Chapter 2.1 - Wings, Lift & Drag Flashcards
Name the 4 Aerodynamic forces?
- Lift.
- Weight.
- Thrust.
- Drag.
How does a pilot achieve Straight Level Flight?
- Thrust must balance Drag.
- Lift must balance Weight.
The Lift force acts through what part of an Aircraft?
Centre of Pressure (CP).
The Weight force acts through what part of an Aircraft?
Centre of Gravity (CG).
How is Relative Airflow defined?
The speed and direction of air movement past a wing.
What is an Aerofoil?
The curvature of a Wing on both Top and Bottom surfaces.
How do you define a Wing Span?
The distance from Wingtip to Wingtip of an Aircraft.
What is the forward part of a wing called?
The Leading Edge.
What is the back part of a wing called?
The Trailing Edge.
What is a Chord Line
The length between the leading and trailing edge of a Wing.
What is the Mean Camber Line?
An imaginary line equal distance between the upper and lower surfaces of a wing.
What is Camber?
Camber is the curvature of a Wing.
The greater Camber a Wing has, the more what can be produced?
Lift.
With a Camber fixed in place by the aircraft manufacture, what can be used to further increase the Camber of a wing?
Flaps.
What percentage of Camber do light training aircraft have?
2% to 4%.
As well as Camber what other wing characteristics is an important factor in Lift?
Wing Thickness.
What percentage of wing thickness do light training aircraft have?
10% - 15%.
What is Angle of Attack?
The angle between relative airflow and the chord line of a wing.
How can a pilot change the angle of attack?
By raising / lowering the nose of the aircraft.
True or False the Angle of Attack is measured between Chord Line and Horizon?
False.
What is CP?
Centre of Pressure. A point on the Chord Line of a wing through which both Lift and Drag force act upon.
The CP is at most forward when the Angle of Attack is at what degree?
16.
What is Static Pressure?
Pressure of the air at a point.
What’s the average value of Static Pressure at MSL?
1013 hPa (Hectopascals).
Static Pressure decreases when Altitude is what?
Increased.
What is Dynamic Pressure?
The extra pressure caused by movement of air.
What is Total Pressure?
The sum of Static and Dynamic Pressure.
What factor can affect Dynamic Pressure?
Air Density.
What changes have an effect on the density of the air?
- Temperature.
- Static Pressure.
At what altitude will the density of the air be half at sea level value?
23,500 feet.
What does IAS stand for?
Indicated Airspeed (in knots).
What does CAS stand for?
Calibrated Airspeed.
What does TAS stand for?
True Airspeed. The real airspeed of the aircraft through air.
What does GS stand for?
Groundspeed.
CAS is the IAS corrected from what errors (2)?
- Instrument Error.
- Position Error.
At sea level TAS and IAS will be equal. However, as an Aircraft climbs, value will change, why is this?
Due to Air Density.
TAS and GS are the same if which factor isn’t taken into account?
Wind.
Name 3 direct control a pilot has when producing lift?
- Airspeed.
- Angle of Attack.
- Shape of Wing (Flaps).
Raising the nose and angle of attack does what to Lift?
Increases Lift force.
Lowering the nose and angle of attack does what to Lift?
Decreases Lift force.
The Angle of Attack for Maximum Lift is also known as what?
The Stalling Angle.
Increasing Airspeed does what to the Lift force?
Increases Lift force.
Decreasing Airspeed does what to the Lift force?
Decreases Lift force.
There is a minimum Airspeed at which a Pilot cannot decrease without losing control of the Aircraft. What is this speed called?
Stall Speed.
Raising the Flaps does what to Lift?
Decreases Lift force.
Lowering the Flaps does what to Lift?
Increases Lift force.
Raising the nose and angle of attack does what to the Drag force?
Increases Drag force.
Lowering the nose and angle of attack does what to the Drag force?
Decreases Drag force.
Increasing Airspeed does what to Drag?
Increases Drag force.
Decreasing Airspeed does what to Drag?
Decreases Drag force.
Raising the Flaps does what to Drag?
Decreases Drag force.
Lowering the Flaps does what to Drag?
Increases Drag force.
In Straight and Level Flight, if a pilot wants to increase Airspeed, what must happen to Angle of Attack?
The Angle of Attack must be decreased to maintain Straight and Level Flight.
In Straight and Level Flight, if a pilot wants to decrease Airspeed, what must happen to Angle of Attack?
The Angle of Attack must be increased to maintain Straight and Level Flight.
Name two types of Drag?
- Induced Drag.
- Parasite Drag.
Parasite Drag consists of what (3)?
- Skin Friction.
- Form (Fuselage).
- Interference Drag.
Induced Drag is produced from what component of the aircraft?
Wings.
What are Wingtip Vortices?
Spirals of air trailing from each wingtip.
True or False. Wingtip vortices are only produced if the wing is at an Angle of Attack with lift being produced?
True.
Low airspeed which require high angles of attack produces what?
High Induced Drag.
High airspeed which require low angles of attack produce what?
Low Induced Drag.
What is Skin Friction?
The movement of air against the surface of an aircraft.
What is Boundary Layer?
Air around the surface of an aircraft.
Name 4 variables factors that impact Skin Friction?
- Total Surface Area of an aircraft.
- Degree of Roughness of the Skin.
- Type of Aerofoil.
- Indicated Airspeed.
Which factor of Skin Friction can be controlled by the pilot?
Airspeed.
What happens to Skin Friction Drag when the airspeed increases?
Increases.
What is Form Drag?
The result of the Boundary Layer producing an invisible turbulent wake.
Name 4 variables that impact the size of Form Drag?
- Frontal area of Wings.
- Frontal area of Fuselage.
- Angle of Attack.
- Degree of Streamlining.
Turbulent Wake is Low when?
- Angle of Attack is Low.
- Airspeed is High.
Turbulent Wake is High when?
- Angle of Attack is High.
- Airspeed is Low.
What affect does Streamlining have on an Aircraft?
Reduces Form Drag.
What is Interference Drag?
Drag produced by the mixing of airflow from various surface areas (such as Wings and Fuselage and/or the Fin and Tailplane).
How can Interference Drag be reduced (2)?
- Use of Fairings and Fillets (smoothing the joints between surfaces).
- Streamlining.
What is the Total Drag Curve Graph?
A graph showing the variation of Total Drag with Airspeed/Angle of Attack combinations.
The optimum speed for the Wings to produce Lift that is most efficient is called what?
Speed for Minimum Drag.
How can a Pilot minimise the Total Drag being produced (2/3)?
- Keeping the Aircraft clean (less skin friction).
- Keeping Flaps retracted.
- Landing Gear retracted (if fitted).
What Angle of Attack is best for L/D Ratio?
4 degrees.
The Indicated Airspeed for Maximum L/D Ratio is also the best speed for (3)?
- Speed for Minimum Drag.
- Speed for Maximum Cruise Range.
- Best Glide Speed.
Fuel efficiency is achieved by having what?
Minimum Parasite Drag.
Better Lift is achieved by having what?
Minimum Total Drag.