The SS-45

In 1970’s, having gone through 2 successful exercises for developing navigational system for aircrafts and because of their confidence in developing Digital computer hardware and software, the Defence Research and Development Laboratory (DRDL), conducted a feasibility study for a 45 kilometer surface to surface missile. Using the Devil missile (Indian Surface to Air missile program in same period) in surface mode with strap down inertial navigation system (SDINS) supported by computer that would implement control, guidance and navigation.

The computer for the SS-45 was built in Special Purpose Computer Division (SPCD) using off the shelf LSIV03 (PDP equivalent) processor module and other interfaces for Gyros, Accelerometers, Telemetry, Launch control etc. using in house using PCB facilities in the country.

This was the first missile borne computer in the country. The launch was planned from SHAR, after going through strenuous exercise of proving the news sub systems in environmental testing labs followed by electronically and mechanical integration to the missile.

A few hours and check out before launch, the core team realized that one more additional transformation was required in the algorithm. So the team worked throughout the night in the blockhouse, implemented the software in the computer and got ready to launch at 0800 hrs in the morning.

When the system was powered next day for the launch, the leveling errors seen on the launch computer in the pre-launch preparation were unbelievably low and this had created a little confusion and thus the system was on for more 2 hours. Finally, they convinced each other that the lower error is because of updates made in the previous night and went ahead with the launch.

At about 1030 hrs., SS-45 Missile took off from the inclined launcher. But within 2 seconds after the closure of the guidance loop, an abort mechanism (provided as an alternative to command destruction system) took over, sensing mal function and dipped the missile into the sea.

Telemetry results that were received for 13 seconds were good and it was found later that the crystal oscillator appeared to have failed stopping the computer. Though there was a lot of discontentment in the core team, they just made the first step into the guided surface to surface missile development in the country.

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