Question

In a solid propellant rocket, the thrust level is primarily controlled by

• A. Injector design
• B. Turbopump speed
• C. Grain geometry and burning surface area
• D. Mixture ratio control

Hint:

For a solid rocket, \[ \boxed{ \text{Grain Geometry} \Longrightarrow \text{Burning Surface Area} \Longrightarrow \text{Mass Flow Rate} \Longrightarrow \text{Thrust}. } \] Different grain shapes (tubular, star, finocyl, etc.) produce different thrust-time profiles.

Answer 1

The Correct Option is C

Step 1: Recall the operation of a solid rocket motor. In a solid rocket motor, the fuel and oxidizer are premixed in the propellant grain. Unlike liquid rockets, there are no injectors or turbopumps to regulate the flow.

Step 2: Determine what controls the thrust. The thrust depends mainly on the propellant burning rate and the exposed burning surface area. These are governed by the grain geometry. Hence, \[ \boxed{ \text{Thrust is primarily controlled by the grain geometry and burning surface area.} } \] Therefore, \[ \boxed{(C)} \] is the correct answer.