This set of Rocket Propulsion MCQs focuses on “Rocket Engines for Manueuvering, Orbit Adjustments or Attitude Control”.
1. What is the nature of thrusters and feed system for attitude control rocket engines?
a) small; common pressurized feed system
b) large; separate turbopump feed system
c) small; separate pressurized feed system
d) large; common turbopump feed system
Explanation: Thrusters used in rocket engines for attitude control, maneuvering and orbital adjustments are usually small. They are located at different spots on the rocket engine but have a common pressurized feed system.
2. Rocket engines used for orbital adjustments are also called as _____________
a) boost propulsion system
b) primary propulsion system
c) auxiliary rockets
d) strap-on motors
Explanation: In addition to orbital adjustments, auxiliary rockets also serve the purpose of maneuvering and attitude control. They are also called as reaction control systems.
3. Reaction control systems produce larger thrust than auxiliary propulsion systems.
Explanation: Reaction control systems are the same as auxiliary propulsion systems. So, the thrust is the same. But reaction control systems produce lesser thrust compared to the main propulsion system.
4. For the application of pure torques in three directions, it requires ______ thrusters.
Explanation: It requires 12 thrusters for the purpose of creating pure torques in the three orthogonal directions. Some of them include roll, pitch and yaw thrusters with control valves.
5. Which of the following modes of firing thrusters leads to pure modulation?
a) Pulsing mode
b) Step input mode
c) Ramp input mode
d) Sinusoidal mode
Explanation: In pure modulation, some of the thrusters are fired in pulsing mode. This is a good method for achieving accurate velocity corrections.
6. A thruster firing repeatedly for 0.010 seconds each time followed by a pause of 0.020 seconds or 0.150 seconds is an example for __________
a) step input mode
b) pulsing mode
c) sinusoidal mode
d) ramp input mode
Explanation: This kind of mode in which the thrusters are fired for a very brief period of time and then a brief pause is maintained just to repeat the whole process again is an example for pulsing mode of operation of the thrusters.
7. ___________ system determines the maneuver to be performed and _________ system sends command signals to specific thrusters for number of signals required.
a) Control; control
b) Guidance; guidance
c) Control; guidance
d) Guidance; control
Explanation: Guidance system identifies the maneuver to be performed and the control system sends the signals to specific thrusters. The signals specify the number of pulses needed to complete the maneuver without fail.
8. What is range of side force required by a ballistic missile during its final closing maneuver just before nearing in on the target?
a) 100-4500 N
b) 200-6000 N
c) 800-8000 N
d) 1000-18000 N
Explanation: The range of side force required is from 200 N to 6000 N. Upper stages of ballistic missiles are highly maneuverable owing to these high side forces that they require.
9. For very short pulse duration of the thruster firing, the specific impulse is degraded by __________
Explanation: The specific impulse degradation can be from 5% to 25%. This is because the performance during thrust build up and thrust decay are inferior compared to that at the rated operating conditions (without any transience).
10. Reaction control of the Space Shuttle is achieved using ________ thrusters.
Explanation: The Space Shuttle uses 38 different thrusters for its reaction control. Some of the thrusters are spare or redundant. Others perform such complex operations as rendezvous or docking maneuvers, station keeping, orbital corrections, etc.
Sanfoundry Global Education & Learning Series – Rocket Propulsion.
To practice MCQs on all areas of Rocket Propulsion, here is complete set of 1000+ Multiple Choice Questions and Answers.
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