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 1795 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: 5800 kN thrust exhaust velocity ≈2714 m/s Isp ≈277 s mass flow ≈2138 kg/s.