mil tech Modern laser guided bombs Dr Carlo Kopp

The Laser Guided Bomb (LGB) remains a mainstay of modern aerial strike warfare, especially close air support operations where munitions must be delivered often in close proximity to friendly ground forces. While laser guided munitions have numerous limitations, their combination of low cost, simplicity, relatively good accuracy and ability to hit moving targets indicate that laser guided munitions will remain in use for a long time yet.

When the first LGBs were introduced by the US Air Force during the late 1960s they were employed mostly against strategic targets in North Vietnam such as bridges, bunkers, tunnel entrances and other hard targets requiring a direct hit to destroy. The reasoning was simple: reduce the exposure of aircraft to hostile anti-aircraft artillery fire, taking a heavy toll of the F-100, F-105 and F-4 fighters, which had to dive bomb such targets from low altitude to achieve any kind of accuracy. Laser guided bombs allowed attacks from much higher altitudes, and small numbers of bombs could produce up to ten times the damage effect compared with unguided or ‘dumb’ bombs by virtue of much greater accuracy. Lesser numbers of aircraft could thus produce the same combat effect, and do so with much lower per aircraft exposure to lethal automatic gunfire. Late in the Vietnam conflict, LGBs were used increasingly against tactical targets along the extensive Ho Chi Minh trail resupply network. Anti- Aircraft Artillery (AAA) revetments, SA-2 A pair of new GBU-54 Laser JDAMs being loaded on a US Air Force F-16C at Balad AB (US DoD). battery sites, convoys, vehicle parks and storage sites were attacked, with the accuracy of these Ground/Vehicle Laser Locator Designator. CAS of the Kaira and Klen series of combined daylight weapons improving per sortie combat effect and operations were historically problematic due to laser designators and spot trackers, embedded in reducing loss rates. The new television- the close proximity of friendly troops to targets the noses of tactical fighters such as the MiG-27 based targeting pods permitted laser designation of and resulting potential for ‘blue on blue’ fratricide Flogger, Su-24 Fencer and Su-22M4 Fitter. The targets even as the aircraft evaded hostile fire. or ‘friendly fire’ losses. Laser guided weapons French deployed the Thomson CSF ATLIS series of The late 1970s and 1980s were a boom period for changed the whole paradigm, one which involved pods, comparable to the . manufacturers of LGBs and targeting equipment. very low altitude strafing, dive bombing and level These were important developments, as they set The US deployed the smaller and lighter daylight lay down attacks since the early 1940s. the pattern for the evolution of targeting systems television AN/AVQ-23 Pave Spike , As laser designators became more widely used by used by aircraft and helicopters, and became and by the 1980s the day/night capable but much ground forces for marking targets, the US Air Force an enabler for the use of laser guidance in other larger and heavier AN/AVQ-26 targeting deployed the AN/AAS-35 Laser Spot weapons. The latter included laser guided artillery pod, with a longwave thermal imager capable of Tracker (LST) pod on the A-10 Thunderbolt and rounds such as the US and seeing thermal emissions from vehicle engines, as A-7D Corsair II CAS aircraft. This device placed a Russian Krasnopol series, tactical anti-armour well as contrast changes due to disturbed soil. symbol on the pilot’s Head Up Display to show the such as the US Hughes AGM-65 Maverick, Importantly, LGBs became a central feature of location of the laser designation thus permitting French AS.30L and Soviet/Russian Kh-25L Karen. Close Air Support (CAS) operations, with US Army attacks using not only LGBs, but also gunfire or Laser guidance rapidly became the technique and Marine Corps ground units being equipped various unguided munitions. The US Navy and of choice for providing precision fire support for with the AN/PAQ-1 (LTD) Laser Target Designator Marine Corps soon followed with the ASQ-173 ground forces. and later AN/PAQ-3 Modular Universal Laser Laser Spot Tracker/ Strike Camera pod for the The first genuinely large scale use of laser guided Equipment (MULE). These were soon followed by F/A-18A/B, usually paired with a compact AAS-38 weapons occurred during the 1991 Desert Storm the AN/PAQ-4, AN/PEQ-1 Special Operating Forces thermal imaging and laser designating pod. campaign, when US forces effectively annihilated Laser Marker (SOFLAM), and AN/TVQ-2 (G/VLLD) The Soviets soon followed with the deployment Saddam’s ground forces in Kuwait and Southern DefenceToday - 41 mil tech rgamd no h bm we lae o the on loaded when bomb the into programmed that to identical pattern digital a with encoded was laser near-infrared pulsed The laser. targeting by the illuminated being ‘spot’ a latter the aimpoint, between the bomb’s direction of flight and intended error angular the measure to used detectors four the bombs’ flight not unlike a weathercock, and the of direction the in point to aligned aerodynamically was module seeker the glass arrangement this In hemispherical lens. a under installed elements annular an airfoil, and a detector, which employs employing four identical usually mount, flexible a on seeker stabilized aerodynamically an involved This arrangement. seeker limited but a simple very used LGBs III, the of advent the Until unit. inertial and seeker laser gimbaled precision high a employed which kit, LGB III Paveway 24/GBU-27 GBU- new the of debut the saw also Storm Desert LGBs. by destroyed claimed were (HAS) Shelters Aircraft Hardened 300 around and vehicles, armoured and tanks IDS. 1,000 Tornado Around RAF the on trialled was pod TIALD the and Eagle, Strike F-15E the on trialled was pod targeting LANTIRN AAQ-14 new Tornado The bombers. IDS of formations for bombers” “master as acting latter the pod, Spike Buccaneers Pave the with equipped Blackburn RAF and Tack, Pave with equipped Phantoms F-4E some were by supplemented These sensor. Tack Pave AVQ-26 the with thermal equipped F-111Fs the and sensor, DLIR/FLIR with the imaging equipped primarily Nighthawk attacked F-117A were targets Strategic LGBs. primarily using targets, strategic infrastructure of range and wide a to waste lay and Iraq, 42 -DefenceToday agile an used weapon III Paveway resulting The viable. more was seeker, laser a with combined unit, inertial accurate less and cheaper much A weapons. accuracy high for expensive too proved guidance inertial Pure impact. to conditions before launch and then fly blind through any weather coordinates target with programmed be would that bomb a involved latter The bomb. guided inertially an develop to intended experiments of outgrowth a was and LGB) Level (Low LLLGB the designated then was kit LGB III Paveway GBU-24/GBU-27 The inputs control system. guidance the lagged by produced head seeker the aligning of method aerodynamic the as flight, of seconds last the during targets, moving problematic, against especially often was Accuracy of reach fire. of defensive out bomber the keeping of terms in mattered range of mile every where drops altitude low for not but drops, altitude high for acceptable was which range, maximum for were trajectory optimal an fly approach to unable typically design was bomb The this several. of limitations The seeker. bomb the on switch thumbwheel a using aircraft, Paveway IIseeker(C. Kopp) The result was the ‘enhanced’ Raytheon/TI EGBU- Raytheon/TI ‘enhanced’ the was result The NATO. of expense the at – leadership Milosevic the for boon propaganda a proved these campaign, this of environment charged politically the in and damage killed, civilians with collateral occurred incidents of number A for. aiming was haze obscuring the illuminated laser spot the bomb lost or rain cloud, to due ballistic LGBs went and lock seeker occasions, other many On identify. to hard targets making haze or precipitation or target, intended the to sight of line due the blocking prosecuted cloud to be not could attacks LGB Often targets. near areas populated densely urban with areas, industrialized laden smog many in and were Balkans, targets the over cover cloud dense with fought was campaign Force Allied Operation the of Most this. of opposite the were Balkans The ranges. design maximum at seekers bomb the by tracked and detected cleanly be to illumination laser allowed atmosphere desert pristine the and find to easy were Targets rapidly. cooled terrain desert the when night at especially contrast infrared high and targets, obscuring cloud often than optimal delivery conditions more for LGBs – an absence presented of environment Eastern desert Middle the Balkans Storm, Desert the During power. air in NATO for challenge conditions unexpected an presented weather foul The production. rate full entering then only was JDAM GBU-31/32 guided GPS/inertially the and use, in weapon smart dominant LGBs the were 1999, in LGB conflict Balkans the of in became embroiled forces proliferation NATO When further globally. technology saw 1990s The staff. command Saddam’s by used bunkers deep bunker busters dropped by F-111Fs against critical class lb 5,000 throat’ ‘deep GBU-28 prototype two the first bomb. The seeker was also adapted for the to enough close by produced concrete the of weakening the exploit hitting round second the with it was not uncommon for two bombs to be dropped, bunkers on attacks In accuracy. high exceptionally provided and Storm Desert during extensively used were GBU-27 carriage compact and GBU-24 The altitude. low from tossed was bomb the where especially I/II range, in increases Paveway useful also but design, seeker aero-stabilised the than accuracy higher much only not provided arrangement This trajectory. ‘P-nav’ or navigation would fly the bomb along an optimized proportional which autopilot inertial an with mated was seeker motion new The seeker. the and of limits gimbal the within orientation – immediate of bomb’s independently the angles off-boresight rates high angular and high very at aimpoint the detector track to the in allowed used This that missiles. to dome, heatseeking similar glass very arrangement a an under in detector laser gimbaled Azov 27NseekerusedwithKAB-500LandKAB-1500Lkits. LT-3 gimballedseeker(ZhenguanStudio) Paveway IIIgimbaledseeker(C. Kopp) KAB-1500LG on display at MAKS-2009(VKuzmin)KAB-1500LG ondisplayat KAB-1500L onanSu-34Fullback. 24/27/28 hybrid seeker which involved integration of a new digital guidance package into the existing laser seeker, which combined a low cost inertial unit, multichannel GPS receiver, and a Mil-Std- 1760C digital umbilical interface. These weapons could be programmed prior to launch with the GPS coordinates of the target no differently than the JDAM, fly a range optimized shaped trajectory, and acquire the laser spot for terminal homing with high accuracy. If laser lock was lost due to obscurants the bomb would fly to the last known GPS coordinates with slightly degraded accuracy. This arrangement proved sufficiently popular that the low cost 1970s technology Paveway II design was also re-engineered, into the Paveway IV hybrid configuration, also equipped with digital GPS/inertial guidance. While not as accurate as the EGBU-24/27/28 seekers, the Paveway IV is just as robust and can fly optimal trajectories. The Boeing JDAM has since been adapted to provide the option of a laser seeker kit. The GBU- 54 500 lb, GBU-55 1,000 lb and GBU-56 2,000 bomb kit. Russian industry continues to supply the lb Laser JDAM or LJDAM sees a DSU-38/B laser laser guided KTRV Kh-25ML Karen missile and the seeker attached to the nose of the bomb to provide KB Tochmash/Nudelman S-25L/LB laser guided terminal homing updates to the weapon’s GPS/ 340 mm folding fin rocket – the latter technology clockwise from top left: inertial guidance tail kit. now being emulated by Western contractors. Luoyang LT-2 on JH-7A bomber. A multimode seeker including a laser semi-active China’s industry is also mass-producing LGB kits. Luoyang LT-3 500 lb round next to LT-2 2,000 lb round homing component is also planned for the new The Luoyang/CASC LT-2 or LS-500J is modeled – the LT-3 is “China’s Laser JDAM” (Zhenguan Studio). second generation Small Diameter Bomb or SDB II on the Russian KAB-500L series but is sufficiently Luoyang LT-2 on CT equipped Q-5C variant bomber. series, currently in development. different to not be a direct clone. This weapon Undesignated LT-2 variant with gimbaled seeker design. The Russians have followed much the same pattern has been deployed on most newer PLA-AF strike as the US in LGB technology. The first generation aircraft, including variants of the A-5C. GNPP KAB-500L 1,000 lb and KAB-1500L 3,000 lb A yet to be designated derivative of the LT-2 weapons used aerodynamically stabilized seekers displayed at Zhuhai in 2008 uses a KAB-1500LG / weather operation. copied from the Paveway II series, and retaining all GBU-24 style gimbaled laser seeker. In conclusion, the current global trend is away of the limitations of the Paveway II series. This year Much more interesting however is the new from specialized bomb kit guidance to hybrid KTRV unveiled the new KTRV KAB-500/1500LG Luoyang/CASC LT-3 500 lb bomb kit, which is a multimode seekers, in which laser or other seeker series kits, which employ a gimbaled semi-active fusion of ideas seen in the US JDAM and GBU-24 technology is mated with a digital autopilot and laser homing seeker modeled on the US GBU- kits. The dual mode LT-3 bomb kit combines a satellite / inertial guidance. These weapons will be 24/27/28 seekers. It is likely that the follow-on satellite / inertial guidance tail kit with a gimbaled more accurate, more robust and more flexible than seeker kit will incorporate the GPS/inertial guidance laser seeker, and is a direct equivalent to the GBU- the orthodox ‘laser only’ bomb kits, which have technology currently marketed in the KAB-500S-E 54 LJDAM design, built for high accuracy and all dominated the market since the 1970s.

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