Lakshmic,Why Gas generator ? You mean to say it is not used for propulsion ? Then why need this big a gas generator (going by Arun-saar's drawings) ? Attitude control or extending aerospike wont need that high pressures. Preventing water entry for underwater operations is about the only other thing I can think of.
I think Ramana was talking about the design of the SUM, not its purpose. It is to be used for Propulsion only. The design, if it is a solid fuel type, is very likely to have a high Loading Fraction and but not necessarily a low Loading Density. In addition, it is bound to have significant chamber pressures, allowing for a short, sweet burn.
IMO it is difficult to see the Agni-III first step to have anything other than a composite casing if the vehicle is to in fact lift off the ground. Perhaps the future work is to make the whole missile as composite body. Certainly a worthwhile goal to try and achieve.On the other hand, the Hindu business line has consistently said that Agni III itself is composite bodied.. whereas the TSS artcles indirectly hint at composite bodied being a future aim rather than current reality...
On a sidenote, Arun_s: The Chamber Pressure stated on the BR Agni page are the time averaged pressures or initial or final pressures from your calculations?
Thanks in advance.
-Vivek