Ikara (missile) - Design and Development

Design and Development

With the development of nuclear power, submarine performance, especially speed, improved dramatically, as did the threat they posed. Simultaneously, sonar detection capability at long range was also improving significantly but the weapons available to surface escort warships were still of the short-range variety. The final British development of the A/S mortar was the Limbo ahead-throwing mortar, its range being a maximum of 914 metres (2,999 ft). Even the latest modern Mark 46 lightweight torpedoes are limited in range to 4 nautical miles (7.4 km), and at their speed of 28 knots (52 km/h) would take 8.5 minutes to travel that distance, and are consequently unable to attack time-urgent targets at extended ranges.

Known initially as Blue Duck, the Ikara was a "Rocket-Thrown-Weapon" with similarities to the French Malafon. It differed from Malafon, in that the torpedo was semi recessed in the body of missile body rather than mounted in the nose. Ikara's range at 10 nautical miles (19 km) was double that of ASROC. Ikara was generally considered a superior system to ASROC as it was accurately guided during flight to ensure optimal targeting. A submarine would be aware from sonar contacts that it was about to be attacked and could engage in evasive changes of course. In ASROC's flight time to maximum range of 55 seconds, a submarine travelling at 25 knots (46 km/h) would move 700 metres (2,300 ft) from its position at launch, and a prediction would be made of the submarine's likely position at torpedo splashdown. But during the design of Ikara around 1960 the range of the acoustic seeker of the Mk.44 torpedo was limited to 457 metres (1,499 ft) and consequently its kill probability was low. The range of the acoustic seeker was later improved.

The Turana target drone was designed and built in Australia as a development of the Ikara anti-submarine weapon system. It was a target drone with remote control that was launched from the Ikara launcher for use in naval anti-aircraft target practice.

Ikara was powered by a two-stage in-line solid-fuel Murawa rocket engine developed by Bristol Aerojet Ltd in the UK and was guided by radio command link until it reached the vicinity of the submarine, determined by the ship's sonar contact, where it would first jettison the rear ventral fin and torpedo rear covering and then release its 12.7 inch Mark 44 or Mark 46 acoustically-guided anti-submarine torpedo. The torpedo payload would descend by parachute while the missile itself was programmed to splashdown some distance away to avoid interference with the acoustic torpedo's seeker head. The torpedo would then begin a circular search pattern to find and lock-on a submarine contact.