Directed InfraRed Counter Measure (DIRCM) Turret

Directed InfraRed Counter Measure (DIRCM) technology has been developed to protect aircraft against attack from sophisticated Infrared guided missiles. DIRCM technology represents the latest step in the evolution of missile countermeasures systems.

DIRCM systems consist of a missile approach warning system that detects the launch and approach of the missile, and a director system, e.g. a turret, that is cued to track the approaching missile. The director turret contains an imaging system that detects the infrared signature of the approaching missile and enables the turret to lock onto and track the missile. Once the turret is tracking the missile, an Infra Red Countermeasure laser (IRCM laser) is fired through the turret at the missile, and the laser beam contains a code that will “jam” the guidance head of the missile and cause it to lose lock on the aircraft.

BAE Systems Australia has conducted the phased development of an Australian DIRCM demonstrator for the Department of Defence. The demonstrator program focused on the development of a compact, low drag turret design. To achieve this, BAE Systems applied a novel optical design to enable considerable miniaturisation of the turret, reducing it to a diameter of approximately 150 mm. Although the development has specifically focused on a low drag design for fast jet applications, a secondary consideration has been to ensure that no design decisions are made that preclude the turret being used on other platforms such as helicopters and transport aircraft.

The turret incorporates an azimuth/elevation gimbal design, with associated optical mirrors, for directing the laser source and also for tracking of the target via the optical aperture. The gimbals are driven by direct drive DC motors with optical encoders providing positional feedback, and elevation stage mounted inertial rate sensors providing rate feedback information.

• Greater than 2 pi steradian field of regard with a single turret
• 360° continuous azimuth stage
• - 10°, + 90° elevation stage
• Slew rates exceeding 1200°/s and acceleration exceeding 4000°/s2,
• Maximum slew time < 0.3 s.
• 4° fine track sensor field of view,
• Maximum tracking rates of 30°/s and maximum acceleration of 10°/s2
• Boresight error < 0.3 milliradians rms