Category Archives: MK 54

48.Airborne Anti Submarine Warfare

(Published SP’s Special Supplement to Aero Inida 2015;19 Feb-21 Feb 2015)

Standoff antisubmarine capabilities continue to be of vital interest to the Navies across the world. The current environment of littoral warfare has once again brought in to sharp focus the threat of the lurking diesel submarine and the means of tackling it by the use of helicopters and aircraft. Some of the noteworthy anti submarine warfare platforms are discussed in brief in the succeeding paragraphs.

The Sikorsky CH-148 Cyclone is a twin-engine, multi-role shipboard helicopter being developed by the Sikorsky Aircraft Corporation. CH-148 is designed for shipboard operations and is intended to replace the CH-124 Sea King. It has a metal and composite airframe. A number of safety features such as flaw tolerance, bird strike capability, and engine burst containment have been incorporated into the design. It  is equipped to search and locate submarines during ASW. The Integrated Mission System and the Sonobuoy Acoustic Processing System are being developed by General Dynamics Canada. The sonar is an L-3 HELRAS, the radar is a Telephonics APS-143B, the Electro Optic System a Flir Systems SAFIRE III, and the ESM a Lockheed Martin AN/ALQ-210. CMC Electronics provides the flight management system CMA-2082MH Aircraft Management System. It carries 2 x MK-46 torpedoes on a bomb rack BRU-14 mounted in folding weapons pylons and a door-arm mounted general-purpose machine gun.


The Agusta Westland AW101 is a medium-lift helicopter used in both military and civil applications. It has a digital automatic flight control system (AFCS) manufactured by Smiths Aerospace. This allows the operation of a four-axis (pitch, roll, yaw, and collective) autopilot and the automatic stabilization system, and is linked in with the aircraft’s flight management systems. The AFCS is a dual-duplex system using two flight computers to provide redundancy and fault-tolerance.

The AW101’s navigation system includes a GPS receiver and inertial navigation system, VHF Omni directional radio range (VOR), instrument landing system (ILS), Tactical air navigation system TACAN, and automatic direction finding. The Mk1 and Mk3 are equipped with a Doppler velocity system (DVS) which provides relative ground velocities; the DVS is also linked into the AFCS as part of the auto stabilization system. For safety, the aircraft is equipped with obstacle and terrain avoidance warning systems and traffic collision avoidance system (TCAS).

The AW101 is equipped with the Blue Kestrel search and detection radar, which is capable of 360 degree scanning and can detect small targets as far as 25 nautical miles. Royal Navy Merlins are equipped with the AQS901 anti-submarine system for processing sonographic data from sonobuoys to detect and target submerged submarines. Most variants of the AW101 are equipped with self-defense systems such as chaff and flare dispensers, directed infrared countermeasures (infrared jammers), ESM (electronic support measures in the form of RF heads), and a laser detection and warning system. Two hard points are present on the underside of the airframe on which it can carry four Sting Ray torpedoes or Mk 11 Mod 3 depth charges.


The Airbus/Agusta Westland produced NH90 is designed to fulfill a NATO staff requirement for a multi-role, medium-sized military helicopter for both land and maritime operations. NH90 is the first helicopter in the world to be equipped with full fly-by-wire flight controls. NH90 is either fitted with Rolls-Royce Turbomeca RTM322 or General Electric T700E power plants.

The NH90 features a range of customizable avionics systems, dependent on customer selection and purpose. On some models, Thales Group provides various parts of the avionics, such as the glass cockpit, full-color multifunction displays, tactical mission and encrypted communication systems, the TopOwel helmet-mounted sight/display, IFF, and navigation systems, and the electrical power generation system. The naval NFH variant is outfitted with dipping sonar and sonobuoy processing equipment.

The Boeing P-8 Poseidon is a military aircraft developed for the United States Navy by Boeing Defense, Space & Security. The P-8 conducts anti-submarine warfare (ASW), anti-surface warfare (ASUW), and shipping interdiction, along with electronic signals intelligence (ELINT) role. The P8 can carry torpedoes, depth charges, SLAM-ER missiles, Harpoon anti-ship missiles, and other weapons. It is able to drop and monitor sonobuoys. It is designed to operate in conjunction with the Northrop Grumman MQ-4C Triton Broad Area Maritime Surveillance unmanned aerial vehicle.

ASW Armament

The ASW armament carried today by maritime aircraft and helicopters includes lightweight torpedoes, depth charges, and bombs.

Air Dropped Depth Charges and Bombs. Depth charges have again come into focus because of the ASW threat in littorals. These can be very effectively utilized for flushing out the lurking diesel submarines. Two depth charges are worthy of mention, these are the MK11 depth charge of UK and the BDC 204 depth charge of Sweden.

The Mk 11 depth charge was developed by British Aerospace (now BAE Systems) for air delivery from maritime aircraft and helicopters. The Mk 11 depth charge was designed for shallow water operations against submarines on the surface or at periscope depths. It is fully compatible for carriage and release from a wide range of ASW helicopters and fixed-wing maritime patrol aircraft. The Mod 3 version incorporates a 4 mm mild steel outer case and nose section, which is designed to withstand entry into the water at high velocities without distortion. It has been cleared for carriage on Lynx, Merlin, NH90, Sea King, and Wasp helicopters.


The BDC 204 depth charge was developed by Bofors Underwater Systems (now Saab Dynamics) for air delivery from maritime aircraft and helicopters of the Swedish Navy. The depth charge can be deployed in patterns, with different depth charges set to detonate at different depths to achieve profound shock and damage to submarines. They have been cleared for carriage on the Boeing Vertol 107 helicopter and CASA C-212 Aviocar maritime patrol aircraft.

Air Launched Torpedoes. Few of the prominent air launched torpedoes are described below.

Stingray is a LWT manufactured by BAE Systems. It has a diameter of 324mm, weight of 267kg, and length of 2.6m. Its speed is 45kts with a range of 8km and its warhead is 45kg of Torpex. It can dive up to 800m.Stingray is fed with target data and other associated information prior to its launch, after entering water it searches for target autonomously in active mode and on acquiring the same, attacks it. It is carried by Nimrod aircraft. Stingray Mod1 is reported to have a shaped charge warhead and improved shallow water performance.

Mk46 Mod5 torpedo is the mainstay of US Navy’s air launched lightweight torpedoes. It is manufactured by Alliant Tech systems. It has a diameter of 324mm, length of 2.59m, with a weight of 231kg.It runs on Otto fuel, has a range of 11km with a speed of 40kts, and can dive upto365m. It has a PBXN-103 warhead of 44kg. It has an advanced digital computer control system with a built in logic and tactics for search and re-attack. It has effectively performed in both deep and shallow waters and can attack both the nuclear as well as the smaller diesel submarine. Over 25000 MK46 torpedoes have been supplied to customers until date. Interestingly the Chinese YU-7 torpedo is said to have been developed from the MK46 Mod2.

The Mk 54 Lightweight Torpedo is a hybrid of technologies taken from MK 46, MK48 and MK50 torpedoes. It is supposed to have homing and warhead of the MK50 and propulsion package of the MK46 torpedo. It has incorporated COTS processing technologies for an advanced guidance and control system. It is stated to have sophisticated shallow water capabilities for littoral threats. The MK54 torpedo has been finalized for P8i aircraft by India.

The A244/S developed by WAAS and currently manufactured by the Euro Torp consortium 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. Its Homing head can function in mixed, active, or passive modes. It has special signal processing to distinguish target from decoys.

A244/S Mod.3 is the latest upgrade of the A244/S. It has more powerful propulsion battery, with an increased number of cells, which ensures a 50% increase in the endurance of the weapon to13.5 km. It has an Advanced Digital Signal Processor module to counter sophisticated torpedo countermeasures .The homing head has preformed multiple transmission and reception beams and multi-frequency operating capability. It can classify and track several targets simultaneously, and discriminate between the target and countermeasures.


 MU90/Impact is in mass production for 6 major NATO and Allied Countries. The MU90/IMPACT torpedo is 323.7mm ‘NATO Standard’ caliber, 2.85 mm long with a weight of 304 kg. It is powered by an Aluminum-Silver Oxide seawater battery using dissolved sodium-dioxide powder as electrolyte with a closed-loop electrolyte re-circulation system, the torpedo is propelled by an electronically controlled high-RPM brush-less motor driving a skewed multi-blade pump jet propulsor allowing a continuously variable torpedo speed automatically selected by in built logic of the torpedo. The control and guidance electronics has embedded operational and tactical software including the signal processing, the data processing, and the torpedo guidance algorithms, which enable the MU90 to continuously self-adapt its configuration and tactics. The inertial system is based on ‘strap-down’ technology enabling all-attitudes capability including bottom following capability. The warhead consists of V350 explosive, fully insensitive, shaped charge warhead, with an impact type exploder incorporating two mechanical and six electrical independent safety devices.

 Low Cost Anti Submarine Weapon (CLAW) A200/A is a miniature torpedo developed by WASS. LCAW has been developed as an intermediary between air launched torpedoes and conventional depth charges. It is a low cost option, which provides propulsion and guidance to a depth charge without the costs of a torpedo. The air dropped version A200/A is deployed from aerial sonar buoy dispensers. The weapon is primarily designed to engage targets in shallow water, like midget submarines. The A200/A version has a length of 914.4mm, weight of 12kg, and a diameter of 123.8 mm. The warhead is a 2.5kg PBX shaped charge and the LCAW has an operating depth from 15m to300m. It has a speed of about 18kts with a range of 2km.

Indian Navy

The Indian Navy has ordered 8 in number of the P-8I Neptune version of the Boeing P-8 Poseidon. The aircraft includes six additional body fuel tanks for extended range from Marshall Aerospace; three of the tanks are located in the forward cargo compartment and three in the rear. In-flight refueling is via a receptacle on top of the forward fuselage, just aft of the cockpit. In order to power the additional electronics, the P-8 has an 180kVA electric generator. The P-8 uses data fusion software to combine its various sensors for target tracking.

The Bharat Electronics Limited (BEL) Data Link II communications allows the P-8I to exchange tactical data between Indian Navy aircraft, ships, and shore establishments. The P-8I features an integrated BEL-developed IFF system. India has purchased AGM-84L Harpoon Block II Missiles and Mk 54 All-Up-Round Lightweight Torpedoes for the P-8I. The Indian Navy inducted its first P-8I on 15 May 2013. The second and third P-8Is were received on 16 and 22 November 2013 respectively. In 2014, several Indian Navy P-8Is conducted search operations for the missing Malaysia Airlines Flight 370. The aircraft carries Raytheon APY-10 multi-mission surface search radar and is likely to have Advanced Airborne Sensor surface search radar and SIGINT package in the follow on program. It has 5 internal and 6 external stations for AGM-84H/K SLAM-ER, AGM-84 Harpoon, Mark 54 torpedo, missiles, mines, torpedoes, bombs, and a High Altitude Anti-Submarine Warfare Weapon system.

India’s Navy has selected Sikorsky Aircraft Corp., a subsidiary of United Technologies Corp. (NYSE:UTX), to fulfill the  Multi-Role Helicopter requirement for anti-submarine and anti-surface warfare (ASW/ASuW). Negotiations will now commence to procure 16 S-70B SEAHAWK helicopters, with an option for eight additional aircraft, along with a complete logistics support and training program. The Indian Navy S-70B variant will include avionics and flexible open architecture Weapons Management Systems that integrate advanced sonar, 360-degree search radar, modern air-to-surface missiles, and torpedoes for the ASW role. A blade and tail fold capability will facilitate shipboard storage.

Indian Navy has a requirement for 120 Helicopters (NMRH) in the 9-12.5 tons category. The NMRH is envisaged to carry out the ASW as well as the ASuW roles. Indian Navy is also interested in procuring 56 light utility helicopters for ASW and other support roles in the 4.5-ton class. In addition, there is a need to build an Indian Multirole Helicopter domestically in collaboration with HAL in the 12-ton class

24. Hovering Danger- Guided Weapons of Naval Helicopters

(Published in SP’s Naval Forces, Jun-Jul 2013)

Hovering Danger- Guided Weapons of Naval Helicopters

The first helicopter to be widely used in the US and the UK navies was the Sikorsky R-4, powered by a radial engine to rotate its main rotor with three blades. Interestingly the earliest use of the R-4/R-5 helicopter was as a ‘plane guard’ to recover pilots in case they ditched near the aircraft carriers. In fact the US Navy at one time opined that the helicopter would never be big enough for useful deployment at sea by the Navy! Today with advancement in technology, the Naval Helicopters are assigned the tasks of; Anti submarine Warfare (ASW), Combat Search and Rescue (SAR), anti ship surveillance and targeting (ASuW), Mine warfare countermeasures (MCM), surveillance, reconnaissance and target acquisition, over the horizon targeting, electronic countermeasures (ECM), communication relay, Naval surface fire support (NSFS), ship boarding and Utility. In fact the capabilities and sub capabilities of the SH-60 helicopter with the US Navy additionally include; Amphibious Warfare, Anti Air warfare, Electronic warfare, Fleet support operations; Command, control and communications etc.

The development of the Naval Helicopter today, owes its lineage to its primary development in an anti submarine role to combat enemy submarines. The US Navy visualised the role of the Naval Helicopter in combating the German Submarines which were threatening US as well as allied shipping. It was envisaged that Coast Guard pilots would fly the helicopters to guard the convoys by scouting for submarines and operate from the platforms on decks of merchant ships. The first Sikorsky R-4 Naval helicopter was inducted in 1943. Thereafter it began the trials for ‘Evaluation of the Ship Based Helicopter in Anti-Submarine Warfare’. In the anti submarine role it was thought that once the sonar of a destroyer detected a submarine the Helicopter would be guided to the submarines location and would drop a MK IX 200-pound depth charge, thereafter it would be replenished from the destroyer. In 1944, trials were carried out to fit the helicopter with dipping sonar, to  make it more autonomous, the fears of excessive noise due to rotors and downward wash proved to be unfounded, further, as a spin off it was observed that helicopters were very useful in alignment of fire control and anti aircraft radars. Thereafter in the late fifties ASW helicopters were equipped with light weight torpedoes and they were extensively used to track and detect nuclear submarines. The Sea King and the LAMPS followed, the current version SH-60 R has upgraded avionics, multimode radar, advanced low frequency sonar, guns, missiles and torpedoes for combating targets in the littoral regions.

Indian Navy has a requirement for both multi role as well as light utility helicopters, to replace its aging Sea Kings and Chetaks. The Multi Role helicopter procurement is at commercial bid opening stage, with two contenders namely Augusta Westland NH-90 and Sikorsky S-70B. Indian Navy has also issued an RFI for 120 Helicopters (NMRH) in the 9-12.5 tons category and RFP is likely in a couple of months. The NMRH is envisaged to carry out the ASW as well as the ASuW roles. Indian Navy has also issued an RFP for 56 light utility helicopters for ASW and other support roles.

The essential weapons on board the Naval helicopters are the aerial torpedo (Light weight Torpedo, LWT) and the anti shipping missiles, therefore it would be worthwhile to look at few prominent weapons in these categories.

Helicopter Launched Aerial Torpedoes

The aerial torpedoes were extensively used in the WW II; however, it is a fact that with the advent of the cruise missile the torpedo has been confined to its role against submerged submarines only. The anti shipping missiles have longer range, much higher speeds and easier deployment than the aerial torpedoes and therefore they are preferred for the anti shipping role.

A244 S Mod 3 is an upgrade of the A 244S from WASS Italy. The main improvements include an acoustic seeker which has pre-formed multiple transmission and reception beams and multi-frequency operating capability. This ensures high performance in very shallow waters and at very long engagement distances. The warhead is Omni-directional type which is designed to maximise the lethal effect. Simultaneous classification and tracking of several targets is possible due to its advanced Digital Signal Processor, which is also able to clearly discriminate between the real and false targets. The battery package has increased number of cells which gives the Mod 3 an increase of about 50% in range. It also features a D-C contra rotating motor with an electronic controller for variable speed propulsion. The main features of its homing head include; active homing ranges greater than 2100 m, very low TS acquisition capability, Narrow and broad band modes, Active /passive modes, capability to detect bottomed targets, classification based upon spatial diversity, multi frequency, and signal processing. Its low noise and programmable acoustic enabling delays detection by the target ship of the oncoming torpedo. With a length of 2.75 m, weight of 250 Kg it has a maximum speed of 38 kts and an endurance of 13500 m/10000 m depending upon low/high speed.

The MU90/IMPACT marketed by the consortium EUROTORP is the main NATO torpedo and is considered to be the most advanced LWT. It weighs 304 Kg and has length of 3.237 m. It is claimed that pre-arrangements to cope with Submarine-Launched Anti-Air-Missile (SLAAM) have already been incorporated in the system. It can operate between depths of 25 m to 1000 m and is navigable up to 3 m. It is claimed that its multi-frequency, parallel processing and simultaneous acoustic modes operation, allow multi-target tracking capability, and provides the weapon with immunity against anti-torpedo countermeasures. The strap down control and guidance capability allows it to manoeuvre in all attitudes. It has an engagement range of 15000 m. The warhead is STAGNAG compliant V350 insensitive shaped charge with an impact exploder. The safeties include two mechanical and six independent electrical devices.

 The MK 54 by Raytheon incorporates the best of technologies from MK 50, MK 48 ADCAP and MK 46 torpedoes. The acoustic head, an upgrade from MK 50, provides low self-noise and superior  performance in littoral areas. Control and guidance is a combination of features from MK 48 and MK 50 with the latest commercial-off-the-shelf (COTS) processing power (14 gigaflops) in an expandable open architecture. The warhead consists of the MK 103 Mod 1 Warhead and the MK 20 Mod 0 Exploder.

 The Flash Black from WASS, currently under development, is claimed to have features of the next generation of LWTs. The design of the Flash Black is highly versatile with the capability to be launched from multiple platforms (underwater and AUV, UUV and USV), against any target and in any environment, including littoral waters and in extremely shallow depths. It can counter even the most sophisticated countermeasures.

Helicopter Launched Anti Ship Missiles

 The major role of the Naval Helicopter in an anti ship operation is that of the Over the Horizon Targeting (OTH) of anti ship cruise missiles (ASCM). This requires that target vessel be acquired, tracked and the data passed on to the main ship and/or carry out mid course and terminal guidance of the launched ASCM. The Naval helicopter is generally armed with lighter missiles capable of destroying smaller craft and crippling larger ships, it provides protection to own ship against patrol boats; fast attack crafts etc. and supports the launch ship against larger enemy ships.

 The AS.12 anti ship missile was inducted in the French Navy in 1960 for attacking ships and submarines on the surface. It had a bulging nose and four clipped triangular wings. It functioned with two solid fuel rocket motors; a powerful booster rocket that burned for 2.2 seconds and a sustainer motor that burned for 28 seconds. The missile guidance was by using four metal vanes around the exhaust nozzle in a thrust vectoring system, the steering signals were sent to the missile by means of two wires which were paid out from two spools on the rear of the missile. A gas operated arming mechanism fed from the sustainer motor, armed the warhead 7.7 seconds after launch. The weight of the warhead was 28 kg.

The Penguin was the first NATO anti ship missile with an infra red seeker developed in collaboration between the Kongsberg Våpenfabrikk and Norwegian Defence Research Establishment, with financial support from West Germany and USA. It entered service in 1972. It could be fired from a number of helicopters like SH 60 Seahawk and Westland Super Lynx. The missile was inertial guided until the autonomous terminal phase. It had a solid rocket engine and a 120 kg warhead.

Another light weight anti ship missile for deployment form the Lynx helicopter is the British Sea Skua, which has a blast fragmentation SAP warhead of 28 kg. It can travel at one of the four preselected heights based upon the prevailing sea surface conditions; it climbs up as it nears the target to acquire it. The Missile homes on to the target illuminated by the helicopters radar.

Marte MK 2/S is an anti-ship missile by MBDA which is fully qualified on helicopter AW 101. The Marte MK 2/S is the technologically advanced version of Marte MK 2 of the Italian Navy’s SH3D helicopter fleet. It has a weight of 310 kg, length of 3.85 m. It is a high subsonic missile with a range of 30 km. Marte  ER is the advanced version of the Marte series, while it retains the existing features like the sea skimming capability, all weather operation and the radar homing head, it has an extended range of over 100 km. The longer range is the result of incorporating a turbo jet engine. This, along with advanced avionics enable the missile to have multiple selectable trajectories and flight profiles, an option for in-flight target re-vectoring is also available. High subsonic speed, ECCM, inertial and GPS navigation would make it a formidable weapon in both littoral as well as high sea environment. It would be fully interoperable with the MK 2/S version.

 DELILAH HL, this missile for the helicopter launch has been developed by Israel Military Industries (IMI) from its successful DELILAH missile. It offers new offensive capabilities for attacking targets in coastal, littoral, blue waters and on land. With a range of over 250 km it allows the helicopter to remain outside the range of long and medium range SAMs as well as the air defence systems of the enemy ship. The missile has a weight of 230 kg, with a length of 3.20 m. It has INS/GPS navigation with a data link for target validation. The warhead weight is 30 kg and it has speeds between Mach 0.3 – 0.7.

 The Exocet AM 39 is the air launched version of the Exocet missile family, and a product of MBDA. The missile weighs 670 kg, it is 4.6 m long and it flies at a speed of 315 m/sec. It has a solid propellant engine, with a booster and a sustainer, and a range of 70 km. Its warhead is 165 kg of insensitive explosive, optimised for HE blast and pre-fragmented effects, with impact fuse and proximity function. It is an inertial guided missile with active radar homing for the end phase. It flies very close to the sea surface (≤ 2m) which gives very little reaction time to the target. It is a battle proven missile.

 Future Trends

Developments in the unmanned rotary craft technology has opened entirely new vistas to weapon designers who are taking inspiration from mini weapons developed for UAVs for incorporation in to the unmanned helicopters. An example of the unmanned helicopter is the MQ 8B Sea Scout, the marinised version of the MQ 8B Fire Scout, being developed by Northrop Grumman for the US Navy. The Sea Scout would be fitted with an Advanced Precision Kill Weapon System which is a laser guided 70 mm rocket. In addition the US navy has asked that RDR-1700 Surveillance Radar be mounted underneath the Sea Scout; this synthetic aperture radar can look through sandstorms and clouds and can track 20 air/ surface targets.

 The transition from the naval helicopter to the smaller and lighter unmanned naval helicopter appears to be certainty (at least partially), which would ensure availability of these unmanned craft on much larger number of smaller ships. This would lead to rapid development of associated weapons, like micro miniaturised missiles and ultra light weight torpedoes, which could relieve the ship of targeting smaller craft and midget submarines in the littoral environment.