The “drag per unit span” () for a diamond-wedge airfoil refers to the aerodynamic force acting parallel to the direction of the oncoming airflow, per unit span length of the airfoil. This force represents the component of aerodynamic resistance that opposes the forward motion of the airfoil through the air.
- Pressure on the top surface (p2) in N/m^2
- Pressure on the bottom surface (p3) in N/m^2
- Airfoil thickness (t) in m
- Drag per unit span (D’) in N/m