15.1 FUNDAMENTALS👌🏼

Question 1

Explain potential energy and formula

Answer 1

• energy at rest/energy that is stored
• PE = mgh

Question 2

Explain kinetic energy and formula

Answer 2

• energy in motion
• KE = 1/2 x mass x velocity^2

Question 3

Newton’s first law

Answer 3

• law of inertia

Question 4

Newton’s second law

Answer 4

• F=ma
• interplay between force and motion
  E.g thrust proportional to mass of airflow through engine x acceleration of air through engine

Question 5

Newton’s third law

Answer 5

• law of action and reaction

Question 6

Explain the Brayton cycle

Answer 6

-thermodynamic cycle of gas turbine engine that produces thrust
- has 4 stages (intake, compression, expansion and exhaust)

Question 7

Explain what occurs at intake (suck)?

Answer 7

• air enters at constant volume.
• Leaves intake at increased pressure and a decrease in volume.

Question 8

Explain compressor (squeeze) ?

Answer 8

• air received from intake at slightly increased pressure, with slight decrease in volume
• air leaves compressor with increased pressure and decrease in volume

Question 9

Explain expansion (bang)?

Answer 9

• takes place in combustion chamber
• pressure remain constant, but marked increase in volume
• expanding gases turn turbine which converts velocity energy to mechanical energy.

Question 10

Explain exhaust (blow) section?

Answer 10

• convergent duct
• converts expanding volume and decreasing pressure of gases to a final high velocity

Question 11

Along the line from 0-2 what change of state occurs

Answer 11

Isentropic compression
Pressure increases, volume decreases

Question 12

Process from 2 to 3 what change of state occurs

Answer 12

Isobaric heating

Question 13

What change of state in lines 3 to 5

Answer 13

Isentropic expansion

Question 14

What occurs from process 0-5

Answer 14

Isobaric heat release into nozzle

Question 15

Formula for force

Answer 15

F = ma

Question 16

What is the formula for work done

Answer 16

W = force x distance

Question 17

Formula for power

Answer 17

• power = Force x distance/time
• power = work/time

Question 18

What is the unit for power

Answer 18

Watt

Question 19

What is 1Nm/s in W

Answer 19

1

Question 20

What is the 1Nm in Joules

Answer 20

1

Question 21

What is the difference between speed and velocity

Answer 21

Speed refers to how fast a object is moving
Velocity refers to speed and direction

Question 22

Explain acceleration

Answer 22

-Rate of change of velocity
-change in velocity (m/s) / time (s)
-m/s^2

Question 23

What are the 2 different types of aircraft engines

Answer 23

• Piston type engines
• Gas turbine engines

Question 24

Which engines performance decrease at higher altitudes

Answer 24

Piston engines

Question 25

Are piston engines or gas type engines more fuel efficient

Answer 25

Piston engines

Question 26

Which engine can operate at very high altitudes

Answer 26

- gas turbines engines

Question 27

Explain turbojet engines

Answer 27

- high aircraft speeds but very loud - has problems with noise and fuel consumption in speed range of 0.8 Mach Pros: simple design, very high speeds Cons: high fuel consumption, loud, poor performance at low speeds

Question 28

Explain turbofan engine

Answer 28

- high aircraft speeds possible with good engine efficiency - produces around 80% thrust - quieter and better fuel consumption

Question 29

Explain a spool arrangement

Answer 29

- consists of a turbine driving a compressor through a shaft

Question 30

Explain twin-spool arrangement?

Answer 30

- high pressure turbine driving the high pressure compressor - low pressure turbine driving the low pressure compressor and fan

Question 31

Explain 3 spool arrangement

Answer 31

- high pressure turbine driving high pressure compressor - Intermediate pressure turbine driving intermediate compressor - low pressure turbine driving the fan

Question 32

Advantages of turbo fan engine

Answer 32

- fuel efficient - quieter - streamlined appearance

Question 33

Disadvantages of turbofan

Answer 33

- heavy - large

Question 34

Explain turboprop engines

Answer 34

- produce shaft horsepower only, which is used to drive propeller - extra turbines - reduction gearbox to drive propeller

Question 35

Advantages of turboprop engine

Answer 35

- very fuel efficient - efficient at mid-range speed and altitude

Question 36

Disadvantages of turboprop engine

Answer 36

- limit forward airspeed - gearing systems are heavy and can break down

Question 37

Explain turboshaft engine

Answer 37

- produces shaft power to drive machinery - requires small, powerful, lightweight engine - e.g. APU supply electric and pneumatic power

Question 38

Advantages of turboshaft engine

Answer 38

- higher power to weight ratio - smaller than piston engines

Question 39

Disadvantages of turboshaft engine

Answer 39

- loud - gear systems are complex and can break down

Question 40

Explain ‘cold section’

Answer 40

Parts of engine from the inlets up through compressors/diffusers

Question 41

Explain ‘hot section’

Answer 41

- refers to ares past the compressors from combustion chamber through exhaust

Question 42

What is the unit of force in the English system measured in

Answer 42

- lbs (pounds)