# Rocket Propulsion Questions and Answers – Engine System Calibration

This set of Rocket Propulsion Multiple Choice Questions & Answers (MCQs) focuses on “Engine System Calibration”.

1. The calibration procedure for the turbopump system is ________ complex compared to gas pressure fed systems.
a) equally
b) less
c) more
d) unrelated

Explanation: The calibration curves cannot be estimated readily without the use of good test data. Hence the calibration procedure for turbopump is more complex.

2. The process of balancing the pressure available to the engine against the pressure drop plus the chamber pressure is called as __________
a) chamber balance
b) engine balance
c) pressure balance
d) overall balance

Explanation: Pressure balance is the term used for denoting the balancing process. The pressure is supplied to the engine by pumps or pressurized tanks. This is an important part of engine calibration for it to operate at desired flow rate and mixture ratios.

3. Which of the following forces on a rocket engine is more significant than the rest of them?
a) Actuator forces
b) Maneuver forces
c) Vibration forces

Explanation: Thrust load is the most significant. The vehicle structure must be able to withstand this load for its successful operation. It is also called axial load and acts parallel to the vehicle’s longitudinal axis. With variable thrusters, this direction can also be manipulated.

4. Under ideal conditions, the ratio of the rated flows has to be _________ desired mixture ratio.
a) Equal to
b) less than
c) more than
d) unrelated to

Explanation: The ratio of rated flows should be equal to the desired mixture ratio under ideal operating conditions. Ratio of the rated flows is given by ṁo/ṁf. One way of doing this is to add pressure drops with appropriately placed orifices, or changing valve positions or regulator setting.

5. The operating mixture ratio is usually ________
a) fuel-rich
b) fuel-lean
c) oxidizer-rich
d) doesn’t matter

Explanation: Operating mixture ratio is usually fuel-rich and the value is determined by optimum specific impulse. This is done because fuel-rich mixtures typically have lower molecular weight. It might also help in afterburning which can improve the overall rocket performance.

6. The calibration procedure for turbopump system is ___________ complex compared to gas pressure fed systems.
a) equally
b) less
c) more
d) unrelated

Explanation: The calibration curves cannot be estimated readily without the use of good test data. Hence the calibration procedure for turbopump is more complex.

7. In a pressurized feed system, the pressurizing gas is supplied from its high-pressure tank through ____ for the pressurization of both fuel and oxidizer.
a) regulator
b) passage valves
c) expansion joints
d) combustion chamber

Explanation: The pressurizing gases first passes through a regulator for pressurization of both the fuel and the oxidizer. Regulators in general, can be used for both liquid and gases and may contain its own restrictor or pressure sensor.

8. The gas pressure in the propellant tank is _________
a) unregulated pressure
b) sea level pressure
c) ambient pressure
d) regulated pressure

Explanation: The gas pressure in the propellant tank is regulated pressure Pgas. It is diminished by the pressure losses in the gas line denoted by ∆Pgas. This gas pressure is augmented by the static head of the liquid.

9. Precise control of engine performance parameters via the use of an automatic feedback system employing a digital computer for control purposes is _________ compared to static calibration of the engine design.
a) simpler
b) complex
c) equally difficult
d) unachievable

Explanation: The use of an automatic feedback system employing a digital computer is complex compared to static calibration. The error in static calibration indicates a deviation from a linear response of the system. Dynamic measurements may incur appreciable errors because of the nonlinear response.

Sanfoundry Global Education & Learning Series – Rocket Propulsion.

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