Chapter 11 Technology Issues: Munitions and Delivery Systems

Chapter 11

Technology Issues:Munitions and

Delivery Systems

CONTENTS

PageIntroduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...................171Anti-Armor Munitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .............172

Top-Attack Munitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...........173Mines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... .. 177Countermeasures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. ... ... ... ..178

Delivery System Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..........181Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..........,...181Missile Guidance Technology . . . . . . . . . . . ..........................181

BoxA. Delivery

Figure No.11-1. Smart

Table No.

Error Budget

BoxPage

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

Submunitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .175

11-1. Anti-Armor Munitions . . . . . . . . . . . . .Page

. . . . . . . . . . . . . . . . . . . . . . . . . . 17611-2. Smart Submunition Sensors . . . . . . . . . . .........................17711-3. Assault Breaker Results . . . . . . . . . . ............................17411-4. Missile Guidance Technologies. . . . . . . . . . . . . . . . . . . .+ ............18211-5. Guidance Technology–NATO Conventional Missiles. . ............184

Chapter 11

Technology Issues: Munitions andDelivery Systems

INTRODUCTIONMunitions currently in the inventory and be-

ing procured, as described in chapter 9, are de-signed mainly to attack soft area targets (e.g.,formations of trucks or lightly armored vehi-cles, or field command posts) and hard fixedtargets (bridges, power stations). The technol-ogies embodied in these munitions—clustermunitions for soft area targets, large unitarymunitions for fixed targets-are straightfor-ward; the munitions themselves are relativelyinexpensive and are considered effective againsttheir intended targets. An important questionis whether new anti-armor munitions now un-der development can be made effective and af-fordable.

New anti-armor munitions under develop-ment, called ‘‘smart submunitions, make useof sensors that autonomously search a targetarea for a tank and are designed to strike thetank on its lightly armored top surface, in somecases using novel lethal mechanisms. If suc-cessful, these smart submunitions will clearlyadd a major new capability to attack armoredvehicles beyond line of sight and without di-rect operator control, but their very “smart-ness” leads to greater cost, greater technicalrisk, and greater risk of being spoofed by coun-termeasures. Thus, if, as a matter of policy andanalysis, it becomes clear that substantial ef-fort should be devoted to attacking tanks, anumber of technological questions come intoplay concerning these new munitions:

• Can they be made to operate reliably, un-der realistic conditions?

● Can they be made to resist likely counter-measures? Or will the deployment of ef-fective countermeasures impose a sub-stantial economic or military cost on theenemy?

● Can these goals be achieved at a reason-able cost?

At this stage of development, it is not possi-ble to say with confidence whether such a prac-tical balance among reliability, countermeasureresistance, and cost can be achieved in the de-sign of smart submunitions, nor which designsare most likely to succeed. To date, tests of pro-totype smart submunitions have been carriedout under artificial conditions that make tar-gets easier to detect—clear weather, high con-trast backgrounds, and, in some cases, artifi-cially enhanced thermal signatures. Becauseof the considerable differences between U.S.and Soviet armored vehicles (Soviet vehiclesgenerally are harder to detect) and between theclimates and terrain of U.S. test ranges andpotential European battlefields (more oftenobscured by fog, rain, and vegetation), it is es-sential that testing be carried out with realis-tic targets, under realistic conditions. A rig-orous testing program, such as that providednow by the Chicken Little and Special Projectsefforts at Eglin Air Force Base, may well bean essential continuing element in the devel-opment and evaluation of these submunitions.

A second issue is the role of mines. Histori-cally, mines have been relatively ineffectiveweapons and have received correspondingly lit-tle analytical attention. A major limitation wasthat they had to be emplaced by hand, a slowprocess that allowed little flexibility to reactto changing circumstances. New technologiesthat permit mines to be delivered by aircraftor artillery may allow mines to play a more im-mediate and responsive role in the attack ofarmored units. For example, mines mightquickly be emplaced immediately in front of

177

172 ● New Technology for NATO: Implementing Follow-On Forces Attack

a moving unit, creating a concentration of ve- them a high probability not only of halting orhicles that could then be directly attacked. delaying a tank but of actually destroying aSuch mines are now being procured; however, tank-are farther down the road. Again, thethe lack of a clear doctrine for their employ- role that such a weapon could play in follow-ment appears to be hindering plans for the ac- on forces attack is a key question that needsquisition of significant quantities. Mines that to be addressed.incorporate new lethal mechanisms-giving

ANTI-ARMOR MUNITIONS

The development of effective anti-armor mu-nitions for follow-on forces attack is compli-cated by two facts: First, the number of tar-gets is large, and they are in enemy territory.An effective weapon will have to be able to en-gage multiple targets per pass, and will haveto tolerate less than pinpoint delivery accuracy.Second, Soviet armored vehicles have over thepast two decades undergone substantial im-provements in armor protection, a trend thatis continuing. Armor has become thicker, newmaterials such as ceramics which offer greaterprotection per pound than steel have been in-corporated, and add-on reactive applique ar-mors which are very efficient in deflecting high-explosive anti-tank munitions are being in-stalled both on new tanks and as a retrofit onolder tanks.1

All of this has meant that, to be effective,new anti-armor munitions must be able to pene-trate greater thicknesses of armor and musthave a higher probability of hitting the tankaccurately—and ideally at a specific, vulner-able point on the tank’s surface. Because ar-mor protection has been concentrated on thefront surfaces of tanks to meet the primarythreat of direct fire from opposing tanks andinfantry-fired anti-tank guided missiles, it isthe top and bottom surfaces that are the mostlightly protected and thus the most vulnerable.Almost all new anti-armor munitions designedto engage armored vehicles at some distanceexploit these vulnerabilities. Increased prob-ability of hitting a target is achieved, first, bymaking the munitions smaller so that more canbe dropped over the target area; and second,in the case of “smart” munitions, by adding

I For more information, see vol. 2, app. 1 l-A, fig. 1 l-A-l.

sensors that can detect the target and guideor aim the munition for an accurate hit.

There is, of course, nothing magic about topattack; indeed if the threat against tanks shiftssubstantially to top attack, future tanks maywell be designed with added top armor protec-tion. Clearly the most effective course in thelong run–though likewise the most expen-sive—is to maintain a balanced variety of weap-ons that attack from all aspects, forcing theSoviets to make compromises in their tank de-signs. In the short run, however, top-attackweapons are likely to prove difficult to counter.As discussed below in the section on ballisticcountermeasures, existing Soviet tank designsare not well suited to retrofitting with top ar-mor because of the prohibitively large weightthat effective armor would add and becauseof the need to maintain unobstructed air flowto the engine radiators.

The choice of warhead technology is anotherfactor in armor/anti-armor competition. Armorwhich is most effective against one of the twoprincipal types of warheads used in wide-areaanti-armor weapons is not generally most ef-fective against warheads of the other kind:Shaped-charge warheads typically penetrategreater thicknesses of armor than do explo-sively formed penetrators (EFPs) but can bemore easily countered; EFPs typically pene-trate less armor’ but are harder to counter. If——

‘Not considered here is another important class of kinetic-energy warheads which are less suitable for submunitions: long,inert, preformed projectiles, such as are used today in armor-piercing, fin-stabilized, discarding-sabot (APFSDS) artilleryrounds. They may be fired by an electromagnetic gun being de-veloped by the Army, DARPA, and DNA. The Air Force’s de-velopmental high-velocity missile (HVM), although powered,is also a long, inert (i.e., nonexplosive), preformed projectile.

Ch. 11—Technology Issues: Munitions and Delivery Systems ● 173

a proposed tank were expected to f ace a threatconsisting primarily of warheads of a singletype, its designers could optimize its armoragainst that type by trading off protectionagainst the other type. An adversary’s abil-ity to use warheads of multiple types forcesdesigners to forego ideal protection against onetype in order to seek balanced protectionagainst all.

Top-Attack Munitions

Three generations of top-attack munitionscould be used for FOFA. These are cluster mu-nitions (the current generation), and two gen-erations of “smart” submunitions now in de-velopment: sensor-fuzed and terminally guidedsubmunitions.

Cluster Munitions

Current-generation anti-armor munitions areunguided cluster bombs. They blanket a largearea with a randomly dispersed shower of smallbomblets. The air-delivered Rockeye, the Com-bined Effects Munition (CEM), the GermanMW-1 submunition dispenser system, and theartillery- or MLRS rocket-delivered ImprovedConventional Munition (ICM, also calledDPICM: dual-purpose improved conventionalmunition) all incorporate armor-piercing shaped-charge warheads. The armor-penetration ca-pability of these munitions is, however, small,so they are most effective against trucks andlightly armored vehicles such as self-propelledartillery, armored personnel carriers, and in-fantry fighting vehicles. Against tanks, theyare effective only if one of the bomblets strikesthe vulnerable area over the engine compart-ment and the turret—which can be as little as1 square meter out of 15 square meters of sur-face on the top of the tank. Because the typi-cal pattern on the ground of these munitionsis one bomblet per 20 square meters, the prob-ability of stopping a tank is obviously not verygreat.3 But against soft targets, cluster weap-

31ncreasing the density of bomblets so as to increase the num-ber of hits per tank becomes a losing proposition because thearea of empty space between tanks is much greater than thearea of tops of tanks.

ons have the potential to cause multiple killsper shot;4 they are also relatively inexpensive(see table 11-1); and the technology and man-ufacturing experience are well in hand.

Possible countermeasures include the use ofapplique armor to add extra protection tolightly armored vehicles and armor skirts5 toprotect the vulnerable tires and radiators oftrucks, dispersing vehicles, and emplacing ve-hicles such as self-propelled artillery in earthrevetments.

Sensor-Fuzed Munitions

A second generation of anti-armor muni-tions–the first generation of “smart” anti-armor submunitions—is now under full-scaledevelopment (see figure 11-1). These submu-nitions--called sensor-fuzed munitions-employautonomous sensors that detect a vehicle andtrigger the firing of an explosively formedpenetrator, also known as a self-forging frag-ment, at the target. The use of a sensor to re-place the random scattering of cluster muni-tions can increase the kill probability, so fewermunitions would be wasted on empty space,and fewer rounds have to be fired or fewer sor-ties flown to achieve the same result. Thesensor can also select a particular, vulnerableaimpoint. Thus the air-delivered Skeet submu-nition uses an infrared sensor to find the hotengine compartment of a target vehicle; theartillery-delivered SADARM uses a combinationof infrared (IR) and millimeter-wave (MMW)radar sensors to locate the center of the tank,where the turret is.

These warheads are expected to be effectivein top attack against existing Soviet tanks; theretrofitting of top-attack protection armor tothese vehicles would be very difficult.’ The ma-jor lethal effect of the explosively formedpenetrator against armor, however, resultsfrom spalling: bits of metal fly off the insideof the vehicle’s armor at high speeds when the

4Some submunitions, such as GEM, DPICM, and the A PAM(anti-personnel, anti-material) also include fragmentation chargesthat can destroy a truck without hitting it.

5For more information, see note 1, app. 11-A, vol. 2.‘For more information, see note 2, app. 1 l-A, vol. 2.


Table 11-1. —Anti-Armor Munitions—

Status Delivery Targets Representative cost*

TOP ATTACK MUNITIONSCluster munitions (small shaped charge; unguided)

Rockeye inv air trucks, self-propelled $100MW-1 inv air arty, other light armor (20,000)CEM proc airICM proc arty/MLRS

Sensor-fuzed munitions (explosively formed penetrator; sensor)Skeet FSD air same as above 5,000

(200,000)SADARM FSD arty/MLRS same plus current

infantry vehicles, some tanks

Terminally-guided munitions (shaped charge; guided)MLRS-TGW R&D MLRS same plus 50,000IRTGSM R&D A T A C M S tanks (1 ,000,000)

MINESScatterable mines

GATOR proc air armored vehicles 500R A A M proc art y (50,000)AT-2 FSD MLRS

Smart minesERAM dead air armored vehicles 10,000Army mine R&D arty, helo

. -- ----

“cost per ind!vldual submunition (cost per 1,000.lb load)

artylnvI!ght armorprocFSDR&D

artilleryInventoryarmored combat vehicles, excludlng tanksprocurementfull-scale developmentresearch & development prior to FSD

warhead strikes and have a high probabilityof killing the crew. Tanks being transportedon trucks or trains to the front, without crews,fuel, or ammunition on board, may suffer lit-tle damage from these munitions. In somecases the munitions may do little more thandrill a small hole that can later be patched orignored.

In the long run, new tanks might be designedwith armors that could defeat munitions of cur-rent designs without adding prohibitively tothe overall weight of the vehicle.7 To increasethe penetrating capacity of explosively formedpenetrators to match these improvementswould mean increasing the caliber of these mu-nitions, thereby undoing the key objective ofcarrying multiple munitions in each rocket, ar-tillery shell, or aircraft dispenser load.8 But

“For more information, see note 3, app. 1 l-A, vol. 2.‘Defense Science Board, Armor Anti-Armor Competition

(Washington, DC: U.S. Department of Defense, OUSDRE, Fi-nal Report, October 1985), p. B-5; T. Hafer, Warhead Technol-ogy Options (Arlington, VA: System Planning Corp., Final Sum-mary Report SPC 924, June 1983), p. 13.

these developments in Soviet armor are manyyears’ away and of course do not come easilyor cheaply: they will be expensive and will stilllikely add some weight to the tank. The para-mount issue in considering countermeasuresis not simply whether they are possible, butrather what cost they impose on the other sidein terms of economics, weapon effectiveness,flexibility, and so on.

Because the search area of these munitionsis small,10 they are most effective when usedagainst concentrated groups of vehicles. Thesmall search area allows relatively unsophisti-cated sensors to be used, keeping costs down.But placing the job of detecting the target inthe hands of an autonomous sensor, withouthuman intervention, raises the obvious possi-bility that these weapons can be fooled,11 pos-sibly by standard camouflage techniques that

‘For more information, see note 4, app. 1 l-A, vol. 2.‘°For more information, see note 5, app. 1 l-A, vol. 2.“For more information, see note 6, app. 1 l-A, vol. 2.


\

176 . New Technology for NATO: Implementing Follow-On Forces Attack

the Soviets are known to practice, such as plac-ing fresh foliage or nets over the vehicle, whichreduces the ability of these simple sensors todetect them against background “noise” or‘‘clutter."12

Clutter is a particular problem when vehi-cles are in wooded or urban terrain, as theywould be when halted in assembly areas; it isless of a problem when vehicles are on openroads. Camouflage becomes less practical asthe tanks approach the area of the direct bat-tle; camouflage piled on top of a tank to con-ceal it from overhead observation by humansor electronic sensors makes it more visible todirect line of sight observation. The use ofsmoke or metallic chaff to obscure sensors ordecoys to distract them could be effective, butthese methods are, from an operational pointof view, far less practical.

The choice of sensor makes some differencein which countermeasures are likely to be mosteffective; however, both IR and MMW sensorshave their vulnerabilities (see table 11-2).13 In-creasing the sensitivity of the sensors can helpto detect camouflaged targets, but also drivesup the false alarm rate. Use of multiple sen-sors in different wavelength bands (“dual-mode” sensors) can likewise help to dis-criminate between real targets and clutter; butthat greater discrimination is paid for ingreater cost and, possibly, reduced reliability.Extensive testing under realistic conditionswill be needed to determine whether a practi-

‘ZBriefings from the “Chicken Little” program office, EglinAir Force Base, and U.S. Army Vulnerability Assessment Lab-oratory, White Sands Missile Range.

‘3These are discussed in more detail below in the section onsensor countermeasures.

Table 11-2.—Smart Submunition Sensors

Sensor ModeInfrared (IR) Millimeter-Wave (MMW)

advantages aimpoint accuracy performance in weatherdisadvantages targets must be hot; jamming possible;

Soviet tanks are multi-domain analysisI R-suppressed; necessary to reject

affected by weather; simple decoysdecoys possible

cal balance between countermeasure resistanceand cost can be achieved in the design of thesemunitions. The Army-Air Force Chicken Lit-tle and Special Projects test programs and thework of the Army Vulnerability AssessmentLaboratory should provide much of this neededdata.

The problem of dealing with countermeas-ures aside, costs are very uncertain at thisstage. Although the fundamental technologyinvolves no new concepts, no manufacturingexperience exists for some key elements, par-ticularly sensors.14 Likewise, although the As-sault Breaker project of the Defense AdvancedResearch Projects Agency demonstrated thatthe basic technology is feasible and available,it left unanswered the question of how muchit will cost to produce a reliable total system.As shown in table 11-3, in none of the 14 flighttests carried out under Assault Breaker wereall functions tested and found successful, al-though in three tests all functions tested weresuccessful, including engagement of multipletargets by submunitions in one test. Success-ful demonstrations of prototype smart submu-nitions in Assault Breaker, and since, havetaken place under artificial conditions-in clearweather, against low clutter backgrounds, andagainst targets with enhanced thermal signa-tures. Again, a thorough, realistic test programin the development stages could reduce thisuncertainty.

Terminally Guided Munitions

Top-attack munitions, which are now in theresearch and development phase, employ sen-sors to locate the target and guide the muni-tion into a direct impact. The terminally guidedmunition is larger than the sensor-fuzed mu-nition, containing a larger, shaped-charge war-head and a more sophisticated-and consider-ably more expensive-electronics package thatis needed to translate sensor images into steer-ing instructions for the tail fins that guide it. 15

“Defense Science Board, op. cit., p. C-2.“For more information, see note 7, app. 11-A, vol. 2.


Table 11 -3.—Assault Breaker Results

M i s s i l e

M i s s i o n f u n c t i o n T-16 T-22

Test number: 1 2 3 4 5 6 7 8 ● 9 1 2 3 4

Target acquisition (radar) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . — — — U U S S S — — — — — STarget position to missile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . — — — U U S S S — — — — — SMissile launch .,...... . . . . . . . . . . . . . . . . . . . . ... ... ... ... ... ... ..S S S S S S S S S S S S S SPrecision guidance (inertial) . . . . . . . . . . . . . . . . . . . . . . . ... ... ... ... ... .U S S S U S U — S S S S S SRadar track target . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. ... ... ... ....— — — U U S S S — — — — — SRadar acquire and track missile . . . . . . . . . . . . . . . . . . . . . . ... ... ... ....— — — U U S S S — — — — — URadar provide guidance update . . . . . . . . . . . . . . . . .. ... ... ......— — — U U S S S — — — — — SMissile trajectory correction . . . . . . . . . . . . . . . . . . . . . .. .. .. ... ... ......— — — — — — S S — — — — — SIn flight dispense.,.. . . . . . . . . . . . . . . . . . . . . .. .. .. .. ... ... ... ....— P S S P S S S S S S S P PPayload pattern generation . . . . . . . . . . . . . . . . . . . . . .. .. .. ... ... ... ....— P S S P S S S S S u s U PPayload descent functioning . . . . . . . . . . . . . . . . . . .. .. ... ... ... ....— U U U S U — — — S U U U PPayload target acquisition and lock-on . . . . . . . . . . .. .. .. .. ... ... ......— — S U S U — — — S — — — —Target engagement (single) . . . . . . . . . . . . . . . . .. .. .. ... ,.. ......— — U U S U — — — S — — — —Target engagement (multiple) . . . . . . . . . . . . . . . . . . .. .. ... ... ... ....— — — — U U — — — S — — — —Target engagement (moving) . . . . . . . . . . . . . . . . . . . .. ... ... ......— — — — — — — — — — — — — ——S — successful testP —partially successful testU —unsuccessful test

— not tested. — calibration test for fixed site radar used (n test 9

SOURCE Steven L Canby, ‘The Operational Llmlts of Emerging Technology, /nternat/ona/ Defense Rewew. August 1985, pp 875.880

This larger warhead is expected to have agreater kill capability than the explosivelyformed penetrator; it also has a much higherprobability than the explosively formedpenetrator warhead of causing catastrophicdamage to a tank.

The search area of these munitions is greaterthan that of the sensor-fuzed munitions. Coun-termeasure issues are largely the same, butweather will be a greater problem because theterminally guided munitions begin their searchat an altitude of 1 kilometer or so, and are there-fore more susceptible to the absorbing effectsof low-lying clouds.

A major issue is whether the larger searcharea and greater lethal effect of TerminallyGuided Submunitions (TGSMs) as comparedto sensor-fuzed weapons will justify their order-of-magnitude greater cost.

Mines

New "scatterable’’ mines and “smart’’ minescould also be used for FOFA. Mines have his-tonically been used to delay or harass enemyforces at best. The need to emplace mines byhand limited flexibility and imposed a large

logistics burden as well. With the developmentof scatterable mines that can be deployed byaircraft or artillery (GATOR and RAAM, nowbeing procured by the Air Force and Army,and the MLRS-delivered AT-2 under joint de-velopment by the United States and severalEuropean nations) and the incorporation ofmore effective lethal mechanisms, mines mayplay a more direct role in halting or destroy-ing armored vehicles.

The major weakness of current remotelydeliverable mines is that they are easily seenon roadways and can be easily cleared fromroadways; in Warsaw Pact forces, severaltanks per battalion have rollers or forksmounted in front for mine-clearing. The effec-tiveness of remotely deliverable mines willclearly be greater when used against a forcemoving off the roads.

“Smart’’ mines, which can sense and attacka tank at some distance, could command a roadfrom concealed off-road positions.16 They are,

“A more detailed description of these systems appears inOTA’s earlier Technologies forNATO’s Foflow-On Forces At-tack Concept–SpeciaJ Report, OTA-ISC-312 (Washington, DC:U.S. Government Printing Office, July 1986), pp. 33-34.


however, expensive, and they raise many ofthe same countermeasure, reliability, and costissues raised by sensor-fuzed weapons. The AirForce recently decided against proceeding withfull-scale development of its smart Extended-Range Anti-armor Mine (ERAM) for budget-ary reasons; the Army is still studying theconcept.

Countermeasures

The competition between new anti-armorweapons and increased armor protection is acontinuing one. The critical questions arewhether quick, easy, and inexpensive counter-measures can defeat the new weapon, and, ifnot, what cost is imposed on the defender if hedecides to develop and deploy an effectivecounter. For example, anew anti-tank weaponmay require the defender to place heavier ar-mor on his tanks, increasing their weight, thusrequiring larger engines which consume morefuel (increasing the logistics burden or hinder-ing mobility) and requiring a larger vehiclewhich is more easily seen and hit on the bat-tlefield. In addition, there is a synergismamong munitions: The greater the variety ofmunitions, the more difficult becomes the jobof defending effectively against them all. If,however, a new weapon could be defeated bya trivial change in operations or hardware,there is clearly a strong case against develop-ing it.

Ballistic Countermeasures

A shaped-charge munition penetrates armorby detonating a precisely shaped explosivewarhead which forms an intense jet of gas andmolten metal. Explosively formed penetrators(self-forging fragments) are metal slugs whichsmash through armor by virtue of their highspeed and mass—i.e., their kinetic energy. Al-though formed by explosives, they contain noexplosives at the moment of contact with thetarget and are called kinetic-energy penetra-tors. The penetrating capabilities of these war-heads are proportional to their calibers (i.e.,diameters); a shaped-charge warhead can pene-trate roughly 10 times deeper into ordinary

steel armor than can a comparably sized ex-plosively formed penetrator.17

On the other hand, shaped charges are mucheasier to defeat with current armors.18 In theearly 1960s, the only armors were aluminumalloys and steel. Increasing the thickness ofsuch armors obviously increased protection,but at a considerable weight penalty. The trendin new armor development has thus beentoward armors which achieve a level of pro-tection equivalent to a given thickness of steel(usually expressed as millimeters of RolledHomogeneous Armor Equivalent) with lighternew materials, such as ceramics, laminates,and reactive armors, which contain small ex-plosive charges that detonate when struck byan incoming warhead, thereby deflecting theshaped-charge jet. These armors are not veryeffective against kinetic-energy penetrators,however.

Improved armor has been applied primarilyto the front surfaces of tanks to protect themagainst the major threat on the battlefield—direct fire from enemy tanks and anti-tankweapons.19 The tops of tanks remain relativelyunprotected.

Thus the first-generation smart munitions(Skeet and SADARM), which contain explo-sively formed projectile warheads, are indeedsufficient to penetrate existing Soviet tankswith a top attack. Retrofitting existing tankswith additional top-attack protection does notappear feasible: a steel deck to protect the tur-ret and engine deck of an existing tank wouldadd a prohibitive amount of weight.20

Future tanks might use more efficient com-posite and hybrid armors to provide effectivetop-attack protection against Skeet andSADARM at a weight penalty less than thatfor steel armor.21 Even so, there is always a

‘7A longer, preformed kinetic-energy penetrator (such as anAPFSDS artillery round) can penetrate a thickness of homogene-ous armor proportional to its length; it can be made to pene-trate farther by increasing its length or velocity rather thancaliber.

“For more information, see vol. 2, app. 11-A (note 8, table1 l-A-2, and figure 1 l-A-2).

‘gFor more information, see note 9, app. 11-A, vol. 2.“For more information, see note 10, app. 1 l-A, vol. 2.“For more information, see note 11, app. 1 l-A, vol. 2.

Ch. 11— Technology Issues: Munitions and Delivery Systems ● 179

trade-off between using more efficient armorto add protection and using it to build a lightertank with no additional protection. The hybridsand composites are not suitable for a retrofitto existing tanks because they must be madeas an integral part of the armor; they cannotsimply be bolted on top. Ceramics, for exam-ple, are brittle and have to be sandwiched be-tween layers of steel in the manufacturing proc-ess. The effectiveness of these new armorsagainst explosively formed penetrators cannot,however, be predicted with certainty by exist-ing theoretical models; improvement of modelsis needed, as are simple controlled experiments.

Operational Countermeasures

Because the sensors employed on smart mu-nitions can search only a limited area, perhapsthe most obvious countermeasure is to increasethe spacing between vehicles both on the roadand when halted in assembly areas. This wouldhave a greater effect on sensor-fuzed weaponsthan on TGSMs, which can search much largerareas .22

Another operational tactic that could reducethe effectiveness of smart munitions would beto take advantage of terrain that produces high“clutter” (natural background camouflage),making it difficult for the sensors to pick outthe target from a sea of confusing signals. Ur-ban areas produce severe clutter in both theIR and MMW bands; using towns as assem-bly areas would make an attack with these mu-nitions very difficult.23

Weather may be exploited to counter sen-sors. Dry snow provides a very high clutterbackground that can swamp the signature ofa vehicle. The frequently occurring low-levelclouds and fog in central Europe interfere withthe performance of IR sensors. Rain affectsboth IR and MMW sensors. Moving when vis-

22 For more information, see note 12, app. 1 l-A, vol. 2.“Steven Canby, “The Conventional Defense of Europe: Oper-

ational Limits of Emerging Technology” Working Papers No.55, International Security Studies Program, The Wilson Cen-ter, Smithsonian Institution, pp. 24-32; also briefing from Vul-nerability Assessment Laboratory.

ibility is poor and halting when it improvesresults in reduced vulnerability, as well as rateof advance.

Camouflage, Decoys, and Jamming

There are two basic technical approaches tofooling sensors. The target can be made toblend into the background, either by camou-flaging the target or by artificially increasingthe background noise or clutter level with elec-tronic jamming, smoke, or chaff; alternatively,false targets can be created, either by deploy-ing decoys or by broadcasting a carefully tai-lored signal which fools the sensor into think-ing it has spotted a target.24

Counter-countermeasures for dealing withcamouflage and clutter include the use of dual-mode (active and passive) and multi-spectralsensors (which are sensitive in more than onewavelength band), and the use of more sophis-ticated “multi-domain” analysis of the infor-mation obtained from a single-mode MMWsensor. For example, analysis of the delays ofthe echos of an MM W radar signal from differ-ent features of an object can yield informationabout the spacing of distinguishing features,which can help to distinguish a tank from back-ground objects. Use of multiple wavelengthbands increases the chances of finding onewavelength at which the background clutterat any given time will not be too bad.

These measures, of course, will increase thecost and complexity of the submunition andare not infallible. Multi-domain analysis, forexample, reduces susceptibility to deceptionjamming but does not eliminate it, as discussedbelow.

Another approach to making target detec-tion difficult is jamming. The aim can be sim-ply to produce so much background noise thatthe target no longer stands out. To jam an ac-tive MMW sensor would require high powerover a wide band of wavelengths and may beinfeasible if the sensor has good counter-countermeasures. 25 The possible use of lasers

“For more information, see note 13, app. 1 l-A, vol. 2.“Briefing from the U.S. Army Vulnerability Assessment Lab-

oratory.


Examples of Simple Countermeasures

Camouflage nets

to jam IR sensors has been raised; but track-ing a rapidly moving submunition and aiminga laser at it is likely to be extremely difficultin practice.

Finally, smoke and chaff are standard de-ception devices. Soviet tanks are equipped withsmoke generators, and the Soviets have con-siderable experience in using smoke to maskground movements from visual observation.However, ordinary smokes are relatively trans-parent to IR and, especially, MMW radiation.Chaff might also be used.26 To shield tanksagainst smart submunition sensors, the chaff

“For more information, see note 14, app. 1 l-A, vol. 2.

would obviously have to be near the groundand would have to be renewed at least everyfew minutes; at the wavelengths in question,large quantities would be required. Both smokeand chaff suffer from the drawback that ade-quate warning of an attack is essential to theireffective use.

Decoys in general pose less of a problem tosensors than do jamming or camouflage. Sim-ple decoys, such as MMW corner reflectors,are easily rejected by multi-domain analysis.To fool multi-domain MMW sensors, decoysmust resemble full-scale models, which obvi-ously are of limited practicality. Simple IR de-coys such as flares or fires can similarly be


rejected.27 IR sensors may, however, be sus-ceptible to decoys that more faithfully repro-duce the power output and temperature of atank engine.28

Even with multi-domain processing, activeMMW sensors are susceptible to deceptionjamming–the broadcasting of signals whichresemble the radiation reflected or emitted bya target, insofar as the sensor and its proces-

2’For more information, see note 15, app. 11-A, vol. 2.‘mAccording to the Vulnerability Assessment Laboratory, such

an I R decoy would require 1 kilowatt of primary power; a smallpropane bottle of the kind used for soldering torches or camp-ing stoves could supply this power level for several hours.

sor can determine. Deception jamming is notan inexpensive countermeasure, and it requiressome knowledge of the operating wavelengthof the sensor and its processing algorithm, butit is nonetheless straightforward from a tech-nology point of view. The Soviets deploy alarge variety of radar jamming equipment, andthus have the technical and operational basefor developing and deploying such a system.Passive MMW sensors are also susceptible todeception jamming, which would require onlymodest power over a wide band of wavelengthssimultaneously; while feasible, this would re-quire several advanced-technology jammers.

DELIVERY SYSTEM ISSUES

Introduction

Aircraft today provide virtually the onlymeans of delivering munitions to targets be-yond the immediate battle area. Aircraft havea flexibility in deployment that ground-launched systems do not; they also place a hu-man observer at the scene. They are limited,however, when used in direct attacks againstfollow-on forces: as discussed in more detailin chapter 9, few aircraft have a night or all-weather capability; all of the NATO aircraftthat could play a role in attacking beyond theimmediate battle area have other missions toperform as well; and the very heavy WarsawPact air defenses could result in significantlosses of attack aircraft, particularly if thoseaircraft must fly very close to or directly overtargets in enemy territory .29

The high cost, long development cycles, andlong procurement programs for new aircraftmean that current aircraft-with the sole addi-tion of the planned F-15E—will constituteNATO’s ground attack air force at least untilthe turn of the next century.

The improvements in delivery capabilitiesthat will occur over the next two decades orso can be expected to come principally fromair-to-ground missiles that will allow attack air-

craft to remain a safe distance from enemy airdefenses, 30 and from ground-launched missilesthat will complement aircraft in reaching deeptargets, particularly at night and in bad weatheror when aircraft are needed elsewhere. Missilescan incorporate precision guidance systemsthat offer substantial improvements in accuracyover that attainable with ground-based ar-tillery, unguided rockets, or air-delivered free-fall bombs. High accuracy becomes crucial inattacking hard, fixed targets such as bridgesand the increasing number of heavily fortifiedcommand, control, and communications facil-ities in Eastern Europe. And regardless of thetype of target, to the extent that precision guid-ance can increase the probability of a kill, theuse of missiles can reduce the number of sor-ties or rounds required to achieve a given ob-jective.

Missile Guidance Technology

The propulsion and airframe technologies ofmissiles are mature. The chief technology choicein these systems is between ballistic missilesand cruise missiles. Ballistic missiles fly fasterand thus can reach moving targets before theymove far; cruise missiles have the potential toachieve higher terminal accuracy on target,

“For more information, see note 16, app. 1 l-A, vol. 2.301mproved me~s for suppressing enemy air defenses are

another important approach to this problem.


though they may take hours rather than min-utes to reach their targets and will require in-flight guidance updates or special seekers tohit moving targets. They may also be more vul-nerable to interceptor aircraft and ground-based air defenses. The major area where newtechnology may play a role in airframe designis in the application of low-observable tech-niques to cruise missiles to reduce their vul-nerability.

What distinguishes the major differing ap-proaches to tactical missile design today andwhat most determines their differing capabil-ities is the technology used for guidance. Twodifferent guidance functions-mid-course andterminal guidance—may be needed. Thesemight use different technologies:

1. For guiding a missile to the general tar-get area-mid-course guidance-someform of inertial guidance is almost alwaysrequired. The only exceptions are veryshort range air-launched missiles that lockonto their targets before launch using oneof the precision terminal guidance tech-nologies described below,31 or that fly theirinitial course in a pure ballistic trajectory.Although inertial guidance is a well-developed technology that has been usedfor decades aboard ships, aircraft, spacevehicles, and ballistic missiles, the tech-nology has historically been quite expen-sive; costs rise quickly with the increas-

————- ——.“TO deliver such a missile, the aircraft must line itself up with

a near straight-line path to the target. Inertial systems maybe needed by short-range missiles that are to be able to fly toa target substantially off axis.

2.

ing accuracy that is required for longerflight times. Thus, the major technicalchallenge in applying inertial systems toconventional missiles is reducing cost.

The precise inertial systems used onnuclear-armed ballistic missiles or fighteraircraft, for example, cost far too muchto justify their one-time use on low-cost,conventionally armed missiles. However,new technologies promise to reduce thecost of inertial guidance systems substan-tially, particularly for short-range appli-cations. Inexpensive miniature inertialsystems using fiber-optic gyros could beused in short-range weapons—and inlonger range weapons, if complementedby any of several devices now availableto recalibrate the system in flight (e.g.,miniature Global Positioning Systemreceivers). For the specific case of long-range attacks against moving targets,another important issue is whether the mid-course guidance system needs to includesome means of receiving an in-flight updateof the target’s location.For attacking hard fixed targets such asbridges or bunkers, mid-course guidancealone is not sufficient; precise terminalguidance, sometimes to within an ac-curacy of a meter or less, is needed. (Forother types of targets, inertial guidancewill as a rule suffice; if the missile can bedelivered to within 100 meters or so of thetarget, cluster munitions can be used toattack soft area targets and smart sub-munitions to attack armored combat ve-hicles. See table 11-4 and, for a more

Table 11-4.—Missile Guidance Technologies

RangeTarget Type Short Long

soft area fixed Inertial better Inertialsoft area moving

(unarmored unit) inertial better inertial( + automatic target recogition or In-flight target update for

cruise missiles)(armored unit) inertial + smart better inertial

submunitions + automatic target recognition or in-flight target update+ smart submunitions

hard fixed man in loop orautomatic better inertial

target recognition + automatic target recognitionSOURCE Office of Technology Assessment 1987


Box A.—Delivery Error BudgetMissiles that carry nuclear warheads can

get by with inertial systems, even at very longranges (thousands of kilometers for ICBMs)and even when targeted against hard pointtargets, because the kill radius of the warheadis large enough to tolerate inaccuracies oftenof hundreds of meters in delivery. However,when conventional warheads are used againsthard fixed targets such as bridges, accuracieson the order of a meter are often essential:a specific support element of a bridge mayhave to be struck. Inertial systems operateby guiding the missile to an absolute geo-graphic coordinate. Even if the guidance sys-tem were perfectly accurate, it would belimited by the uncertainty with which theabsolute geographic coordinate of a fixed tar-get is known-and that uncertainty is toolarge to allow the required one meter or lessaccuracy,

detailed discussion of the limitation of in-ertial systems in attacking fixed-point tar-gets, see box A. Precision terminal guid-ance on existing missiles is achievedthrough the use of a human controller—a“man in the loop’ ‘—who, for example,might observe the target through a TVcamera mounted on the nose of the mis-sile and steer the missile into it by radiocontrol.

A key issue in precision terminal guidance ishow much effort should be given to developinga next-generation system that can operate au-tonomously. An automatic target recognitionsystem could reduce the burden on a humancontroller; in the case of air-launched missiles,for example, it would allow the pilot to launchhis missile and immediately exit the area. Incertain proposed missions that could strain thecapabilities of man-in-the-loop systems (e.g.,long-range attack of hard fixed targets), auto-matic target recognition may be essential. Y e tthe development of such systems involves ahigh technical risk; so far, none of the manylaboratory efforts or prototypes have provedreliable enough to justify procurement, and in-

deed critics suggest that automatic target rec-ognition faces fundamental obstacles that mayprove insurmountable.

Mid-course Guidance

Inertial.—An inertial navigation system con-tinually recalculates its current position byadding up the many small changes it sensesin the missile’s acceleration and rotation. Evensmall errors in those measurements are quicklycompounded, causing the accuracy of the sys-tem to decrease with time (drift). Measures toreduce drift quickly drive up the costs of tradi-tional mechanical inertial navigation systems.

The new technologies of ring-laser gyro-scopes and (especially) fiber-optic gyroscopespromise to reduce the costs of inertial systemssubstantially, although not necessarily to im-prove performance. Such inexpensive and lessaccurate inertial systems could have importantapplications in short-range missiles (e.g., ashort-range air-launched stand-off missile car-rying smart submunitions that have a largesearch area to compensate for delivery errors),and in longer range missiles if used in conjunc-tion with techniques to periodically recalibratethe inertial system. These techniques includethe Global Positioning System satellites, whichcan provide, via an on-board receiver, a geo-

P/Joto credft U S Deparfmenf of Defense

Air-launched cruise missile uses TERCOM and otherprec is ion guidance,


graphic fix within 13 meters in absolute co-ordinates; and various map update systemssuch as terrain comparison (TERCOM) which,at set intervals, compares the terrain profilebelow with a stored map to correct any driftin the inertial system. GPS receivers are likelyto be jammed in the immediate target area,so terminal accuracy is determined by the driftof the inertial system from the last ( unjammed)update. The services have in addition beenreluctant to place themselves in a position ofhaving to rely on the survival of satellites inwartime. TERCOM, which is employed on ex-isting U.S. cruise missiles, is an alternativetechnique, although mission planning is time-consuming, detailed maps are required, andthus retargeting flexibility is obviously verylimited.

In-flight Target Location Update.–At longerrange, a moving target will have moved fartherby the time a missile arrives; this is especiallythe case for slow-flying cruise missiles. One pos-sible solution, discussed below, is to equip acruise missile with an automatic target recog-nizer so that it can search for the target as itflies a course along a likely route, such as a road.Another approach, employed in the AssaultBreaker demonstration program (and applicableto both cruise and ballistic missiles) is to relay

updated target location data to the missile inflight. This data would be developed by a radarsurveillance and target acquisition system suchas Joint STARS, and transmitted to the missilevia a radio link.

Because of cost and technical problems, pro-vision for an in-flight update was dropped fromthe design of at least initial versions of the ArmyTactical Missile System (ATACMS); it maybeadded later as a block improvement. Analysishas shown that the loss incapability due to lackof update is not severe for ATACMS. Technicalissues that need to be considered are beamingof an update to a missile while lofted (or acquisi-tion of the guidance signal by the missile at loweraltitude in time to act on it) and the susceptibil-ity of such an update link to jamming.

Precision Terminal Guidance

Man in the Loop. –The current generation ofprecision-guided conventional missiles makesuse of technology that was first employed bythe U.S. Air Force in Vietnam some 20 yearsago. Human control of the missile is main-tained to acquire and select the target and, insome cases, to guide the missile throughoutits entire flight. A variety of techniques areused (see table 11-5); for example, a laser seeker

Table 11-5.—Guidance Technology—NATO Conventional Missiles

Launch mode Targets Status Guidance technology

primarily inertialconv. Tomahawk sea areaATACMS ground area, armorSRSOM air armorIAM air fixed

precision terminal (man in loop)HVM air, ground armorFOG-M ground armorMAVERICK air armorCOPPERHEAD artillery armorPAVEWAY 2 air fixedGBU-15 air fixedAGM-130A air fixed

precision terminal (automatic target recognition)LRSOM air(/ground) areaCMAG ground/air all —

procFSDR&DR&D

FSDR&Dinvinvinvinv/procFSD

R&DR & D

iner t ia l /TERCOMinertial (ballistic)inertial (+ sensor?)inertial

laser command guidance (“beam rider”)fiber-optic data linkIIR lock-on before launchlaser designatorlaser designatorTV/n R radio data linkTV/n R radio data link

inertial/GPS/TERCOM + terminal seekerLADAR, SAR, MMW

targets: area: soft area targets (SSMS, SAMS, field command posts)fixed: hard fixed ta~gets (bridges, power stations, bunkers)armor: moving armored combat vehicles

status inv inventoryproc procurementFSD: full-scale developmentR&D research and development, prior to full+cale development

SOURCE Office of Technology Assessment, 1987


on the missile can guide the missile to a spoton the target illuminated by a laser beam, ora TV camera on the missile can send a pictureback to the aircraft cockpit where a weaponsofficer is steering the missile via radio control.32

All these techniques share some common char-acteristics. High accuracy—on the order ofmeters—is possible; the presence of a‘ ‘man inthe loop” may avoid many countermeasureproblems such as electronic decoys or back-ground clutter; the technology is for the mostpart mature and involves little technical risk;and costs are, very roughly, on the order of$100,000 per missile.

On the other hand, these missiles are all ofrelatively short range (tens of kilometers); mostrequire a clear line-of-sight to the target; andthus most of the air-delivered models still re-quire aircraft to fly close to their targets andto remain there throughout the flight of themissile. A general problem with laser-guidedweapons is that the laser can be obscured bysmoke around the target area; laser-guidedweapons are also somewhat less accurate thanTV-guided models. A general problem with ra-dio data links, used to transmit TV picturesfrom the remotely guided GBU-15s, is thatthey can be jammed.

Despite these basic limitations, some im-provements in this generation of weapons arepossible without going to a radically new gen-eration of technology. Range can be extended:for example, the AGM-130 has roughly doublethe range of the GBU-15 from which it is de-rived by the addition of a simple (but expen-sive) solid-fuel rocket motor. Jam-resistantdata links are being developed for the GBU-15 and AGM-130. Fiber-optic data links couldprovide jam resistance for missiles launchedfrom the ground.

Automatic Target Recognition.—Automatictarget recognition, if successful, clearly couldincrease the effectiveness of missiles in all mis-sions, and could increase the survivability ofaircraft by allowing them to leave the area im-

~ZThese specific technologies are described more thoroughlyin OTA's special report, Technologies for NATO's Follow-OnForces Attack Concept, July 1986, pp. 24-27.

mediately after launching the missile. How-ever, as indicated in table 11-4, automatic tar-get recognition may bean enabling technologyfor attacking hard fixed targets at long rangewith nonnuclear missiles.

At long distances, attacking hard fixed tar-gets would strain the capabilities of the man-in-the-loop guidance systems that are now theonly means of providing the required preciseterminal accuracy. Establishing radio contactwith the missile as it approaches the targetarea is difficult at long range. The control air-craft would have to arrange to be in positionat the right instant to have a clear line of sightto the missile, unobscured by terrain or vege-tation, and jamming of the radio data linkpresents an increasing threat at greater rangefrom the control aircraft. Automatic target rec-ognition, which could free the missile from theneed for human control while providing highterminal accuracy, is the only practical alter-native.

For a second mission-long-range attack ofmoving armored combat vehicles whose loca-tion will have changed substantially during theflight time of the missile-a possible solution,discussed above, is to provide an in-flight up-date of the target location from a system, suchas the Joint STARS radar, with weapon guid-ance capability. Alternatively, the missilecould be equipped with an autonomous capa-bility to search for the targets while flyingalong a likely route such as a road.

Both of these missions would also requirea mid-course guidance system capable of de-livering the missile to the general target area(see discussion of inertial systems above).

The technology for automatic target recog-nition has proved problematic to date. The sen-sor (e.g., a TV camera or radar) must providea high-quality image of the target area for rec-ognition; even then, picking out the target froma complex image, and distinguishing it fromsimilar objects (e.g., a tank from a truck) is avery challenging computational task, espe-cially because it must be carried out in realtime. Mobile targets pose a special problemin that they may be facing any direction-and


Photo credit’ McDonnell Douglas Corp

F-15E equipped with LANTIRN pods.

a tank looks quite different when viewed fromdifferent angles.

All sensors are subject to countermeasures,including decoys and camouflage as discussedabove in the section on smart submunitions;signatures of fixed targets may be quite vari-able depending on the season and weather asfoliage and snow cover change. Although ele-ments of an automatic target recognize havebeen demonstrated in the laboratory, completeworking systems have remained elusive. Forexample, continuing problems in achievingreliable automatic target recognition in theLow Altitude Navigation and Targeting In-frared for Night (LANTIRN) infrared target-ing system for fighter aircraft may lead to thatfeature being dropped from LANTIRN. Anautomatic target recognize for an autonomousmissile would have to perform even more relia-bly: LANTIRN was designed to identify thetarget but still allow a human to make the fi-nal launch decision; an autonomous missilewould be entrusted to perform the entire jobon its own.

Even if the technology can be made relia-ble, placing an automatic target recognize ona cruise missile poses some engineering chal-lenges as well. An imaging sensor and its asso-ciated computer processor would add a con-

siderable power requirement over that ofexisting cruise missile electronics; this will re-quire heavier generators and, with the extraheat generation, a cooling system for the elec-tronics.” Advances in the miniaturization ofelectronics may solve this problem. The useof currently available sensor technology—millimeter wave radar and imaging infrared—would also pose a packaging problem, becausean additional system would be required for ter-rain following. A more advanced sensor, CO2

laser radar, is being pursued by several con-tractors; both target-acquisition and terrain-following/obstacle-avoidance functions couldbe carried out by this single sensor. Much ad-ditional development of this sensor will be re-quired; however, it is also likely to be the mostexpensive option.

The lowest technical risk approach to auto-matic target recognition might involve clevercombination of existing capabilities to performa limited mission. For example, low-cost iner-tial/GPS guidance could be used to steer acruise missile close to a road or railroad, anda relatively simple imaging sensor could iden-tify the road and keep the missile precisely ontrack; it could also detect trains or groups ofvehicles. An autonomous capability againstfixed targets might be provided in the nearterm similarly by demanding less than com-plete autonomy or flexibility. A short-rangestandoff missile could be guided from a presetlaunch point to the target area by a simple in-ertial system; a sensor system, supplied withinformation about the orientation of the tar-get and its general characteristics (e.g., typeof bridge, number of spans), might then be ableto perform the somewhat simplified target rec-ognition task.34

33Capt. R.B. Gibson, USAF, et al., Investigation of the Feasi-bility of a Conventionally Armed Tactical Cruise Missile, Vol.1 (Wright-Patterson Air Force Base, OH: Air Force Instituteof Technology, report AFIT/GSE-81D-2, December 1981), p. 7.

siThi9 concept is being pursued in the Autonomous GuidedBomb program of the Air Force Armaments Laboratory.

Documents

Chapter 11 Technology Issues: Munitions and Delivery Systems