12.6 Basic Aerodynamic Theory

12.6.2 Describe what an aerofoil is and distinguish between different aerofoil designs.

An aerofoil is a shape that is designed to produce lift when it moves through a fluid, such as air.

12.6.4 Define:

(a) leading edge;

• is the forward-facing edge that meets the oncoming airflow.

(b) trailing edge;

• the rear of the aerofoil where the upper and lower surfaces meet.

(c) chord;

• is the length measured along the chord line between the leading edge and the trailing edge of an aerofoil.

(d) chord line;

• is a theoretical straight line drawn from the leading edge to the trailing edge of the aerofoil.

(e) thickness;

• is the distance between the upper and lower surfaces of the aerofoil.
• measured perpendicular to the chord line.

(f) camber.

• The amount of curvature of an aerofoil.
• The greater the curvature, the greater the camber. 
• Camber is a direct measure of an aerofoils coefficient of lift (CL).

• High camber aerofoils
  • high lift, low airspeed aircraft
  • eg. Fletcher/Cresco crop duster 
   

• Medium camber aerofoils
  • light training aircraft
  • eg. Cessna 152
   

• Low camber aerofoils
  • high airspeed aircraft
  • eg. F-16 Fighter Jet
   

12.6.6 Define relative airflow and angle of attack.