Question

If a rocket engine produces 30 kN thrust operating at chamber pressure of 4 MPa with throat diameter of 100 mm, then the thrust coefficient of a rocket engine is:

• A. 0.96
• B. 0.85
• C. 0.92
• D. 0.94

Hint:

Thrust coefficient relates actual thrust to chamber pressure and throat area—it indicates nozzle performance.

Answer 1

The Correct Option is A

Given: \[ F = 30{,}000\ \text{N}, \quad p_c = 4 \times 10^6\ \text{Pa}, \quad d_t = 0.1\ \text{m} \] Throat area: \[ A_t = \frac{\pi}{4} \cdot d_t^2 = \frac{\pi}{4} \cdot (0.1)^2 = 7.854 \times 10^{-3}\ \text{m}^2 \] Thrust coefficient: \[ C_F = \frac{F}{A_t \cdot p_c} = \frac{30{,}000}{7.854 \times 10^{-3} \cdot 4 \times 10^6} \approx 0.956 \approx 0.96 \]