Most air-to-air missiles kill their targets by turning a good part of the relatively small warhead's explosive power into a rapidly expanding ring of high-velocity fragments that increase the weapon's lethal radius. Some surface-to-air missiles have aimable warheads that increase the chances of knocking out the target. The next generation of air-launched weapons also are expected to have aimable warheads - especially if they are to be dual role, and effective against surface as well as air targets.

An active-imaging radar fuze operating at frequencies above 200GHz using conformal antennas would be ideal for miniature munitions, says AFRL, and would be more easily integrated with guidance systems using imaging seekers. Equally importantly, an aimable warhead combined with an imaging fuze could allow one air-launched weapon to be used against both air and ground targets.

This is the goal of the US Air Force's Joint Dual-Role Air Dominance Missile (JDRADM) concept, proposed as a replacement for both the air-to-air AIM-120 AMRAAM and anti-radar AGM-88 HARM and a way to increase the firepower of the missile-limited F-22 and F-35. Under previous efforts AFRL has looked at how the missile seeker could be used to aim a directional fragmentation warhead against air or ground targets. SWIFT will look at using the fuze.

My colleague, Douglas "Missiles" Barrie, points me to a late-1990s US/UK program called PIOS (Programmable Integrated Ordnance Suite) that sought to develop an imaging-infrared target detection device (aka fuze) and directional fragmentation warhead. The fuze had two side-looking fisheye lenses providing a spherical view . The warhead had six curved sides and its initiation could be controlled to center the fragments on a selected aimpoint on the target.

PIOS involved AFRL, DERA (now Qinetiq), Raytheon and British industry, but Douglas says the UK withdrew from a planned jointly funded Phase 2 and its fate is unclear.