From ARES Blog

 

On The Nose - Making Missiles go Faster

Posted by Graham Warwick at 11/10/2008 9:38 AM CST

 

Indian researchers say they have tested a novel and simple way to reduce the drag and increase the range of high-speed missiles. In hypersonic shock-tunnel tests reported in the journal Physics of Fluids, the technique resulted in a 47% reduction of drag on a blunt cone representing the nosecone of a missile or space vehicle.

 

Blunt noses are used to reduce the aerothermal loads on missiles at high speed, but they increase wave drag. Researchers at the Indian Institute of Science (IISc) in Bangalore tested various ways of reducing drag, including mounting an aerospike on, or ejecting a supersonic gas jet from, the tip of the nose. But these methods, while they work, are difficult to apply, they say.

 

In contrast, the technique tested by IISc is simple, and could be applied to existing missiles - including India's surface-to-air Agni, they note. Basically it involves coating the nose of the missile with a layer of chromium. When the nose heats up at hypersonic speed, the metal evaporates and reacts exothermally with the oxygen in the airflow. The heat released reduces the pressure and density behind the bow shockwave, which reduces the drag.

From Times of India

 

IISc has idea for better missiles

4 Nov 2008, 0432 hrs IST, Prashanth G N , TNN

 

BANGALORE: IISc’s new piece of research on reducing drag experienced by flying objects and helping them fly longer is finding its way into India’s missile establishment. Scientists at DRDO are excited and the organization is planning to “apply the findings’’ in a major way to its missile research and production programmes.

 

The research, which has been published in the science journal ‘Physics of Fluids’, has made an impact among India’s defence think tank with many of them discussing the implications of the research. Scientists told TOI that DRDO heads have been “excited’’ by the new research and “that it will be used in future vehicles.’’

 

The research suggests that the nose portion of a missile or launch vehicle be coated with a thin layer of material such as chromium, which will reduce drag or atmospheric resistance. This will enable it to fly faster and longer.

 

How does this happen? The metal coating evaporates due to the heating of the missile nose during its hypersonic flight. Then the evaporated metal particles in atomic form react exothermically with oxygen atoms surrounding the body to release additional heat. Lastly, the air in the front of the missile gets heated up and in turn, reduces drag by up to 47%.

 

DRDO scientists say this new method will ensure that without spending additional energy or having to fit anything extra on the nose of the missile or rocket, the overall aerodynamic drag of the vehicle can be controlled and efficiency of hypersonic flight of the vehicle enhanced.

 

The new technology also costs nothing. Officials say once the chromium mix coating is prepared, it can be applied even by “the man on the street.’’

 

In all, three factors have persuaded DRDO to take the research seriously — radical cut in costs to enhance range of missiles, no need to import material or know-how and enhancement of range of missiles without any need for additional devices.

 

DRDO scientists are also of the view that the method of applying the chromium coat can be extended to existing stockpile of missiles (Agni), which makes the method more relevant and attractive.

Adding devices would have meant changes in existing missile structure, which can now be avoided. “We are very much into the research findings,’’ an official said.

 

Coming from an Indian research institute and at no cost and to a critical sector like defence, which is in urgent need of indigenous intellectual property, it is a shot in the arm for both IISc and DRDO.

Link to IISc report.