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Subject: Alternative Carrier Concepts
VGNTMH    5/21/2007 3:33:02 AM
**** SINGLE DECK CARRIERS **** Given the very wide beam of catamaran and trimaran craft, has anyone thought of developing a through deck aircraft carrier with the flight and hanger decks on the same level? That is a catamaran or trimaran carrier with a greatly enlarged island incorporating the hanger. With frigate like hanger roller doors out onto the flight deck. The island hanger might take up 30 to 50% of the surface area of the main deck. The general effect might be a bit like the General Dynamics version of the LCS, though more extreme with an even larger flight deck and a through deck. Such a design might have several advantages: • Simplicity, from the removal of the need for lifts. • Strength, as the flight/hanger/main deck would not need to include several large holes for the lifts. • Lower centre of gravity as there could be one fewer decks and the fight deck could closer to the waterline. Though of course the principle disadvantage would be low hanger capacity. Other disadvantages might be: • Possibly narrow flight deck. • Larger wind currents from the larger island interfering with landings, even STOVL landings. • Stability problems due to the large island offset to one side. Does anyone think this idea might have any merit? Has anyone prepared any designs or concepts along these lines? Presumably this concept would relate more to smaller STOVL or helicopter carriers but theoretically a larger angled deck CATOBAR carrier might also be possible. Especially as the angled deck might counter weight the enlarged island. Another possible option might be to have the hanger at the forward end of the flight deck, under and in front of the STOVL ski jump, with a hanger door to starboard and the ski jump to port, with the ski jump maybe a third of the way back from the bow. **** WIND OVER DECK **** Also, as many catamaran or trimaran craft have speeds (at least in calm sea states) of 40, 45, or even 50 knots, is their any possibility of the high wind over deck speeds being used to assist the launching and recovery of STOL aircraft or UAVs? Here I was thinking primarily of using turbo prop light STOL transport type aircraft as carrier based AEW, ASW, or COD aircraft, with the later being used to fly supplies in and casualties out from forward operating amphibious task groups. True, the wide hanger island could greatly restrict the possible wing span of these STOL aircraft, and a STOVL ski jump would interfere with run ups into the wind. But wind speeds of 80km/hr upwards would certainly help! The advantage of this arrangement would be that no catapults would be required, but longer endurance fixed wing aircraft might still be able to be operated.
 
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Herald1234       6/21/2007 11:05:53 AM

Herald

The main reason is that it make no sense in a economic point of view.
 
The main reason is that it makes no sense from an engineering poont of view.

A medium conventional carrier cost 2 B€ to buy.
 
Four billion Euros. You always underestimate the costs. Why is that? 

A single fighter cost about 180 m€ minimum in life cost (initial procurement, annual training, minimum service crew cost)
 
You come by those figures where? Naval fighters will cost 30% more than their land based counterparts usually because of the twin engines, stronger airframes and the rather ignored added maintenance burdens brought on by the catapult launch and arrestor cable trap stress loading upon the airframe. Now add to that the higher training costs............................etc.   

Either you try to make a very small carrier to save money with reduced capacity in plane to be less than those 2 B€ but considering that for the same displacement a catamaran cost more, it would be difficult to save more than few hundred million € so the equivalent of few planes, and this for an umproven design with few planes.
 
That made no sense at all. Your lower bondary limit on SIZE is your hardstand space and your clear rolling takeoff run. It hasd nothing to do with sdaving money. it actually costs more to build too small to comfortably move around a usable airgroup.

There is no place for a less than a conventional 35 000 tons carrier.It makes no sense considering fighter cost.
 
At this point it makes no sense to design a CATOBAR less than 45,000 tonnes.
 
STOVAL you can squeeze down to 20,000 tonnes..
Now a very big navy which have already conventional carrier, could find the need of a cheap "escort carrier" in number I mean a carrier which would carry maximum a single fighter squadron (about 8/10 conventional fighters) to be used mainly  as an air defense ship as well as a LPH and would be in the 20 000 tons class.Then a trimaran:or catamaran hull could make sense with a single catapult or a skijump.Indeed the saving would make sense if we consider to get 20/30 small escort carrier.However this requirement do not exist since WW2.Even the danger of tactical nukes did not pushed US navy to egt this sort of ships in cold war so today, it would be quite unlikely.A big ship make more sense for volumetric efficiency and ship cost/plane.
 
What a load of baloney about the effiiiency of catamarans as aircraft platforms. Instability and volumetric inefficiency aside[see above]
 
Take a torpedo or antiship missile in one of the outrigger hulls watch; your ship list uncontrollably and SINK.  I WROTE that the USN knew what it was doing. The LPHs, LHAs, and other amphibious ships were designed ,pmphull for very good reason.
BTW you need always a landing track about 190 m mimimum and requirement of having a ship capable of air operations in sea state 5 at least.

 And you learned this lesson well when I taught it to you in another discussion about carriers five months ago, but you don't have to do that if you use a STOVAL like the Queen Elizabeths.
 
It also explains why the British went for STOVAL originally with the Harrier and whu the Invincibles saw the light of day.
The Harrier history lesson was substantially accuraten; but you forgot two things in your discussion; a, the British designed the Harrier to meet a battlefield CAS requirement. The naval variant grew out of the RN's realization that then Harrier gave them a through deck cruiser option. Since then the Marine Corps and the RN both have doctine adopted STOVL as part of their respective air elements. It gives them UNIQUENESS in that it allows them to operate first class aircraft in a third world setting from an unimproved field or patch of ground. The Rafale can't bomb from a patch of grass. The Harrier and its successor,  the Sparky II, both can.


Herald
 
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french stratege       6/21/2007 5:12:26 PM
Herald
you forgot two things in your discussion; a, the British designed the Harrier to meet a battlefield CAS requirement
Herald I wrote:
Fighters were not needed anymore and only bomber were still needed mainly for CAS.
Quite clear,no?
The Rafale can't bomb from a patch of grass. The Harrier and its successor,  the Sparky II, both can.
That is true, as F18 or F16.
Now Rafale (or F18) can bomb from a small straight part of road if it is 600 long.Or from a field if it is prepared with a bulldozer and steel plates.
A Harrier which has to take off vertically has a very weak bomb load and autonomy.
 
 
 
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Herald1234    Where will most of the fighting be done?   6/21/2007 11:17:57 PM
Where there are good road nets or where you have water buffalo grazing.next to the Sparky II being bomb loaded and fueled?

One more thing. What makes you think that a Sudanese MiG or two doesn't need to be splashed before you send the Khartoum stooges and their local PRC bandit regime puppetmasters a  JDAM  diplomatic protest note?

SEAD is first, DEAD is second, IAS osd third, then you slaughter them on the ground with CAS.

Herald

 
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kurt    variable configuration catamaran carrier design   6/27/2012 7:59:35 AM
I toyed with this idea for some time, what if you take two ships with a rotation joint that can form a catamaran as well as a very long landing deck?
The islands must be limited to one of these ships. The advantage is that a long landing deck enhances the ability to operate heavy aircrafts as well as superior, normally land-based, fighters. A carrier would then be a mobile airfield that works in cooperation with airfields on land and is capable of handling medium sized tanker aircrafts for longer range strikes and aerial munition transports for longer operation endurance. Specific carrier based leadership abilities can be reduced, resulting in lowered costs, because they are redundant with land based or auxilliary transported assets.
The design problem would be to create a suitable joint area above the water level far enough apart, most likely connecting two hangar levels, that can be brought into 2 positions with suitable removeable joints that are strong enough to withstand rough seas and allow enough stability for operation as long and as catamaran carrier.
Problems of rolling can be handled by catamarans via flooding the waterline compartments - creating a SWATH version of themselves.
The big stealth and speed killer are bowwaves, so a DG-hull or another wavebinder similar design will likely catch on.
In construction, a major advantage would be if you can built each half separate. The rotation joint should be able to join and disjoin while entering harbours, docks or channels.
Having two rumps doubles the resilence to modern missiles that has almost no increase for ship size, but for ship hulls far enough apart.
 
 
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HeavyD       6/27/2012 9:00:47 AM
Precision munitions have made it possible for close air support to be provided by a growing number of platforms, including the C-130J.  I'm talking Hellfire, Griffin, laser-guided 70mm Hydras, etc.
 
This means that a 2000 lb smart payload can be more effective with less collateral damage than a 8000 lb dumb payload, and that Harriers, V-22 Osprey, and all manner of rotor wing aircraft can fill this particular mission in an environment where forces enjoy 100% air superiority which is almost always the case.
 
This is why I believe in the Keep it Smaller and Simple philosophy for most carrier resources.
 
That said one major benefit of a Cat/Tri would be the increased deck space for aircraft marshaling and storage to support sustained ops.
 
The new America class LPH sure has one crowded deck, so I believe that a variation of a multi-hull would be for extendible/foldable deckspace:  Imagine a 30' by 200' deck that is hydraulically raised from 90 degrees vertical to horizontal and flush with the deck.  When conducting air ops, aircraft can be parked there and out of the way of the flight line.
 
 
 
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kurt       6/27/2012 1:14:03 PM


Precision munitions have made it possible for close air support to be provided by a growing number of platforms, including the C-130J.  I'm talking Hellfire, Griffin, laser-guided 70mm Hydras, etc.

 

This means that a 2000 lb smart payload can be more effective with less collateral damage than a 8000 lb dumb payload, and that Harriers, V-22 Osprey, and all manner of rotor wing aircraft can fill this particular mission in an environment where forces enjoy 100% air superiority which is almost always the case.

 

This is why I believe in the Keep it Smaller and Simple philosophy for most carrier resources.

 

That said one major benefit of a Cat/Tri would be the increased deck space for aircraft marshaling and storage to support sustained ops.

 

The new America class LPH sure has one crowded deck, so I believe that a variation of a multi-hull would be for extendible/foldable deckspace:  Imagine a 30' by 200' deck that is hydraulically raised from 90 degrees vertical to horizontal and flush with the deck.  When conducting air ops, aircraft can be parked there and out of the way of the flight line.

 
Multi-hull would allow to locate all the wet decks in between the hulls and carry increased numbers of light to medium armoured vehicles as well as in between the hulls rather a flotilla of small stealth ships for littoral presence and increased naval group surviveability by multiplying contacts in threat environments, serving as mothership.
Carrying in between the hulls also allows very long, fast and large transport ships (small short range LST) with very high stealth, possibly submersible for transit, that allow operations with rapid shocks. Such shocks can be unloading lots of troops on the beaches within a very short time, using rapid shore transit hovercrafts, as well as unloading a swimming missile arsenal in order to conduct advance high risk environment strikes. That's a small arsenal ship secondary role for the large transport which is already meant to safely transit the littorals and would take over part of the usual dangerous carrier missions there.
Why stick to the Osprey if a simple COI aircraft that can double as trainer is good enough for bombing. The Osprey is OK for transports, but in my opinion a STOL concept would be cheaper. It's like Harrier and Viggen.
 

 
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