SDB enters the frame

Boeing's GBU-40 Small Diameter Bomb (SDB) is expected to get the go-ahead for Low-Rate Initial Production (LRIP) next month, with Initial Operational Test & Evaluation (IOT&E) next year. LRIP should begin in April 2006 with full production in 2007. It will arm the F-15E and both Hornet and Super Hornet as well as the F/A-22 and F-35 Joint Strike Fighter.

While there is no stated requirement at present for the SDB to arm the RAAF's Hornets it will almost certainly arm Australia's F-35s and there is no reason to suppose the RAAF won't try to acquire the weapon to extend the capabilities and flexibility of its F/A-18s in the interim.

The SDB is a 250lb weapon with GPS/INS guidance and a fold-out wing kit to provide stand-off range. It was designed to suit a number of USAF requirements: more targets (and kills) per sortie; reduced collateral damage though increased accuracy and a smaller warhead; an autonomous attack capability; reduced logistics footprint and the ability to generate sorties rapidly.

It is designed to attack concealed, covered and hardened targets, both fixed and moving, and is designed as a complete system consisting of the weapon itself, a carriage system weighing some 350lb which carries four weapons at once, the integrated logistics support and a PC-based mission planning system designed to reduce mission planning time. The weapon is designed for in-flight re-targeting which in turn enables what the USAF calls dynamic Launch-Acceptable Release (LAR) calculations, based on the extant rules of engagement.

Development of the SDB Increment II variant for moving targets is planned to start in 2006 as the baseline Increment I system goes into production.

An F-15 or F/A-18 could carry up to 20 SDBs so would be able to take out an entire airfield or complex of targets in a single sortie, says Boeing. The SDB has a multi-role penetrating/fragmentation warhead whose penetrating capability against hardened targets is a function of the weapon's velocity. It will penetrate hardened targets at ranges of between 35 and 50nm; and will be effective against less-hardened targets at ranges of 40-60nm. Its unit cost hasn't been revealed but is reckoned to be less than US$40,000 a shot, though still more than a standard JDAM kit.

By Gregor Ferguson, Adelaide