Lift Force Formula |
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\( L \;=\; \dfrac{1}{2} \cdot C_l \cdot \rho \cdot v^2 \cdot A \) (Lift Force) \( C_l \;=\; \dfrac{ 2 \cdot L }{ \rho \cdot v^2 \cdot A } \) \( \rho \;=\; \dfrac{ 2 \cdot L }{ C_l \cdot v^2 \cdot A } \) \( v \;=\; \sqrt{ \dfrac{ 2 \cdot L }{ C_l \cdot \rho \cdot A } }\) \( A \;=\; \dfrac{ 2 \cdot L }{ C_l \cdot \rho \cdot v^2 } \) |
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| Symbol | English | Metric |
| \( L \) = Lift Force | \( lbf \) | \(N\) |
| \( C_l \) = Lift Coefficient | \( dimensionless \) | \( dimensionless \) |
| \( \rho \) (Greek symbol rho) = Air Density | \(lbm \;/\; ft^3\) | \(kg \;/\; m^3\) |
| \( v \) = Air Velocity Related to Wing | \(ft \;/\; sec\) | \(m \;/\; s\) |
| \( A \) = Lift Surface Area | \( ft^2 \) | \( m^2 \) |
Lift force, abbreviated as\( \)L, also called lift, for an body moving through a fluid (gas or liquid) or air, is the force exerted perpendicular to the direction of travel. It's a fundamental aerodynamic phenomenon that describes the force exerted on an object (such as an aircraft wing or a rotor blade) perpendicular to the direction of an oncoming fluid flow, typically air. Lift is what allows aircraft to generate upward motion and counteract the force of gravity.
Lift is primarily generated due to differences in air pressure on the upper and lower surfaces of a wing or airfoil. When an airfoil moves through the air at a non-zero angle of attack (the angle between the chord line of the airfoil and the oncoming airflow), it causes the air to flow over and under the airfoil, creating different pressure distributions.
The Bernoulli's principle, which relates the speed of a fluid flow to its pressure, helps explain the lift generation. As the air moves faster over the curved upper surface of the airfoil, its pressure decreases. Meanwhile, the slower-moving air beneath the airfoil has higher pressure. This pressure difference results in an upward force, perpendicular to the direction of the airflow, known as lift.
