Krasnopol projectile is produced in two variants, namely, Krasnopol and Krasnopol-M. The former is a 152mm two-section projectile designed to operate with both towed and self-propelled guns and howitzers. It, however, has a shortcoming that it is incompatible with 2S19 auto-loader due to the projectile’s length.
Krasnopol-M is a 152mm/155mm projectile. It is an improvement over Krasnopol and is fully compatible with 2S19 auto-loader, which makes it usable with western produced 155mm howitzers.
Other than that, both have the same attack profile (diving top attack as illustrated in Fig. 9), targets engaged and the type of warhead used. The target ranges are similar; 20km in the case of Krasnopol and 17km for Krasnopol-M. Fig. 10 shows the photograph of Krasnopol projectile.
Krasnopol projectile follows a ballistic trajectory approaching the target once it is fired. Subsequent to its firing, a forward observer illuminates the target with a laser designator at a maximum range of 7km. The seeker in the front-end of the projectile locks on the target and the guidance and control system corrects its flight path in order to impact on the selected/illuminated point. Krasnopol projectile follows a top-attack pattern to achieve an optimised probability of kill against the armoured target.
M-712 Copperhead is a 155mm-calibre terminally laser-guided projectile with a minimum and maximum range of 3km and 16km, respectively. It has two operational modes: ballistic mode and glide mode. Ballistic mode is used when the cloud ceiling is high and visibility condition is good. Terminal guidance begins at 3km from the target. Glide mode is used when the cloud ceiling and/or visibility is too low to allow use of ballistic mode. The attack profile in the case of Copperhead projectile is laser-illuminated point attack. Fig. 11 shows Copperhead projectile in flight as it nears the target.
Copperhead projectile was successfully used during Operation Desert Storm in 1990-91 and Operation Iraqi Freedom in 2003. It is in use by various Armed forces, including Australian army, United States army, Egyptian army, Jordanian armed forces and Taiwanese army.
Laser-guided bombs
Of all the variants of laser-guided munitions, laser-guided bombs are the most widely exploited weapons if the number of user countries and if laser-guided bombs used in warfare in the past are any indication. Paveway family of laser-guided bombs has revolutionised tactical air-to-ground warfare by converting dumb bombs into smart precision-guided munitions. Paveway family of the laser-guided bomb is the preferred choice of Air Forces worldwide, as these have proven their accuracy and efficacy in almost all major conflicts in the past. The family has evolved over the years and has seen continuous capability enhancement with newer versions. It has seen four generations, namely, Paveway-I, -II, -II Plus, -III and -IV.
Paveway-I used a gimballed seeker head, a computer control group (CCG) and a set of air foils. The seeker head operated in bang-bang mode, which meant that control surfaces were deflected either fully or not at all. This led to a sub-optimal flight trajectory. Bombs that could be fitted with Paveway-I LGB kit included M117, M118E1, MK-82, MK-83, MK-84, MK-20, CBU-74/B, CBU-75/B, CBU-79/B and CBU-80/B. More than 10,000 Paveway-I LGBs were used by the US Air Force in South East Asia with great success.
Paveway-II (Fig. 12) has a nose-mounted seeker head and fins for guidance. Manufactured by Defence contractors Raytheon and Lockheed Martin, it also uses the bang-bang guidance concept. That is, fins deflect fully or do not deflect at all.
Paveway-III is an improvement over Paveway-II and uses a more efficient proportional guidance technology. Produced by Raytheon, it was introduced into service in 1983.
Paveway-IV (Fig. 13) is an advanced and highly accurate laser-guided weapon. It is the most recent member of the Paveway family. Manufactured by Raytheon Systems Ltd, the UK, Paveway-IV entered into service in 2008. It will replace Paveway II and enhanced Paveway-II weapon systems as well as the 453.6kg (1000-pound) unguided general-purpose bomb. Paveway-IV employs a combination of semi-active laser guidance and INS/GPS guidance to combine the flexibility and accuracy of laser guidance and all-weather capability of INS/GPS to give significantly improved battlefield performance.
Griffin laser-guided bomb kit is manufactured by Israel Aerospace Industries and is designed to retrofit the existing MK-82, MK-83 and MK-84 dumb gravity bombs. The kit employs a laser-seeker head and a set of steerable tail planes for guidance. The CEP is estimated to be 5m. It is in use by Israeli Defence Forces, Indian Air Force and Colombian Air Force.
Sudarshan laser-guided bomb kit developed by Aeronautical Development Establishment of DRDO and manufactured by Bharat Electronics is another LGB kit. It was introduced in Indian Air Force in 2013. The CEP is estimated to be 10m. In future, Sudarshan LGB kit will incorporate a GPS sensor to improve its performance.
Laser-guided missiles
Laser-guided missiles use both beam riding as well as semi-active laser-guidance concepts. RBS-70/RBS-70NG and LAHAT are examples of laser beam-riding missiles. These were briefly described in part 1 of the article. AGM-114 Hellfire-II is a combat-proven tactical surface-to-surface and air-to-surface missile system that uses semi-active laser homing. Fig. 14 shows Hellfire-II fired from a land vehicle.
Hellfire family comprises Longbow Hellfire and Hellfire-II missiles. Hellfire-II missile has a maximum range of 7km (direct fire) and 8km (indirect fire). The missile can be launched from multiple air, sea and ground platforms, either in autonomous mode or with remote designation. A variant designated AGM-114L uses millimetre-wave radar guidance. Manufactured by Lockheed Martin and introduced into service in 1984, its primary use is as air-to-surface to engage and defeat individual static or moving advanced armour, mechanised or vehicular targets, patrol craft, buildings and bunkers. AGM-114K, AGM-114M, AGM-114N and AGM-114R are laser-guided variants.
New developments
While laser-guided bomb kits continue to improve in terms of hit accuracy, operational range, guidance technology and so on, in recent years, there has been emphasis to improve guidance technology to improve the weapon’s performance in adverse weather conditions. This has been made possible by combining laser guidance with global positioning system (GPS)/inertial navigation system (INS). Laser joint direct attack munition (LJDAM) is an example.
Another major development has been the use of guidance technology in smaller ammunition. In the recent past, field trials have shown encouraging results in laser-guided bullets.
Joint direct attack munition (JDAM) is a low-cost guidance kit used to convert existing unguided free-fall bombs into near-precision-guided weapons. The JDAM kit consists of a tail section that contains a GPS/INS and body strakes for additional stability and lift. JDAM is produced by Boeing.
LJDAM expands the capabilities of the JDAM by combining a laser sensor kit with a JDAM kit. LJDAM has the accuracy of a laser-guided weapon and all-weather capability and longer range of GPS/INS guided weapons. It can precisely hit both stationary and mobile targets. LJDAM has been integrated with GBU-38 and is operational on the US Air Force F-15E and F-16 and the US Navy F/A-18 and A/V-8B platforms. It is planned to integrate LJDAM with GBU-31 and GBU-32. Fig. 15 shows Boeing LJDAM on F-16 fighter aircraft (lowermost weapon in the figure).
Laser-guided bullet development at Sandia National Laboratories is making headlines as it is expected to significantly increase the range of sharp shooting. Modern bullets gain their accuracy from a technique known as rifling, in which the rifle barrel has a series of spiralling grooves etched into it. The spiralled grooves give a spin to the bullet, thereby stabilising its flight path. The laser-guided bullet developed at Sandia National Laboratories is fired from a smooth bore barrel and is stabilised by four steerable fins at its rear (Fig. 16). The fin movement is controlled by a computer chip, which, in turn, is driven by a signal from an optical sensor on the bullet’s nose. The intended target is illuminated by a laser beam and the bullet uses steerable fins to adjust its mid-flight trajectory. The operation is similar to that of a laser-guided munition, which makes a laser-guided bullet nothing but a miniature laser-guided munition.
According to one computer simulation, an unguided bullet fired at a target at 800m would miss the target by about 9m. The laser-guided bullet, on the other hand, would cut that inaccuracy to just 20cm. Knowing peculiarities of ballistics, the accuracy gets better for longer ranges.
Dr Anil Kumar Maini is former director, Laser Science and Technology Centre, a premier laser and optoelectronics research and development laboratory of Defence Research and Development Organisation of Ministry of Defence
Nakul Maini is currently pursuing Masters at University of Bristol, UK. He was working as a technical editor with Wiley India Pvt Ltd
