Fundamentlas

Question 1

What is windmilling

Answer 1

Airspeed turns propeller and turns engine with a negative AoA & torque value

Question 2

As angle of attack changes what else does

Answer 2

Thrust produced

Question 3

What’s the window for efficiency for angle of attack

Answer 3

Small

Question 4

What happens when brake moments become large

Answer 4

Blade angle moved into reverse pitch

Question 5

Where is leading edge in feathered position

Answer 5

Presented into oncoming airflow

Question 6

What direction does partial force work in

Answer 6

Direction of rotation and drives propeller

Question 7

What drag increases in windmilling propeller

Answer 7

Increases aircraft drag considerably

Question 8

What position reduces increased aircraft drag

Answer 8

Feathered

Question 9

What is slip

Answer 9

Geometric pitch minus effective pitch

Question 10

How is slip given

Answer 10

% of geometric pitch

Question 11

What is bottom of the blade called

Answer 11

Butt

Question 12

How does aerofoil produce lift

Answer 12

aerodynamic action

Question 13

What happens to AoA during constant pitch

Answer 13

Decreases and becomes negative due to an airspeed increase or decrease in rotational speed

Question 14

Is damage permitted in the blade root area

Answer 14

No damage or repair work

Question 15

What makes decibel levels go down

Answer 15

As blades are added

Question 16

What does a propeller do

Answer 16

Convert engine torque into thrust

Question 17

What does a propeller accelerate

Answer 17

Large mass of air slowly rearwards

Question 18

When is turboprop most effective

Answer 18

Low speed (subsonic region)

Question 19

What is plane angle perpendicular to

Answer 19

Engine

Question 20

What is blade angle

Answer 20

Angle between chord line and plane of rotation

Question 21

AoA + what = blade angle

Answer 21

Helix angle

Question 22

In a fixed pitch propeller what is blade angle

Answer 22

Angle of incidence

Question 23

Where is blade angle measured from

Answer 23

Blade face

Question 24

What % of prop radius is blade reference station for blade angle

Answer 24

50-75%

Question 25

What is Angle of attack (AoA)

Answer 25

Angle between profile chord line and relative airflow

Question 26

What do you add to make RAF ( relative airflow )

Answer 26

Vector of airspeed velocity + propeller rotational velocity

Question 27

What does increase airspeed do to helix angle and AoA

Answer 27

Helix angle increases & AoA decreases

Question 28

What is a fixed pitch propeller limited to

Answer 28

Good take off/climb & cruise Also towing

Question 29

What does an increase in propeller rpm do to helix angle and AoA

Answer 29

Decrease helix angle & increase AoA (for more thrust)

Question 30

At constant speed what is the sum of propeller break moment & engine torque

Answer 30

Zero

Question 31

At a constant pitch what happens in regards to airspeed and AoA

Answer 31

Airspeed increase or rotational speed decreases while AoA will decrease and be negative

Question 32

How does root loses occur

Answer 32

It is rounded for strength which causes loses in aerodynamic efficiency

Question 33

What cases tip loses

Answer 33

Tip vortices and induced drag at high rotational speeds and compressibility effect

Question 34

What does washout do

Answer 34

Maintains constant AoA at different rotational speeds along blade

Question 35

How is the leading edge twisted for washout

Answer 35

Downwards from root to tip

Question 36

What is pitch distribution

Answer 36

Blade angle is smaller the further away for centre axis which keeps constant AoA

Question 37

What is geometric pitch

Answer 37

Blade angle = pitch , in one rotation propeller moved forward axial by geometric pitch

Question 38

What is effective pitch

Answer 38

1 revolution the aircraft moves forward by effective pitch

Question 39

What is propeller thrust related to

Answer 39

Engine output power

Question 40

What is normal propeller efficiency range

Answer 40

80-90%

Question 41

What angle is aerodynamic twist moment

Answer 41

High blade angle

Question 42

What angle is centrifugal twist movement

Answer 42

Low blade angle

Question 43

What are 2 causes of vibration

Answer 43

Engine and gearbox & aerodynamic loads

Question 44

What’s the effect of vibration

Answer 44

Structural failure

Question 45

How is vibration reduced

Answer 45

aerofoil and tip design being correct

Question 46

Where are highest vibration loads felt

Answer 46

80% of blade length

Question 47

What’s the most attractive way to have the best power absorption

Answer 47

Increase number of blades

Question 48

How do aircraft wings compensate for roll

Answer 48

Generate more lift on the downside

Question 49

When is twist effect compensated and what for

Answer 49

Cruise speed & compensate for yaw

Question 50

How is yaw compensated

Answer 50

Vertical stabiliser mounted obliquely 1 degree or 2 to longitudinal axis

Question 51

When does a spiralling rotation to slipstream occur

Answer 51

High rotational speed of aircraft propeller

Question 52

How does pilot compensate for gyroscopic effect

Answer 52

Rudder and elevator offset at takeoff

Question 53

what is the critical engine

Answer 53

Engine that creates smaller yaw moment should the other engine fail

Question 54

What does the propeller do if the critical engine fails

Answer 54

Propellers turn both inboard downwards (opposite direction) to decrease yaw moment

Question 55

How do we reduce decibel levels on a propeller

Answer 55

Add more blades