The Trishul (Trident) is a short range, quick reaction, all weather surface-to-air missile designed to counter a low-level attack. It has been flight tested in the sea-skimming role and also against moving targets. It has a range of 9 km and is fitted with a 5.5 kg HE-fragmented warhead. It's detection of target to missile launch is around 6 seconds. The missile can engage targets like aircraft and helicopters, flying between 300 m/s and 500 m/s by using its radar command-to-line-of-sight guidance. It operates in the K-band (20 - 40 GHz), which makes it difficult to jam. In the K-band three-beam system, the missile is initially injected into a wide beam, which then hands it over to a medium beam, which passes over to a narrow beam, guiding it to the target.
The Trishul SAM, being test-fired from a launcher at INS Dronacharya
The Trishul has high manoeuvrability and is powered by a two-stage solid propellant system, with a highly powered HTBP-type propellant similar to the ones used in the Patriot. It is constructed of maraging steel to withstand the stress. Successful flight trials in a tube launched mode using folded fins against balloons and Pilot-less Target Aircraft (PTA) targets were carried out. One flight trial was guided throughout the trajectory using fixed line of sight and infra-red gathering guidance systems as per programmed flight. The army variant, Trishul Combat Vehicle (TCV), is based on a tracked BMP-1 infantry combat vehicle and houses all equipment including radars, command-guidance system and missiles.
David C Isby of Jane's Defence Weekly reported that after a spate of unsuccessful tests, it was decided that the Trishul SAM will not be fielded as an operational system but will be continued as a technology demonstration program. Trishul was one of the longest-running Indian Defence Research & Development Organisation (DRDO) missile development programs. The program began in 1984, and more than 40 test flights have been conducted. Defence Minister George Fernandes told Indian Parliament that while the Trishul had demonstrated a number of complex technologies, including an ability to defeat sea-skimming targets, it still had not been proved to be effective. By continuing the program as a technology demonstrator, India hopes that some of the technology from Trishul can be incorporated in other missile projects. The official cost of the Trishul program has been some Rs.3 billion (US $62.5 million).
The Trishul SAM being test-fired from the Trishul Combat Vehicle (TCV)
The Trishul missile had been intended to be a multi-service design. The Indian Air Force, which had intended to adopt the Trishul for an airfield-defence role, recently turned against the project. The Army has also stated that the Trishul was unlikely to meet its requirements for a replacement for the Russian-designed OSA-AKM (SA-8b Gecko) self-propelled SAM system. The Indian Navy had designed recent warships to include the Trishul as their armament, so the decision not to make the system operational is likely to require selection of an alternative system and modification of the warships that were to use the Trishul missile. This lead to an expansion of the Indian procurement of the Israeli-built Barak SAM system, of which seven systems were already ordered and another 10 systems have been planned for.
