- Profile Drag = Skin friction + Form Drag
Skin Friction – Stickiness or skin friction of air due to its viscosity as it passes over the surface of the wing and other pars of the aircraft.
Form Drag is due to the shape of aircraft.
Profile drag is directly proportional to the square of the speed and parallel to the direction or the motion of the wing as relative airflow.
- Parasite Drag – Parasite drag is due to the non-lift contributing aircraft parts i.e., landing gear, fuselage etc.
Parasite drag is directly proportioned to the square of the speed and parallel to the direction of motion of a/c or relative airflow.
- Induced Drag – Induced drag is the price we pay for the lift. Induced drag is a direct result of the force resulting from the downward velocity imparted to air.
Induced Drag is a part of lift, value vanes with lift created by the wing.
Induced Drag increases as AOA increases and decreases as AOA decreases, therefore, Induced Drag increases as airspeed decreases and decreases as airspeed increases.
Induced Drag is less than 10% of total drag at high speeds, 20% during climbing and 70% during Take Off.
Induced Drag is inversely proportional to the square of the speed and parallel to the direction of the motion of the wing or the relative airflow.
Boundary layer is the laminar flow of air over the skin of the airfoil.