This set of Rocket Propulsion Question Bank focuses on “Engine Controls”.
1. The complexity of the control elements of the engine systems depend mostly on ___
b) Launching site
Explanation: The mission determines how complex the engine system will be. If the mission is to reach Mars and deploy a rover, the level of complexity involved will be more compared to a mission to launch a rocket to intercept a missile above the atmosphere.
2. Single-shot devices are _______
a) Devices with a single-engine
b) Devices which are deployed only once
c) Devices which can fire a single missile
d) Colloquial term for missiles
Explanation: Single-shot devices are those which are deployed once. An example would be Rocketdyne’s X-1.
3. Valves, regulators and pressure switches come into picture while considering ___
a) Solid rocket engines
b) Liquid rocket engines
c) Both solid and liquid rocket engines
d) Neither solid nor liquid rocket engines
Explanation: Valves, regulators and pressure switches are required for controlling and regulating the flow of liquid propellants in rocket engines which use them. The use of such equipment adds to the complexity of liquid propellant rocket engines compared to other types.
4. ___ are used to protect personnel and equipment in case of malfunction.
a) Ejection seats
b) Parachute system
c) Rocket casing
d) Safety controls
Explanation: Safety controls are maintained in a rocket with the special intention of protecting personnel and equipment in case of its malfunction. When a situation arises where we need to choose as to give weightage to safety or improve the performance and efficiency of a device, the preference will always be towards safety.
5. In which of the following cases does the electrical valves automatically return to their normal positions?
a) Nonhazardous shutdown
b) Hazardous shutdown
c) Cold start
d) Warm start
Explanation: A failure in electrical power supply may lead to a nonhazardous shutdown in a rocket. In such a case, all the electrical valves return to their normal configuration.
6. ___ permits the simulation of operation of critical control components without actual hot operation of the rocket unit.
a) Checkout controls
b) Safety controls
c) Thrust vectoring control
d) Operating control
Explanation: In some rocket engines, there are provisions for actuation of principal valves without having propellant or pressure in the system. Check-out controls enables such a provision to be executed.
7. How is stable operation of liquid propellant flows achieved?
a) By means of some kind of a pressure feed system
b) By utilizing the gravitational force on the liquids to the rocket’s advantage.
c) By using suitable pipes and valves which can minimize vibrations
d) Liquid flow system in general are inherently stable
Explanation: The liquid flow systems used in liquid propellant rocket engines are inherently stable. This means that when there is a disturbance in the hydraulic system (like a sudden increase or decrease of flow), the system tries to reduce the effect of disturbance on its own.
8. Start delay includes the time taken to ___
a) Close valves
b) terminate combustion
c) Lower the flow
d) raise chamber pressure
Explanation: Start delay is the time required to do a number of operations. This involves the time to purge the system if required, open valves, initiate combustion, and raise the flow and chamber pressure to their rated values.
9. Which of the following pressurization systems take more time to start for similar engines?
a) Turbopump system
b) Gas pressure feed system
c) Both requires the same time
d) Start time is independent of such systems
Explanation: For same kind of rocket engine, turbopump system will require more time to start. This is because of an additional time delay involved in such systems for starting the gas generator or preburner and for bringing the turbopumps up to a speed.
10. How much time does it generally take to start a small thruster with a pressurized feed system?
a) 3-15 ms
b) 1-5 s
c) 3-15 s
d) 1-5 ms
Explanation: It takes about 3-15 ms for starting small thrusters with pressurized feed system. For a turbopump-fed system, this time can be about 1-5 s.
Sanfoundry Global Education & Learning Series – Rocket Propulsion.
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