Technology Explained

As capable as the system may appear to be, it has its opponents, who generally claim that any aircraft that penetrates the outer defences need not do any more than launch a small standoff missile with a 1 Megaton+ nuclear warhead which need not hit anything, but will definitely make a mess if it goes off anywhere within 5 to 10 nm of the carrier. One may assume that only the USSR would possess that capability, otherwise, it is unlikely that conventional aircraft following conventional attack profiles would be successful. The Royal Navy had structured its air defence system into the US system, up to the Falklands events, intending to rely on US AEW capability when operating in range of hostile land-based aircraft. As a consequence, the RN assumed it would carry out independent operations only in the North Atlantic, where it would have to deal with long-range maritime patrol aircraft, such as the Tu-20 Bears and Tu-16 Badgers, later perhaps the reported turbofan successor to these ex-bombers. The primary line of defence is the subsonic Sea Harrier FRS. Mk 1, armed with Sidewinder AAMs and 2 x 30 mm cannon. Its radar has very limited range and does not possess lookdown-shootdown capability, a serious deficiency in the air defence role. The Harrier is backed up by the 45 nm GWS-30 Sea Dart area defence SAM, launched primarily from the type 42 destroyer or Invincible class carrier. Point air defence was to be provided by the GWS-25 Seawolf SAM, carried by some frigates, though many vessels carry the Short Seacat. As the events of May and Jurie W82 were to prove, this system was inadequate, as the RN lost three warships and two landing ships to direct bombing attacks and a destroyer and transport to Exocet sea skimmers. The principal cause was the lack of AEW, though the Harrier’s limited CAP payload range (in spite of which 30 Argentines were downed with no losses) and deficiencies in and/or lack of adequate close-range SAM cover share the blame. As a counter measure, the RN is fitting Phalanx to its Invincible class carriers and after 11 weeks of development, deployed an AEW Sea King helo, fitted with a modified EMI Searchwater radar set, adapted from Nimrod MR. 2. This AEW helo is a very basic substitute for the E-2C and is limited in range and capability. It is unlikely anything will be achieved with the Harrier’s payload/range, though its radar is to receive an update. In its current form, the RN air defence system cannot deal with any high performance strike aircraft and has limited capability against standoff sea skimmers.

The Soviet Navy, or Voenno-Morskiy Flot, has limited, if any, air cover, that being provided by the rather mediocre Yakovlev Yak-36 Forger, armed with AA-8 Aphid IR AAMs, embarked on Moskva and Kiev class helo carriers. The principal area defence weapons are the 20 nm SA-N-1 Goa SAM, carried by Kresta I and Kynda cruisers and destroyers, and the newer 30 nm SAN-3 Goblet SAM, which arms the Kiev, Moskva and Kresta II classes. Intruders penetrating the SAM screen must face the SAN-4 close-in SAM system and radar-directed guns (presumably derivatives of the 23 mm Gatling used in strike aircraft), these weapons carried by the Kiev, Kirov classes aside from smaller vessels.

A new vertical launch area defence weapon, the SA-N-6, is entering service on the Kirov class battlecruisers and Sovryemeniy class destroyers. As the V-MF operates without viable air cover, this reflects in their in-depth SAM and gun defences, a modern battlecruiser being armed with two classes of SAM backed up by guns. The question is, of course, how effective are these systems against small, fast, low-flying targets (it appears nobody is willing to try them out). The lack of AEW, some degree of which may be provided by the Ka-25 Hormone 8 helo otherwise tasked with missile targeting, would be a major weakness – the low performance of the Forger does little to offset that weakness. Changes are likely to occur when the reported 80,000-ton conventional carrier enters service, but that may be some time in the future. At this stage, Soviet surface vessels would appear to be vulnerable to some sea skimmers and standoff weapons, given there is adequate standoff jamming (ECM) to degrade their detection capability. As the Russians do not have reasonable AEW, their vessels must employ radar constantly (unlike US carrier battle groups, which often operate under radio/radar silence), leading to the option of using antiradiation missiles – attackers may employ ECM to penetrate the relatively small 30 nm defensive perimeter and then launch ARMs. The limited radar horizon would make strikes far easier for F-111 class aircraft.

Having examined the air defence systems, briefly, we may now look at each class of weapon.

The most effective class of weapon, in terms of lethality, range and flexibility, are fighter aircraft. In order to be successful in this role, they must have the following attributes – lookdown shootdown radar, track-while-scan capability against multiple targets, all-weather radar-guided missiles and short-range dogfight missiles, good climb rate, top speed and dash capability and maximum endurance for combat air patrol (CAP). Only the F-14 and the F-18 meet these requirements, being tailored for the role. The Sea Harrier cannot satisfy the role and it is unlikely the AV-8B or future Sea Harrier versions will satisfy anything but basic defence against lower-performance aircraft – high-performance platforms (F-111 class) with standoff missiles will penetrate. (The author points out that an Amraam-fitted Sea Harrier will lack radar range, dash speed and CAP endurance to cope with a threat such as the Tu-26 Backfire, though it could obviously handle anything put up by Third World countries. ) The outlook for the future may focus on supersonic V/STOL or STOV L fighters, however at this stage, the USN has too much invested in conventional carriers and Britain cannot afford anything more than improving the Sea Harrier. The situation will change when the survivability of a conventional carrier degrades to a level unacceptable to the USN, then some spending will occur.

Area Defence Weapons are an important part of any air defence structure, filling the gaps in the fighter screen and stopping intruders that found their way through. Probably the most lethal weapon in this class is the vertical launch SA-N-6, supposedly derived from the SA-10. This 1500 kg missile is fitted with active radar guidance (see TE, June 1982), and has a cruise velocity close to Mach 6; its limitation lies in its 27 nm range. Long range, on the other hand, is the strength of the British Aerospace Dynamics Sea Dart, which can hit targets beyond 45 nm (classified). The Sea Dart employs a rocket booster for launch and initial acceleration to Mach 2; after burn-out, a variable thrust Rolls-Royce Odin ramjet powers the missile during its Mach 3. 5 cruise. Illumination for the semi-active radar guidance is provided by the Marconi type 1022 and 909 surveillance and tracking radars, operating in the E/F and G/H Bands respectively (two 909 sets provide illumination).

The GD RIM-66C Standard 2 ER is an improved, extended . range version of the Standard missile replacing Terrier on cruisers and destroyers. It is the primary weapon of the CG-47 Aegis cruiser, which launches the missile from the Martin Marietta EX-41 Vertical Launching System. Unlike versions of the Standard launched by other vessels, RIM-66A/67A, Standard 2 does not require continuous target illumination, thus reducing the time available for the target to take defensive measures. RIM-66C employs the same airframe as earlier models, including the Mk 30 Mod 2 sustain engine and Mk 12 Mod 1 booster, allowing a Mach 2. 5 cruise, but the guidance has been altered. The missile employs an inertial reference unit for midcourse guidance and receives target position updates from the massive RCA SPY-1A E/F band phased array surveillance/tracking radar. The SPY. 1A employs four fixed, flat, electronically phased arrays, each tilted slightly upward, providing continuous 360-degree radar coverage from the horizon up. The phased array has no moving parts, the shape and direction of the search or tracking beam being controlled very rapidly by electronic means; this allows the system very short reaction time and the ability to track targets as soon as detected. The SPY-1A operates in conjunction with a set of Mk 99 fire control systems. Target illumination is carried out only for the terminal homing phase of the Standard, which has a band monopulse seeker installed instead of the usual conical scanning unit. CG-47 has four SPG-62 illuminators, all slaved to the SPY. 1A, which provides all tracking information. The missile is fitted with impact and proximity fusing.

The Standard/Aegis weapon system is being retrofitted to some DD-963 destroyers converting them to the CG-47 cruiser, also raising the cost to a staggering $1400 million apiece; the question is, whether the system will perform. The SPY-1A can apparently track hundreds of targets at once and has a search range of the order of 200 nm, rather excessive for the 60 nm SAM it operates with. On the other hand, an immensely powerful radar of this kind would be nearly impossible to jam at a missile launch range. Whatever arguments one may raise for or against the system, its excessive cost (the USN wants 16) will confine it solely to the USN inventory.

If an aircraft or missile penetrates the area defence missile screen, it must be stopped by a close-in Point Defence Weapon. These come in various types, whether missiles or guns currently or lasers and particle beams in the future. The missiles in use employ a number of guidance systems, as follows: Seacat employs Command-to-line-of-sight (CLOS) in one of its various forms. When optically tracked, the operator steers the missile onto the target with pitch/yaw commands via a radio command link; the missile has a flare on its tail which allows the operator to clearly identify It as it flies to the target. In spite of its clear weather limitation and demands on operator skill, Seacat managed to down six Argentine aircraft during the Falklands war; while operated in confined spaces (San Carlos) it was not confused or affected by land mass, as are radar-guided weapons.

This class of weapon cannot effectively cope with sea skimmers, as its ability to track a target depends on operator skill, which is inadequate for the manoeuvring trajectories of modern weapons.

An improvement is offered by the GWS-25 Seawolf, which employs fully automatic CLOS or semi-automatic CLOS guidance. In the fully automatic mode, the type 967/968 search radars detect and track all targets in range. If a trajectory indicates a hostile target, the monopulse type 910 tracking radar locks on, after missile launch tracking the target and up to two missiles. The system calculates course corrections for the missile from track information and steers it into the target. The missile flies at Mach 2+ and is fitted with a proximity/impact fused 13. 4 kg warhead.

Given that the radar has difficulty tracking the target, TV tracking is employed for the target, radar tracking missile only. Steering it to the LOS. Seawolf was the only missile system the RN deployed in the Falklands with the capability to stop sea skimmers (during its trials, Seawolf apparently downed a six-inch cannon shell in flight), it also took its toll of aircraft, in one instance decimating an incoming wave of A-4s by downing two and ditching one of four. Its disadvantage is its lack of fire and forget capability only two missiles may be handled at a time, which suffices for self-defence but won’t really help vessels to be covered. A further weakness, in this sense, lies with Current (perhaps by time of reading changed) threat assessment software which apparently looks for trajectories aimed at the launch vessel only, i. e. a passing Exocet aimed for someone else could be ignored.

The Soviet SA-N-4 appears to employ similar guidance, using a low-light TV system for backup target tracking: one could assume that the Soviet weapon would force more operator control over threat assessment (less automation).

Another commonly used weapon is the Raytheon RIM-7 Sea Sparrow, a modified version of the early AIM-7 AAM. Sea Sparrow is currently being replaced by two newer weapon systems, the Ram and Phalanx. General Dynamics RIM-116A Ram is a specialised weapon tailored to the task of stopping sea skimmers. The Ram (rolling airframe missile) employs a Sidewinder engine (this implies a velocity around Mach 2. 5), warhead and fusing. Stinger IR seeker, and is launched from a rifled tube; this imparts rotation during launch.

The standard launcher is derived from a Phalanx, with 24 launch tubes, and would be aimed in the direction of the incoming missile during the several seconds after detection. Ram is then launched, employing twin aerials on its nose to passively home in on the sea skimmer’s radar transmissions. Once within adequate range, the IR seeker, resistant to most common countermeasures, engages and initiates terminal homing. The GaAs laser optical proximity fuse then detonates the 11. 4 kg fragmentation warhead. Ram is to enter production this year, to arm USN, West German and other (NATO?) vessels. Ram offers the advantage of being a fire-and-forget multishot weapon; the only serious weakness it may have could prove to be an inability to find small turbojet missiles with a lot of IR background radiation; rocket-propelled weapons have hotter and larger exhaust plumes (e. g. Exocet) and should be readily detected.

General Dynamics’ Phalanx is a system based on the proven M-61A1 six barrel Gatling gun. The M-61 fires 20 mm ammunition at the rate of 6000 rounds/minute (100 rounds/second) and is the standard cannon fitted to US fighter aircraft. Phalanx uses an M-61 which is coupled to a tracking radar and computer, all mounted on a rotating platform. The system employs closed-loop tracking, where the radar tracks the incoming missile and the fired stream of ammunition. Shells fired by the system have flat rear faces, to reflect the radar energy, the nose of each shell is configured to convey a maximum ability to penetrate surfaces with small radii of curvature. The position of the stream of gunfire is thus monitored and the computer steers it onto the target, constantly attempting to zero the position error between the target and the end of the stream. Phalanx does an impressive job of chewing drones to pieces in mid-air. The weapon should work effectively on most current sea skimmers. The advantage of the system is its suitability for retrofits, as it is a self-contained weapon requiring little more than electrical power hookups.

Phalanx is being fitted to all USN carriers, replacing Sparrow launchers, in most instances. Most surface vessels will be fitted, including the FFG-7, which is being supplied to the RAN. At the time of writing. HMAS Adelaide was not fitted, but her sister ships were scheduled to receive the system. HMS Illustrious sailed for the South Atlantic, in mid-1982, after a rushed fitting and testing of the system, as it was obviously reasoned that a sneak Exocet attack by the Argentines could not be ruled out.

The future Outlook for point defence systems is bright (it has to be, looking at some of the sweet little missiles being cooked up worldwide), it appears a lot of research is being focused on beam weapons (see TE, December 1981), particularly lasers.

Lasers offer the advantages of agility and multishot capability sizzling the target to a crisp in 1-3 seconds, but their weakness lies in the requirement of clean optics, something a trifle difficult to guarantee in a maritime environment. Further problems revolve around the tracking systems, which should be accurate to 10 rad at least, this is rather difficult to achieve. The teething problems are not insurmountable, but they will take time and cost a lot of money. A practical laser weapon will not enter service in the next few years. High-energy electron beams and particle beams are being experimented with, but they are far behind lasers and would suffer the same difficulties with tracking.

Naval air defence philosophies will remain a battleground for various factions throughout the world, as all sides try to counter the opposition’s, and their own, antishipping weapons, generation after generation. As effective as some systems are, they always seem to appear too late and in too little numbers. In this sense, defence planners should carefully consider their choice of weapon, to avoid rapid obsolescence. Sea skimmers are here to stay and the RAN should take decisive measures if it wishes to stay afloat.

The future will tell how appropriate current decisions are.