Aerospace systems (copy)

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Systems

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161 Terms

1

Systems

A set assembled from a number of subsystems or individual components connected to each other, and capable of treating physical matter, energy, or information, in order to meet the purpose or number of purposes

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2

Systems Engineering

A holistic interdisciplinary management process, aimed at evolving a lifecycle balanced set of system solutions which satisfy customer needs.

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3

Pyramid of systems (Fill in blanks from top to bottom)

Enterprise, System of Systems, System, Subsystem, Components

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4

Factors influencing system design

Advancement in technologies, Competition, Specialization

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5

Principle of systems thinking (two terms)

Hierarchy, Viability

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6

System engineering problem solving STEP 1

Understand the Problem context

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7

System engineering problem solving STEP 2

Identify and Understand the problem

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8

Structure of Systems Engineering 1

SE Management

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9

Structure of Systems Engineering 2

Requirements and Architecture definition

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10

Structure of Systems Engineering 3

Development of subsystems

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11

Structure of Systems Engineering 4

System integration and Verification

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12

Lifecycle

The evolution with time of a System from idea to disposal

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13

Lifecycle Stage

An identified Objective in the Life of a system, used to manage the resources and activities of a project

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14

Lifecycle proccess

A squence of tasks needed to achieve a defined goal, within the objectives of a lifecycle phase

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15

Generic process model (1st one)

Waterfall model

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16

Process interdependencies in V model (one example)

Systems architecture and system integration

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17

System Design Methodology (3points)

Initiation of creative processes, Envisage all elements needed for system design, Assurance that the design has appropriate consequences on environment and society

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18

Two types of Customer needs

Direct, Latent

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19

Types of Systems Architecture (two types)

Integral, Modular

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20

Two methods used for Concept design

Traditional Brain storming, Brain ball method

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21

Aerospace system

Systems used on board and aircraft or spacecraft

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22

on-board Aerospace system (4)

Hydraulic, Pneumatic, Electrical, Landing gear

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23

How do we classify Aerospace systems? (from perspective of safety)

Primary, Secondary, Auxiliary

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24

What are the design specs for Aerospace Systems? (+ give an example)

Qualitative and quantitative definition of system functions, Definition of environmental characteristics, Maintainability. Example = Temperature

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25

What are the most important constraints for the design of the Aerospace systems? (example)

Weight, Available Volume (in terms of fuel systems)

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26

What does a Functional diagram represent?

It represents the functions performed by system components

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27

Name a technical drawing type

Drawing of parts

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28

Name all the quantities defining power

Mechanical (velocity), Mechanical (Angular velocity), Electrical (Voltage), Fluid-Hydraulic (Pressure), Fluid-Gaseous (specific Enthalpy)

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29

Name an on-board system and the type of power it consumes

On-Board lights, electrical

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30

What is the viscosity of a fluid?

Represents the fluids resistance to flow

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31

What is dynamic viscosity?

Measure of a fluids resistance to flow when an external force is applied to it

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32

What is kinematic viscosity?

Dynamic viscosity per unit density

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33

What is vapour pressure?

a measure of the volatility of a liquid

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34

What is the 'Flash point' of hydraulic fluid or fuel?

the lowest temperature where a fluid evaporates enough to burn if ignited

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35

What is 'Auto-ignition point'?

the lowest temperature when flame is generated in presence of air, with no external ignition.

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36

What is compressibility of fluid

the property of a fluid to change volume when subjected to changing pressure

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37

What is the bulk modulus? (give the unit)

a measure of compressibility, Psi

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38

What is 'effective bulk modulus?'

Bulk modulus that considers gas in the system

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39

Define Pascal's Principle

pressure change in one part is transmitted without loss to every portion of the fluid and to the walls of the container

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40

What is the 'pressure drop' phenomenon?

when a fluid flows in a pipe of constant section and height, with no exchange of energy with the external world, it anyway decreases its pressure

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41

What is Reynolds number?

a dimensionless number used in fluid mechanics to indicate whether fluid flow past a body or in a duct is steady or turbulent

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42

What is the 'hydraulic diameter'?

the cross-sectional area of the channel divided by the wetted perimeter

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43

For turbulent flow, friction coefficient is a function of which parameter?

mean flow velocity

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44

What is the 'loss coefficient'?

measures the minor loss to the change in velocity due to friction through pipes, fittings, and valves

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45

What is the purpose of hydraulic systems?

Transformation, distribution and utilization of mechanical energy through the use of incompressible fluid at high pressures

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46

What type of hydraulic device generates and maintains pressure inside hydraulic system?

pumps, valves, hydro-accumulators

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47

What are the main positive aspects of Hydraulic Systems? (3 points)

high efficiency of the power transmission, ability to withstand overloads without damage, high reliability

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48

Which aircraft systems are powered by hydraulics? (2 examples)

Flight controls, Airbrakes

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49

What are the advantages of high pressure hydraulic installations?

smaller size of actuator/cylinders for the same level of power/force required, less weight

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50

Which types of pump works on fluid-dynamic principle? (2 examples)

centrifugal, axial

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51

Which type of volumetric-positive displacement pump you know? (2 examples)

rotary, reciprocating

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52

What is the required number of pistons for smooth operation of piston pump? (numerical range)

7-9

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53

How operating pressure affects the flow capacity of positive displacement pumps?

Flow rate decreases due to loss of volumetric efficiency as the pressure increases (variation is small)

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54

Why should we keep pressure constant in hydraulic systems?

the system control is based on regulating the constant pressure in the installation

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55

What are the methods of flow regulation for volumetric pumps?

Pump with constant delivery with a regulator valve, Pump with variable flow delivery

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56

What is the purpose of piping in on-board aerospace hydraulic systems?

Distribution of flow and pressure

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57

What is the role of hydraulic accumulator?

short emergency operation, damping of pressure fluctuations

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58

What types of hydraulic accumulator you know?

Spring, Direct gas-fluid, gas-piston, gas-diaphragm, gas-bladder

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59

Name two types of hydraulic actuators?

Spring, gas-piston

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60

What is purpose of heat exchanger in hydraulic system?

control temperature, and therefore viscosity

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61

What is function of relief valve?

control pressure in a system

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62

What is function of check valve?

Prevent backflow

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63

What is purpose of hydraulic distributor?

Regulate the flow of a fluid

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64

Which on-board systems use pneumatics? (2 examples)

Air conditioning, defrosting

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65

What is the main source of air for pneumatics, and where it comes from?

Bleed air (air from jet engine)

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66

What is purpose of a compressor, explain how compressor works?

Transforms mechanical energy into potential energy (air pressure). Uses kinetic energy of the rotor to slow the flow of a fluid and therefore increase pressure

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67

What is purpose of a turbine, explain how turbine works?

extracts energy from fluid flow and converts it into useful work. airflow moves the turbine blades which transfers energy to a rotor

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68

How should we start a main aircraft jet-engine with pneumatic system?

with a burst of compressed air on the jet-engine turbine

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69

What is purpose of wheels in lending gear assembly?

Support for the tire, connections for bearings axle and brakes

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70

What is purpose of brakes in wheel assembly, and how they function?

Provide slowdown and stopping of the aircraft during landing and taxiing

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71

What type of brakes you know? (2 types)

Drum brakes, disc brakes

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72

What are the main components of Disk Brakes?

Rotor disc, Stator disc

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73

How disk brakes functioning?

The brakes act by introducing a friction torque which tends to slowdown the rotation of the wheel

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74

What materials are used for making disk brakes rotors and stators?

combination of steel and composite carbon base materials

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75

How brakes Anti-Blocking System (ABS) works on aircraft?

avoid wheel locking by modulating the braking system pressure

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76

What are the main parameters we should know in order to estimate how much airplane kinetic energy on lending is dissipated by the brakes?

riving torque, brake torque, tangential or horizontal force on the ground, friction torque

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77

Which aircraft systems use the electrical power as the energy source?

Navigation instruments, cabin lighting, navigation lights, anti-ice protection

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78

What are the electrical power sources on board of the aircraft? (6 sources)

Main aircraft engines, A.P.U, connection with ground network, Pneumatic engines, R.A.T, batteries

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79

How we can convert AC to DC?

AC to DC conversion with Transformer Rectifying Unit TRU

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80

How we can convert DC to AC?

DC to AC conversion with static inverters

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81

How we can store electrical power on board of the aircraft?

Batteries

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82

What types of the batteries you know? (4 types)

Pd, Ni-Cd, Ag-Zn, Li-Ion

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83

How we can prevent electrostatic charges to damage the aircraft? (3 points)

establish electrical continuity between all the external structural elements of the aircraft, introduce electrical charge sinks, aircraft grounding at landing

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84

What is stands for "Ram Air Turbine"?

a small turbine that is installed in an aircraft and used as an alternate or emergency hydraulic or electrical power source

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85

Name one component of Aircraft Electrical System: Generation

Stator

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86

Name one component of Aircraft Electrical System: Regulation

Alternator

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87

Name one component of Aircraft Electrical System: Distribution

Cabling

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88

Name one component of Aircraft Electrical System: Auxiliary Systems

Terminals

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89

Name one component of Aircraft Electrical System: Utilization

Switches

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90

What is the voltage + frequency of AC current used on aircraft?

115/270V, 400Hz or variable

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91

What is the voltage of DC current used on aircraft?

28V

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92

What does IDG stand for?

Intergraded drive generator

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93

Name the flight control surface required to produce pitch

Elevators

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94

Name the flight control surface required to produce yaw

Rudder

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95

Name the flight control surface required to produce roll

Ailerons

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96

What are the Primary Flight controls?

Control of aircraft movement around the principal axes of inertia

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97

What are the Secondary Flight controls?

Flaps, spoilers, airbrake, engine control-thrust reversers, landing gear extraction-retraction

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98

Which combination of the control surfaces represents: Elevon?

Elevator, Aileron

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99

Which combination of the control surfaces represents: Flaperon?

flaps, ailerons

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100

Which combination of the control surfaces represents: Taileron?

Elevator+ Aileron on tail

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