JNTU B.Tech II INTRODUCTION TO SPACE TECHNOLOGY Previous Question Paper (November/December - 2020 - R13)

To calculate the burnout velocity (v_b) of the rocket, we use the Tsiolkovsky rocket equation: v_b = I_sp × g₀ × ln(m₀ / m_f). Given values are: propellant mass (m_p) = 2,700 kg, structural mass (m_s) = 250 kg, warhead mass (m_w) = 50 kg, and specific impulse (I_sp) = 300 s. Taking standard gravity (g₀) as 9.81 m/s².

First, calculate the initial mass (m₀) and final mass (m_f):

Now, substitute these into the rocket equation:

The burnout velocity is approximately 6,777.55 m/s.

The Rocket motor principle is based on Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction. A rocket motor carries both fuel and an oxidizer (propellant). When the propellant burns in the combustion chamber, it produces high-pressure, high-temperature gases that are accelerated and expelled through a nozzle at high velocity. The momentum change of the exhaust gases creates an equal and opposite force, known as thrust, which propels the rocket forward.

Rockets are classified based on the type of propellant used:

• Solid Propellant Rockets: The fuel and oxidizer are mixed into a solid rubbery mass called the 'grain'. These are simple, reliable, and have long shelf lives, but they are generally difficult to throttle or shut down once ignited.
• Liquid Propellant Rockets: Use liquid fuel and liquid oxidizer stored in separate tanks and fed into the combustion chamber via pumps. These offer high efficiency, can be throttled, and are restartable, though the mechanical systems are complex.
• Hybrid Rockets: Utilize a combination of both, typically a solid fuel grain and a liquid or gaseous oxidizer. They offer a balance of safety and controllability.