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Home > Back Issues (Journal) > Journal V24 N4 (Oct - Dec 1998) > The Anti-Ship Missile - A Revolution in Naval Warfare

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The Anti-Ship Missile - A Revolution in Naval Warfare
by MAJ Stephen Sim

PREDATOR OF THE SEA

On 21 Oct 1967, the Eilat, an Israeli destroyer burst into flames and sank into the Mediterranean amidst a thick cloud of smoke. She had been struck by two Russian-made SSN-2 missiles fired by a small Egyptian Osa fast attack craft which did not even bother to leave Alexandria Harbour. The missile came to be known the world over as the Styx.

The incident created shock waves throughout the Western world, which had, until then, largely ignored the destructive powers of the anti-ship missile and its potential in winning a decisive naval battle. The ensuing years saw the Western countries in a frenzy to develop their own anti-ship missiles and shipboard defence systems, the latter to protect the ships against these missiles. These early efforts laid the foundation for the emergence of the present day anti-ship missile which are faster, smaller, smarter, more accurate and more deadly over longer ranges compared to those in the 1960s.

The first real test of the modern anti-ship missile came in the Falklands War in 1982. The British destroyer HMS Sheffield, an advanced modern warship, was destroyed by a single French made Exocet fired from an Argentinean Super Etendard fighter aircraft. Two more Exocets were subsequently used with success against the large container ship, Atlantic Conveyor. Such was the lethality of the anti-ship missile which left even the most heavily armed and defended warships vulnerable. The advent of the anti-ship missile signaled the end of guns and artillery as the mainstay of naval weapons. Naval tactics and operations as well as the design of warships also saw radical transformations as a consequence. Indeed, the anti-ship missile is nothing short of a revolution in naval history for it ushered in the modern age in naval warfare, the abandoning of archaic and traditional war fighting methods and the dependence on science and technology to achieve military success.

BIRTH OF A MENACE

Although the anti-ship missile has its roots as a simple radio-controlled glider bomb developed by Siemens-Shuckert Werke of Germany in 1915, its first operational use was during World War II. In the summer of 1944, Allied ships in the English Channel were bombarded by German made Mistels. The Mistel was actually a composite aircraft consisting of a Ju 88 rebuilt with a gigantic warhead (approximately 7000 lbs) in place of the crew compartment and guided by radio from a fighter which flew to the target area actually mounted above the pilotless bomber. The missile was crude and rudimentary and had limited success against the Allied ships. Its smaller cousin, the HS 293, essentially a 2304 lb bomb propelled by an underslung rocket, had far more success. Some 2300 HS 293s were launched during World War II and it had the distinction of being the first missile ever to destroy a warship in battle when it sank the escort HMS Egret on 27 August 1943. The HS 293 had a manual guidance system which required an operator to steer the missile to its intended target via radio remote control. The missile was air-launched and had a range of up to 11 miles.

Like the Germans, the Americans also used missiles during World War II. In May 1945, Bats hung under the wings of US Navy PB4Y-2 Privateer patrol bombers sank many Japanese ships, including a destroyer from a range of 20 miles. The 1880 lb missile distinguished itself from all other missiles in those days in that it had a much more advanced guidance system made possible by a small radar in the nose. The missile homed in on the radar reflections from the target ship - the first appearance of active radar homing technology.

Strangely enough, American missile development seemed to have taken a step backwards in the immediate post-war period when it opted for the manually guided Bullpup. The air-launched missile was produced in huge quantities for use by many American aircraft ranging from the A-4 Skyhawks and the F-104 to the P-3 Orion. The first batch of Bullpups entered service in 1959. It was crude in comparison with the Bat and was essentially a 250 lb bomb with a rocket at the back. The missile was guided to its target by an operator through a miniature joystick on the launch aircraft.

While the Americans abandoned radar guidance in the 1950s, the Swedes adopted the radar homing technology from the Bat. A collaboration between a group of Swedish companies and a British rocket-motor supplier saw the introduction of the RB 04 in 1958. The missile utilised active-radar homing and had a range of 20 miles. It was designed to be air-launched (such as from the AJ37A Viggen) and had a 661 lb warhead. The RB 04 had a true "fire-and-forget" capability. As soon as the launch aircraft had sighted the distant target on radar, it could cue the missile's own radar to lock on, and the aircraft would release the missile. The aircraft could then turn away immediately, leaving the missile to home on the target by itself.

THE MODERN AGE

Up until the late 1950s, all anti-ship missiles were either rocket-propelled bombs or essentially small airplanes packed with explosives, and could be launched only by an aircraft. The next major development arrived in the form of the Russian-made SSN-2 Styx. The missile had a range of 26 miles and a speed of 600 mph. Its guidance system was considerably more sophisticated than those mentioned earlier. Mid-course guidance was either through auto-pilot or radio-command guidance, while the terminal guidance could have active-radar or infra-red homing. With a launch weight of 5550 lbs and a warhead of 882 lbs, the Styx could destroy all but the largest warship, and cause severe damage to the latter. Perhaps the most significant feature of the Styx was that it was packaged into aluminum box launchers which were then installed on small fast patrol boats (FPBs) such as the Komars and Osas which displaced no more than 250 tons. This effectively gave small FPBs the fire-power to threaten their more illustrious brethren, the destroyers and cruisers. Indeed, capital ships armed only with guns were at the mercy of these fast-moving missile-armed FPBs and this was amply demonstrated in the sinking of the Eilat.

The next stage of development of the missile was the introduction of sea-skimmers, such as the Russian SSN-7 which had active-radar homing and a range of up to 35 miles. It was also the first missile to combine sea skimming with submerged launch capability. The SSN-7 was developed in an era when it was realised that reaching a heavily armed warship bristling with radar equipment required that the missile come in as low above the water as possible to avoid radar detection. Sea-skimmers are held by radio altimeter and autopilot at a very low height above the sea to avoid radar detection. Examples of other early sea skimmers include the Israeli Gabriel, the Swedish RB 08 and the Norwegian Penguin.

By the late 1960s, the missiles bore much resemblance to the modem ones which we are familiar with today. The missiles were no longer merely bombs with a rocket attachment at the back, nor small airplanes packed with explosives, but had purpose-built rocket propulsion, cruciform wings and were compact, sleek and aerodynamic. The missiles were usually small enough to reduce the possibility of radar detection at long ranges and were agile and fast to avoid being shot down by shipboard defences. In addition, most were sea-skimmers to further make radar detection difficult. Terminal pop-up attacks were also frequently incorporated to present the missile radar seeker a better view of its target prior to homing as well as to confuse the target ship's defences in the last few vital seconds before impact. The missile warheads had a delay fuze to ensure hull penetration prior to detonation of the explosives in order to inflict maximum damage to the target

The present day anti-ship missile is epitomised by the Harpoon, a "fire-and-forget" cruise missile built by MacDonnell Douglas. The Harpoon entered service with the US Navy in 1976 as the Block lA. The Block lA was powered by a small turbojet engine which gave it a range in excess of 60 miles. It was armed with a 500 lb penetration/blast type warhead which was capable of disabling all ships except large cruisers and carriers. Mid-course guidance was by a strapdown inertial platform and the terminal guidance was active homing through a Texas Instruments frequency-agile radar. The missile was equipped with a host of ECCM (Electronic Counter Counter-measures) such as passive-homing, re-acquisition and fly-through recovery, etc. that ensured a high kill probability. The terminal phase can either be a sea-skim or a pop-up manoeuvre. The Harpoon can be launched from aircraft, ships (including FPBs) and submarines. Several versions of the Harpoon have been developed over the years incorporating improvements in the range, the guidance system and ECCM features.

The greatest rival to the Harpoon is arguably the Exocet, built by Aerospatiale of France. Like the Harpoon, the Exocet has a "fire-and-forget" capability, a mid-course inertial guidance and active-radar homing in the terminal phase. However, unlike the Harpoon, the Exocet has rocket propulsion giving it a higher cruise speed but a shorter maximum range. The rocket propulsion also enables the missile to be fired at only a few seconds notice. The Exocet is a sea-skimmer, cruising at an altitude of 8 feet all the way to the target. Detonation of the warhead can be either through delay action or proximity fuze.

The Harpoon and Exocet have been widely exported to navies around the world and both missiles have demonstrated operational success particularly during the Falklands War in 1982 and the Gulf War in 1991. Such reported successes have made the anti-ship missile almost mandatory on modern warships and its incorporation into the ship's weaponry has greatly influenced modern ship design and even naval operations.

Technology Evolution

Until the Eilat saga in the mid l960s, the primary anti-ship weapons were naval guns and, to a lesser extent, torpedoes. In spite of modern sophisticated fire control systems, gun fire is relatively inaccurate since the ballistics of the ammunition is heavily dependent on meteorological conditions such as wind, temperature, precipitation, etc. This limitation, together with the small warhead on most gun ammunition, meant that more rounds would be needed to achieve the same degree of damage to the enemy vessel which would otherwise be inflicted by a single anti-ship missile.

As a result of this limitation, heavier calibre guns were mounted on warships to increase the lethality and range. This was evident during World War II which saw the commissioning of mammoth guns with calibre ranging from 15-in to 18-in on the battleships. Artilleries of such calibre require platforms of monstrous proportions. For instance the Yamato of the Japanese Navy, armed with nine 18-in guns in three turrets, was 263m long and displaced an outrageous 71 659 tons - the largest and most heavily armed battleship ever to put to sea. The more familiar Iowa of the US Navy, armed with nine 16-in guns in three turrets, measures 270m and displaced 55 710 tons. Yet in spite of such grandeur and spectacle, the humble FPB could have easily inflicted substantial damage on the colossal Yamato and Iowa with the longer range, greater accuracy and a more lethal warhead, which the anti-ship missile offers.

Torpedo-armed ships are likely to be FPBs due to the short ranges of torpedoes. In this case, high speed and manoeuvrability are essential to enable the FPB to get close enough to the enemy ship and fire the torpedoes. As torpedoes are of much shorter ranges than guns and missiles, the FPB would be subjected to enemy fire well before it is in a position to launch its torpedoes. Although torpedo-armed FPBs are still very much in use in many navies in the world, their roles are generally limited to strike operations against gun boats or the harassment of merchant shipping. Against missile-armed warships, the torpedo-armed FPB is virtually helpless.

The anti-ship missile scores on many counts over guns and torpedoes. For example, a single Exocet is able to strike an enemy ship beyond the horizon (up to 20 miles) at high sub-sonic speed with deadly accuracy and deliver a 364 lb warhead that is sufficient to inflict considerable damage and incapacitate all but the largest warship. Two or more salvoes would be capable of disabling the latter. In contrast, to achieve such ranges, a gun calibre of about 15-in or greater would be needed, and more rounds would have to be expended due to inherent inaccuracies of ballistic flight. While the Exocet firer is free to manoeuvre upon releasing the weapon, the gun platform has to maintain a constant lock-on using the fire control system or gun fire director, and this exposes the ship to subsequent attacks.

As mentioned earlier, a huge platform would be needed for mounting heavy calibre guns. The anti-ship missile, on the other hand, is light and compact and can be found on small FPBs, giving the latter a destructive power equivalent to a large gun-armed capital ship. For example, the Harpoon RGM-84A weighs only 1470 lb, a third of which is the warhead, and it can be fired from a 21- in tube of a submarine. Eight Harpoons can easily be mounted on a FPB displacing no more than 250 tons. FPBs are much cheaper compared to destroyers and frigates, and present an inexpensive solution to third world countries in search of a capable and modern naval force. Following the sinking of the Eilat, large numbers of missile-armed FPBs were acquired by navies throughout the world. The appearance of the anti-ship missile marked the end of the big guns of World War II and battleships were largely consigned to the annals of military history and in naval museums.

Besides giving the FPBs the fire power of much larger warships, the anti-ship missile enables large warships to specialise in other aspects of naval warfare such as AAW and ASW. For instance, firing compact missiles at frigates and destroyers means that they are able to dispense with large calibre guns for anti-ship operations. In place of guns, other weapons and equipment may be fitted, such as surface-to-air missiles, electronic warfare systems, ASW systems, etc. Only small calibre guns are retained on the ships for anti-air defence and anti-ship missile defence.

The anti-ship missile also triggered the development of hard-kill and soft-kill anti-ship missile defence systems (ASMD). As a result of the proliferation of the anti-ship missile, most modern warships such as destroyers and frigates, and to a lesser extent, corvettes and FPBs, are equipped with ASMD systems for protection. Such defence systems were non-existent before the 1950s. The need for hard-kill missile defences saw a new generation of highly accurate, small calibre guns with astonishingly high rates of fire designed strictly to shoot down incoming missiles. Examples of such guns are the Vulcan Phalanx and the Goalkeeper. Short range missiles such as the Israeli Barak and the British Sea Wolf, were also developed to shoot down incoming anti-ship missiles. In addition, chaff systems have also become common place, even in FPBs, to provide some form of protection against anti-ship missiles. The anti-ship missile had not merely influenced the development of existing weapons and equipment but was also responsible for the emergence of entirely new technology.

INFLUENCES ON NAVAL OPERATIONS

The pivotal factor influencing the way modern warships operate is the missile's lethality and effectiveness over long ranges. Not only do missiles extend the range of a ship's striking power, but the ship extends the range of missiles even more. As such, modern naval battles are fought over long distances and involve, almost without exception, an exchange of missile fire.

Effectively, the range of the missile only extends to the distance at which the force is able to locate the enemy ship. There is very little value in having missiles with ranges in excess of 40 miles when the detection means reaches to little more than the visual horizon. The need to maximise the range of the missile imposes tremendous demands on shipboard sensors such as radar, electronic warfare, long range air surveillance, etc. Development of radar and electronic warfare systems have progressed at a frenetic pace since the early 1960s and long range air surveillance from maritime patrol aircraft have become a common feature in present day naval operations. Targeting accuracy have been greatly enhanced through the availability of the NAVSTAR Global Positioning System and improvements in missile guidance technology. Modern missiles are quite capable of hitting their targets even after a flight of some 100 miles or more.

Early naval battles involving gun battles were close range, straight forward affairs where both sides attempted to fire as early and as many rounds as possible against the enemy ship. Such exchanges often involved heavy casualties on both sides and bore very little subtlety and sophistication. The modern naval battle, in contrast, has evolved into a cat and mouse game fought at long ranges, the objective being to localise and engage the enemy ship without revealing and exposing oneself to enemy fire. Such encounters are necessarily complex and heavily dependent on technology and military hardware.

ENTERING THE NEXT MILLENNIUM

The evolution of the anti-ship missile continues as it attempts to adapt and overcome advances in ASMD technology. In 1993, the US Navy conducted a test at Point Mugu. A number of anti-ship missiles, including the Exocet MM38, Harpoon Block lDs and straight flying supersonic targets, were fired with a view to testing their invulnerability to shipboard defences - all missiles were shot down. It was obvious that the development of ASMD technology has reached a point as to render current anti-ship missiles ineffective. Defence industries all over the world have stepped up their efforts to develop a new generation of anti-ship missiles capable of defeating the advanced shipboard defence systems of today.

Several fundamental requirements shape the design of the new generation anti-ship missile. First of all, the missile should be capable of attacking not only when the target is isolated on the open sea, but also when it is in a bay, among islands, surrounded by other vessels, or even in harbour. Similarly, the missile should have "fire-and-forget" capability to minimise the risk to the launch platform and allow several salvoes to be fired in rapid succession. To increase the probability of reaching the target, the missile should have low observability characteristics. This implies an ability to cruise at sea-skimming height at high speed and approach the target from any direction using a dog-leg track at supersonic speeds. For a high kill probability, the missile should strike close to the waterline and ideally in the vicinity of the engine room. It should also penetrate the hull prior to detonation.

Given the above conditions, the anti-ship missile of the 21st century is likely to be powered by a ramjet engine. Ramjet propulsion combines the long range of a turbojet and the high speed of a rocket. Another significant advantage which it offers is throttle control. A ramjet powered missile will be able to achieve an initial cruise to the target area at a relatively low supersonic speed (about Mach 2) at sea-skimming altitude, followed by a sudden pop-up manoeuvre and a furious Mach 3.5 zigzag dive onto the target. At Mach 3.5, the missile is able to cover 35 kilometres in half a minute, or over one kilometre in one second. This will leave very little warning time for the shipboard defences to react and hence enhance the probability of reaching the target. The new generation missile is likely to have dual seekers to enhance the probability of hitting the intended target and achieving a kill. An active-radar system provides autonomous guidance and all-weather capability, while an infra-red imaging system provides the precision and increases the probability of hitting the engine room. Other target-imaging options are millimetric wave and laser radars.

It is obvious that the anti-ship missile of the 21st century will be radically different from those that we know today. The missile represents an amalgamation of microwave, airframe, propulsion, ordnance, control and computer technologies. As we enter the next millennium, we witness yet another transformation in the design and capabilities of the anti-ship missile. Within a short span of some 30 years, the anti-ship missile has positioned itself as the pillar of the warship's offensive capability. With increased capabilities, complexity and virtually no competitors, it will remain so for many years to come.

Bibliography

1. Trevor N. Dupuy, International Military and Defense Encyclopedia, Brassey's (US), Inc.

2. Nels A. Parson, Jr., Missiles and the Revolution in Warfare, Harvard University Press, 1962.

3. Robert Berman & Bill Gunston, Rockets & Missiles of World War III, Bison Books, 1983

4. Richard K. Betts, Cruise Missiles - Technology, Strategy, Politics, Brookings Institution, 1981

5. Armada International Staff; Supersonic Anti-ship Missiles Needed, Armada International, Aug/Sept 1993.

6. Roy Graybrook, Anti-ship Missiles - Pay Your Money and Take Your Choice, Asia-Pacific Defence Reporter, Aug/Sep 1994.

MAJ Stephen Sim is currently the CO of an RSN ship. He graduated with a B.Eng degree in Electrical Engineering from the National University of Singapore. MAJ Sim has held various appointments on board other RSN vessels as well as within MINDEF.

 
Last updated: 18-Jul-2005


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