Drag

What is Drag?

Drag is the total aerodynamic resistance experienced by an aircraft as it moves through the atmosphere. It always acts in the direction opposite to the aircraft's flight path relative to the airflow.

Components of Drag

Drag is divided into two main categories:

• Parasite Drag: Not related to lift production, arises from moving the aircraft structure through the air. It increases rapidly with speed and includes:
  • Form (Pressure) Drag: Caused by the shape of the aircraft and the pressure difference between the front and rear surfaces.
  • Skin Friction Drag: Results from the friction between air molecules and the aircraft's surface within the boundary layer.
  • Interference Drag: Occurs where different airflow streams meet, such as at wing-fuselage junctions.
• Induced Drag: Directly linked to the production of lift. It is highest at low speeds and high angles of attack, decreasing as speed increases.

Direction of Drag

Drag always acts parallel and opposite to the relative airflow (relative wind). In contrast, lift acts perpendicular to this direction.

Energy Loss and Wake

Drag and the wake behind the aircraft represent a loss of energy (momentum) to the airflow. This energy is dissipated as turbulence and heat, reducing the efficiency of flight.

Minimizing Drag

Aircraft are designed to minimize drag through streamlined shapes and smooth surfaces, improving performance and reducing fuel consumption.