Answer Happy

a) What is the purpose of an inhibitor material, as used in solid rocket propellant grains? Sketch any propellant grain with inhibitor material applied (sketch either 3D or three view / sectional sketch, by hand or using any suitable digital means). [5 marks] b) Explain what is the function of the following propellant additives: (i) hydrogen fluoride (HF) in Inhibited Red Fuming Nitric Acid (IRFNA), (ii) a plasticizer in composite propellant. [4 marks] . . = . . = . = c) The Indian ISRO's LVM3 S-200 Solid Rocket Booster (SRB) has the following dimensions and propulsive characteristics: SRB mass before launch (m.) =280000 kg; SRB mass after burn-out (mb) = 40000 kg; nozzle throat diameter (dt) = 0.8 m; nozzle exit diameter (dexit) = 3 m. burning time (tend) = 120 s; average thrust (F) = 5000 kN (measured at sea level); average pressure inside combustion chamber (p) = 6.5 MPa; average nozzle exit pressure (Pexit) = 55 kPa; In this question you are required to calculate: 1) SRB performance at sea level altitude (pa = 101.325 kPa): () average combustion products mass flow rate ™ ? [2 marks] (ii) nozzle exit velocity Uexit ? [2 Marks] (iii) characteristics velocity C*? [2 Marks] (iv) thrust coefficient CF? [2 marks] (v) specific impulse Isp? [2 Marks] . . =