JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech IV LAUNCH VEHICLE AND MISSILE TECHNOLOGY Previous Question Paper (September - 2020 - R15)

Both rockets and missiles rely on the principle of Newton's Third Law of Motion, utilizing high-velocity exhaust gases generated by internal combustion to produce thrust. They share fundamental subsystems, including propulsion systems (solid or liquid propellant engines), airframes, and aerodynamic control surfaces for stability during flight.

The primary differences lie in their purpose and guidance: a rocket is generally an unguided vehicle used for space launch or artillery, where the trajectory is determined by the initial launch angle and gravity. In contrast, a missile is a precision-guided weapon system equipped with an onboard guidance, navigation, and control (GNC) system, allowing it to adjust its flight path in real-time to intercept a moving or static target. Furthermore, missiles incorporate a payload section specifically designed as a warhead with fusing mechanisms, whereas rockets typically carry scientific instruments or satellites.

The selection of materials for launch vehicles is critical due to the extreme environments encountered during ascent. Key criteria include:

• High Strength-to-Weight Ratio: Materials must be lightweight to maximize payload capacity while possessing sufficient structural integrity to withstand high aerodynamic loads and internal pressure.
• Thermal Stability: Materials must resist extreme temperature fluctuations, from cryogenic temperatures of liquid propellants to the intense aerodynamic heating during atmospheric re-entry or high-speed flight.
• Fracture Toughness and Fatigue Resistance: The material must resist crack propagation and cyclic loading stresses experienced during engine ignition, vibration, and acoustic loading.
• Corrosion Resistance: Compatibility with propellants, such as liquid oxygen or hypergolic fuels, is essential to prevent chemical degradation of tanks and plumbing.
• Fabricability: The ability to be machined, welded, or formed into complex geometries like thin-walled pressure vessels is vital for cost-effective manufacturing.
• Low Thermal Expansion: Maintaining dimensional stability under varying thermal loads is necessary to ensure the alignment of sensitive guidance and control components.