C11 - Aircraft Drag

Question 1

What is Total Drag (2)?

Answer 1

• Induced Drag.

- Parasite Drag.

Question 2

What is Parasite Drag (3)?

Answer 2

• Form Drag.
• Skin Friction Drag.
• Interference Drag.

Question 3

What is Profile Drag (2)?

Answer 3

• Form Drag.

- Skin Friction Drag.

Question 4

Define Form Drag?

Answer 4

Rearwards acting force as a result from the shape of an Aerofoil.

Question 5

Define Skin Friction Drag?

Answer 5

Drag caused directly from the Boundary Layer.

Question 6

Define Interference Drag?

Answer 6

Generated by the mixing of Airflow between components of an Aircraft.

Question 7

Define Induced Drag?

Answer 7

Caused by the production of Lift.

Question 8

True or False. Airspeed and Drag are proportionate to each other?

Answer 8

True. The faster the Airspeed, the greater the Drag force.

Question 9

‘____’ affects both the magnitude of the surface pressure and the cross-section that it acts over.

Answer 9

Streamlining.

Question 10

The width of the wake is ‘____’ for streamlined objects because the separation point occurs further to the ‘____’ (2)?

Answer 10

• Smaller.

- Rear.

Question 11

How is Form Drag affected by Streamlining (2)?

Answer 11

• The amount of streamlining aft of the point of maximum thickness.
• The Kinetic Energy of the Boundary Layer.

Question 12

True or False. The Kinetic Energy of the Boundary Layer is affected by the surface conditions?

Answer 12

True.

Question 13

Smooth surface supports ‘____’ Boundary Layer further across its surface?

Answer 13

Laminar.

Question 14

Rough surface has a ‘____’ Boundary Layer which produces ‘____’ (2)?

Answer 14

• Turbulent.

- More Drag.

Question 15

Name the size of wake depending on surface conditions (2)?

Answer 15

• Smooth Surface = Wide Wake.

- Rough Surface = Narrow Wake.

Question 16

Name four factors affecting Skin Friction Drag?

Answer 16

• Speed.
• Surface Area.
• Boundary Layer.
• Surface Roughness.

Question 17

How does Speed affect Skin Friction Drag?

Answer 17

The faster the airflow, the greater the Skin Friction Drag. Speed and Skin Friction are proportionate.

Question 18

How does Surface Area affect Skin Friction Drag?

Answer 18

The larger the Surface Area, the larger the Boundary Layer/ Surface Area and Skin Friction are proportionate.

Question 19

How does Boundary Layer Conditions affect Skin Friction Drag?

Answer 19

Turbulent Boundary Layer causes more Skin Friction Drag than a Laminar Boundary Layer.

Question 20

How does Surface Roughness affect Skin Friction Drag?

Answer 20

A rough surface increases the depth of the Boundary Layer.

Question 21

How can an Aircraft keep Skin Friction Drag to a minimum?

Answer 21

By keeping the Aircraft smooth, clean and free from dirt and ice.

Question 22

How can an Aircraft reduce the amount of Interference Drag?

Answer 22

Introducing fillets and fairing the places where Interference Drag is greatest.

Question 23

True or False. Parasite increases as the square of the speed?

Answer 23

True.

Question 24

Parasite Drag is ‘____’ to V²?

Answer 24

Proportional.

Question 25

Name two parts of the Aircraft which increases Frontal Area and Parasite Drag?

Answer 25

- Landing Gear. | - Flaps.

Question 26

What is the Parasite Drag Equation?

Answer 26

½ pV² x S x Cdp.

Question 27

What is Cdp?

Answer 27

Coefficient of Parasite Drag.

Question 28

True or False. The Parasite Drag is not proportional to the Airspeed squared?

Answer 28

False.

Question 29

True or False. The Parasite Drag is not proportional to the Aircraft’s Surface?

Answer 29

False.

Question 30

True or False. The Parasite Drag is proportional to the Coefficient of Parasite Drag?

Answer 30

True.

Question 31

Name two causes of Induced Drag?

Answer 31

- Vortices. | - Downwash.

Question 32

Name three primary influences on Induced Drag?

Answer 32

- Speed. - Weight. - Manoeuvre.

Question 33

How does Speed affect Induced Drag (2)?

Answer 33

- The higher the speed, the smaller the Vortices, the less Induced Drag. - The slower the speed, the larger the Vortices, the more Induced Drag.

Question 34

Induced Drag is ‘____’ to IAS²?

Answer 34

Inversely Proportional.

Question 35

Induced Drag is ‘____’ to Aspect Ratio?

Answer 35

Inversely Proportional.

Question 36

What is the Induced Drag formula?

Answer 36

½ pV² x S x Cdi.

Question 37

What is Cdi?

Answer 37

Coefficient of Induced Drag.

Question 38

Coefficient of Induced Drag is ‘____’ proportional to Aspect Ratio and ‘____’ proportional to the Coefficient of Lift Squared (2)?

Answer 38

- Indirectly. | - Directly.

Question 39

When Speed ‘____’, the Induced Drag increases?

Answer 39

Decreases.

Question 40

Name three components which can reduce Induced Drag?

Answer 40

- Winglets. - End-plates. - Wingtip Fuel Tanks.