Transcript
by Captain Adam W. Lange At 0100 hours on 17 January 1991,eight AH-64 Apaches from the 101st Air-borne Division (Air Assault) depart froma staging airfield in Western Saudi Ara-bia on a mission code-named “Nor-mandy.” The decisive point of the opera-tion is the destruction of two key Iraqiradar sites located about 35 miles apart.Split into two teams of four in order toservice both targets at once, both teamsconduct a 90-minute, low-altitude, night-vision goggle flight into Western Iraq un-der strict radio listening silence. At ex-actly 0238 hours, the Apaches fire a vol-ley of 27 Hellfire missiles, destroyingcritical targets at each radar site. Four and one-half minutes later, with the first shots of Operation Desert Storm suc-cessfully delivered, over one hundred Coalition jets begin streaking up a“blind” Iraqi air corridor approximately20 miles wide enroute to multiple targetsin Baghdad. Mission complete, the Apaches cautiously wheel around to be-gin their egress home, and the PersianGulf War is on... The mission described above is, bynow, known by many to be the real-life,secretive start of Operation DesertStorm. It also provides an excellent ex-ample of the capabilities of the Army’sHellfire missile system; an extremely le-thal and effective point weapon systemcapable of precision accuracy and de-struction when properly employed. Cur-rently, the Hellfire missile is an exclu-sively aviation-employed weapon sys-tem, launched by Army and MarineCorps aviation units from a variety of helicopter platforms, to include the AH-64A Apache, the AH-1W Super Cobra,the OH-58D Kiowa Warrior, and theSpecial Operations UH-60 variant. Whydiscuss an aviation weapon system inthis forum, which is fundamentally dedi-cated to armored ground systems andtraining? The answer is simple. Groundmaneuver commanders take note: theHellfire missile system is your weaponsystem, too!While it is true that the Hellfire missileis utilized by aviation forces conductingaviation missions, it is almost alwaysdone so in support of the ground maneu-ver commander’s tactical plan. Thus, it isprimarily used to achieve a desired effectfor the ground maneuver commander atmany levels, ranging from battal-ion/squadron to echelons above corps. Inaddition, aviation brigades will seldom,if ever, operate entirely independently of their sister units on the ground. Often,attack and armed reconnaissance aircraftare attached or OPCON to battalion- andbrigade-sized units as part of an aviationtask force. Our present combined armsdoctrine supports this point of view,strongly emphasizing the need for closeair/ground integration to exploit timelymaneuver in all battlefield dimensions,and to allow for the massing of all de-structive fires — both surface-to-surfaceand air-to-surface. 1 Like any other battlefield weapon sys-tem which they employ, all commandersand operation planners, both air andground, must have a basic understandingof how the system works, its capabilities,and, most importantly, its limitations.This, in turn, will help to ensure properplanning for use of the Hellfire missileas a contributor to the commander’s tac-tical plan. That plan could very well seeHellfire-armed aircraft employed in awide variety of missions, such as theanti-armor counterattack; in a reserverole, as part of a larger unit’s deep fightagainst selected high value/high payoff targets; as part of a Joint Air Attack Team (JAAT); or in an engagement areain the close battle. Missile Data and Specifications Table 1 outlines some of the basic mis-sile data and specifications of the Hell-fire (Anti-Tank Guided Missile or AGM114) system.As indicated in Table 1, there are sixdifferent production models in the U.S.missile inventory, each with different de-sign features and capabilities. These dif-ferent models are: ã AGM-114A. This missile is the srci-nal design Hellfire missile with basicsub-components and a low-smoke rocketmotor. It flies the highest trajectories of the six missile models. ã AGM-114B. This missile has an im-proved low visibility (ILV) capability; itflies lower trajectories than the AGM-114A, and contains a minimum-smokerocket motor (less than the AGM-114A).The AGM 114-B contains a Safe andArm Device (SAD) which provides anelectrical and mechanical blockage inthe rocket motor firing train, making itapproved for U.S. Navy shipboard useby the Marines, as well as being compat-ible with Army aircraft. ARMOR — January-February 1998 25 Getting the Most from a Lethal Missile System HELLFIRE ã AGM-114C and AGM-114F. Thesemissiles have the same ILV capability asthe AGM-114B. They fly the same lowertrajectories with the same minimumsmoke rocket motor, but do not containthe SAD. ã AGM-114K. This missile has thehighest probability of re-acquiring a tar-get if the missile flies into low clouds. Itis the only missile produced with an in-ternal guidance algorithm to account forthis condition by design. If the missileloses laser lock after initial acquisition,the seeker section will continue to pointat the target. Instead of continuing toclimb and fly a normal profile, the mis-sile is programmed to turn and point inthe same direction as the seeker. Thiscauses the missile to fly down (out of the clouds) toward the target and maxi-mize the probability of re-acquiring thetarget. ã The AGM-114F and AGM-114Khave an additional warhead for improvedperformance against reactive armor. 2 Editor’s Note: Martin Marietta Tech-nologies is now building another ver-sion, the AGM-114L, for the Longbow Apache system. It is similar to the AGM-114K (Hellfire II) but has a millimeter wave, fire-and-forget guidance system. How the Hellfire Missile System Works Originally designed for use in the anti-tank role, the Hellfire missile has alsobeen used successfullyto engage other targetsas well. Point targetssuch as bunkers, ra-dars, large antenna ar-rays and communica-tions equipment, smallbuildings or towers,and even fast-movingboats can be effec-tively neutralized ordestroyed. If needed, itcan even be employedin the air-to-air roleagainst slow-movingor hovering helicop-ters. The name “Hellfire”is derived from an ac-ronym for Heliborne-launched, Fire and Forget , but the namecan be misleading. 3 Fire and forget givesthe impression that themissile guides itself tothe target autono-mously without furtherinput by the air crewsafter launch. This, however, is amisconception and only partiallytrue. The Hellfire missile is aguided munition, much like theolder TOW missile. It requires acoded laser beam to be placed onthe target, and the missile will actu-ally follow or “ride” the properlycoded beam to the point of impact.Thus, the missile never actually ac-quires the target in question, butrather acquires the laser beam. Thelaser designator or “observer,”either airborne or ground-mounted,must always positively control themissile after it is launched in orderto bring it to bear on the target inquestion.Regardless of specific model, eachHellfire missile has five basic sections ormajor sub-components that allow it tooperate during the sequence from launchto detonation. These sub-componentsare: the propulsion section, laser seeker,guidance section, control section, and thewarhead.The propulsion section is located be-tween the guidance and control section,near the aft end of the missile. It has asolid fuel propellant that burns approxi-mately 2-3 seconds, depending on theoutside air temperature. The purpose of the propulsion section is to generateenough thrust to separate the missilefrom the launcher, to attain the 10 Gs of thrust necessary for arming the missile,and powering it to the target. The rela-tively short burn time is more than suffi-cient to allow the missile to reach itsmaximum effective range of 8 kilome-ters. In fact, the missile is capable of de-stroying targets beyond 8 kilometers, butthe overall probability of hit ratio (P h )decreases as distance increases.Located in the nose of the missile, thelaser seeker is programmed from insidethe aircraft to receive a specific lasercode. When the missile recognizes thiscode being emitted from a designatorand reflected off of the target, it “lockson” to this emission. After lock-on, theseeker then sends this information to theguidance section which directs the mis-sile to the target. After receiving infor-mation from the laser seeker, the “brainsof the missile,” or guidance section,computes steering command data to sta-bilize the missile and then transmits thisdata to the control section.The control section, located at the veryaft end of the missile, contains a pneu-matic actuation system that convertssteering commands into mechanical finmovement. It is this fin movement that Weight (each missile): 100.9 lbs (108 lbs - L Model) Length: 64 inches (69 in. - L Model) Diameter: 7 inches Wingspan: 12.8 inches Max. Velocity: 950 mph - 475m/sec - 1393 fps (1.4 mach) Velocity required to Arm: 10 Gs (normally achieved 150-300m in front of the aircraft) Warhead: Copper-lined conical shape charge, High Explosive Anti-Tank (HEAT) -explosive force equivalent to 35mach Sub-components: 5 sections - Seeker; Warhead; Guidance; Propulsion; Control Launch Motor: Solid Fuel (2-3 seconds to motor burnout after launch) Effective Range: 500m minimum range; 8000m maximum effective range Missile Battery Life: 46 seconds +/- 2 seconds Maximum Rate of Fire: 1 missile every two seconds Number of models: 6; AGM-114A/B/C/F/K/L Manufacturer(s): Rockwell International Systems Division and Martin Marietta Inc. Table 1. Missile SpecificationsFigure 1. Hellfire Missile 5 26ARMOR — January-February 1998 directs air flow over the missile muchlike the wings on an airplane, allowingthe missile to turn and maneuver towardthe reflected laser energy of the target.The warhead is the last section to con-tribute to the firing sequence. Upon col-lision with the target, an impact sensorsends an electrical signal to a fuse in therear of a copper-lined shape charge,causing detonation. This charge providesthe explosive and penetrating force nec-essary to defeat the armor of a tank ordestroy “softer” targets. Only the AGM-114F/K/L models, however, possess theadditional ability to defeat modern reac-tive armor systems. 4 Figure 1 shows acutaway of the basic Hellfire missile andits sub-components. Methods of Employment and Planning Considerations There are different techniques for tacti-cal employment of the Hellfire missileon the battlefield. These techniques areultimately driven by the two engagementmethods by which the missile can becontrolled to the target: autonomous andremote. An autonomous engagement re-quires the aircraft launching the missileto guide it all the way to the target afterthe missile is away. In this method, asingle aircraft and its crew will locate,identify, fire, and guide the missile untildestruction of the target in the same wayan M2/M3 Bradley crew employs itsTOW missiles. In contrast, a remote en-gagement requires an aircraft to serve asa launch platform, providing a missilefor another aircraft or a ground observer,designating with a laser, to guide themissile to its intended target. A grounddesignation station such as an FO orCombat Observation Lasing Team(COLT) accomplishes this with lasingdevices like the G/VLLD or MULE.With a remote engagement, the air crewis responsible only for delivering themissile toward the general location of the target, but is no longer responsiblefor its guidance once it leaves the exter-nal launch rails. This allows remote en-gagements to provide one distinct advan-tage over autonomous engagements. Us-ing this technique, the launch aircraft isoften able to remain masked behind ter-rain, greatly reducing its visible launchsignature while delivering missiles to-ward the target array, thereby increasingaircraft survivability - a force protectionconsideration. Remote engagements, however, requirea great deal more coordination and plan-ning between the “shooter” and the “ob-server.” This is especially true when air-craft and ground designators, such as theCOLTs, are working together. Unim-peded radio communication and infor-mation transfer between these elementsare a must for successful target destruc-tion and to reduce the risk of fratricide.Ground commanders and operationsplanners wishing to utilize Hellfire mis-siles in this manner must be aware of this prerequisite. They must closely co-ordinate with supporting aviation unitsfor the location of pre-planned aerial bat-tle positions/attack-by-fire positions andground remote designation positions/ob-servation points to support this air andground interaction. On combined armsbattlefields with limited terrain for bothcover and concealment or observa-tion/fields of fire, this can have serious planning implications concerning land management and clearance of fires. In addition to the two methods of en-gagement, there are four modes of deliv-ery that aircrews can utilize when firingthe Hellfire missile. These deliverymodes are important to consider becausethey are driven by three important fac-tors: distance to the target, the weather(primarily visibility and cloud ceilingheight), and terrain conditions underwhich the missile will be fired. Theseconditions will always require carefulplanning consideration when attemptingto integrate air and ground fires into thetactical plan because they affect the rela-tive trajectories of Hellfire missiles whenfired. Higher trajectories can have seri-ous ramifications if an attack mission isplanned or executed during a period of marginal weather with low cloud ceil-ings, especially if conducted at maxi-mum standoff ranges. The reason for thisrevolves around the laser guidance sys-tem employed by the missile. As a gen-eral rule of thumb, when a Hellfire mis-sile flies through obscuration (fog,clouds, smoke) or if the designator failsto lase the target properly until impact,the missile loses laser lock and will belost for good. It will not regain sight of the target, even if designated again. Aspreviously mentioned, only one model of Hellfire missile, the AGM-114K, has abuilt-in system to assist in the reacquisi-tion of the target after laser lock-on islost, but these missiles have yet to beproduced and distributed in quantitieslarge enough to ensure that this problemwould not be a factor. The AGM-114Lwhen fielded will, however, provide atrue fire-and-forget capability.The first delivery mode is known asthe Lock-on Before Launch (LOBL)technique. In this mode, the missile laserseeker acquires and locks-on to thecoded laser energy reflected from thetarget prior to launch. The advantage tousing this particular delivery mode isthat the air crew is assured that the mis-sile has already positively locked on tothe target prior to launch from the air-craft, thereby increasing its P h and reduc-ing the possibility of a lost or uncon-trolled missile. The disadvantages of a ARMOR — January-February 1998 27 Figure 2. LOBL Trajectories (AGM-114A) 6 Figure 3. LOAL-DIR Trajectories (AGM-114A) 7 LOBL delivery revolve around the tra- jectory of the Hellfire missile as itstreaks toward its target. LOBL engage-ments cause the missile to fly the secondhighest trajectories of all delivery modes,and the altitude the missile reaches is afunction of distance to the target. Simplyput, in LOBL mode, the farther the tar-get, the higher the missile flies. Figure 2shows examples of the maximum trajec-tories of an AGM-114A missile duringdifferent engagement ranges. As thegraph in Figure 2 depicts, the missilewill reach a maximum altitude abovelaunch point of 1700 meters at its maxi-mum effective range of 7 kilometers.This altitude can be decreased only if thedistance between the launch aircraft andthe target is reduced. Thus, to compen-sate for a low cloud ceiling, an aircraftmay need to expose itself to threat weap-ons ranges in order to ensure a success-ful engagement.One method to reduce the maximumaltitude of the Hellfire’s flight trajectoryis to select the Lock-on After Launch -Direct (LOAL-DIR) delivery mode. Thisdelivery mode results in the lowest of alltrajectories during missile flight becauseit is employed using a laser designationdelay. In this particular mode, the aircraftlaunches a missile toward the directionof the target before it is designated by alaser. As a result, the missile travels“blind” initially. It will climb slightly,but remain relatively low until the laseris activated after a pre-determined time.Once the missile acquires reflected laserenergy, it pitches up to achieve an opti-mum dive angle at the target. Overall,depending on the length of laser delaytime, the maximum altitude reached dur-ing the flight trajectory is much lower; adistinct advantage over all other deliverymodes. Figure 3 depicts the lower trajec-tories that may be achieved usingLOAL-DIR. A 12-second designationdelay would cause the missile to reachits apex at only 800 feet when fired at amaximum engagement range of 7 kilo-meters. The downside to this method,however, is that air crew is not assuredof positive lock-on prior to launch. Inaddition, if the laser designation delay istoo long, the air crew runs the risk thatthe missile may never actually acquirethe reflected energy or that it may lack the maneuver distance and time requiredto impact on the target. Thus, overall P h may be reduced.The last two delivery modes are uniquein that they allow the launch aircraft toremain masked behind terrain to reduceits firing signature and increase aircraftsurvivability. These delivery modes areknown as Lock-on After Launch - High(LOAL-HI) and Lock-on After Launch -Low (LOAL-LO). The first mode,LOAL-HI, allows the missile to clear a1,000 ft. high terrain feature to front of the aircraft, provided the aircraft remainsa minimum of 1500 meters away fromthat terrain feature. In addition, themaximum effective range of the Hellfireis increased to 8 kilometers using thismethod. This technique is most effectivein a remote engagement. The major dis-advantage of employing the LOAL-HImethod, however, is that the missile fliesthe highest trajectory of all deliverymodes and is most susceptible to a break in missile lock due to penetration of low-lying clouds. Therefore, it requiresthe fairest of weather conditions to en-sure target destruction. As with theLOAL-DIR mode, a laser designationdelay can help to lower maximum alti-tude attained to some degree. Figure 4depicts typical trajectories achieved atthe maximum effective range.Using the last delivery mode, LOAL-LO, will help to reduce the maximum al-titude of the Hellfire trajectory some-what, but will also limit the size of theterrain mask utilized by the aircraft forsurvivability. Employing this technique,the missile is able to clear a 260 ft. highterrain feature to the front of the aircraftas long as the aircraft maintains a mini-mum of 600 meters standoff distance.Maximum effective range of the Hellfireis again extended to 8 kilometers usingthis technique. Figure 5 depicts thenominal trajectories attained by engage-ments using this delivery method. Limitations of Lasers As previously mentioned, positive andprecise laser guidance of the Hellfiremissile until impact is absolutely essen-tial to the probability of hit and targetdestruction. Like the missile itself, thelaser energy used to designate the targetis also susceptible to factors of terrain,weather, and distance. Again, these fac-tors must be adequately planned for priorto execution whenever possible to ensuresuccessful target destruction. In particu-lar, five conditions of laser designationor negative illumination factors must betaken into consideration and compen-sated for. These conditions may be pre-sent regardless of whether the designa-tion is performed from an aerial platformor a ground-based system. The fivenegative illumination factors are: beamdivergence, attenuation, backscatter, over-spill, and underspill. 10 Beam divergence is a phenomenon thatoccurs with all directed light energy, butit varies amongst different types of laserdesignators. Beam divergence is theever-increasing width of a beam of light 28ARMOR — January-February 1998 Figure 4. LOAL-HI Trajectories (AGM 114-A) 8 Figure 5. LOAL-LO Trajectories (AGM 114-A) 9
