IISc. helps raise missiles range

Missiles such as the Agni that was test-fired last week could receive a bigger boost to their range thanks to a technological innovation by scientists at the Indian Institute of Science.

By coating the nose of the missile with a layer of chromium, scientists at the Department of Aerospace Engineering and Department of Inorganic and Physical Chemistry have demonstrated how the missile’s range could be increased by 30 per cent — without any increase in fuel expenditure.

The chromium coating reduces the aerodynamic drag encountered by the vehicle by up to 47 per cent, said K.P.J. Reddy from the Department of Aerospace Engineering. He led the team of scientists in this project.

He said: “As the chromium coating evaporates with the enormous frictional heat generated during hypersonic flight, it reacts with the oxygen atoms present in the atmosphere and produces chromium oxide. This reaction is exothermic, that is producing more heat, thereby decreasing the density of the air around the nose of the missile. As the pressure reduces, so does the drag force, which in turn enables the missile to increase its range.”

While the nose of the missile is conventionally blunted in order to reduce the problem of heating, this increases drag, which considerably reduces the range. “Large amounts of fuel are needed to compensate for the drag and to give the vehicle thrust. With this technology, we increase the range without using additional fuel.”