The Drag Index, also known as the Drag Area Index, is a performance parameter in aircraft design and aviation that quantifies the aerodynamic drag experienced by an aircraft in relation to its size or frontal area. It provides insight into an aircraft’s aerodynamic efficiency, especially in terms of how it encounters air resistance.Formula for Drag Index (DI):
The formula for Drag Index involves calculating the total drag force (Drag) divided by the reference speed (Speed). The formula is as follows:
- Drag Index (DI): A dimensionless parameter representing the aerodynamic drag experienced by the aircraft.
- Drag Force (D): The total drag force experienced by the aircraft during a specific condition or phase of flight, typically measured in newtons (N) or pounds-force (lb).
- Speed (V): The reference speed used for the calculation, which can vary depending on the context (e.g., cruise speed, takeoff speed, etc.). It is usually measured in meters per second (m/s) or knots (kt).