Predators with an Accurate Mind of their Own

When they started to strike the Greater London area in June 1944, the V-1s were portrayed in Britain as a crude and cowardly means to attack the civil population. Today the cruise missile is being widely adopted as a technologically brilliant and tactically essential means to engage a wide variety of military targets.

Winged autonomous ground attack weapons are increasingly taking over the role of the aircraft in the crucial final phase of ground attacks. The South African Kentron Mupsow was recently unveiled, but had already undergone unpowered flight tests in 1997.

The V-1 is a useful starting-point for a discussion of present and future cruise missiles, as it highlighted many of the economic and operational considerations that apply today. Its merits included day/night all-weather operation, simplicity and low cost of construction. Approximately 32 000 were made. It was difficult to defend against, since it had a high speed (644 kilometres per hour), represented a small target and cruised above the effective reach of light anti-aircraft artillery.
On the down side, around 25 per cent of V-1s crashed before reaching Britain, due to poor reliability. Guns and fighters each destroyed about 25 per cent of the remainder, and balloons accounted for a further three per cent. Of the 5000 V-1s launched against Antwerp from October 1944, only 211 reached the target area, largely due to the effectiveness of proximity-fuzed shells.
Today's cruise missiles naturally provide major improvements over the V-1 in most respects, although not all are capable of day/night all-weather operation. To achieve a reasonable degree of immunity from air defence systems, the modern missile can employ defensive routing, avoiding known threat areas and making use of the natural screening provided by valleys and mountains. It can also have reduced signatures, and use low altitude, high speed cruise. Navigation accuracy can benefit from the combination of inertial and satellite systems, and by automatically comparing sensed ground profiles and imagery with digitally-recorded maps. In turn, precise knowledge of missile location over a known landscape allows it to be flown low without the use of active sensors. Accuracy in the terminal phase can benefit from human or automatic target recognition. Preliminary damage assessment can be provided by data-linking missile imagery to an aircraft or a communications satellite.
The following discussion considers how some leading cruise missiles exploit modern technologies in order to enhance penetration capability, range and navigation accuracy, and to provide improved attack profiles and damage assessment. Warhead technology will be considered separately in Armada 4/99.
The Simplest (Corresponding table in this region)The simplest form of a relatively long-range guided weapon is a fixed-geometry glide missile such as the Boeing Jdam (Joint Direct Attack Munition) or the Dasa AFDS (Autonomous Free-flight Dispenser System). A highly effective way to extend range is to add wings of high aspect ratio, which prior to release must be stowed aft in order to permit multiple store carriage. By spreading the aerodynamic lift across a much wider span, the lift-related drag of the missile is reduced, and the glide-slope angle (as dictated by lift/drag ratio) is improved accordingly.

Projekt Fernfeuer In October it will be 60 years since the Berlin-based Argus Motorenwerken began work on its Projekt Fernfeuer to develop what we would now term a cruise missile. By 1941, the design was based on a small pulse-jet, which was first flight tested on a Go 145 biplane in April of that year. Since the German Air Force had suffered heavy losses in daylight raids against Britain, and since the German Army was then making only slow progress with the V-2/A-4 ballistic missile, Hitler gave his support to the cruise missile concept. This world-first was brought to reality jointly by Argus and Fieseler under the designation V-1, Fi 103 or FZG (Flug-Ziel-Gerät) 76. The V-1 delivered an 830 kilogram warhead, representing almost 40 per cent of launch mass. Its accuracy was remarkable for its day, most rounds falling in an ellipse ten kilometres across-track and five kilometres along-track, relative to aim-point. Some measure of effectiveness was provided by tracking the three per cent of rounds that were equipped with radio transmitters. Range from a ground launch was limited to 238 kilometres, hence London's suffering largely ended when launch sites in northern France were overrun by Allied ground forces. However, approximately 1600 V-1s were launched against Britain from He 111 bombers.

Examples of unpowered air-to-ground missiles with flip-out high aspect ratio wings include Israel Military Industries' Msov (modular stand-off vehicle), South Africa's Kentron Raptor 1, and America's Raytheon AGM-154 Jsow (joint stand-off weapon) pronounced "jay sow."
Deliveries of the Jsow began in July 1998, following the award of the first low rate initial production contract in February 1997. The baseline AGM-154A employs an integrated GPS/Inertial Navigation System with provision for up to eight navigation waypoints, and carries a warload of 145 BLU-97B Combined Effects Bomblets submunitions. The Jsow can store up to eight pre-planned missions and receive target data while attached to the parent aircraft in flight.
Raytheon is developing the anti-armour AGM-154B version with six BLU-108 Sensor-Fuzed Weapon submunitions and the AGM-154C with imaging-infrared sensor, AWW-13 datalink, and the BLU-111 general purpose unitary warhead from the 227-kilogram Mk 82 bomb. The possible use of a Royal Ordnance Broach tandem warhead or a kinetic energy penetrator from Lockheed Martin, Matra BAe Dynamics or Rafael is also being studied. The Jsow derives from the United States Navy Aiws (Advanced Interdiction Weapon System) programme for a single weapon system to replace the Walleye, Skipper, Maverick and its older laser-guided bombs. The new missile was required to provide a range of 28 kilometres from low level release and 74 kilometres from altitude, and to be price-capped at $ 50 000 (in 1985 values) without warhead. The Air Force joined the programme in 1992, when it was redesignated Jsow.
Future Jsow development possibilities include a powered version with a range of 185 kilometres. Such a missile, powered by a WJ-24-8 turbojet, was demonstrated by a flight under joint Raytheon/Williams International funding on 29 September 1995. It may also be noted that the imaging-infrared seeker of the AGM-154C provides the potential for autonomous target recognition.

Cruisers

Tomahawk: The cruise missile that has accumulated most operational use is the BGM-109 Tomahawk, for which Raytheon is now the single source (originally developed by General Dynamics and McDonnell Douglas). Some 288 were fired during Desert Storm, and others have since been used against Iraqi targets (including 23 in June 1993). In August 1998, 66 were fired against terrorist targets in Afghanistan, and 13 against a target in the Sudan.
The Tomahawk is described as a day/night all-weather system, although one guidance element would appear to be daylight-only. It is suitable for horizontal or vertical launching, and it has been fired from ships, submarines and ground vehicles. Work on an air-launched version was terminated in 1984. There are four basic versions: the BGM-109A for nuclear land attack, the -109B for conventional ship attack, the -109C for conventional (unitary warhead) land attack and the -109D for land attack with submunitions. The UGM-109 is the submarine-launched variant.
The nuclear land-attack version is a long-range missile with an inertial navigation system that is updated at preselected points by a radar altimeter-based terrain contour-matching (Tercom) system. In the case of the conventionally armed land-attack Tomahawks, Tercoms augmented just prior to the attack by digital scene-matching area correlation Dsmac provide for greater accuracy.

The Raytheon BGM-109 Tomahawk is the standard American strategic cruise missile for firings from surface vessels and submarines.

The Tomahawk can cruise high or low, but its speed is given as Mach 0.50 to 0.75, and press reports suggest that Mach 0.55 (675 kilometres per hour) at low level is typical. In relation to manned aircraft attack speeds this is slow, but the Tomahawk can employ evasive routing.
The BGM-109C/D Block III introduced a GPS receiver, time-of-arrival software, an updated Dsmac-IIA system, increased fuel, an improved engine and a 317 kilogram warhead with PBXN 107 explosive in a titanium case, replacing the original 454 kilogram Bullpup warhead. Both versions of the Block III were flight tested in 1991.
Britain has purchased 65 of these missiles for its nuclear-powered attack submarines (SSNs). One example was tested off America's West Coast in November 1998. All targeting for Royal Navy Tomahahwks takes place on shore, the data being either pre-loaded while the boat is in dock or transmitted to the SSN while it is on patrol.
In 1994, Hughes (now Raytheon) was awarded a sole-source contract to remanufacture Tomahawk Block IIs to Block III standard. The company was also awarded the development contract for the Tomahawk Baseline Improvement Program, leading to a more capable Block IV missile, to which standard 875 earlier missiles were to be modified.
Raytheon has subsequently proposed a new-build, simplified Tactical Tomahawk that (if the Navy buys 1353 rounds) could be produced for less than $ 570 000, compared to $ 1.4 million for the Block IV as initially planned. Part of the cost reduction would be achieved by replacing the Williams F107-WR-402 turbofan with the slightly less powerful Teledyne J402-CA-400 turbojet used in the Harpoon/Slam family. This would admittedly provide somewhat less range, but the Tactical Tomahawk would still be capable of 1850 kilometres at low level. Cost is further reduced by deleting the requirement to launch from submarine torpedo tubes, which allows a simpler, lighter airframe.
The new design would also introduce a forward-looking television camera and satellite datalink, providing imagery of earlier attacks and an indication of impact accuracy. The Tactical Tomahawk would also have bladder tanks for reduced cost, a more jam-resistant GPS receiver, and an inertial navigation system based on ring-laser (rather than mechanical) gyros. The warhead bay is sized to accommodate a hard target penetrator, or twelve Northrop Grumman Bat (Brilliant Anti-Tank) or 12 Textron SFW (Sensor-Fuzed Weapon) submunitions.
At launch the missile would carry Dsmac data for several alternative targets, but it could also be re-assigned in flight to attack a different target using only GPS/INS navigation. In a new type of mission profile, the Tactical Tomahawk would be able to loiter for up to two hours while waiting to receive target co-ordinates from a variety of possible sources. If the Raytheon proposal is approved, deliveries of the Tactical Tomahawk will take place from 2001 to 2007.

Unpowered, but Stealthy The cheaper unpowered cruise missile offers the advantage of inherent stealthiness: no noise, no heat plume. Depending on its navigation system, it can be as accurate as the powered variety, but its range directly depends on the altitude at which it is launched (strictly speaking, the Raptor 1 is a long-range laser-guided glide bomb, but a more refined navigation system is envisaged). Furthermore, it cannot fly any long distance at low level to exploit cover from terrain. Eric H. Biass

Alcm: The Boeing AGM-86B entered service on the B-52 in 1982, and is in broadly the same weight and range categories as the BGM-109A. Navigation is provided by a combination of inertial and radar altimeter-based contour matching. The AGM-86B is supplemented in the US Air Force nuclear weapon inventory by the stealthy Boeing AGM-129A ACM (Advanced Cruise Missile), which reportedly provides major advances in range, survivability, accuracy and targeting. Deliveries began in 1990, but procurement is believed to have been restricted to 1000 units.
Approximately 300 AGM-86Bs have been converted to -86C Calcm standard (the new C standing for "conventionally-armed"), with 454-kilogram warheads and GPS receivers for improved accuracy. During the Gulf War, B-52Gs are believed to have released over 90 Calcms in attacks against eight Iraqi targets, and around 70 have been used since.

The Boeing AGM-86B Air-Launched Cruise Missile (ALCM) in later production form, with a modified (non axisymmetric) nose to reduce radar signature.

In 1998, Boeing was awarded a contract to upgrade 28 AGM-86Cs to Block IA standard, with jam-resistant eight-channel GPS receivers and other improvements. The Block II upgrade of the AGM-86C was planned to have a hard target penetration warhead in the form of either the Royal Ordnance Broach or Lockheed Martin Advanced Unitary Penetrator (AUP-3M). However, recent reports indicate that there are problems in achieving the desired impact angle and the necessary accuracy. The Block II may thus be limited to a 900-kilogram blast-fragmentation warhead.

KH-55: Russia's equivalent of the Boeing AGM-86B is the Raduga Kh-55SM (AS-15), which is powered by an Omsk TRDD-50 turbofan and employs inertial guidance with some form of Tercom update.

The Simplest: Unpowered MSOV (IMI) Total Warhead Length Span Range [kg] [kg] [m] [m] [km] 1050 675 3.97 2.70 100 Status: under development, project unveiled at 1997 Paris air Show, features modular submunition underbelly bay, on-ground or in-flight mission programming. Raptor 1 (Kentron) Total Warhead Length Span Range [kg] [kg] [m] [m] [km] 980 550 3.65 3.70 60+ Status: original TV-guided Raptor out of production, used during Angolan war but unveiled in 1998; smarter and more autonomous guided version under consideration. JSOW AGM-154 (Raytheon) Total Warhead Length Span Range [kg] [kg] [m] [m] [km] 681 227 4.10 n/a 75 Status: AGM-154 A in production, uses INS+GPS, first used in Jan 1999 when three were released from US Navy F/A-18s against an Iraqi SA-3 site.

Wide angle view
Imaging infrared	Contoured image	Geometrical reference model	Correlation factor

Narrow angle view
Imaging infrared 6°x4°	Contoured image	Geometrical reference model	Correlation factor
Is seeker technology, both in terms of algorithmic processing and resolution, ripe enough for accurate supersonic attack? These two simulated sequences of an attack from a Matra BAe Apache/Storm Shadow illustrate the difficulty. After radar navigation close to target, imaging infrared angle is narrowed to reduce processing time.

Navigation Where guidance is normally the term used to designate a system that helps a missile to home onto its target, navigation is a more appropriate word for qualifying the homing device of the brilliant cruise missile. The ideal brilliant cruise missile should be able to find its assigned target on its own, as a pilot would: first by flying in the general direction of the target, then by «visually»spotting the actual target. The first segment can be done by using gyro-based navigation (mechanical or laser) or GPS - or a combination of these - in association with brief radar flashes towards the ground to reset position by comparing the terrain under with a grid map stored in memory. This enables very convoluted flight paths to be followed to avoid known air defence positions and fly low under horizontal cover provided by terrain. The second segment is the trickiest, and needs to rely on the very latest technologies in the field of image processing. Whether the sensor is an infrared or millimetric radar sensor, it will require high resolution to enable the missile to recognise its target by comparing what it sees ahead with pictures stored in memory. The art will be mastered when the missile is capable of dealing with changing situations due to jamming, camouflaging (and even altered target appearance resulting from damages from an earlier attack). One can imagine the required computing capacity. Eric H. Biass Kepd 150: A lighter variant with reduced range (Kepd 150) has been proposed for Sweden's JAS39, and a captive flight of a ballasted mock-up took place on that aircraft in August 1998. LFK has proposed an active radar ship-launched version (KEPD 150-SLM) as a Harpoon replacement for the German Navy, but there are doubts whether that service can fund such a programme. The second member of the Taurus Systems family of cruise missiles is the lighter KEPD 150 proposed for Sweden's Gripen multi-role fighter. Future customers for anti-ship missiles may well demand more range than the current generation (a trend exemplified by the 270 kilometres of the KEPD 150-SLM), but there is no consensus of opinion on whether the missile should be supersonic or subsonic and stealthy. The Dasa/Bofors MAW Taurus or KEPD 350 hard target cruise missile is equipped with a Williams P8300-13 turbofan and a TDW Mephisto penetration warhead. Mupsow: The Mupsow is a South African development on which Kentron has been working under contract from the Air Force since 1991. According to Kentron, full-scale development has now reached an advanced stage, with several glide launches having been performed. No powerplant has been selected so far. Payload would primarily be anti-runway, but unitary high explosive and, more interestingly, "Broach-like" types are envisaged. Hypersonic France is the leading Western power to advocate the development of a supersonic anti-ship cruise missile, although Aerospatiale is also working as a minor partner of Norway's Kongsberg in the subsonic NSM (New anti-Ship Missile) programme. In October 1998 the Délégation Générale pour l'Armament (DGA) signed a definition study contract with Aerospatiale for the ANF (Anti-Navire Futur), based on the Vesta ramjet technology demonstrator, three flight tests of which are scheduled by 2002. The ANF (an Exocet replacement) is to have a range of 150 to 200 kilometres and a cruise speed of Mach 2.5 to 3.0. The programme starts with the ship-launched version, which is due for flight test in 2002 and deliveries from 2004. The initial production batch for the French Navy is expected to cover 100 to 200 rounds to arm 12 ships. There will be an air-to-surface version developed in the 2004 to 2007 time frame, and submarine-launched and coastal battery versions between 2006 and 2009. Reports suggest that Britain and Italy may join the ANF programme. East The ANF will be the West's first supersonic anti-ship missile, but Russia already has two such weapons in service and new supersonic and hypersonic designs in development. The Mach 3 Zvezda-Strela Kh-31A (AS-17) is light enough to be carried by the MiG-29, but is claimed to be effective against vessels of up to 8000 tonnes. It has been ordered by China and India, and a sea-skimming target derivative (MA-31) jointly developed with Boeing has been tested by the US Navy. Russia's lead in supersonic missiles is shown by the Mach 3 Zvezda-Strela Kh-31 (AS-17), which is used in both anti-ship Kh-31A and anti-radar Kh-31P forms. The much heavier 3M-80E (SS-N-22), designed by Raduga and manufactured by Progress, likewise uses a combination of rocket and ramjet propulsion. It cruises at 2800 kilometres per hour, reportedly at a height of 20 metres, descending to seven metres in the terminal phase. In addition to its active radar mode, it can employ anti-radiation and home-on-jam modes. Assessed by Nato as the most potent challenge to existing shipboard defences, the 3M-80 entered service in 1980 on Sovremenny-class destroyers. The 3M-80E has been exported to China, and has been exhibited as a centreline store on a Sukhoi Su-33, although this combination may be no more than a proposal. Altair is said to have proposed a coastal defence system based on the 3M-80. There have been references to a 3M-82 Moskit-M of 150-kilometre range.

Cruisers
Tomahawk BGM-109A (orig. Gen. Dyn.)
	Weight Warhead Length Span Thrust Range	[kg] [kg] [m] [m] [kn] [km]	1360 (W-80)** 6.25 2.62 3.11 2400	Status: In production, the109A is the nuclear attack variety with an INS updated at preselected waypoints by radar-altimeter-based Tercom.
Tomahawk BGM-109B (Raytheon)
	Weight Warhead Length Span Thrust Range	[kg] [kg] [m] [m] [kn] [km]	1360 454 6.25 2.62 3.11 480	Status: In production, -B variant is for ship attack, relatively short range, inertial mid-course guidance and radar derived from Harpoon, includes radar altimeter for sea-skimming.
Tomahawk BGM-109C (Raytheon)
	Weight Warhead Length Span Thrust Range	[kg] [kg] [m] [m] [kn] [km]	1360 454 6.25 2.62 3.11 480	Status: In production, -A version for conventional land attack, day/night, all-weather system suitable for horizontal or vertical launch, Tercoms augmented just prior to attack by Dsmac providing greater accuracy.
ALCM AGM-86B (Boeing)
	Weight Warhead Length Span Thrust Range	[kg] [kg] [m] [m] [kn] [km]	1452 (W-80)** 6.32 3.66 2.67 2800	Status: Many converted to AGM-86C standard. Initially developed as air-to-surface turbofan-powered, swing-wing nuke. Inventory supplemented by AGM-129A ACM.
CALCM AGM-86C (Boeing)
	Weight Warhead Length Span Thrust Range	[kg] [kg] [m] [m] [kn] [km]	1452 454 6.32 3.66 2.67 2800	Status: Following 1980s agreements on nuclear weapons reduction, a number of original Alcm warheads had to be pensioned off. About 300 airframes have been recycled into conventional cruise missiles with an alleged 160 put to good use over Iraq.
Slam AGM-84E (Boeing)
	Weight Warhead Length Span Thrust Range	[kg] [kg] [m] [m] [kn] [km]	628 227 4.49 0.91 2.94 110	Status: Land attack derivative of Harpoon, deliveries began in 1988, first operational use in 1991 Gulf War. It combines inertial and satnav nav with man-in-the-loop terminal guidance via imaging-infrared seeker.
Kh-35 Uran* (Zvezda)
	Weight Warhead Length Span Thrust Range	[kg] [kg] [m] [m] [kn] [km]	600 145 4.40 1.315 n/a 130	Status: Production, anti-ship missile nicknamed Harpoonsky in West. Initial flight is inertially controlled then final homing is with active radar. All fins, including those of jettisoned booster are folded and deploy after launch.
Kh-59ME* (Raduga)
	Weight Warhead Length Span Thrust Range	[kg] [kg] [m] [m] [kn] [km]	930 320 5.69 1.30 n/a 115	Status: Production, known to Nato as AS-18 Kazoo; belly-pod turbine-powered version of the TV-guided Kh-59; canards deploy. Essentially designed for the Russian counterpart of the Fairchild A-10, the Sukhoi Su-24M Frogfoot.
Jassm AGM-15 (Lockheed M.)
	Weight Warhead Length Span Thrust Range	[kg] [kg] [m] [m] [kn] [km]	1000 450 4.27 n/a 4.25 450	Status: Production to begin in 2001 with US forces projecting a 2400-unit purchase. Uses stealth technology and flies direct to target. A variety of warheads are under consideration.
Apache AP (MBD)
	Weight Warhead Length Span Thrust Range	[kg] [kg] [m] [m] [kn] [km]	1230 n/a 5.10 2.84 n/a 140	Status: Europe's first conventionally-armed cruise missile, is intended solely for destruction of runways. France placed 100-unit order. Export version is known as the Black Pearl.
Scalp EG (MBD)
	Weight Warhead Length Span Thrust Range	[kg] [kg] [m] [m] [kn] [km]	1300 n/a 5.10 n/a 2.84 200+	Status: Around 1300 ordered by Britain and France, deliveries in 2001, same engine as Apache, but is a longer-range hard target penetrator.
Kepd 350 (Taurus)
	Weight Warhead Length Span Thrust Range	[kg] [kg] [m] [m] [kn] [km]	1400 n/a 5.00 n/a 6.67 350+	Status: Germany dropped Apache-buying plans to develop Taurus (Dasa & Bofors). All-weather with imaging-infrared and millimetre-wave terminal guidance. Should run around $ 675 00 per unit.
Kepd 150 (Taurus)
	Weight Warhead Length Span Thrust Range	[kg] [kg] [m] [m] [kn] [km]	1060 n/a 4.50 n/a 5.78 200+	Status: The lighter Kepd variant for Sweden's JAS39, mock-up flight took place in August '98.
Kepd 150-SLM (Taurus)
	Weight Warhead Length Span Thrust Range	[kg] [kg] [m] [m] [kn] [km]	1800* n/a 5.80 n/a 5.78 270	Status: LFK had proposed this ship-launched version for German Navy but current funding restrictions might prevent such a deal.
Mupsow (Kentron)
	Weight Warhead Length Span Thrust Range	[kg] [kg] [m] [m] [kn] [km]	1200 n/a 4.92 1.9 not defined n/a	Status: awaiting launch customer for final, powered development, glide tests carried out; hybrid navigation, data link, choice of TV, IIR or MMW seekers; anti-runway submunitions, unitary warhead or bunker penetrator payloads offered.
Kh-31A (Zvezda)
	Weight Warhead Length Span Thrust Range	[kg] [kg] [m] [m] [kn] [km]	600 90 4.70 1.103 n/a 50	Status: in production; a version, presumably sans warhead, was delivered to the United States as target for anti-missile missile tests. Ramjet-powered, it is a popular sight under Russian aircraft at air shows; claimed to kill 8000-tonne displacement ships.
3M-80E (Raduga/Progress)
	Weight Warhead Length Span Thrust Range	[kg] [kg] [m] [m] [kn] [km]	4150 300 9.385 n/a 2.10	Status: unclear, produced for, inter alia, the Udaloy class. Unbelievably called Moskit (mosquito), this massive fire-and-forget missile known to the West as the SS-N-22 Sunburn is powered by ramjet and it flies at Mach 2.5.
				Notes:* indicates with boost motor; ** = nuclear warhead; MBD = Matra BAe Dynamics