US Navy Ultracarriers?

[Triton]

Donald M. Fort, a Defense Constultant for Analytic Services, Inc. and formerly the Rand Corporation, the Center for Naval Analyses, and the US Air Force, wrote an article titled "Ultracarrier" in Proceedings of the US Naval Institute that appeared in its December 1978 issue. In this article, Fort proposed an even larger aircraft carrier than the Enterprise and Nimitz-classes, with a length of 1,310 feet and a displacement of 500,000 tons full load at a cost of $828 million in 1976 dollars.

Specifications of Fort "Ultracarrier"

Dimensions (feet)

• Length (total): 1,310
  Length (waterline): 1,250
  Beam (waterline): 280
  Draft (maximum): 75
  Flight deck width: 400

Displacement (long tons)

• Light ship: 400,000
  Full load: 500,000

Propulsion

• Nuclear (shp) 280,000
  Conventional (shp) 120,000
  No. of shafts: 6

Aviation Features

• No. of aircraft: 100
  No. of aviation elevators: 4
  No. of catapults: 6

Speed (knots)

• Maximum 26
  Cruise (nuclear) 23

Has the Department of the Navy or Department of Defense ever considered carriers larger than Enterprise or Nimitz class and was Fort's proposal ever given consideration?

Or prior to the ordering of CVN-71, USS Theodore Roosevelt, during the Reagan Administration, were previous carrier proposals only based on Elmo Zumwalt's "High-Low" philosophy: VTOL Support Ship (VSS), Sea Control Ship (SCS), or CVV (Aircraft Carrier, Medium Sized)?

Fort, Donald "Ultracarrier" Proceedings of the US Naval Institute (December 1978):

http://i21.photobucket.com/albums/b291/barquitos/P-Files/Ultracarrier1.jpg
http://i21.photobucket.com/albums/b291/barquitos/P-Files/Ultracarrier2.jpg
http://i21.photobucket.com/albums/b291/barquitos/P-Files/Ultracarrier3.jpg
http://i21.photobucket.com/albums/b291/barquitos/P-Files/Ultracarrier4.jpg
http://i21.photobucket.com/albums/b291/barquitos/P-Files/Ultracarrier5.jpg

 

[dragon72]

Only 100 aircraft. Doesn't seem worth it.

 

[starviking]

From a brief browse of the files it seems a third of the weight of the Ultracarrier is 'passive protection'. Armoured Supercarrier!

 

[XP67_Moonbat]

YGBSM! Getting around a 1096' Nimitz was aleady fun enough for me. What's another 300 feet?

 

[Skybolt]

If I remember well, Freedman in his US Carriers, A design History talks about a 100.000 ton monster as one of the alternates to Nimitz. This evening I'll try and find the exact citation.

 

[sferrin]

If I remember well, Freedman in his US Carriers, A design History talks about a 100.000 ton monster as one of the alternates to Nimitz. This evening I'll try and find the exact citation.

The Nimitz is a 100,000 ton monster. (The latter ships are around 102,000 tons full load.)

 

[XP67_Moonbat]

Hey, I lived on one for 5 years. Tell me about it!

 

[Triton]

Fort's "ultracarrier" design has six catapults compared to the four on Enterprise and the Nimitz class. Would two additional catapults be advantageous enough to justify a larger class of ship?

I also noticed that the aircraft elevators are in the center in this design. Does the placement of the elevators in the center of the ship provide advantages or disadvantages? The Enterprise and Nimitz class have elevators located on the outer edges of the ship.

Although it can carry only 6 additional aircraft compared to the Nimitz-class, the "ultracarrier" has a much larger flight deck. Does that offer any advantages?
With its dimensions, could the "ultracarrier" operate aircraft that are too large to currently operate on the Enterprise or Nimitz class?

I understand that the design is too large to operate in some waters and ports/bases would have to be modified to accomodate them.

 

[Charles Gray]

The Ultracarrier design was based on hte idea of being "hard to hurt". Much of it's extra weight was designed aroudn the idea of passive protection-- the central elevators are an example of that. You could probably support far more aircraft on it, but 1. the navy wouldn't be able to put aircraft on all the carriers and 2. such a large ship is still sinkable by a nuke and so you wouldn't want to put everything on it. (Note that this was written back when the nuke-attack on a CVBG was a real possibility in the context of the cold war.)

 

[madmike]

is the same old story: ships so large had just a simple problem: no dock to be built, no docks to be mantained.

And no possibility to passing choke points like the sumatra strait, hormuz strait, and so on.

They are only good exercises.

 

[Skybolt]

Found. In 1963 the Navy was once against stymied in her request for a new nuclear carrier (what would had been the CVAN-67). So they studied a new type of CONVENTIONAL carrier able to offer the same operational flexibility of the Enterprise with a fossil fuel powerplant. The study ended up with three concepts, progressively larhger. The CVAL (L for Large) was Enterprise-size, was 1040 feet long, displacement (light) 64052 tons, 88150 tons fully loaded, steaming duration same as CVA-67 but with 6433 tons of JP-5 and 3150 tons of ordnance (CVA-67 numbers were 5835 and 2140 tons respectively). The next in line, CVAXL, was the largest possible ship that could be built and maintained in existing facilities (graving docks etc). It was 1080 feet long, 66650 tons light and 97360 tons fully loaded. It had double the JP-5 reserves of the CVA-67, i.e. 11221 tons, and 3150 tons of ordnance (same as tte projected CVAN-67). BTW, CVAN-67 had less JP-5 fuel than the CAXL, "only" 8071 tons. The monster I remembered was the last of this line, the CVAXXL. It was behind US graving dock capacity and derived form the combination of JP-5 and ordnance reserves of the CVAXL with a ship endurance matching the aviation operational endurance (data are classified, but I suppose circa 20000 miles). Result: 1300 feet long, displacement 82917 tons light and 110719 tons fully loaded. Aviation complement unknown, but circa 100 with a TFX ad VAX based flight group (in 1963 the projected 1970-1975 flight group was based on 12 TFXs and 51 VAXes plus some A-6s and a score of special types).

 

[Triton]

is the same old story: ships so large had just a simple problem: no dock to be built, no docks to be mantained.

And no possibility to passing choke points like the sumatra strait, hormuz strait, and so on.

They are only good exercises.

Thanks for the information madmike. If it was too large to navigate the Strait of Hormuz, then a ship of this size would have very limited utility. I was thinking that the "ultracarrier" might have been a good design for duty in the Persian Gulf with its six catapults and armor. Since Ultra Large Crude Carriers (ULCC) have been built as large as 1504 feet long as the Seawise Giant, later Knock Nevis, in my ignorance I presumed that ships this large could safely transit the Strait of Hormuz and have no problems operating in the Arabian Sea.

Since carriers aren't escorting Atlantic convoys to supply NATO allies in waters with Soviet subs and it seems that carriers are on consistent duty in the Persian Gulf, I was wondering if one or two carriers of this size would be useful to the US Navy.

Found. In 1963 the Navy was once against stymied in her request for a new nuclear carrier (what would had been the CVAN-67). So they studied a new type of CONVENTIONAL carrier able to offer the same operational flexibility of the Enterprise with a fossil fuel powerplant. The study ended up with three concepts, progressively larhger. The CVAL (L for Large) was Enterprise-size, was 1040 feet long, displacement (light) 64052 tons, 88150 tons fully loaded, steaming duration same as CVA-67 but with 6433 tons of JP-5 and 3150 tons of ordnance (CVA-67 numbers were 5835 and 2140 tons respectively). The next in line, CVAXL, was the largest possible ship that could be built and maintained in existing facilities (graving docks etc). It was 1080 feet long, 66650 tons light and 97360 tons fully loaded. It had double the JP-5 reserves of the CVA-67, i.e. 11221 tons, and 3150 tons of ordnance (same as tte projected CVAN-67). BTW, CVAN-67 had less JP-5 fuel than the CAXL, "only" 8071 tons. The monster I remembered was the last of this line, the CVAXXL. It was behind US graving dock capacity and derived form the combination of JP-5 and ordnance reserves of the CVAXL with a ship endurance matching the aviation operational endurance (data are classified, but I suppose circa 20000 miles). Result: 1300 feet long, displacement 82917 tons light and 110719 tons fully loaded. Aviation complement unknown, but circa 100 with a TFX ad VAX based flight group (in 1963 the projected 1970-1975 flight group was based on 12 TFXs and 51 VAXes plus some A-6s and a score of special types).

Thanks for the information Skybolt. That's very interesting and I wasn't aware that the US Navy had considered fossil fuel-powered carriers of the size of the Enterprise-class or larger.

 

[funkychinaman]

I was going to raise a question similar to the where-to-dock question: where/how would you build it?

 

[Michel Van]

I was going to raise a question similar to the where-to-dock question: where/how would you build it?

that no problem
the the CVAXXL is only 1,300.0 ft or 396,24 Meter long

around 1976 they build Supertanker like "Pierre Guillaumat" with 1,359.0 ft or 414,2 meter
http://en.wikipedia.org/wiki/Batillus_class_supertankers

 

[Triton]

I was going to raise a question similar to the where-to-dock question: where/how would you build it?

that no problem
the the CVAXXL is only 1,300.0 ft or 396,24 Meter long

around 1976 they build Supertanker like "Pierre Guillaumat" with 1,359.0 ft or 414,2 meter
http://en.wikipedia.org/wiki/Batillus_class_supertankers

So I have heard that ships of this size are too big to transit the English Channel, Strait of Malacas, and the Strait of Hormuz reducing their usefulness. Is this true? Are they too big to steam to the world's troublespots?

 

[Michel Van]

So I have heard that ships of this size are too big to transit the English Channel, Strait of Malacas, and the Strait of Hormuz reducing their usefulness. Is this true? Are they too big to steam to the world's troublespots?

the CVAXXL draught is 22,86 meter

the English Channel has 147.6 ft or 45 meter deep water
so the CVAXXL or Supertanker can ship into Rotterdam harbor

the Strait of Hormuz is main route for Supertanker
every day, 15 tankers pass through that strait !
so also a CVAXXL

Strait of Malacca's is to undeep (82 ft or 25 Meter) for Supertanker and CVAXXL
(there only safety range of 7 ft or 2,14 meter !)

the Panama and Suez channel are to small for today big Aircraftcarrier like USS Enterprise.

 

[TomS]

the Panama and Suez channel are to small for today big Aircraftcarrier like USS Enterprise.

US carriers routinely pass through the Suez canal.

 

[lantinian]

The requirement for a ship to pass trough the Panama Canal has been a limiting factor in all US Navy ship designs, including the so called Tillman Maximum Battleships from 1916. The US owned the Panama Canal till the 1980's

If that requirements still stands, it will be a pity though, since the Navy will not be able to use a trimaran hull for a carrier, which will be pretty good choice for this particular design. Strike that. As they are working on widening the Panama Canal now, they as well might start the design work again.

Once thing about this 1976 design is the ability no just to having 50% more catapults but also two landing strips. As the landing strips vectors cross behind the carriers the all aircraft landing on this thing will come by the same vector but split up to land on whichever flight runway is ready.

Also, I believe this design can also launch 5 aircraft and land 1 at the same time or land 2 and launch 4 at the same time, effectively accomplishing the job of 2 super-carriers which can only launch 2 and land 1 aircraft at the same time.

 

[funkychinaman]

That requirement must be long gone, because the last US carriers built that could make it through the Panama Canal were the Essex class.

 

[lantinian]

Well, it must be damm inconvenient then to go from the Pacific to the Atlantic taking the long way around. A faster, trimaran hull will definitely be an advantage then.

 

[TomS]

It's not a frequent problem for ships to move form Atlantic to Pacific -- when they do, they usualyl do it in the course of a deplyment to the Middle East.

There's no particular reason that a large trimaran would be any faster than a conventional hip; the peculiar advnatages of trimarans for high-speed tend to show up most in smaller designs. And the structural issues of very large multi-hulls are not well understood. Ther'es certainoy a lot of stress loading on whatever members connect the hulls together.

A single ultra-large carrier that can launch as many aircraft as two supercarriers isn't necessarily a huge operational improvement over the two separate carriers. For starters, it can only be in one place, so it can't cover two separate deployments, whether in different places or at different times.

 

[lantinian]

For starters, it can only be in one place, so it can't cover two separate deployments, whether in different places or at different times.

If that argument were true, the US would stick the the WWII type of carrier structure with 100+carriers of all sizes. Obviously there is benefit from a bigger ship.
It seams from the recent budget announcement the US might go to 10 carrier groups from 11. If that trend continues, I suspect the next carrier designed from ground up will indeed be bigger.

There's no particular reason that a large trimaran would be any faster than a conventional hip;

I think there is. It's similar to the area effect tule in supersonic flight. In general all multihull vessels are much faster than similarly powered single hull ones. I may not know the exact reasons to list here but that is a fact. Also stability in particular is significantly improved, something that can be a lifesaving benefit on a carrier design.

This particular arrangement with the 4 lifts in the middle is particularly good for lowering the carrier signature and increasing survivability. Todays carriers are somewhat exposed with those huge wholes in the sides.

 

[Triton]

For starters, it can only be in one place, so it can't cover two separate deployments, whether in different places or at different times.

If that argument were true, the US would stick the the WWII type of carrier structure with 100+carriers of all sizes. Obviously there is benefit from a bigger ship.
It seams from the recent budget announcement the US might go to 10 carrier groups from 11. If that trend continues, I suspect the next carrier designed from ground up will indeed be bigger.

There's no particular reason that a large trimaran would be any faster than a conventional hip;

I think there is. It's similar to the area effect tule in supersonic flight. In general all multihull vessels are much faster than similarly powered single hull ones. I may not know the exact reasons to list here but that is a fact. Also stability in particular is significantly improved, something that can be a lifesaving benefit on a carrier design.

This particular arrangement with the 4 lifts in the middle is particularly good for lowering the carrier signature and increasing survivability. Todays carriers are somewhat exposed with those huge wholes in the sides.

I guess the answer to this question depends on if the United States Navy will invest in manned or unmanned aircraft. One of the curators at the Smithsonian National Air & Space Museum believes that the F-35 will be the last manned aircraft program. I wonder if the Navy of the future will consist mostly of UCAV-carrying aviation cruisers very similar to the BAe Systems UXV combatant.

 

[TomS]

For starters, it can only be in one place, so it can't cover two separate deployments, whether in different places or at different times.

If that argument were true, the US would stick the the WWII type of carrier structure with 100+carriers of all sizes. Obviously there is benefit from a bigger ship.
It seams from the recent budget announcement the US might go to 10 carrier groups from 11. If that trend continues, I suspect the next carrier designed from ground up will indeed be bigger.

I think it is very unlikely. The current carriers are at the limits of the existing infrastructure (drydocks, piers, etc) and are if anything overlarge for the actual embarked air wing, which is not likely to rise in the near future.

There's a sweet spot in carrier designs, and the current US ones seem very close to it. If one looks at attempts at smaller carriers using modern aircraft, the show decreasing returns on investment, especially below 60,000 tons. But as you go over 100,000 tons, you run into the limits of airwing affordability and available port facilities.

There's no particular reason that a large trimaran would be any faster than a conventional hip;

I think there is. It's similar to the area effect tule in supersonic flight. In general all multihull vessels are much faster than similarly powered single hull ones. I may not know the exact reasons to list here but that is a fact. Also stability in particular is significantly improved, something that can be a lifesaving benefit on a carrier design.[/quote]

It's just that the advantage of the multi-hull approach declines in larger ships. Escorts are often near their theoretical hull speeds, so the reduced resistance of a trimaran hull makes a dramatic difference in actual speed achieved for a given installed power. Large ships like carriers are already well below their theoretical hull speeds, so the drag reduction from switching to a trimaran hull doesn't produce a dramatic increase in speed.

You have to be careful with stability. If the magnitude of ship motion is reduced, that's usually good. But if ship motions become faster, then things can actually get worse. A long gentle roll is actually preferable to a short fast one for carrier landings. Multihull configurations are also susceptible to weird corkscrew motions as waves act on the separate hulls in succession instead of all at once. The high speed catamarans, for example, have reputations for very unpleasant ship motions (Swift isn't nicknamed "the vomit comet" for nothing...)

Tris suffer badly on another aspect of seaworthiness -- damaged stability. If the sidehulls have significant displacement, the consequences of asymmetric flooding can be quite pronounced.

 

[tinlail]

Another rational I have heard for carrier fleet sizing is take the number of trouble spots you want to be able to patrol at a time, and multiple for 3 (1 sailing, 1 training/docked, 1 overhaul). This use to drive the Navy to wanting 12 carriers, apparently we have lost a area to patrol now. Then build carriers as large as you can afford too make them. This theory say that carriers should be as large as possible.

Of course things like new dry docks and piers limit what a navy can afford.

 

[lantinian]

TomS, thanks for the interesting insights

 

[Just call me Ray]

If that argument were true, the US would stick the the WWII type of carrier structure with 100+carriers of all sizes. Obviously there is benefit from a bigger ship.

The primary benefit of a larger ship is just to provide more deck space for launch and recovery, not necessarily to store more jets.

 

[Bruno Anthony]

Food for thought:
http://www.dtic.mil/dtic/tr/fulltext/u2/a328353.pdf

 

[airman]

I know about the "supercarriers" for example : http://en.wikipedia.org/wiki/USS_United_States_%28CVA-58%29