Tarawa Lha As Basis For A Cvs?

[roughneck06]

I was reading a thread on NAVWEAPS.com on what if the USSR had developed
a carrier force in the 1960s and the US/NATO response had it occurred. One person posted the thought of a CVS based on the Tarawa class LHA would have been build to replace the Essex class carriers used as CVS as they ended their service lives/ supplemented the existing force. Angled deck on the Tarawa based CVS of course, no Amphib docking well, space for marines, and a nair group that consisted of S-2s, later S-3 vikings, AEW, Helos, AV-8As, limited capability to embark A-7s, F-8s, later to get F/A-18s to replace F-8s for Air defense/CAP.

Any thoughts about configuration of the Island??? Would it be similar to the Tarawa's as an LHA?  would an island from a CV 59, CV 63, other be more appropriate?Self defense armament? Same as historical intially? I think I just might have to do a WiF based on this concept. Also- nominations for names?

A final thought- with the end of the Cold war.... these might be aquirred by other navies- nominations?

Thanks in advance for your ideas and comments!

[Matt Wiser]

Interesting idea. You'd have to swap the Marine C3 spaces for an ASW control center,so the Island might be unchanged. The S-2s were largely gone by the time the first of the class came on in '75, so S-3s from the outset. F-8s were gone by '77, leaving either AV-8As or A-7s as your air defense/strike aircraft until the F/A-18 comes along in 1984-85. Self defense weapons fit would be the same as the baseline Tarawas, with CIWS displacing the 5" guns as the Phalanx becomes available, and Sea Sparrow being augmented by RAM when it comes. Of course, a bow sonar and a towed array sonar would be mandatory. The hull would have to be lengthened for arrester gear, and the bow cats. More if you plan on having waist cats on the angled deck.  

[anthonyp]

In The Manifesto, I thought how to do up a proper VSS, which could be used as a Helo ASW carrier in a pinch.  I based it on the Tarawa hull, but got rid of the guns and boat well, modified the island a little.  One of them, the Porter, I even gave a skijump to play with.

Somewhere on this hard drive, there's some pics...

(muzak plays)

Found them!  And the description from The Manifesto

After the USN determined that the smaller Defiant class would not be able to replace the large supercarriers on station in deepwater, the USN built an enlarged version of the VSS in order to see if the enlarged version of the VSS is any more effective than the smaller VSS's. The first of this new class, the USS Zumwalt, was completed in 1978 and proved better suited to deepwater operations, but still not up to the level needed to replace the supercarriers. Even with the failure to effectively replace the Nimitz's, the Zumwalt class had many more pros than it did cons. In the end, six were built (Zumwalt, King, Porter, Radford, John Paul Jones, and Towers). These ships were built to a modified Tarawa Class LHA design. It removed the deck guns, boat dock, and had a smaller island, but its deck dimensions were the exact same (save the starboard elevator replacing the aft one, making it look like a prototype Wasp class). The USS Porter had a ski-jump installed over the port bow in 1988, and was used to test that concept until the ship was decommissioned in 1999.

The entire class was decommissioned between 1997 and 2004 as a cost-savings for the USN. As with the Defiant class, rumors persist that these decommissioned ships will be sold abroad (Taiwan and South Korea among the candidates). The US Congress has made noise about handing the youngest member of the class over to the USCG to supplement their Pacific operations, even though the Coast Guard doesn't see the need for additional carriers. The material condition of these ships is said to be serviceable at best, and the USN is not interested in pouring money in to the class in order to refit them for further service. If not sold abroad, they will be sunk in either SinkEx's or reefed somewhere off the US coast.

2 Zumwalt Class 1978 to 1982
36 AV-8N (USN Sea Harriers)
3 EH-3M (Similar to the RN's AEW Sea King)
6 SH-3H
6 SH-53D (ASW version of the MH-53D)
6 SH-2F

6 Zumwalt Class 1982 to 1993
18 FV-12A
18 AV-8R (updated AV-8N)
3 EH-53E (shown in the "Current Projects" forum)
4 SH-53E (ASW version of the MH-53E)
6 SH-60B
8 SH-65B

6 Zumwalt Class 1993 to 1997
18 FV-12D
18 AV-8B
3 EH-53E (shown in the "Current Projects" forum)
4 SH-53E (ASW version of the MH-53E)
6 SH-60F
8 SH-65B

6 Zumwalt Class 1997 to 2004
18 FV-12D
18 AV-8B+
3 EV-22E
4 SV-22C (ASW version of V-22)
6 SH-60F
8 SH-65D

USS Zumwalt (CVH-8)


USS Porter (CVH-10)


I'd be interesting to see what a baby angled deck would look like on either a Tarawa or a Wasp hull.

[Sentinel Chicken]

Out of curiousity, isn't the Tarawa a single-screw design? And probably a bit too slow to operate as a CVL/CVS?

[jcf]

Out of curiousity, isn't the Tarawa a single-screw design? And probably a bit too slow to operate as a CVL/CVS?

Twin-screw, 24 knots.

[GeorgeC]

I drew a SCS earlier this year, based on the Principe de Asturias with about 3000 tons shaved off:

[Sentinel Chicken]

I got to thinking more of this topic this evening and whipped this up:



The dashed lines are the outlines of the original LHA deck. The gray items are obviously the island and the aircraft crane aft of the island.

The scale bar is 100m long with 10m divisions.

The items in red are a standard Nimitz-class catapult and arresting wire "box". I got them from a deck plan of the CVN-71 and scaled to the size of the LHA diagram. So those are items that I considered I'd need if I wanted to operate something the size of the S-3 Viking.

I tried to limit myself to making as few changes as possible. So for v1.0 of our Tarawa-class CVS, the hull length is unchanged, the island and its location are unchanged.

We need an angled deck and the width of the landing area is the same as on a Nimitz-class carrier as well as the width of the arresting gear. So the first step is to make a deck overhang on the port side. This gives room for the angled deck and the arresting gear. There is a sponson on that side that runs about 2/3 the length of the hull.

I'm assuming that the weight of the island means I don't need a similarly sized sponson on the starboard side and since I can't move the island as I'm trying to keep the changes to a minimum, I have two smaller sponsons that each support new deck elevators.

The air wing would be pretty simple, just SH-60s and S-3 Vikings. I'm not sure how much hangar space I have in this version, but it can't be too much.

I tried squeezing both cats on the bow, but it can't happen without either shortening the island or lengthening the hull. So putting one of the cats on the waist seemed like a reasonable solution.

Problems I see with this version:

1. Simultaneous landing/takeoff operations aren't possible. You can see that the Viking on the bow cat overlaps into the landing area. Not to mention it's a tight fit behind the bow cat, even if you kept your wings folded.

2. Landing aircraft would have to be either taxied back up the landing zone to the aft elevator or across the bow cat to the forward elevator.

3. Is there a seakeeping/balance issue with the sponsons as I have it? Somehow it doesn't seem stable or too heavy on the port side.

4. No organic air defense. Not sure if this is an issue as I'd imagine a CVS operating with an AEGIS screen to fill the role of air defense. I suppose if we had some AEW Vikings that would help with OTH threat detection.

Thoughts and commentary?

[Son of Damian]

I think the result would be something similar to what India is going to do to Admiral Gorshkov

[RLBH]

Problems I see with this version:

1. Simultaneous landing/takeoff operations aren't possible. You can see that the Viking on the bow cat overlaps into the landing area. Not to mention it's a tight fit behind the bow cat, even if you kept your wings folded.

It ought to be possible to rearrange the below-decks fittings to accomodate the CIC and other goodies in the original island, seeing as the well deck is no longer required. That might allow the bow catapult to come over to starboard, which would give some simultaneous ops capability, and reduce the chance of your CIC being hit by stray cannon fire (although that shouldn't be much of an issue for a CVS vice an LHA). You should also be able to rework the hull aft to be a little more hydrodynamic, so speed may increase.

2. Landing aircraft would have to be either taxied back up the landing zone to the aft elevator or across the bow cat to the forward elevator.

Probably not a problem, as this is likely to be the case on CVF and the French second aircraft carrier; I think it's been the case on a few earlier ships, too, but I can't be certain. Anyhow, if it were an issue, you could probably develop a half-sized lift to park on the port side somewhere. The possible problem I can see is whether there is enough runout for the arrester gear whilst leaving room to turn around; that was the problem with the Clemenceau as built.

3. Is there a seakeeping/balance issue with the sponsons as I have it? Somehow it doesn't seem stable or too heavy on the port side.

Hard to be certain without more complete plans, but it looks alright. Moving the island outboard might help, and shouldn't be as much of an issue if the original island is reduced in size as I suggested in (1).

4. No organic air defense. Not sure if this is an issue as I'd imagine a CVS operating with an AEGIS screen to fill the role of air defense. I suppose if we had some AEW Vikings that would help with OTH threat detection.

The size of ship is similar to HMS Ark Royal (the old one), and she proved able to operate Phantoms, so this ship ought to be able to operate F-18s, especially with C-13 catapults. I actually suspect the C-13 is overkill for just S-3s, so that may be an advantage. Perhaps the F-18 isn't as good in air defence as the F-14, but it's certainly better than an S-3; it would give some strike capability too, should that be needed.

Thoughts and commentary?

The current crop of carriers only have three arrester wires, too, so I'd suggest that the forward one (which is apparently almost never used) could be savely deleted; it certainly seems a little close to the deck-edge for comfort.

All told, it's probably easier to design a CVS from scratch or to wholly update the Essex class than to try converting an LHA. The well deck and vehicle capacity is detrimental to any other sort of ship, especially as the waterplane area aft would tend to make stern motions slightly worse, and make landings a greater challenge.

[Sentinel Chicken]

Based on RLBH's suggestions, this is v2.0 of a CVS based on a LHA hull. Changes made from v1.0:

1. Hull extension at the stern to possibly improve the hydrodynamics so the waterplane area aft isn't so flat. This allows the landing area to be a bit longer.

2. Deleted the #4 wire.

3. Resized the island and moved it aft and outboard.

4. Moved the bow catapult to the starboard and angled slightly to improve clearances for simultaneous landing/launch ops.

5. Moved the forward elevator aft to make room for the bow cat.

6. Longer sponsons on both sides now, the one on the starboard will of course have cutouts for the elevator and that should compensate for moving the island outboard.

7. I noticed that some of the defensive weapons of the Tarawa were mounted on the island. These have now been relocated to the corners similar to what larger CVNs would have but with only 2 Phalanx CIWS and two early style Sea Sparrow launchers.

The length of this layout probably approximates that of an Essex class. The Tarawa is about 820' and the Essex class was a bit over 870'.

[jcf]

The C-13 catapult has a stroke of 250'... what you see on deck is only part of the story.

The Tarawa has a hangar clear height of 20', the CVS designs were to have a hangar height of 22' to allow for the E-2.
CVS design SCB 100.68 of Sep 1963:
43,400 tons
LOA: 860'
LWL: 830'
Beam: 101'
Draft: 29.6'
Flight Deck: 860 X 190
(2) C 13 catapult, (3) elevators
The angling of the angled deck was minimized in a fashion similar to that of the attack carriers to "decrease the effects of island induced turbulence during no wind conditions as well as to permit a ship of better length-to-beam ratio". The deck layout resembled that of the Nimitz class and the CVV design.

There was a CVS design dimensionally similar to an LHA, Tarawa numbers in brackets;
SCB 100.71, Apr 1964:
50,000 tons (39,300)
LOA: 815'  (820')
LWL: 770'  (778')
Beam: 122'  (106' 8")
Draft: 32'  (25.74')
Flight Deck: no data (820 X 106.5)
(2) C 11 catapult, (3) elevators
The change to the smaller C 11 catapult meant that heavier high-performance aircraft could not be carried e.g. no Phantoms.

The final CVS designs were longer and bulkier; up to 57,497 tons, 820' LWL X 124' Beam X 34' Draft, C 13 catapults were once again specified.

CVV from Greg's earlier posts for reference:


The hard truth, however, is that small carriers are less cost effective than large carriers.

Cheers, Jon

[Archibald]

The hard truth, however, is that small carriers are less cost effective than large carriers.

Except when you have few money, like the French navy  
I understand why the CVV and simbling were never bought by the USN... they were simply a step backward when compared to huge Nimitz.  

[RLBH]

I like v2.0 very much; the stern treatment isn't quite what I had imagined, but lengthening probably is a good idea. Since this is but a deck-level plan, I shall assume that the waterline is tapered a bit more.

I'll take three, with the air wing painted EDSG over Sky    

[GTX]

Except when you have few money, like the French navy

I couldn't have put it any better myself!

Regards,

Greg

[Bryan H.]

All told, it's probably easier to design a CVS from scratch or to wholly update the Essex class than to try converting an LHA.

I've always thought that a moderized (from the keel up-to year 2000 standards) Essex class would be a good solution for the US and it's allies.  Not too big not too small.  The basic design & deck plan are good.  Using modern techniques (computer aided drafting, etc...), the internal structure could be modified without the massive engineering effort of the 1940's era.  The hanger could be raised, providing room for E-2's and other tall aircraft.  The powerplant could be modernized.  The defensive armament, electronics, C3, etc... could all be modernized.  

The whole package could be 'mass produced' to lower individual unit cost by exports to interested 'friendly/allied' nations (ie. UK, France, Italy, Australia, Germany, Brazil, Argentina, Japan, Korea).  The US would need a certain number of it's own.  I'm sure an Essex (part deux) would be useful in many areas where a full size Nimitz is too big.  They could also be produced faster and in greater numbers than Nimitz carriers; 'quantity has a quality all of it's own.'  They'd be great for convoy escort duties and as and adjunct to the Nimitz's.  Additionally, they'd spread the risk of loss since they'd be more numerous than the Nimitz's.  

Of course, a small multi-role carrier would revive interest in compact fighter/attack aircraft (ie. F-8's, A-4's, A-7's, navalized Mirage F.1's, navalized SEPECAT Jaguars, etc...)

Bryan