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Any one for IRIS-T

LIKE THAT OF THE RAFAEL Python 4, the German-led IRIS-T development programme, which also involves Canada, Greece, Italy, Norway and Sweden, focuses on the close-in air battle, rather than the extended within-visual-range engagement which was the original driver behind the Matra BAe Dynamics ASRAAM.

Prime contractor Bodenseewerk Gerätetechnik (BGT), which was involved early on in the ASRAAM, says that the then-US/UK ASRAAM programme was designed to intercept the Soviet air force by multiple-wave attacks, first using medium-range missiles, and the remainder with ASRAAMs at ranges of 10km (5.4nm)

"The major requirement for ASRAAM was F-pole [effectively keeping the launch aircraft as far from the target while still achieving a missile kill] ," says BGT.

The IRIS-T, on the other hand, is designed specifically for the "fur-ball". The missile's mid-body wings support controllability at high angles of attack, while the tail-control fins combine with thrust-vectoring vanes mounted in the exhaust nozzle for high manoeuvrability.

Speed is less of a priority than in the ASRAAM design, although the manufacturer claims that the IRIS-T will be faster than today's Sidewinder missiles, having slightly higher thrust and - according to windtunnel tests - lower drag. Despite the IRIS-T's relatively large aerodynamic surface area, BGT claims that its wings, control Ìns and forward destabililsers put together have less drag than the Sidewinder's rollerons.

The core of the missile is BGT's infra-red imaging seeker, which instead of having a single detector element with a field of view of about 3 degrees like earlier IR-seekers, builds an image from a row of detector elements which scans rapidly across the target. Each of the elements has a resolution in milliradians, allowing the seeker to distinguish much more clearly between its target, background sources and any flares the target may release.

The IRIS seeker allows the missile to acquire targets at up to 90 degrees off-boresight and three to four times further away than can today's Sidewinder, claims BGT - which also builds various versions of the Sidewinder missile under licence in Germany.

The IRIS seeker was test fired in 1996, mounted on a Sidewinder airframe. In two test launches against a Dornier SK6-towed target approaching head-on at 5km range, the missile successfully hit the target at off-boresight angles of up to 50.4 degrees at launch.

BGT anticipates that the partner countries will sign a memorandum of understanding committing them to the missile in August, with a contract scheduled to follow by the end of November (Flight International, 23-29 April).