Indicates a downward vertical aerodynamic force. This would typically represent the aircraft’s weight, which acts vertically downward due to gravity.
- Z: This represents the vertical aerodynamic force acting on the aircraft. It can be either positive (upward) or negative (downward) depending on the sign convention used. In this equation, it’s treated as negative, indicating that it acts downward.
- ρ: This is the air density at the altitude where the aircraft is flying. It is typically measured in kilograms per cubic meter (kg/m³).
- u₀: This is the freestream airspeed or velocity of the aircraft. It represents the speed at which the aircraft is traveling through the air and is typically measured in meters per second (m/s).
- S: This represents the reference wing area. It is the effective frontal area of the wings, which is important for calculating lift. It is typically measured in square meters (m²).
- Cl: This is the lift coefficient. It quantifies the lift generated by the aircraft’s wings for a given angle of attack. It’s a dimensionless parameter that depends on the wing’s shape, angle of attack, and other factors.
- Δu: This represents the deviation or variation in airspeed (velocity) from the freestream airspeed u₀. It’s typically used to account for changes in airspeed due to dynamic conditions and is measured in meters per second (m/s).