Principles of flight

Question 1

Formula % power efficiency of an engine

Answer 1

(Power output divide power input) x 100

Question 2

How can the power output of a turbo prop engine be expressed?

Answer 2

Propeller thrust x TAS

Question 3

How can the power input of a turbo-prop engine be expressed?

Answer 3

Torque x propeller RPM

Question 4

How does the efficiency of a turbo-prop vary with speed?

Answer 4

Increases rapidly at low speed, falls to zero at high speeds

Question 5

How do you increase the solidity of a propeller?

Answer 5

Increase the number of prop blades

Question 6

What does increasing the solidity of a prop achieve?

Answer 6

Absorbs extra torque available from a more powerful engine and converts it to extra thrust

Question 7

What design features of a prop blade mitigate against the adverse effects of compressibility due to high speeds at the prop tips

Answer 7

Broader chord to reduce blade aspect ratio and curved blades increasing sweep at the trips

Question 8

What is the benefit of counter-rotating props?

Answer 8

It mitigates any swing caused by asymmetric blade effect

Question 9

Formula tubo-jet thrust

Answer 9

M x (Ve - Vi)

Mass x (Velocity Exhaust - Velocity Intake)

Question 10

Formula turbo-jet power

Answer 10

M x (Ve - Vi) x TAS

Mass x (Velocity Exhaust - Velocity Intake) x TAS

Question 11

How does the efficiency of a turbo-jet vary with speed?

Answer 11

Increases slowly at low speed but the efficiency continues to increase into the supersonic speed range

Question 12

How much fuel energyis water producing heat rather than thrust in a turbo-jet engine?

Answer 12

75%

Question 13

How can a turbo-jet enhance its thrust without overheating the turbine stages?

Answer 13

Using afterburner/reheat increase exhaust velocity

Question 14

How does a turbo-fan produce more thrust without increasing combustion temperature?

Answer 14

Uses mechanical energy from an additional turbine stage to drive fan stage, increasing by-pass mass flow to produce more thrust

Question 15

How does efficiency of a turbo-fan engine vary with speed?

Answer 15

Increased by-pass thrust means efficiency increases quickly even at low speed. Efficiency will decrease at supersonic due to drag from fan

Question 16

Immediate and secondary effects of asymmetric thrust?
Which way will the sideslip indicator move?

Answer 16

I - Yaw towards dead engine
S - Roll towards dead engine
SSI - Towards the live engine

Question 17

Would X make asymmetric control more or less difficult
Higher speed
Max thrust
Loss of a critical engine

Answer 17

Higher speed - Less difficult
Max thrust - More difficult
Loss of a critical engine - More difficult

Question 18

Method of regaining control in the event of an asymmetric engine failure…
Below V1
After T/O

Answer 18

Below V1 - Reduce all thrust to idle
After T/O - Maintain wings level and stop yaw with rudder

Question 19

At or near VMCA, how do you prevent yaw if full rudder already applied?

Answer 19

Up to 5 degrees of bank towards live engine

Question 20

V? - Min speed maintain directional control on runway, by rudder alone.

Answer 20

VMCG

Question 21

CIC, TDT, RAF

Answer 21

Control - Identify - Confirm
Thrust - Drag - Trim
MIs
Radio - ATO Cx - FRCs

Question 22

Phenom VMCA

Answer 22

Minimum control speed - 97kts IAS

Question 23

Below what speed does air behave like an incompressible fluid

Answer 23

250-300kts

Question 24

How is mach number calculated?

Answer 24

Ratio of TAS over local speed of sound

Question 25

MFS

Answer 25

Mach free stream - Mach no. of airflow past aircraft unaffected by its passage

Question 26

ML

Answer 26

Local mach number- Mach no. of airflow over the a/c measured at a localised point

Question 27

MCRIT

Answer 27

Critical mach no. - Speed at which first area of aircraft hits mach 1

Question 28

What happens at MCRIT

Answer 28

Shockwaves begin to form

Question 29

MDET

Answer 29

Mach detachment no. End of transonic flight and beginning of true supersonic

Question 30

When a/c approaches mach 1, centre of pressure moves rearwards causing an increasing nose down pitch force, this is known as?

Answer 30

Mach tuck

Question 31

On large multi engine a/c what is the solution to mach tuck

Answer 31

All flying tail plane

Question 32

How do we delay formation of shockwaves?

Answer 32

Thin wings, swept wings, area ruling, supercritical wings

Question 33

Disadvantageous of thin wings

Answer 33

Poor lift at low speed, difficult to incorporate ancillaries, structural integrity

Question 34

In a/c design, what ensures a smooth change in cross-sectional area from nose to tail?

Answer 34

Area ruling

Question 35

Name of altitude where MMO and aerodynamic stalling speed converge called?

Answer 35

The buffet boundary

Question 36

Dutch roll occurs when

Answer 36

Strong lateral stability, weak directional stability