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This article investigates identification of aircraft aerodynamic derivatives. The identification is performed on the basis of the parameters stored by Flight Data Recorder. The problem is solved in time domain by Quad-M Method. Aircraft dynamics is described by a parametric model that is defined in Body-Fixed-Coordinate System. Identification of the aerodynamic derivatives is obtained by Maximum Likelihood Estimation. For finding cost function minimum, Lavenberg-Marquardt Algorithm is used. Additional effects due to process noise are included in the state-space representation. The impact of initial values on the solution is discussed. The presented method was implemented in Matlab R2009b environment.

The prediction of the separation trajectories of the external stores carried out on military aircraft is an important task in the aerodynamic design area having the objective to define the operational, release envelopes.To attain this purpose it was developed technique based on the Nonlinear Panel Method with unsteady free wake formulation to obtain flow field predictions about manoeuvring aircraft -external store configuration just before and during the separation. The comparison with a flight test as well as wind tunnel investigations have proved the reliability of this methodology for many kinds of stores and release envelope investigated. Nevertheless in the flow regimes characterized by non-linear phenomena a more accurate approach is needed.This work consists of concepts and some results solutions for aircraft -external store configuration interference. A Computational Fluid Dynamics (CFD) technique based on Nonlinear Panel Method is the primary goal of the investigation. This methodology applied to significant experimental cases has proved its validity evidencing a further improvement with respect to standard store separation trajectory program procedure. The main emphasis is placed on practical, cost-effective engineering solution of the complex problem with reasonable computational efficiency allowing the computer code to run on PC computers.