Lift Formula

Understanding Lift

• Lift: A force that enables an aircraft to rise off the ground.

• Lift Formula: A mathematical representation of the lift force that relates the various parameters affecting lift.

Wing and Air Characteristics

• Mean Camber Line:

  • The precise center of the wing's thickness when sliced in half.

  • Matches the top and bottom slices of the wing.

• Leading Edge:

  • The point where the mean camber line meets the front end of the wing.

• Trailing Edge:

  • The point where the mean camber line meets the rear end of the wing.

• Chord Line:

  • A straight line joining the leading edge and trailing edge.

• Relative Airflow:

  • The direction of the air movement relative to the wing.

• Angle of Attack:

  • The angle between the chord line and relative airflow.

• Airspeed:

  • The speed at which the aircraft flies through the air.

• Wing Surface Area (S):

  • The projected area of the wing.

• Air Density (Rho):

  • The mass of air molecules within a specific volume; higher density indicates more air molecules present.

The Lift Formula

• Lift Formula: L = Cl1/2ρV^2S

  • L: Lift force

  • Cl: Coefficient of Lift

  • Rho(ρ): Air Density

  • V: Airspeed

  • S: Wing Surface Area

• Lift (L):

  • The force created by the wing's movement through air.

• Coefficient of Lift (Cl):

  • Represents how much lift the wing can produce at any position of the angle of attack; determined during wing design.

• Key Variables:

  • Angle of Attack: A key component affecting the coefficient of lift, easily controlled by the pilot.

  • Air Density (Rho aka ρ): Related to lift, defined as the mass of air per volume.

  • Airspeed (V): Refers to how fast the aircraft moves through the air, impact on lift.

  • Wing Surface Area (S): Larger surface areas can generate more lift.

Relationship between Parameters

• Formula indicates the interconnected nature of airspeed and angle of attack in maintaining consistent lift.

  • For constant lift:

    • Increased airspeed requires a decrease in angle of attack.

    • Decreased airspeed requires an increase in angle of attack.

Example Scenario

• Two aircraft producing the same amount of lift while maintaining level flight:

  • Top Aircraft:

    • Higher angle of attack, slower airspeed.

  • Bottom Aircraft:

    • Lower angle of attack, faster airspeed.

  • This comparison illustrates how adjustments in angle of attack and airspeed can maintain the same lift force.