With blade element theory, a surface ( e . g . wing ) may be made up of many sections ( 1 to 4 is typical ), and each section is further divided into as many as 10 separate subsections.
22.
His approach lays down the well-known " blade element method " incorporating two-dimensional, non-linear sectional airfoil data from tables, a fundamental engineering approach that even today remains the basis for most helicopter rotor design analyses.
23.
The first one is the thrust coefficient of the rotor, which is the one which should be corrected for high rotor loading ( i . e ., for high values of a ), while the second one ( c _ t ) is the tangential aerodynamic coefficient of an individual blade element, which is given by the aerodynamic lift and drag coefficients.
