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Rocket Propulsion Mcqs

Q:

Which of the following can’t happen if a chemical rocket engine were to use gelled propellants?

A) Increase in specific impulse B) Increase in density impulse
C) Possibility of short-duration pulsing D) Much less likely to have explosions
 
Answer & Explanation Answer: A) Increase in specific impulse

Explanation: Depending upon the gelling agent, specific impulse might change. Because of the dilution of the propellants with a gelling agent, there is generally a small decrease in specific impulse. It will also lead to less efficient atomization or combustion.

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50
Q:

Which of the following is not a method of achieving a variable thrust?

A) Injecting liquid into the gas streams before injection B) Varying injection element area
C) Varying the nozzle throat area D) Varying feed system pressure drops
 
Answer & Explanation Answer: A) Injecting liquid into the gas streams before injection

Explanation: Injecting gas into liquid streams before the injection is a method for achieving a variable thrust but not vice versa. Varying injection element area can be done via selectable manifolds and movable injector elements.

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37
Q:

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
 
Answer & Explanation Answer: B) complex

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.

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37
Q:

The gas pressure in the propellant tank is _________

A) unregulated pressure B) sea level pressure
C) ambient pressure D) regulated pressure
 
Answer & Explanation Answer: D) regulated pressure

Explanation: Not available for this question

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63
Q:

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
 
Answer & Explanation Answer: A) regulator

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.

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39
Q:

The calibration procedure for turbopump system is ___________ complex compared to gas pressure fed systems.

A) equally B) less
C) more D) unrelated
 
Answer & Explanation Answer: C) more

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

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36
Q:

The operating mixture ratio is usually ________

A) fuel-rich B) fuel-lean
C) oxidizer-rich D) doesn’t matter
 
Answer & Explanation Answer: A) fuel-rich

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.

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43
Q:

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
 
Answer & Explanation Answer: A) Equal 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 m?o/m?f. One way of doing this is to add pressure drops with appropriately placed orifices, or changing valve positions or regulator setting.

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