Had an interesting discussion about why the National Security Cutter retained the Phalanx Close In Weapon System (CIWS) while the very similar weapons suite on the Freedom class Littoral Combat Ship used the Rolling Airframe Missile (RAM) system instead.
Mk 49 Rolling Airframe Missile Launching System Photo credit: Darkone 13 Aug, 2006, via Wikipedia
My friend contended that, while the Phalanx is very maintenance intensive, the launcher for the RAM is virtually maintenance free, which would benefit the relatively small crew. He also noted that the current models have an excellent anti-surface capability and longer range than the Phalanx.
This got me to thinking. I won’t make a recommendation, but will discuss alternatives that might be considered. I’ll talk about who is using the RAM and how, and discuss how the Coast Guard might use it, and its advantages and disadvantages as a possible replacement for the Phalanx and possibly even the 57 mm. But before we get to that, as we are always told, you have to start with the mission.
Why do we have weapons on these ships? Certainly there are the traditional law enforcement missions. Cutters need to be able to fire shots across the bow as a signal. They may need to use disabling fire stop a fleeing felon. Since 9/11, the need to be able to sink or at least stop a vessel being used by terrorists has been recognized. The current choice of weapons also indicates a desire for self defense against cruise missiles.
Other missions that these systems might also be used for include, enforcing a blockade, or escorting ships subject to attack by small craft, including a possible swarm attack typified by the apparent tactics of Iran’s Islamic Guard Corp. Combat with other warships is apparently not planned since there are no cruise missiles. Naval Surface Fire Support is also not currently planned. (There is a discussion of possible Coast Guard cutter war time roles here, part 1 and here, part 2.)
Any replacements should be able to do the following at least as well as existing and planned systems:
- Warning Shots across the bow
- Disabling fire against small craft
- Defend against cruise missiles
- Sink or at least disable a medium to large merchant ship
Of these, the first two are relatively easy and don’t require sophisticated systems. A .50 cal sniper rifle and crew served .50 cal machine guns could probably fill the requirement. Certainly the Mk38 mod2 which is equipping the Webber Class Fast Response Cutters is adequate for the roles. It is the last two that are difficult. Of these I would prioritize stopping a ship based terrorist attack ahead of the ability to defend against cruise missiles, not only because it seems more probable, but also because if a terrorist attack of this type occurs, the Coast Guard will be uniquely positioned to counter it. If we fail to do so, the Coast Guard will receive the majority of the blame.
I have expressed my reservations before, about our ability to sink or disable medium to large ships (here and here). If it has not already been done (which I doubt), then the service needs to do some testing of their available weapons to determine if they are up to the job.
It is because the Phalanx might have the ability to penetrate the side of a ship and continue on to damage the ships engines that caused me to have doubts about replacing the Phalanx system. High explosive rounds, even nominally armor piercing rounds like those available for the 57 mm, are unlikely to do this, because they will usually explode after penetrating the ship’s side and leave the heavy machinery largely unharmed. (During WWII it was common for heavy bombers to attack factories and apparently damage them heavily, but in fact while the roofs were blown off, the machinery was essentially untouched and was back in operation the next day.)
- Mk 110 Bofors 57 mm currently installed on the NSC and projected for the OPC.
- Phalanx_CIWS currently installed on the NSC. No plans for OPC.
- M242 Bushmaster 25 mm chain gun in Mk38 mod2 mount, an American version of the Israeli “Typhoon.” Planned for the OPC and installed on the Webber class Fast Response Cutters.
- RIM-116 Rolling Airframe Missile launched from the 11 round SeaRAM stand alone weapons system.
- RIM-116 Rolling Airframe Missile launched from the 21 round Mk Mk49 guided missile launching system (GMLS)
- ROSAM Mk49 stabilized .5o cal gun, an American version of the Israeli Rafael “Mini-Typhoon” (and here (video)). Two units planned for each OPC.
The 25 mm Mk 38 mod2 mount:
Mk38 mod2 25 mm U.S. Navy photo by Mass Communication Specialist 2nd Class Jason Behnke
If the Phalanx has a ship stopping ability not available in the 57 mm and the RAM, that needs to be replaced, the Mk 38 mod2 is a likely candidate for the job. This mount is already in use in the Coast Guard. It is planned as the primary weapon for the Webber class and as a secondary weapon for the Offshore Patrol Cutter. This weapon can fire an armor piercing discarding sabot round (APDS-T) that may have the ability to penetrate the side of a merchant ship and continue on to damage its engines or steering gear. I don’t know if this round is in the Coast Guard, or even the Navy’s inventory. I believe it is used by the Marines.
M791 APDS-T 25mm round. Credit: Image is from U.S. Army Field Manual 3-22.1 p.32 via Wiki
If this weapon with the APDS-T round is adequate for stopping larger ships, it could go a long way to meeting the Coast Guard’s needs for the counter terrorism mission, but without testing, doctrine and training, it is difficult have that confidence.
ROLLING AIRFRAME MISSILE (RAM)
RAM is a supersonic, lightweight, quick reaction, fire-and-forget missile providing defense against anti-ship cruise missiles, helicopter and airborne threats, and hostile surface craft. The missile’s autonomous dual-mode, passive radio frequency and infrared guidance design provides a high-firepower capability for engaging multiple threats simultaneously.
Currently it is launched either from the Mk49 21 cell launcher or from the stand-alone SeaRAM which is basically a Phalanx with an eleven cell launcher mounted in place of the 20mm gun. The SeaRAM is new and is currently mounted only on the USS Independence class Littoral Combat Ships.
RAM began as a passive radar homing missile with infrared terminal homing for the the purpose of countering anti-ship cruise missiles (ASCM). It has since been further developed to permit infrared homing from launch, to permit engaging non-radar-emitting targets. Further changes to software permitted the missile to engage slower targets, including helicopters, aircraft and surface vessels. The most recent changes (block 2) have improved its performance against highly maneuverable ASCMs and reportedly doubled its effective range.
There has been a development that may mitigate the high cost of the RAM rounds, and add versatility. Raytheon just demonstrated they can fire the Griffin missile from the RAM launcher. Griffin is a smaller (45 pound), shorter ranged (5.6 km), surface to surface missile that can be laser guided. This and the evolution of the RAM suggest that there will be continued improvements and increased flexibility in RAM based systems.
The RAM was a joint US/German project. It is installed in about 165 ships including all 27 German frigates, corvettes, and fast attack craft. Among these are the Gepard Class Fast Attack Craft (FAC) that are only slightly larger (391 tons) than the Webber Class Fast Response Cutters (353 tons). (The Gepard also has a 76mm and four surface to surface cruise missiles.) None of these German combatants have any other CIWS. All but the ten Gepard class have two launchers, including the relatively small 1,840 ton corvettes of the Braunschweig class, about the size of the Bear Class 270 foot WMECs.
Photo: Schnellboot P6121 S71 Gepard / Typ 143A Gepard-Klass. Darkone, 9. August 2003
Every US Navy surface combatant built since 1990 except the 331 ton Cyclone Class coastal patrol craft and Destroyers and Cruisers equipped with longer ranged AAW missile system, is equipped with the RAM system, and it has been back fitted to many others. In addition to the Littoral Combat Ships, this includes Enterprise and Nimitz class aircraft carriers; Wasp, Tarawa, and America class amphibious assault ships (LHD/LHAs); San Antonio class amphibious transport dock ships (LPHs); and Whidbey Island and Harpers Ferry class dock landing ships (LSDs). On all of the US Navy ships except the LCSs and the San Antonio Class, there is a mix of RAM and Phalanx CIWS, and most also have a Sea Sparrow system. The San Antonio Class is unique in having only Ram and an alternate gun system, a pair of 30 mm chain guns in Mk 46 mounts, which are also included in the LCSs’ anti-surface mission module. The RAM is the most sophisticated and longest ranged organic weapon on the LPDs and LSDs.
According to Wikipedia the RAM system is currently in service with South Korea, Greece, Turkey, and Egypt in addition to Germany and the US Navy. The UAE is also getting the system. South Korea is using RAM on all their newest classes of surface combatants but apparently favors using it in combination with the 30 mm Goalkeeper CIWS. Greece uses it, in addition to a 76 mm, on seven 580 ton Roussen Class FACs, as does Turkey on their new “Milgem” Corvettes. Egypt is using them in combination with both a Phalanx and a 76 mm in their new Halter Marine built “Ambassador” class FACs. The United Arab Eremites (UAE) is using RAM on their 915 ton Baynunah class corvettes in combination with a 76 mm and vertical launch Evolved Sea Sparrow Missile (ESSM).
Comparing the RAM with the Phalanx:
Phalanx has some advantages. It is a stand alone system that can continue to function after the ship’s air-search radar, fire control systems, and CIC are destroyed, and the ships power is off-line. Unlike RAM, it can also be manually controlled with some precision for functions like firing warning shots and disabling fire. Its non-explosive, high velocity, very dense projectile may even be more useful than the 57 mm for penetrating the engines of medium to large vessels.
But the primary reason to have a Phalanx is to shoot down incoming cruise missiles. (For warning shots or disabling fire the Mk38 mod2 is probably better.) It is in this mission, that the RAM appears to have its great advantage.
An operations research study done for Australia “Limitations of Guns as a Defence against Manoeuvring Air Weapons,” (pdf) by Christian Wachsberger, Michael Lucas and Alexander Krstic, Weapons Systems Division, Systems Sciences Laboratory, DSTO-TN-0565 concluded,
“In the near future, strategic and other critical assets will be subject to attack from a new range of air threats, including highly accurate aircraft-launched weapons that offer long stand-off ranges and which are capable of traveling at high speed as well as manoeuvrings at high g rates. This study uses simple probability theory to determine the relative utility of current generation airdefence guns against this type of highly maneuverable weapon. The rationale for this study is that whilst guns may have the advantages of offering a low cost-per-shot and reasonable magazine capacities, they are also severely limited in their abilities as they are only designed to fire at a predicted intercept point in space. As a result, should the target alter its direction during an engagement, the target will no longer pass through the projectile’s flight path.”
The Phalanx may still be effective a against subsonic cruise missiles with limited maneuverability that arrive consecutively, but looking at even the non-maneuvering examples in this study, it is apparent that high probabilities of hit only occur as the missile gets very close. That means that it probably cannot deal with multiple threats arriving simultaneously, as they would in a well planned attack. Because the RAM is a fire and forget weapon, with a greater range than the Phalanx, several can be launched to deal with several missiles before the first inbound cruise missile is destroyed, while the Phalanx would be fully occupied dealing with one missile.
Comparing the RAM with the Mk 110 57 mm gun:
The 57 mm Mk 110 has a longer maximum range than RAM. At close range it can be targeted with precision.
RAM, unlike the 57 mm, uses IR to home on some targets. That means it might be seduced by IR decoys or be effected by obscuration such as rain, fog, or smoke.
Still, the RAM block 2 reportedly has an effective range similar to the 57 mm and enjoys the same “fire and forget” advantages against cruise missiles compared to the 57 mm that it does against the Phalanx.
It also looks like it has a better chance of dealing with swarming small craft.
The warhead is also about four time the size of the 57mm, so it can also have an impact on the attempt to stop or sink a merchant under terrorist control.
Alternative Weapons Fit: These are the alternative ship configurations that might be considered (I’ll leave off the crew served M2 .50 cal. and smaller). I’ll highlight what I believe are the pros and cons of each.
For the National Security Cutter:
- NSC now: Mk 110 57mm gun forward, Phalanx aft
- NSC mod 1: Replace the Phalanx w/SeaRAM 11 cell RAM launcher
- NSC mod 2: Replace Phalanx with Mk49 21 cell RAM launcher, add two Mk 38 mod2 25 mm guns.
- NSC mod 3: Replace Phalanx and Mk110 57 mm gun with two Mk49 21 cell RAM launchers, one forward and one aft and add two Mk38 mod2 25 mm guns.
NSC mod 1 (Replace the Phalanx w/SeaRAM 11 cell RAM launcher):
- Pro–Probably better as a counter to multiple anti-ship cruise missiles. Additional ASuW and AAW capability. Retains stand-alone/automatic engagement feature of Phalanx.
- Con: Limited number of rounds. May not offer the reduced maintenance requirements of the Mk 49 launcher. Looses the possible ship stopping ability of the Phalanx.
NSC mod 2 (Replace Phalanx with Mk49 21 cell RAM launcher, add two Mk 38 mod2 25 mm guns):
- Pro: Mk 49 GMLS should offer reduced maintenance compared to the Phalanx, better capability against cruise missiles, aircraft, and surface targets. 25 mm restores and possibly exceeds ship stopping ability of Phalanx.
- Con: Looses stand-alone/automatic engagement capability of Phalanx. Support requirements for additional Mk 38 mod2 mounts may offset reduction due to Phalanx replacement.
NSC mod 3 (Replace Phalanx and Mk110 57 mm gun with two Mk49 21 cell RAM launchers, one forward and one aft and add two Mk38 mod2 25 mm guns):
- Pro: Fewer different types of systems simplify maintenance, training, support. Best 360 degree protection against cruise missile attack. Probably the best system agains “swarm attacks.” Will benefit most if there are continued improvement in systems compatible with Mk 49 GMLS.
- Con: Loses the flexibility, extreme range, and possibly all weather capability of the 57 mm. Looses stand-alone/automatic engagement capability of Phalanx. Support requirements for additional Mk 38 mod2 mounts may offset reduction due to Phalanx replacement.
For the Offshore Patrol Cutter:
- OPC planned: Mk 110 57mm gun, one Mk38 mod2 25mm gun, two ROSAM Mk49 .5o cal guns
- OPC mod 1: Replace Mk 110 57mm gun w/Mk49 21 cell RAM launcher, Mk38 mod2 25mm gun, two ROSAM Mk49 .5o cal guns
- OPC mod 2: Replace both the Mk 110 57mm gun and the Mk38 mod2 25mm gun with Mk49 21 cell RAM launchers, replace the two ROSAM Mk49 .5o cal guns with Mk38 mod2 25mm guns
OPC mod 1: (Replace Mk 110 57mm gun w/Mk49 21 cell RAM launcher, Mk38 mod2 25mm gun, two ROSAM Mk49 .5o cal guns):
- Pro: Better against cruise missiles. Possibly reduced support requirements. Within range, probably will score hits faster than 57 mm and those hits will be heavier. Will benefit if there are continued improvement in systems compatible with Mk 49 GMLS.
- Con: Loses the flexibility, extreme range, and possibly all weather capability of the 57 mm.
OPC mod 2: Replace both the Mk 110 57mm gun and the Mk38 mod2 25mm gun with Mk49 21 cell RAM launchers, replace the two ROSAM Mk49 .5o cal guns with Mk38 mod2 25mm guns
- Pro: Fewer different types of systems simplify maintenance, training, support. Best 360 degree protection against cruise missile attack. Within range, probably will score hits faster than 57 mm and those hits will be heavier. Best system agains “swarm attacks.” Will benefit most if there are continued improvement in systems compatible with Mk 49 GMLS.
- Con: Loses the flexibility, extreme range, and possibly all weather capability of the 57 mm.
We need more info:
To make good decisions the Coast Guard needs good information, some of which may be readily available, some of which may require experimentation.
- How effective are each of these systems in stopping ships?
- How much do atmospheric conditions effect the RAM?
- Can the Coast Guard get the APDS-T round for the Mk 38 mod2?
- What are the support requirements for the various systems?
- Are additional capabilities coming for these systems?
The initial studies that chose systems for these ships were done very long ago, a lot has changed since then. Perhaps it is time to take another look.
Thanks to Bill, Bob, Lee, and Brent for their thoughts, all errors and opinions are of course my own.