Application of a modified Newton-Raphson method for estimation of vortex flow parameters

The vortex flow[1,2] in the wake of a large airplane is hazardous to other aircraft, particularly during landing. For the first time, modern methods of parameter identification have been applied to the analysis of vortex flow. Because the identification problem involves parameters which are nonlinearly related, an iterative method is required. A modified Newton-Raphson method3,4 was employed to calculate a maximum likelihood estimate of the unknown parameters. The estimate is related to one which minimizes the mean-square difference between the measured and calculated flow velocities. This iterative procedure had been previously used to determine stability derivatives of airplanes from flight data.4