After the failed first test of Agni-III, about nine months earlier, there had been a test flight of Agni-III, the first ever. However, the maiden flight encountered problems a minute after lift off and was not entirely successful in meeting the mission objectives. From whatever data was available, we were able to determine the reason for failure. It turns out from the CFD simulation that I have carried out during thepost flight analysis that during the initial ascent phase of themissile, the external freestream air interacts with the hot rocket exhaust of the first stage rocket motor and creates a pocket of recirculating hot gases just behind the vehicle. Agni-III uses a flexible nozzle for thrust vector control. In order to allow the nozzle to deflect, an annular gap was left between the nozzle and the
It took us nearly two months of extensive analysis, CFD simulation from my side and simulation of the flight electronics by other teams, to establish this phenomenon as the cause of failure. It took another six months to design a flexible barrier which would protect the base shroud from the hot gases while simultaneously allowing the nozzle to flex. Again from several CFD simulations, I was able to provide the thermal and pressure loads which the thermal barrier would experience and thus should be designed to withstand. Another month for launch preperations and we were ready for launch on 12th April.
The four minutes on 12th April, were undoubtedly among the most exciting moments of my career at DRDO. Four minutes during which our entire efforts are put to test. Four minutes because it corresponds to the powered phase of the flight during which all flight events including separation of the expended stages take place. Beyond that, good old gravity takes over Smile We were in a building about 1km from the launch pad from where we could feel the noise and vibration from a thrust of hundred tons. The flight video and the trajectory were projected in real time. The sky was fabulously clear and visibility was great. The cameras were able to track the missile more than a hundred kilometres. It was even possible to make out in the flight video when the first stage separation occurred.
Thirteen minutes from lift-off and it was all over. The round of applause that followed would probably have drowned the noise during lift-off Smile It was one of the most thrilling and professionally satisfying moments of my life and one which I would cherish for a long time to come.
cylindrical shell of the missile instead of closing it entirely.
It was through this gap that the recirculating hot gases entered the portion of the missile (called base shroud) and caused damage to the electronic components present there.
It was through this gap that the recirculating hot gases entered the portion of the missile (called base shroud) and caused damage to the electronic components present there.
It took us nearly two months of extensive analysis, CFD simulation from my side and simulation of the flight electronics by other teams, to establish this phenomenon as the cause of failure. It took another six months to design a flexible barrier which would protect the base shroud from the hot gases while simultaneously allowing the nozzle to flex. Again from several CFD simulations, I was able to provide the thermal and pressure loads which the thermal barrier would experience and thus should be designed to withstand. Another month for launch preperations and we were ready for launch on 12th April.
The four minutes on 12th April, were undoubtedly among the most exciting moments of my career at DRDO. Four minutes during which our entire efforts are put to test. Four minutes because it corresponds to the powered phase of the flight during which all flight events including separation of the expended stages take place. Beyond that, good old gravity takes over Smile We were in a building about 1km from the launch pad from where we could feel the noise and vibration from a thrust of hundred tons. The flight video and the trajectory were projected in real time. The sky was fabulously clear and visibility was great. The cameras were able to track the missile more than a hundred kilometres. It was even possible to make out in the flight video when the first stage separation occurred.
Thirteen minutes from lift-off and it was all over. The round of applause that followed would probably have drowned the noise during lift-off Smile It was one of the most thrilling and professionally satisfying moments of my life and one which I would cherish for a long time to come.
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