Submunitions are now generally required to incorporate their own autonomous target detection and acquisition device, which is the reason why they are often referred to as "smart weapons". Generally of the size and shape of a large preserves can -- hence the name "Skeet" used by Textron -- they tend to function along the same basic principle, whereby the "can" -- warhead cum sensor -- is tossed into the air in such a way that it wobbles. At a given height (as opposed to altitude) its downwards-looking sensor is thus forced to look at the ground in a closing spiral pattern until it meets a pattern that matches what it was programmed for. The warhead, generally a shaped charge (but an explosively formed penetrator is an alternative) is instantly triggered. This is the case of the air launched Textron Sensor Fuzed Weapon and the Russian SPBE-D on the one hand and the barrel-launched Giat-Bofors Bonus, Giws Smart and Aerojet Sadarm on the other.
The Textron Systems CBU-97A/B Sensor Fuzed Weapon (SFW) is an SUU-66/B Tactical Munitions Dispenser with a warload of ten BLU-108/B submunitions, each with four Skeet warheads. The Skeet is a squat, cylindrical sensor-fuzed warhead with an infrared sensor, a safety and arming device, a thermal battery and a copper liner. The SFW with its load of 40 smart warheads can be released at heights up to 20 000 feet and at speeds up to 1200 kilometres per hour.
After being dropped from the SFW, each BLU-108 is slowed and turned to the vertical by a parachute. An altimeter-activated rocket motor then reverses the descent and spins the submunition, which throws out the four Skeets. Spring-loaded arms impart a wobble to the Skeet, so that it spins about an inclined axis. Its dual-spectrum infrared seeker thus scans a circle that moves outward from the BLU-108, the scan diameter initially increasing as the Skeet climbs, and then decreasing as it falls. On detecting the heat of a tank, the Skeet fires an explosively-formed projectile at the top of the vehicle.
The SFW entered low rate initial production (LRIP) in 1992, and the first full-rate production contract was signed in 1996. The system attained initial operational capability with the US Air Force in 1997.
The SFW P3I (pre-planned product improvement) variant is being developed to increase the number of kills per pass by improving performance in the face of countermeasures, reducing false sensor alarms, optimising warhead aimpoint and increasing target area coverage. The first test was carried out in April at Eglin AFB, Florida, with the release of the new weapon from an F-16. The SFW P3I scored four times more hits on the targets, and immobilised more than twice as many vehicles as the current SFW, which already exceeds its operational requirement. The area covered by the SFW P3I was almost twice as great as that for the in-service SFW.
Six BLU-108s form the warload of the GPS/INS-guided AGM-154B version of the Raytheon Jsow, a swing-wing gliding dispenser. The BLU-108 can also be delivered by means of the Raytheon Tomahawk and Land Attack Standard Missile, and the Boeing Slam-ER.
The Skeet warhead (with a tantalum rather than copper liner) is also used in the Wam (Wide Area Munition). Known as the Hornet in the US Army, it may be emplaced by a variety of means, including airdrop. After landing, legs are deployed to erect the mine, and then acoustic sensors are extended. The acoustic and seismic system detects, classifies and tracks any nearby target, and fires the Skeet over it. Recent Hornet improvements include remote on/off control, so that friendly troops can pass safely through the mined area. Another modification is an embedded GPS receiver, so, that the controller can locate all munitions precisely. It can be programmed to attack a specific tank in a convoy.
A further weapon based on the Tactical Munitions Dispenser (TMD) is the CBU-87/B Combined Effects Munition (CEM), which houses 202 BLU-97/B Combined Effects Bomblets (CEB) and an optional nose-mounted FZU-39/B proximity sensor. This allows dispensing at a height that can be pre-set while the CEM is still on the aircraft, as an alternative to using a time-delayed break-up. The CEB combines a shaped charge to defeat armour, a fragmentation case, and a zirconium ring for incendiary effects. The CEM entered LRIP in 1983.
The Gator Weapon System is known as the CBU-89/B to the US Air Force and as the CBU-78/B to the US Navy. The SUU-65 TMD in this case contains 94 minelets, including BLU-91/B anti-armour devices with magnetic influence fuzes.
Another way to deploy anti-armour mines from aircraft is the Alliant Tech-systems Volcano, which can be fitted to the side of a helicopter such as the Sikorsky UH-60. The Volcano consists of the M139 mine delivery system with a dispenser control unit and four launcher racks, all four with mountings for 40 M87 canisters, each housing six minelets. The Volcano control unit generates firing signals according to the speed of the launch vehicle and the desired minefield density. The mines receive their arming signals and self-destruct time after being ejected from the canisters.
Believed to be the first smart weapon of its kind to have been put into service in the world, the Bazalt SPBE-D -- RBK-500 cluster combination operates similarly to the Skeet, but ejection of 15 submunitions occurs directly from the cluster. They then descend under parachute, and use a dual-spectrum infrared sensor.
A completely different type is the Lockheed Martin Missiles and Fire Control Locaas (Low-Cost Autonomous Attack System), which is currently in the middle of a three-year advanced technology demonstration (ATD) programme for the US Air Force. The Locaas is one of the options in the Miniature Munitions Capability (MMC) programme, in which the Air Force is scheduled to complete its analysis of alternatives as these lines are printed. If selected to go forward, it might enter service as early as 2007.
A winged vehicle, it made its first flight powered by a Hamilton Sunstrand TJ-50 turbojet in December 1997. However, reports indicate that a Technical Directions (TDI) engine may be used if Locaas is chosen for production.
The Locaas has GPS/INS navigation, a ladar seeker that produces a three-dimensional target image and automatic target-recognition software. It can, for example, reject a tank if programmed to search for a Scud missile launcher, but can subsequently return and destroy the tank if it finds itself running low on fuel. Target unit price is $ 33 000 in FY98 values.
It is envisaged that three Locaas would be carried in the Jassm (Joint Air-Surface Stand-off Missile), four in the standard US Air Force SUU-65 dispenser and ten in the proposed Lodis dispenser. Up to 24 Lodis could be carried by a B-1B and around 20 by a B-2A. The Locaas would be carried externally by an F-16 and internally by the F-22 and F-117. It could equally well be delivered by the US Army's Multiple Launch Rocket System (MLRS) or Army Tactical Missile System (Atacms).
The initial requirement called for a "range" of 185 kilometres ("range" presumably meaning radius) and the ability to search an area of 50 square kilometres at 100 kilometres from the launch point.
The most interesting features of the Locaas is probably its Alliant Techsystems multi-mode warhead. This is basically an explosively-formed penetrator warhead, but (according to the points at which it is detonated and the sequencing) it can be made to function in a long rod mode for close-in heavy armour targets, or in an aerostable slug mode for heavy armour at longer stand-off distances, or in a multi-fragment mode for lightly armoured vehicles and soft targets such as radars.
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|Date:||Dec 1, 2000|
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