in order make taxiing on the deck easy. While there is often a lot of overhanging flight decks, you still need a carrier to be relatively broad.
 
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blacksmith    RE:Area of improvement - hull speed   2/16/2005 12:39:15 AM
Waterline speed is a function of the surface wave and therefore does not affect submarines. When a ship exceeds its waterline speed, the bow wave is longer than the hull. This forces the ship to have to climb the face of the bow wave. The power increase vs. speed increase above the waterline speed is way out of proportion to simply be caused by wetted area. Long skinny ships can't be very high or they become unstable. CVs have to carry a large flight deck well above the water. This effectively limits how narrow the beam can be. Long skinny ships are also volumetrically inefficient, reducing their utility. High speed catamarans ignore those problems by using two hulls for stability and a large superstructure for rigidity and volume. High speed ferries have hulls with length to beam ratios meeting or exceeding 15 to 1. This ratio lets them largely ignore the waterline length limitations of their smallish size.
 
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reefdiver    RE:Area of improvement - propulsion   2/16/2005 5:45:55 PM
Perhaps the Pursuits Dynamics "underwater jet engine" would be a good idea for propulsion of carriers (and submarines). They require steam to operate, something a nuclear reactor is very good at making... No rotating parts, no props, no bearings, and quiet. They're testing marine outboard prototypes. I have no idea if it could be scaled up to a carrier, but I thought an article I once read insuinated unlimited scalability. Here's a link to an article with technical picture: http://www.newscientist.com/article.ns?id=dn3321
 
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reefdiver    RE: Maybe revive the WWII pykrete carrier idea...   2/16/2005 5:54:22 PM
Recall the WWII British idea of building a carrier out of pykrete - ice mixed with sawdust. This mix results in an ice lasting many times as long as normal ice, and more importantly, a much, much, less brittle ice. Comparisons with bullets fired into a block of normal ice demolished the ice, where pykrete just chipped a bit. The very serious proposal was for a 2000 ft long, 300ft wide carrier, but the war ended too early for its construction. The concept included generators to run cooling systems. Here's one of several URL's I've seen about it: http://www.cabinetmagazine.org/issues/7/floatingisland.php Maybe this is the solution for the Navy's seabasing concept. Don't know if it would be a wise idea to deploy an ice-base to the tropics though...
 
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blacksmith    RE:Area of improvement - underwater jet   2/21/2005 12:15:30 AM
What Pursuit Dynamics is pushing is essentially a viscous pump. It will not be as efficient as a prop. Same dynamics apply. Thrust is produced by change in momentum which is the Mass of the fluid times the change in velocity. If you take a little mass and accelerate it a large amount (delta V is big). If you have a large prop and move a lot of water (large mass) then the acceleration is smaller (delta V is small). However, the energy required is proportional to the square of the velocity (E=mv**2). This is why turbojets are inefficient and turboprops are (relatively). The Pursuit Dynamics thing is a jet. Small diameter says high speed exhaust. Hence, inefficient. The fact that you can doesn't mean that you should.
 
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hybrid    RE: Maybe revive the WWII pykrete carrier idea...   2/21/2005 2:38:13 AM
"Maybe this is the solution for the Navy's seabasing concept. Don't know if it would be a wise idea to deploy an ice-base to the tropics though..." Um...wouldn't this take an unnaturally (read insanely) large volume of wood pulp to build even one large ship of 2000 ft long? I'd bet that you could wipe out entire forests for one iceberg ship.
 
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perfectgeneral    RN see this as a mathematical equation   4/10/2005 10:01:27 AM
http://www.navynews.co.uk/articles/2005/0503/0005033101.asp (RN) 'Navy News': 'Determining the exact nature of the CVFs is like working through a complicated mathematical equation, into which are inserted such variables as mission requirements, type of aircraft, and cost, most of which have to be traded off and counterbalanced. The current calculations have come up with an impressive answer, capable of delivering an air strike of a potency never before available to the Senior Service. Sortie generation – the ability to get groups of Joint Combat Aircraft (JCAs) into the air – is the key driver, and the latest figure set is 108 launches in the first 24 hours, reducing to 72 per day for ten days and 36 for a further 20 days. This requires a flight deck of four acres – the equivalent of two Invincibles plus nine tennis courts – which would result in a carrier of 65,000 tons when fully loaded, stretching 280 metres in length.' The article goes into re-roling Ark Royal to fill in for Ocean. Maybe this will be it's future role after the CVFs are built?
 
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Staflar    how useful   12/21/2010 12:19:18 PM
I wonder if the aircraft carrier is still a useful enough weapon system. to even justify the cost of building and operating them.
In the modern battlefield it's not really the case anymore that you can "hide" something like a carrier.
Also with the firepower of ballistic missile submarines and guided missile cruisers and destroyers being able to hit hundreds of land based targets at a fraction of the cost of sending out carriers I really wonder if you can still justify operating them.
For sure there is of course the intimidation factor.
They are big visible flying the flag symbols of a nations military might, as such they could perform the function of deterrence and basically scare smaller powers into doing what you want without firing a shot.
In achieving dominance at sea really nothing beats attack submarines they are the best and most advanced weapon systems in denying others use of the sea.
I suppose there are some small niches where large conventional carriers would be very useful like amphibious invasions where you want to have close air support and do not have access to any airfields from which to operate fighters or bombers.
But it's a very small niche.I am certainly not entirely sure that the US navy considers carriers it's main naval weapon system in the case of a large conventional conflict.
Rather it's function is like what i described more of a political nature...scare and intimidate the natives of smaller powers and "fly the flag".
 
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Phaid       12/22/2010 12:01:53 PM
In achieving dominance at sea really nothing beats attack submarines they are the best and most advanced weapon systems in denying others use of the sea.
 
That's just it though, attack submarines are denial weapons only.  They can't transport anything, can't provide air cover for other ships that are transporting things, can't do wide-area reconnaissance, can't provide support for troops ashore.  On the other hand, being a true sea power requires being able to do all of those things.
 
Re: the original question, a Nimitz sized carrier is just about right.  Much larger becomes too big to sustain and places too many eggs in one basket, any smaller and the striking power gets reduced to the point that it isn't worthwhile.  This doesn't mean that smaller carriers are useless, but that if you can afford to build and operate three or more Nimitz-sized carriers there is no good reason to operate anything smaller.
 
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Reactive       12/22/2010 1:46:35 PM

I wonder if the aircraft carrier is still a useful enough weapon system. to even justify the cost of building and operating them.

In the modern battlefield it's not really the case anymore that you can "hide" something like a carrier.
 
Not from space you can't, but very few nations have the capabilities necessary to keep eyes on at minute-to-minute intervals. The next generation of US carriers will have a markedly reduced radar signature relative to the Nimitz.
 
Also with the firepower of ballistic missile submarines and guided missile cruisers and destroyers being able to hit hundreds of land based targets at a fraction of the cost of sending out carriers I really wonder if you can still justify operating them.

But all of those targets require some form of prior identification, many of the important comms and sensor assets are mobile and in all honesty you're going to have to have literally tens of thousands of cruise missiles standing by to "defeat" an enemy that way - when carriers are operating in support of a land-based force, who do you call for a timely airstrike? A cruise missile that might take half an hour to arrive on target? Planes can strike multiple targets and also engage other enemy planes to well over double the radius that a surface fleet could do, it's more efficient, you have a system using lift that can loiter, perform recon and engage when necessary over contested territory.
 
 For sure there is of course the intimidation factor.

They are big visible flying the flag symbols of a nations military might, as such they could perform the function of deterrence and basically scare smaller powers into doing what you want without firing a shot.
 
They're far more than symbols.
 
In achieving dominance at sea really nothing beats attack submarines they are the best and most advanced weapon systems in denying others use of the sea.
 
The thing about Carriers, is that you can't view them in isolation, you need an escort fleet to protect them, subs to perform ASW, and logistics ships to maintain them - they are intensive undertakings that only a couple of Navies can honesty afford to operate in sufficient numbers to be a credible threat. I'd rather the RN axed the idea and invested more in Subs and next-gen frigates, take a specialised role within the NATO framework and excell at it -the QE CVF's will have 2/3rds of the tonnage of a Nimitz class but will actually operate (due to budget limitations) 1/3rd or less of the air-wing, up to an upper limit of less than half of a Nimitz. We can't afford to operate as a "mini-me" version of the US anymore, we have to go back to specialist operations, where we can be of real use in the coalitions we are bound to be part of.

I suppose there are some small niches where large conventional carriers would be very useful like amphibious invasions where you want to have close air support and do not have access to any airfields from which to operate fighters or bombers.
 
That's not a small niche, and what about when you are operating in support of friendly troops over Taiwan or in the Korean peninsula? 

But it's a very small niche.I am certainly not entirely sure that the US navy considers carriers it's main naval weapon system in the case of a large conventional conflict.
 
I think you're wrong there, 10 Nimitz carrier groups aren't something you invest in for dick-waving purposes only.

Rather it's function is like what i described more of a political nature...scare and intimidate the natives of smaller powers and "fly the flag".

To a degree all power is about that, but the US can afford to back up that threat with real action, Britain and France like the prestige that carriers bring, and the exclusivity as it were of being part of a small club of carrier-operating nations, the difference being that they invest a huge proportion of their surface and sub fleets to protection of single assets that in any case have a fraction of the capability of a Nimitz-class carrier and are unlikely to ever be deployed against anything other than a third-rate power. Prestige comes at a price, and you have to be able to pay it.
 
R

 
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