Indigo Corkscrew was the development name of the AMES Type 86 radar used on the mobile Bloodhound II and Thunderbird IIStage 1 1/2 SAGW systems. Indigo Corkscrew was a Continuous Wave (CW) radar, replacing the pulsed Red Brick in the Bloodhound system. Continuous Wave radars possess improved jam resistance but more importantly, better low-level performance. In the Thunderbird II system the Type 86 was called AD10. The Type 86 was originally developed for the Army's Thunderbird.
TIRs (Target Illumination Radar) provide the guidance signal for semi-active missiles. The TIR emits a signal to illuminate the target aircraft. The missile seeker homes in on the radar signal reflected from the target. The large central dish is the main transmitting antenna. The parabolic dish on the side is the receiver antenna. The small circular dish between the two large dishes is the countermeasures assessment antenna. The rectangular box on the opposite side of the main dish is the in-flight reference antenna for the missile.
Indigo Corkscrew was later renamed Firelight on export versions of the Bloodhound system for Sweden, Switzerland and Australia. For fixed installations such as that at RAF West Raynham, the Type 87 Blue Anchor (exported as Scorpion) was used.
The Indigo Corkscrew shown here is on display at the Aerospace Museum at RAF Cosford.