The Ship Model Forum

How much heavier is the 76mm?

_________________
De quoi s'agit-il?

At least 35%.

_________________
Proper Preparation Prevents Poor Performance

That might be a consideration, then. If speed is important, you would want to make sure your ship is as light as possible, and if two weapon systems are going to be equally effective 90% of the time with significant weight&space savings for one of them, then the decision would be obvious.

_________________
De quoi s'agit-il?

I understand the point with ships that are operating close to their weight to power threshold like a PC. However, because we are talking about a nuclear powered ship it's speed is really going to be a function of the hull speed instead of horsepower acting against weight. I would suggest the weight difference between a 57mm gun and a 76mm is going to be so little it's not even worth mentioning in this particular case. Because internal workings usually dictate the size of the gun shield and thus the mount, the size of the gun shield might be enough of a difference to consider. These guns would go on the sides of the ship between the super structure and the rail.

They would have less than 180 degree firing limitations, and this is a little bit of a weakness. It's caused because the super structure is on one side of them and the hanger is on the other. However, both forward and aft are covered by Phalanx, RAM, and an 8" gun. If the ship were to need to unmask a 57 or 76mm gun, it would only need to maneuver a little. I think if the ship were engaged in surface action it would likely be maneuvering so much those guns would be available to everything.

It sounds to me like the 76 is the most appropriate. I am still curious why the US ever went with the BAE 57mm when the 76mm Otto offers so much.

_________________
Proper Preparation Prevents Poor Performance

I think we're talking about two different issues here:
What I'm talking about is the choice of the 57mm over the 76mm on the LCS, which is the only ship where the Mk110 mounting is being used thus far, afaik.

What you're talking about is the CGN-42, and I don't see any signs of a intermediary gun on the brass model at all, 57mm or 76mm.

So there's not reason why you have to debate at all about putting the 76mm on the CGN-42, as I see it...

_________________
De quoi s'agit-il?

You're right. This is the CGN-42 thread.
While you are right about the brass model, it does not have 8" guns, VLS, RAM, or a stern boat deck either. I am not reproducing the brass model in plastic. The modern ship is a continued development of the ship the brass model represents, the "Modified Virgina-class CGN". The changes being discussed through the thread from the armament to the helicopter hanger and equipment are in an attempt to meet modern mission needs as opposed to the mission needs of the '70s.

Small craft are a great enough threat where it would be preferable to incorporate such a weapon onto the CGN. Here there would be an intermediary gun if volume permits.

_________________
Proper Preparation Prevents Poor Performance

Then there is no decision any where on using the Mk110 57mm on the CGN-42, is there? So your worry about having to justify the superior 76mm is a non-issue. Just go with the 76mm if you've satisfied your own requirement.

_________________
De quoi s'agit-il?

The issue I am struggling with is the fact that the US Navy has decided to use the 57mm over the 76mm superrapid fire on LCS. We have bought the last generation of 76 a lot in the past, so I am trying to figure out why the 57mm has been chosen over the new version of the 76. Is the 57 actually better? Did the Navy just want to give BAE another contract? The foreign LCS requirements included a 76mm whereas ours is the 57, so I am trying to probe the readers to see if anyone knows why the 57 should be used over the 76 or if they know why the 57 was chosen for LCS over the 76.

_________________
Proper Preparation Prevents Poor Performance

I don't know the details Dave but we've been manufacturing OTO 76mms "under license" since we decided to use them on the Perrys. It's possible the license ran out or OTO wanted too much to renew it or any one of a number of things. The USCG used the OTO 76mms as well but all new construction is using the Mk-110. Something else to consider is that the 76mm SR hasn't been exported (to my knowledge) yet. Maybe OTO/Italy doesn't want anyone else to have it? Again, I'm just speculating. Should give you some things to think about though. You know how I feel about the 76mm SR

_________________
Drawing Board:
1/700 Whiff USS Leyte and escorts 1984
1/700 Whiff USN Modernized CAs 1984
1/700 Whiff ASW Showdown - FFs vs SSGN 1984

Slipway:
1/700 Whiff USN ASW Hunter Killer Group Dio 1984

That is an interesting point. Well, I think if we asked for them they would let us buy them if not build them.

The concern is for both this thread and the one I think Timmy was illuding to is the Advanced LCS-2 thread I have running. The Advanced LCS-2 is going to get more guns, and the issue there is placement of the weapons. As I have stated on that thread, I figure about the only place where you can fit any more with good internal room and clearance for helos is just aft of the helicopter hanger on the flight deck. The flight deck will be restricted, and the landing zones for the helos will have to be slightly changed. The small size of the mount and greater firepower are preferred for the LCS's swarm-busting mission. Deck space on the CGN-42 might be so small (I still need to acquire or deduce the dimensions of the super structure) either no medium caliber gun can be afforded or the smallest mount avaialble, and that that would be the 76mm SR. As Cliffy B has illuded to, acquisition is the question I am exploring.

And Cliffy loves that mount. I can understand why!

_________________
Proper Preparation Prevents Poor Performance

G'day Mate,
Speaking CWIS's I would use my old favorite the 30mm GOALKEEPER!! Why?? even though it weigh's more than Phalanx, 1/ it has longer range and 2/ can function as a secondary antiship weapon ( remember this is the same gun as used in the A10 warthog and can chew up Tanks) a thin hulled warship or pirate craft is going 2 be extremely unhappy!! And 3/ Its just cooler....

And if I was in charge of building the real ship, I'd give each Gkeeper a Fat below decks magazine with say 10,000rds per mount ( selectable between Highexp, AP,and anything else thats possible!)
My 55 cents worth!!

Cheers Bruce

PS: From my research and correspondence with former CGN sailors the limiting Factor for speed has always been the reduction gearbox's for the steam turbines, even so the Original Virginia class CGN's reportedly had anywhere from 35,000Shp to 60,000Shp per shaft and had a top speed of 40knots (again depending on the book...some simply say 30+) Speed is not a problem for a CGN

_________________
building:
1/72 RC USS LONG BEACH CGN9
1/72 RC USS CALIFORNIA CGN36
1/72 RC USS SAIPAN LHA2
1/72 RC USS JOHN PAUL JONES DDG53
1/72 RC USS SHARK SSN591
1/72 RC USS SEAWOLF SSN21
1/72 RC USS ALBANY CG10

Bruce... You are a weirdo man !!!

I would suggest you consider Goalkeeper for Longbeach!

_________________
Proper Preparation Prevents Poor Performance

Recall the primary concern of the LCS is speed, so there, weight-savings is a lot more important than for your CGN-42, even if the savings appear minimal. Again, for your CGN-42, I don't think you'll have any objections to a 76mm.

_________________
De quoi s'agit-il?

HAHAHAHAHAHA!! I just like the sheer nastiness of the thing!! Oddly I DO have 2 Goalkeeper's coming for LB picking them up next weekend!! at TF72 annual regatta, along with a pair of Mk45 5" guns which I shall modify 2 resemble a compact (modernised??) version of the mk-71 8" and some VLS cells.... She will look very mean once all her teeth go on!

Sorry fa going OT!!

Just had an even weirder idea mate! How about ditching the stern launch bay and sticking with standed RHIB cranes.... and here's the weird part a detachable advanced mini sub for sec ops!! something designed 2 slot straight up into a docking bay underneath the ship or one either side of midships keel area.
OK I need 2 rest now !! brain hurts.....

Cheers Bruce

_________________
building:
1/72 RC USS LONG BEACH CGN9
1/72 RC USS CALIFORNIA CGN36
1/72 RC USS SAIPAN LHA2
1/72 RC USS JOHN PAUL JONES DDG53
1/72 RC USS SHARK SSN591
1/72 RC USS SEAWOLF SSN21
1/72 RC USS ALBANY CG10

Goalkeeper has reached the end of the line. It requires space below deck. The USN has replaced Phalanx with RAM and Evolved Sea Sparrow. The remaining Phalanx guns are being upgraded to the Block 1B standard. The block 1B has a longer barrel which required a brace to be added, an upgraded radar, and an auxilary infrared targeting system. Its entering its second life as an anti-surface, anti-light aircraft weapon. The best way to stop most anti-ship missiles is to saturate active homing system with microwaves and blind it.

_________________
╔═════╗
║ Seasick║
╚═════╝

The 57mm (2.25 inch) gun was selected because of its very fast fire rate, large magazine, and rapid training speed. Blowing light targets away is the main mission of the gun. Fire rate was more of a requirement than weight of the bursting charge. You don't want to be on the business end of this weapon.

_________________
╔═════╗
║ Seasick║
╚═════╝

Seasick laid out a pretty good iteration of the programs bit I would like to add some clarification. While Goalkeeper will not replace Phalanx in the US Navy, other navies such as the South Koreans on their very state of the art KDX-III prefer it over other CIWS systems, and if marked with the Phalanx Block 1B guidance and control, it would be by far the best CIWS system available.

The other is that ESSM and RAM have supplemented Phalanx, not replaced it. There were a couple of years where the Navy thought it would no longer need Phalanx, but they realized they were wrong. To great cost the Navy paid Raytheon to rebuild the production lines. The production lines that had built Phalanx originally had been retooled and converted for other use, so whole new lines had to be built. Now, after the decision to stop putting Phalanx on DDGs, all new DDGs are being equipped with them again. DDGs are being delivered with provisions for two Phalanx mounts, one new Phalanx Block 1B mount aft and readied for a one forward when funding and production comes available. The ships that were delivered without it are being back fitted with them.

On a side note, there is a shortage of new Phalanx mounts, because the US Army is buying them as fast as the Navy. It turns out that Phalanx is a remarkable anti-mortar weapon and is being used to great effect.

_________________
Proper Preparation Prevents Poor Performance

The South Korean Navy decided to spend the money for Goalkeeper, Phalanx now has an expanded mission from its original mission of anti-missile defense. On Aegis equipped USN vessels the Evolved Sea Sparrow Missile (RIM-162A) has been adopted for the Ship self-defense and CIWS roll. Phalanx block 1B supplements in the CIWS roll for missiles but adds an anti-surface and anti-light aircraft roll. The Phalanx Block 1B has a lengthened barrel with a brace to increase accuracy, and a new radar that is harder for incomming missiles to detect. The 20mm cannon is better than the 30mm of the Goalkeeper because of its larger magazine gives it more shots at the target. One hit from a 12.75mm saboted tungstun penetrator can destroy control surfaces or destroy the homing sensor blinding it, the second and third hits will most likely destroy the missile. RAM (RIM-116) has the advantage of being able to manuver to hit the incomming missile if it tries to evade. Also since RIM-116 uses a passive infra-red seeker like the Sidewinder (IIRC the same one as the AIM-9X) so the missile can't "see" it coming near as easily. The Phalanx guns used by the USMC and US Army are earlier versions of the Phalanx with software upgrades. They have a 25% kill rate against mortars which is fairly good. The statistic is low because the mortars are not always launched toward the Phalanx. Mortoars fired with an aim point near the Phalanx are usually shot down.

_________________
╔═════╗
║ Seasick║
╚═════╝

Not to dispute anyone but:
Mark 75
Under USN nomenclature, the Compact is designated as the Mark 75. USN ships use the Mark 92 FCS which is the USN's version of the Signall M20 series FCS. The Naval Systems Division (NSD) of FMC Corporation and General Electric Co. (Ordnance Systems Division) were both licensed by OTO-Melara and competed for the right to manufacture the Mark 75 in the United States. In 1975, FMC/NSD (now part of United Defense) won the competition and the first gun mount produced in the United States was delivered in August 1978. Since 1981 all Mark 75 orders for the USN were competed for by FMC/NSD and OTO-Melara.

The Compact was developed from the earlier 76 mm/62 M.M.I. mounting and uses a two-piece water-cooled barrel with a replaceable liner. The gun is fitted with a small-hole muzzle brake and fume extractor. The shield is made of fiberglass.

There are reports that the Compact has reliability and accuracy problems. When fired at maximum ROF, there is a tendency for the mount to "self-destruct," in the words of one of the Project Engineers who worked on the weapon. During a test shoot, the weapon was unable to hold a 20-round burst on a 20 x 20 foot (6m x 6m) target at 500 yards (460 m).

Mark 110

A 30 September 2003 United Defense press release stated that the United States Coast Guard had selected the Mark 3 to arm its new Maritime Security Cutter, Large (WMSL, formerly the National Security Cutter). At that time, the USN designated this weapon as the "EX-57 Mk 3" with the "EX" standing for "Experimental." The first WMSL was originally scheduled to enter service in 2006, but this has been delayed for various reasons to the spring of 2008.

A 13 January 2004 United Defense press release stated that the USN designation for the Bofors Mark 3 had now been changed to "EX 110 Mod 0" at the request of the USN. This change of designation followed a successful firing test of 29 practice rounds and 26 rounds of 3P service ammunition at the Dahlgren Main Range in Dahlgren, Virginia. The initial test firings were conducted to verify the test range instrumentation and to document the gun system's characteristics for the upcoming Test Readiness Review of the EX 110 Mod 0 gun safety qualification project.

In September 2004, the Coast Guard announced that this weapon had been accepted into service and would now be designated as the Mk 110 Mod 0/57mm Gun. An article by Lt. Timothy Hacket (USCG) in the October 2004 issue of "Deepwater News" reported that: "Between November 2003 and September 2004, well over 2,000 rounds of 57 mm ammunition were successfully test fired. The test firings have been conducted in three phases to evaluate blast effects, ballistics, and serviceability . . . The serviceability testing included multiple 120-round firing evolutions at high firing rates to determine the gun’s sustainability. During one week’s course of firing, the test team successfully fired well over 620 rounds and collected a wealth of data . . . A nomenclature request has been submitted to establish the WMSL’s GWS [Gun Weapon System] to include the Mk 110 Mod 0/57 mm Gun, Mk 46 Mod 1 Optical Sighting System, AN/SPQ-9B Radar, and the Mk 160 Gun Control System ballistic computer."

A 25 October 2004 United Defense press release stated that the USN had selected the Mark 110 "as the Close-In Gun System (CIGS) for the baseline design of the new DD(X) Destroyer program . . . The function of the Mk 110 Naval Gun is to provide key ship self-protection and attack capabilities. The Mk 110 will work in concert with other combat systems being developed by United Defense, such as the ship's 155-mm Advanced Gun System (AGS) and the Mk 57 Vertical Launching System."

In a 01 November 2004 USCG Press Release concerning a day of Human Systems Integration (HSI) testing on the 57 mm Mark 110, participant GM3 [Gunner's Mate 3rd Class] Robert Boyer reported that "[the 57 mm Mark 110] is a huge upgrade from the 76 mm. As far as maintenance and accuracy of the new weapon, the all-around ability is a lot easier to handle compared to our current armament. I'll definitely look forward to working on the 57 mm gun." In this same release, Gunner’s mate PO3 [Petty Officer 3rd Class] Mike Sanders is quoted as saying that it "only takes up to three people for loading or unloading the 57mm with more room to move compared to seven people loading or unloading the 76 mm."
http://www.navweaps.com/Weapons/WNUS_Main.htm

So, there seems to have been a sustained fire accuracy problem with the 76mm. The problem seems to have been eliminated by the latest version, the SR (which also has a higher ROF), but rather than buy that, the Navy has chosen to go with the 57mm Mark 110, which also has lower manpower requirements compared to the 76mm.

There is a concern I am surprised Seasick has not brought up with the stern boat deck: Vibration. With those great, big screws chruning around and hammering the bottom of the ship, how much vibration would be experienced directly at the stern?

Norman Polmar stated that there was a porposal that a 61-cell Mk41 VLS be put in hanger area of the original Virginias for TLAM and ASROC use, but the vibration was going to be too much for the missiles and connectors under all speeds and conditions. I wonder how this would effect a boat deck.

_________________
Proper Preparation Prevents Poor Performance