4.~ERIC4.~CRUISE~ISSILES

lTU. W. WARU

Mankind's stnvlng to establish a superior poten-tial for extermination of antagonistic fellow beings,as a deterrent to those whom he feels threatenhis way of life or even existence, has motivatedthe development of successive generations of'super weapons' and counter weapons. Thus it isthat we now hear the acclaimation for what sup-poses to be the newest brainchild of this humanfear and insecurity, the American cruise missiles.Much has been written about this new American'wonder weapon' and its capabilities which willargueably give America an advantage over theSoviet Union in the event of an 'ultimate con-flict'.

But just what is a cruise missile? The term issomewhat vulnerable to ambiguous interpretationas the weapon is actually a hybrid of featuresfrom other specific weapon categories. A workingdefinition used by the United State's Navy and AirForce describes the cruise missile as an unmannedweapon system which:

Has a warhead (either conventional or nuclearlIspropelled bVan air-breathing engine.Operates in sustained aerodynamic flight (that is,uses wings for lift like an airplaneJ.

Considering the concept in the light of thisdefinition we may conclude that the cruise missileis not a new phenomena. Cruise missiles were thenfirst used operationally from June 1944; this paGe-setter was then the German V-7 flying bomb of theSecond World War. This was the introductionof a new dimension to warfare. Weighing 5000pounds, 27 feet long and 33 inches in diameter,this ramjet-powered cruise missile carried a 2 000 Ibwarhead over distances of up to 500 miles.Despite inspiring initial dread probably comparableto Hannibal's use of elephants, the V-7 was notvery effective as a weapon, plagued by the pro-blem that was to prove to be the most markedweakness of cruise missiles - guidance! Theaccuracy of the V-7 could hardly be calleddeadly at the best of times, and total guidancefailures of the present autopilot were not un-common.

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After the Second World War the developmentof cruise missiles was pursued mostly howevertaking a back seat to the development of mannedaircraft and rockets.

In America however, before the advent of the'ultimate weapon' - the Inter-Continental Bal-listic Missile (ICBM) overshadowed all else, somecruise missiles were taken into service by both theUnited State's Air Force and Navy.

The first cruise missile to enter service with theUnited State's Air Force was the TM-67 ManinMatador. This missile in arming Pilotless BomberSquadrons in Germany in 1954 became the firstcruise missile to serve after the V- 7. Poweredby an Allison turbojet the Matador is describedas a swept-wing pilotless aircraft, which had acruising speed of some 600 mph and a rangequoted as 500 miles. The Matador was, however,subject to guidance limitations. The system ofcommand radio guidance they employed, requiredthe missile to be constantly in view of a net-work of ground radars. Positive control wastherefore only possible to the line of sight limitsof the last ground station.

An improved version of the Matador, the TM-76Mace, followed into the United State's Air Forceinventory, being deployed in Germany in 1959.Mace, using an uprated version of the AllisonJ33 turbojet engine used on Matador, could cruisefaster and had a greater range. Its greatestadvantage was, however, the improved guidancesystem. Early models of the Mace TM-76A wereequipped with the Goodyear Atran guidancesystem, overcoming the line-of-sight limitations ofthe Matador. The Atran system was a terrain-recognition guidance system which compared theterrain below the missile with the pre-programmedflight path plotted over a strip map. Thissystem is however considered to have been aheadof its time and on later, longer range versionsof Mace, the TM-76B, were guided by anAchiever internal guidance system.

The United State's Air Force also accepted intoservice an intercontinental-range cruise missile;

Scientia Militaria, South African Journal of Military Studies, Vol 8, Nr 3, 1978. http://scientiamilitaria.journals.ac.za

this was the SM-62 Northrop developed Snark.This was a subsonic weapon powered by a Prattand Whitney turbojet engine and said to have a5000 mile range. The guidance system was anunusual hybrid, combining celestial (star-tracking)and internal functions; after initial problems withthis navigational system had been ironed out Snarkentered service with the United State's AirForce in 1958.

The United State's Navy's answer to Marador andMace was the SSNM8 Voughr Regulus. Reguluswas a subsonic cruise missile of tailless swept-wing aircraft appearance powered by an Allisonturbojet engine, boost launched from the deck ofa surfaced submarine by twin rockets; its rangewas 500 miles. Guidance was by a radio commandsystem vyhose>unreliability and inaccuracy limitedthe effectiveness of the weapon.

Finally in this 'first generation' of United State'scruise missiles was Rockwell Hound Dog air-to-ground. This was a supersonic cruise missilepowered by a Pratt and Whitney turbojet engineto speeds of slightly over Mach 2 and a rangeof some 600 miles. Hound Dog used an internalnavigation system. This missile entered service in1961 and survived well into the seventies, andalthough manufacturer activity on Hound Dog hasceased the operational status of missiles in theUnited State's Air Force inventory is uncertain.

Despite the advent of Inter-Continental BallisticMissile technology which has stifled any opera-tional cruise missiles, a considerable amount ofdevelopment work was carried out during the1960s and early 1970s on missiles which neverentered service.

Now the forerunner of a resurgent generation ofcruise missiles is undergoing Operational test andEvaluation and can be considered as virtuallyaccepted into service with the United State'sNavy. This is MacDonnell Douglas' Harpoonanti-ship missile. Described as a high-subsonicanti-ship tactical cruise missile Harpoon is designedfor launch from surface ships, maritime patrol andattack aircraft, and attack submarines. Guidanceof the missile will be by pre-programmed altitudereference plus radar altimeter during the cruisewith active homing radar being used for the termi-nal phase, with propulsion by a Teledyne CAEturbojet cruise engine the Harpoon's range is over50 nautical miles.

So on to what has been attracting so much

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attention to cruise missiles of late, America'sdevelopment of a new generation of strategiccruise missiles. The cruise missile owes thisnew found strategic value largely to improvedguidance techniques, although also to the develop-ment of small lightweight turbofan engines withlow fuel consumption plus the miniaturisation ofwarhead technology.

The guidance sy,stem which plays such a bigpart is the Terrain Contour Matching (Tercomlsystem. This sytem operates by comparing themeasured terrain being flown over with a digitalmap of the area derived from intelligence gatheringsources, should the missile have deviated fromcourse the control surfaces are activated to putit back on its programmed track. Target and routedata are read into the missile guidance system,prior to launch. Even with modern computerminiaturisation it is not possible to store mappingsof the entire route to a target. Terrain contourmatching is therefore used at certain 'mappingareas' en route to update an internal navigationsystem. This combination of Tercom and in-ternal navigation is known as TAINS (Tercom-aided Internal Navigation Systeml. Accuracy usingthis system is claimed to be very high, achievingCircular Error Probability (CEPlof only tens of feet.

As to the missiles themselves, two developmentprograms are being run concurrently. TheBoeing AGM86 Air-Launched Cruise Missile(ALCM) and the General Dynamics BGM 109Tomahawk Sea-Launched Cruise Missile (SLCMl.The two missiles have a significant number offeatures in common.

With Tomahawk the original concept was to pro-vide a naval cruise missile capable of launchfrom a submerged submarine or surface ship, withair and land-launches as further possibilities. Theresultant missile has two variants, a 'land-attack'strategic version and an 'anti-ship' tactical version.Both versions are suitable for launch from standardtorpedo tubes and indeed the missile resembles aflying torpedo with small 'pop-out' wings, air-intake and Zeppelin-like tail surfaces. Both versionsshare a common cruise engine, a Williams Re-search turbofan, and have the same cruise speed,some 880 km/h, flight wl!1 be at low level foroptimum penetration capability. The Ami-ShipTomahawk will have a probable range of some300 nm and will be fitted with a conventionalwarhead, while the land attack version has a rangetarget of 1 500 - 2000 nm and will have anuclear warhead option. The anti-ship version will

Scientia Militaria, South African Journal of Military Studies, Vol 8, Nr 3, 1978. http://scientiamilitaria.journals.ac.za

use many subsystems of Harpoon including theguidance package. The land attack version willutilize a TA/NS system with a possible means ofimproving accuracy being the United State'sNavy-developed SMAC (Scene Matching AreaCorrelation) terminal homing system, which utilizesphotographic techniques to refine the final Tercomupdate and direct the missile to its target.

The air-launched cruise missile is very similarin concept to Tomahawk although differing inshape. It was designed to be launched from theSRAM missile launcher now to be utilized with theB-52 following the scrapping of the B-1. Theair-launched cruise missile has a fuselage of triangu-lar cross-section against which and into which thewings, rudder, tailplane and air-intake fit when themissile is stowed on the launcher. The sameWilliams Research turbofan used on air-launchedcruise missile is used on Tomahawk and a Tercom,internal navigation system combination also servesto guide the air-launched cruise missile. The con-straint of compatibility with the SRAM launcherresulted in a comparatively small missile with asubsequent range of some 1 300 km, however alonger-range version (AGM-86BJ with extendedfuselage and larger win span is expected to haveabout twice the range of the original air-launchedcruise missile, but will need to be carriedexternally on the aircraft.

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Thus while the prospects seem bright for America'snew weapon system there are some.cautionary points to be considered. Firstly, othercountries have not neglected cruise missiles, in-deed the Soviet Union has deployed a varietyof cruise missiles ever since the very late 1950sand has an estimated 5 000 odd in service pri-marily with its naval forces. Then critics of theAmerican reliance on cruise missiles point out someweakness in the system. The missiles must bepre-programmed and so once launched cannot bere-directed to new targets, also they can avoidonly previously known fixed defensive sites.Further due to their small size the missiles carryno electronic countermeasures and are also vulnera-ble to supersonic interceptor missiles because oftheir subsonic speeds. So all in all howeverpromising the concept and encouraging the earlytrials the missiles are still far from operationaland may suffer some inherent disadvantages.

Air PiclOnai, vol 40, no 1, January 1978 1M Allard:Cruise Mlssilesl.

2. MtllliilY Review, vol 57, no 3, March 1977 (L.G. Lundqust:A Field Artillery Cruise Missilel.

3. AVlallon and Marme, vol 3, no 29, September 1976,IALMC: Air-launched Cruise Mlssllel.

4. AVlalion Week and Space Technoiogv, vol 106, no 21,23 May 1977 ICA Robinson, Jr Cruise Missile HaltConsidered).

5. RT. Perry ledl: Jane's Weapon Svslems (London, 1978l.

Scientia Militaria, South African Journal of Military Studies, Vol 8, Nr 3, 1978. http://scientiamilitaria.journals.ac.za