Optimization of Grain and Nozzle Geometry in Solid Rocket Booster Gslv

The project upgrades the GSLV Mk-III solid booster via a high-density composite propellant (65% bimodal AP, 18% spherical Al, 12% HTPB binder including 1.5% additives) augmented with 1% copper chromite, 1% lecithin, 1% TEPANOL and 2% iron oxide, achieving 1,795 kg/m3. An 8-lobed finocyl grain with tapered fins gives a large initial surface area for rapid pressurization and a progressive→neutral burn over 110-120 s; the grain is carbon-fiber reinforced to withstand up to 12 MPa. A flex nozzle with 0.61 m throat, 15:1 expansion (exit Ø 2.36 m), and a carbon-carbon throat coated with ZrC is optimized for sea-level/vacuum. Predicted performance: 5,800 kN thrust, exhaust velocity ≈2,714 m/s, Isp ≈277 s, mass flow ≈2,138 kg/s.