| INTERNATIONAL DEFENCE REVIEW - FEBRUARY 01, 2006
A different kind of smart: weapons becoming autonomous and precise
Bill Sweetman
Four new-in-service weapon families illustrate different ways of tackling hard and mobile targets. writes Bill Sweetman
·JDAM has unlocked a simple and accurate guidance system.
·Now the challenge is to make weapons smaller and lighter.
With Boeing's highly automated plant in St Charles, Missouri, turning out Joint Direct Attack Munition (JDAM) guidance tailkits like packets of cornflakes, and almost every aircraft in the US inventory cleared to carry the weapon, the days when guided bombs were few and far between and hard to deploy seem like ancient history. But JDAM itself, although an inexpensive and simple solution to many problems, does not meet every need, and the same basic technologies - compact and low-cost sensors electronics, desktop mission planning and better targeting - are now being applied worldwide to a range of new weapons. Between 2004 and 2006, at least four entirely new precision-guided weapons should enter service, and there are more waiting in the wings.
In the US, the focus is on two areas. One is to exploit the accuracy of JDAM's basic guidance technology - which combines a simple inertial measurement unit (IMU) with a Global Positioning System (GPS) receiver - in new and smaller weapons which allow each aircraft to carry more bombs while limiting collateral damage. These smaller weapons are also suited to stealth platforms such as the Joint Strike Fighter (JSF) - with its restricted internal weapon bay - and unmanned aerial vehicles (UAVs).
The other thrust is to combine JDAM technology with other sensors, making it possible to engage moving targets.
In the coming year, the US Air Force (USAF) is expected to launch development of a terminal-homing moving-target system.
At the same time, though, the effectiveness of basic JDAM-type weapons is being increased. The US is quietly developing and deploying a system that significantly increases weapon accuracy over an entire theatre, with only minimal impact on the weapon and none on the carrier aircraft or the human operator.
Supporting many of these projects is the steadily improving ability of aircraft-mounted sensors to find, classify and identify targets at long range, and to provide weapons with the data that they need to achieve a high-confidence hit. Also, improved, more accurate targeting pods and active electronically scanned array (AESA) radars are demonstrating that they can produce GPS targeting co-ordinates in real time, allowing fighters to release multiple JDAM-class weapons on targets of opportunity. In late 2005, for example, an F/A-18E/F Super Hornet testing the new Raytheon APG-79 AESA successfully delivered multiple JDAMs on to co-ordinates provided by the radar.
To some extent, these developments explain why there is no longer any great pressure to produce a more accurate version of JDAM. Various seeker-based JDAM versions, including the US Navy-sponsored DAMASK and Hornet Autonomous Real-Time Targeting (HART), have been proposed over the years, but have been dropped because systems such as AESA, and steadily improving GPS guidance systems, have been able to provide the needed accuracy at lower cost.
Outside the US, however, some nations are developing weapons that can achieve JDAM-like accuracy, autonomy and economy without relying on the US-operated GPS network. Other programmes, such as the UK-sponsored MBDA/Boeing Brimstone, are designed to address the moving-target requirement.
Small Diameter Bomb
Due to enter service with the USAF in September 2006 is the Boeing GBU-39/B Small Diameter Bomb (SDB). Operational testing started in November 2005. These tests should be completed by mid-2006, concurrent with the delivery of the first low-rate initial production (LRIP) lot of weapons. The first aircraft armed with SDB will be the F-15Es of the 48th Fighter Wing at RAF Lakenheath.
Boeing is currently under contract to deliver 768 bombs and 175 release units. A full-rate production decision is due in 2006, with an order for 1,200 weapons and 300 launchers due in Fiscal Year 2008 (FY08). Production of 2,000 launchers and 24,000 weapons is due to continue through FY21.
Boeing completed SDB development testing in September 2005. In development testing, 37 SDBs were released against fixed targets. Thirty-five weapons were successful, each hitting within an average of 1.1 m from its surveyed target aim-point. Key tests included the single-pass release of four bombs against four separate targets, at a range of 37 km. The weapon demonstrated its range in May with an 88 km flight from an altitude of 30,000 feet, hitting within 85 cm of its target. In a test with effective GPS jamming in May, a bomb flew 56 km and landed within 2 m of its designated impact point, using its inertial measurement unit and onboard logic to overcome jammi |
