The Coefficient of Lift compares the amount of lift (L) generated by the power source of the aircraft to the dynamic pressure (q)
    and the area of the wing span (A). This equation is listed here:

        C_L = L/( (1/2) ρv^2A )

    C_L - Coefficient of Lift

    L - Lift

    ρ - Density of air

    v - Velocity over airfoil

    q - Dynamic pressure

    This COI (Coefficient of Lift) is a way of expressing how well the plane will perform with a given angle of attack (the angle between the flat ground and the cord of the     airfoil). The better the Coefficient of Lift, the more efficient the plane will fly in terms of speed, how much it will carry and how much fuel it will burn per hour.

    The graph below shows how the coefficient of lift acts as the angle of attack increases for two different planes.
   
   

     As listed on the graph, the two planes are a Cessna 172 and a BAC lightning. The 172 is a plane made for short distances, at a slow rate compared to the Lightning which is made for         supersonic speeds and agility. The Lightning also has a much shorter, more aerodynamic wingspan. It is not coincidence that the Lightning acts mostly linearly than the 172 that shows a     definate point where it reaches optimum efficiency. The more aerodynamic design provides the Lightning with a good performance at all angles of attack.