Farnborough Air Show

Raytheon UK Helps The RAF’s Smartest Bomb Get Smarter

 - July 8, 2012, 6:10 AM

No civilian casualties…low collateral damage…restrictive rules of engagement. Today, the air-ground attack mission is more demanding than ever. The Paveway IV precision-guided weapon produced by Raytheon UK is already the Royal Air Force’s smartest bomb. A proposed series of improvements should make it even more flexible and accurate.

“The RAF has released more than 1,000 Paveway IVs in three years, achieving close to 100 percent reliability,” claimed T.J. Marsden, chief engineer for the weapon, in a recent briefing at Raytheon UK’s Harlow facility. He described how a five-year development program from 2003 added dual-mode guidance and sophisticated fuzing to a 500-pound warhead. Paveway IV entered service in November 2008 on the RAF’s Harrier GR.9s, which have since been retired. It was soon also qualified on the Tornado GR.4, and integration on the RAF’s Eurofighter Typhoons is nearly done. The weapon will also be carried by the UK’s F-35 Lightning II stealth fighters, externally or internally. It is replacing the RAF’s earlier generation of Paveway II smart bombs, which have warheads twice the size. This means that more weapons can be carried, and more targets covered, per sortie.

The guidance is by laser and/or a second-generation GPS-aided inertial navigation system (GAINS). The latter includes Raytheon UK’s own anti-jamming technology. Through clever electronics design, the weapon’s azimuth and impact angles can be preprogrammed, as can three fuzing options–airburst, impact or post-impact.

These options can be set before takeoff, but can also be changed from the cockpit in flight before release. This feature “gives aircrew huge flexibility in achieving the exact effect desired,” said an RAF weapons instructor. He also praised the “generous launch envelopes.”

The fuze, which is supplied by Thales Mission Electronics in the UK, also features a safety function that will not allow an off-course munition to arm. Other key subcontractors include Portsmouth Aviation (the tail fins) and EDO MBM Technology (aircraft connectors and containers).

Although Raytheon UK holds overall design authority (DA), the Paveway IV’s electronics controller and warhead design was done in the parent company’s missile business in Tucson, Arizona, which retains the DA for these elements. But two new UK-designed warheads are in prospect, provided that the UK Ministry of Defence (MoD) proceeds with an upgrade program called SPEAR (selective precision effects at range) Capability 1.

Marsden explained that Raytheon UK is exploring the blast and fragmentation effects of a possible low collateral damage warhead. The group funded some smaller companies and universities to do finite element modeling, work which will now be taken further in a ministry of defense contract. By using the best possible tools to assess potential designs, Marsden explained that expensive manufacturing and testing of prototypes can be reduced.

The new warhead would be the same size, shape and mass as the current one, to minimize the work needed to integrate it onto the airframes. The same would apply to the proposed compact penetrator warhead. Raytheon is working on this with QinetiQ, which already has a MoD contract to explore a long, thin warhead encased within a shroud. At the moment, the RAF uses Raytheon’s much larger 2,000-pound Enhanced Paveway III to penetrate hard targets.

Paveway IV already has some capability against moving targets, thanks to the “pursuit mode” of laser guidance. But by introducing a digital laser seeker and a “proportional navigation” guidance mode, that capability can be enhanced thanks to a higher trajectory and greater maneuverability, Marsden said. The company believes that, when combined with the low collateral damage warhead, the moving target capability would make Paveway IV particularly effective against “time-sensitive targets, such as leadership, even when encountered in urban areas.”

Raytheon claims that Paveway’s IV’s range is already “significantly greater than any other precision-guided bomb.” But there is potential to double the range through additional of a pop-out wing kit. Together with a possible data link, these upgrades may also be implemented in the SPEAR program (see box).

The RAF is the sole user of Paveway IV at the moment. Marsden said there is some export interest, and the “hardback” design of the weapon would allow an easy fit to different aircraft. However, according to the UK National Audit Office (NAO) in 2007, the MoD allocated nearly $90 million so that BAE Systems could integrate the Paveway IV onto the Typhoon.

Would other warplane primes charge similar sums? The weapon itself is described by Raytheon as “low-cost.” According to the same NAO report, the unit production cost of the 2,300 Paveway IVs that the MoD originally ordered was just $48,000.