C11 - Aircraft Drag Flashcards
What is Total Drag (2)?
- Induced Drag.
- Parasite Drag.
What is Parasite Drag (3)?
- Form Drag.
- Skin Friction Drag.
- Interference Drag.
What is Profile Drag (2)?
- Form Drag.
- Skin Friction Drag.
Define Form Drag?
Rearwards acting force as a result from the shape of an Aerofoil.
Define Skin Friction Drag?
Drag caused directly from the Boundary Layer.
Define Interference Drag?
Generated by the mixing of Airflow between components of an Aircraft.
Define Induced Drag?
Caused by the production of Lift.
True or False. Airspeed and Drag are proportionate to each other?
True. The faster the Airspeed, the greater the Drag force.
‘____’ affects both the magnitude of the surface pressure and the cross-section that it acts over.
Streamlining.
The width of the wake is ‘____’ for streamlined objects because the separation point occurs further to the ‘____’ (2)?
- Smaller.
- Rear.
How is Form Drag affected by Streamlining (2)?
- The amount of streamlining aft of the point of maximum thickness.
- The Kinetic Energy of the Boundary Layer.
True or False. The Kinetic Energy of the Boundary Layer is affected by the surface conditions?
True.
Smooth surface supports ‘____’ Boundary Layer further across its surface?
Laminar.
Rough surface has a ‘____’ Boundary Layer which produces ‘____’ (2)?
- Turbulent.
- More Drag.
Name the size of wake depending on surface conditions (2)?
- Smooth Surface = Wide Wake.
- Rough Surface = Narrow Wake.
Name four factors affecting Skin Friction Drag?
- Speed.
- Surface Area.
- Boundary Layer.
- Surface Roughness.
How does Speed affect Skin Friction Drag?
The faster the airflow, the greater the Skin Friction Drag. Speed and Skin Friction are proportionate.
How does Surface Area affect Skin Friction Drag?
The larger the Surface Area, the larger the Boundary Layer/ Surface Area and Skin Friction are proportionate.
How does Boundary Layer Conditions affect Skin Friction Drag?
Turbulent Boundary Layer causes more Skin Friction Drag than a Laminar Boundary Layer.
How does Surface Roughness affect Skin Friction Drag?
A rough surface increases the depth of the Boundary Layer.
How can an Aircraft keep Skin Friction Drag to a minimum?
By keeping the Aircraft smooth, clean and free from dirt and ice.
How can an Aircraft reduce the amount of Interference Drag?
Introducing fillets and fairing the places where Interference Drag is greatest.
True or False. Parasite increases as the square of the speed?
True.
Parasite Drag is ‘____’ to V²?
Proportional.
Name two parts of the Aircraft which increases Frontal Area and Parasite Drag?
- Landing Gear.
- Flaps.
What is the Parasite Drag Equation?
½ pV² x S x Cdp.
What is Cdp?
Coefficient of Parasite Drag.
True or False. The Parasite Drag is not proportional to the Airspeed squared?
False.
True or False. The Parasite Drag is not proportional to the Aircraft’s Surface?
False.
True or False. The Parasite Drag is proportional to the Coefficient of Parasite Drag?
True.
Name two causes of Induced Drag?
- Vortices.
- Downwash.
Name three primary influences on Induced Drag?
- Speed.
- Weight.
- Manoeuvre.
How does Speed affect Induced Drag (2)?
- The higher the speed, the smaller the Vortices, the less Induced Drag.
- The slower the speed, the larger the Vortices, the more Induced Drag.
Induced Drag is ‘____’ to IAS²?
Inversely Proportional.
Induced Drag is ‘____’ to Aspect Ratio?
Inversely Proportional.
What is the Induced Drag formula?
½ pV² x S x Cdi.
What is Cdi?
Coefficient of Induced Drag.
Coefficient of Induced Drag is ‘____’ proportional to Aspect Ratio and ‘____’ proportional to the Coefficient of Lift Squared (2)?
- Indirectly.
- Directly.
When Speed ‘____’, the Induced Drag increases?
Decreases.
Name three components which can reduce Induced Drag?
- Winglets.
- End-plates.
- Wingtip Fuel Tanks.
