32. Naval Armament on a Warship – A Perspective

(Published Defence ProAc Biz News Jan-Feb 2014)

Blue water navies defend and attack with a variety platforms utilizing wide range of weapons. The three-dimensional operations of a formidable navy involves aircrafts, surface ships, and submarines. Each of these platforms has weapons designed for its specific role. A naval force far away from its homeport is thus fully capable of meeting threats arising from the air, surface or under water. The aim of this article is to provide a perspective in to major classes of weapons currently in the armory of a war ship, namely, the torpedo, the missile, and the naval gun. Elaborate discussion on the Naval Gun has been included as it has withstood the test of time and continued to prove its relevance despite rapid developments in missile technology.

Torpedoes

Submarines continue to pose formidable threat to the surface warship, as the water medium is not conducive to, easy target detection, rapid weapon speeds, acoustics, and electromagnetic wave propagation. Varieties of weapons are available, which include, mines, depth charges, anti submarine rockets, and light & heavy weight torpedoes. The torpedo remains the main underwater weapon because of its, improved target detection & ECCM capabilities, high speeds in excess of 50 kts and massive destructive power.

Lightweight torpedoes are launched by surface ships, helicopters, and fixed wing aircrafts. A few of the notable light weight torpedoes include the European MU 90 produced by EUROTORP, The Mk 54 by Raytheon and the A244S developed by WASS. The MU90 is a NATO-standard-caliber (323,7mm) fire-and-forget LWT of 304 Kg and 285 cm length, designed to counter any type of nuclear or conventional submarine. The US Mk 54 torpedo is 271cm to 287cm, weighs between 276 Kg to 293 Kg, and has a diameter of 32 cm. Its processing power, coupled with the MK 48 ADCAP and MK 50 detection, editing and tracking algorithms, provides an effective weapon in both littoral and open-ocean waters. The A244/S is a 324mm diameter, 2.8m long, and 244kg weight torpedo. It has a cruise/surge speed of 30/39kts, with a range of 6km and depth up to 600m.

A lightweight, anti-submarine torpedo TAL that can be launched from both, surface ships and helicopters has been developed by NSTL, a DRDO laboratory. It is being produced by BDL Hyderabad. It has a speed of 33 kts, a range of 7 km, and a warhead with an explosive weight of 50 kg. Twenty-five TAL torpedoes have been ordered by the Indian Navy.

Surface ships in anti submarine role mainly launch heavyweight torpedoes. Few of the notable heavy weight torpedoes include the US Mk 48 ADCAP, the Russian 53-65 KE, the Italian Blackshark and the German Seehect. Hughes Aircraft produce the US MK 48 ADCAP wire guided torpedo. This thermal torpedo has a range of 30Km at 65kts and 50Km at 40kts. The Russian 53-65KE has speeds in excess of 45kts, a range of 19Km. It is a wake homer using kerosene and oxygen for propulsion. Whitehead Sistemi Subacquei has developed Blackshark also known as A184. It has advanced ECCM, motor design and battery, giving it a speed of +50Km at +50kts. Atlas Elecktronik manufactures Seehecht, DM2A4. It was the first torpedo to be fitted with a fiber optic wire guidance system. Indian Navy has issued an RFI for heavy weight torpedoes for its Scorpene submarines and warships in pipeline. In future, it is likely to deploy the indigenous Varunashtra on its ships as and when it is available.

Cruise Missiles

Cruise missiles had suffered major design problems and failures. They have gained tremendous popularity after surmounting their shortcomings. This has been possible with advances in propulsion (small turbofan jet engines resulted in smaller and lighter airframes), miniaturization of electronic components (smaller on board   computers led to much better guidance and control abilities), high-density fuels, much better explosives, and smaller warheads. Sea skimming at sub-sonic to supersonic speeds, way point programming, and accurate targeting have made cruise missiles weapons of choice at sea.

Some of the naval cruise missiles worth mentioning are the Brahmos, the Tomahawk, the Klub, and the Exocet. Brahmos produced by BrahMos Aerospace Pvt Ltd, which is a JV between India and Russia. At speeds of >2.8 mach, it is the fastest missile in the world. With induction in to the Indian Navy and the Indian Army (Land attack version), it has also become a cross service missile. Further, it is likely to be inducted in to the Indian Air Force and Indian Naval submarines once trials are completed. Tomahawk by Raytheon, is perhaps the most famous and widely used cruise missile. The current version is network centric and can utilize data from a variety of inputs like UAVs, satellites and ground forces. Retargeting during its flight is possible due to its loitering feature. The Russian Klub is an anti shipping subsonic missile with a supersonic terminal speed of 2.9 mach. It has a warhead of 200kg and a range of 220km. Exocet missile produced by MBDA is a sea skimming turbojet missile with a range of +180km. It has a warhead of 165kg. Indian Navy has ordered the submarine fired version of this missile, namely the SM 39, for the Scorpene submarines under acquisition.

The Naval Gun The naval gun has seen large variations in its caliber since its advent on the 16th century Galleys. Explosive filled shells have replaced the solid shots. The arrival of precision guided missiles and carrier-based aircraft has led to two distinct approaches in design of current generation of naval guns. The first approach rests on the premise that the naval gun has only a secondary role restricted to shore bombardment or protection against small ships. The second view is that it is still has potential as an anti aircraft, anti fast missile craft and anti missile weapon. These approaches have led ships to carry a 3 to 5 inch caliber gun for shore bombardment, anti surface and anti aircraft role and/ or a small caliber rapid firing gun for anti air defense and anti missile role. The naval ships have therefore been equipped with a heavy gun, an auxiliary gun, and a small caliber gun for close air/ missile defense. Some of the heavy guns in use are, the American 5” Mark 45, OTO Melara 76 mm gun, Bofors 57/70 mm, and, OTO Melara 127/64. Some of the auxiliary guns include, OTO Breda 40/L70 twin, Mauser EADS MLG 30/27 mm, Rheinmetall GDM-08, Oerlikon Gam/BO 1, and Allied Telesyn DS 30M Automated Small Calibre Gun System . Examples of close in weapon systems are Mauser Oerlikon MeRoKa, Signaal GAU-8/A, Raytheon Phalanx and GE / GDC MK 15 Mod 2. Some of the noteworthy heavy guns and CIWS are discussed in brief in succeeding paragraphs.

Heavy Gun Systems The Italian 127mm Oto Melara, has a firing rate of 45 rpm, total weight of just 22 Tons and ability to fire the ammunition of the American 5” Mark 45 gun. Its Vulcano rounds (HEFSDS) include, GPS/IMU guided ammunition capable of engaging land targets at a range >100 km, and unguided ammunition with an infrared seeker, with a range of 70 km in anti surface warfare role. VULCANO is a family of Extended Range (ER) unguided ammunition and Long Range (LR) guided ammunition for the 127mm naval guns as well as 155mm land artillery systems.

The Russians have developed three fast firing automatic guns, AK-176M: L/59 caliber, 120 rpm; AK-100: L/59, 60 rpm; and AK-130: L/54, 84-rpm. The 100mm A190 (E) variant offers much higher accuracy with 80 rpm, in addition to the unguided shells; it is also available with rocket-assisted and guided long-range shells.

The 155mm (6-inch) Advanced Gun System (AGS), manufactured by BAE Systems (Minneapolis), provides a heavy volume, precise and sustained gun fire support to forces on land. The AGS would be fitted on three Zumwalt (DDG 1000) class destroyers to support their Naval Surface Fire Support (NSFS) missions. Up to 10 Long Range Land Attack Projectile (LRLAP) rounds per minute can be fired from each gun from an automated 304 round magazine. The LRLAP ammunition is being developed by BAE Louisville, Kentucky and Lockheed Martin Missile and Fire Control, Florida. The LRLAP is capable of hitting targets up to a range of 137 km with the rocket booster assisted launch. The LRLAP deploys its fins after ejection from the barrel and a combination of GPS and Inertial Navigation System guide it. However, since the AGS design is specific to the Zumwalt class, it cannot be retrofitted on any of the existing ships; BAE has therefore come up with 155 mm AGS-Lite (AGS-L). The AGS-L can fire the LRLAP round up to a range of 74 nautical miles at the rate of six rounds per minute for land targets and is also able to fire a high capacity ballistic 155 mm ASuW projectile (ASuWP).

Close in Weapon System CIWS A close in weapon system is a last ditch measure to target incoming anti ship missiles/aircraft. CIWS gun systems have suffered from some drawbacks as compared to CIWS Missile systems, firstly, gun systems are unable to target missiles which use way point targeting. Secondly, CIWS gun systems take time to train on to other missiles, which may be targeting the ship, and there is a probability that the missile on being hit may not deviate sufficiently from its path. Lastly, the effective kill range of gun systems is much less than 4500 meters, and is said to lie between 500 meters and 800 meters, which gives an interception time of about ½ a second against supersonic anti ship cruise missiles (ASCMs) and implies that fragments from the destroyed missile could still hit the ship. CIWS gun systems have been retained as a terminal effort to tackle on coming ASCMs, in fact CIWS today employ both guns as well as missiles.

 

The US navy has ~250 of the Raytheon’s Mk 15 Mod 21-28 Phalanx CIWS autonomous combat systems. The Phalanx System is designed as a standalone-integrated system. It encompasses search, detection, target declaration, tracking, threat elevation, engagement, fire control, and damage assessment. This ensures rapid reaction time required for CIWS. Being a standalone system with its own radar and electro-optic system, it can be also be deployed by bolting to decks of ships which do not have any type of combat system. The Phalanx system has the M61A1 20 mm Gatling gun, providing a rate of fire between 3000-4500 kinetic energy rounds per minute. The gun is electronically controlled and pneumatically driven. The round is 20 mm MK 149 armour piercing discarding sabot produced by General Dynamics Ordnance and Tactical Systems. The Block 1B configuration with FLIR caters for defence against asymmetric threats such as UAVs, small, fast surface craft, and slow-flying aircraft. The SeaRAM Mk 15 Mod 31 CIWS, under development, is designed as a companion system based upon the Block 1B Phalanx to target supersonic ASCMs. The gun has been replaced with an 11 cell RIM 116 Rolling Airframe Missile (RAM) launcher. The RAM is a Mach 2+ missile with a blast fragmentation warhead of 11.2 Kg. It has a range of 9 km. In case of the CIWS, companion systems having both the gun and the missile launcher appear to be the future trend.

The major guns of the Indian Navy include the Russian 100 mm and the Italian 76.2 SRGM (produced at BHEL Hardwar under TOT). Its CIWS gun systems include AK630 and the marinised BMP 30 mm Russian guns. For defense against very close quarter, boat swarms it has deployed the indigenous 12.7 mm HMG. Indian Navy has been searching for a main gun in the 127 mm or higher calibers, which can be produced in India along with its ammunition. The TOT should also include production of future upgrades. The economics of scale can easily be achieved if a gun system compatible with requirements of the Indian army (on the lines of the 30 mm BMP or the 12.7 mm HMG) can be selected. With respect to CIWS the Indian navy needs to replace its 30 mm gun in future with a higher caliber gun system compatible with the Indian Army and the Indian Air Force. The DAC has cleared a proposal for 116 in number 30 mm guns for the warships in 2012. A RFI for 30 in number 40mm guns with EOFS was also issued in 2011.

Conclusion The torpedo is set to remain the foremost weapon against the lurking submarine for a long time to come. The missile proliferation will continue with the advancements in emerging technologies and micro miniaturization. However, the missile will gain supremacy only when it becomes cost effective vis-à-vis the gun and its ammunition. The naval gun will continue to be a part of a warship’s armament for the next 10 to 15 years. This is because of its rugged design and ability to remain cost effective as compared to missiles by continuously evolving and incorporating technological advancements not only in the mount but also in its ammunition, to meet emerging threats at sea and in the littorals.

Commonality in weapon systems leading to local production is the only way to self-reliance in, surface-to-surface missiles, anti-air and anti-missile defense, and medium and small caliber gun systems.

 

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