# Estimation of Stability Parameters for Wide Body Aircraft Using Computational Techniques
## 1 Introduction
In order to predict the responses for unsteady and nonlinear flight envelopes in high maneuvering operations, extensions to aerodynamic models need to be incorporated [25]. Due to extreme flight conditions, civil or military aircraft may cross normal operating limits. Therefore, prevention or recovery methods are also required to be incorporated in the aerodynamic model [26]. The development of extensive aerodynamic modeling techniques can fulfill these requirements [19]. Information about identification of model can also be obtained from dynamic test methods [27]. The modeling of rotorcraft aerodynamic interference has proven to be a challenging problem due to the complex flow-field interactions between the rotors and other aircraft subsystems. An effective and efficient aerodynamic simulation tool was proposed by combining a Lagrangian solver [21; 28]. Data obtained from a quick accesses recorder (QAR) is another efficient way to determine the effects of extreme weather conditions [22; 29]. [PERSON] introduced the theory of aerodynamic derivatives in 1911, and it has remained unchanged as the standard pattern for the interpretation of the aerodynamic loads in equations of motion (EOMs). Aerodynamic forces and moments are assumed to be the functions of control angles, disturbance velocity, and rates of control angles. At low angles of attack (AoA) and in slow-moving airplanes, aerodynamic loads can be easily modeled by using static derivatives. However, at high AoA, dynamic derivatives can greatly affect the stability characteristics [30]. The variation in the stability derivative can be taken into account by adding the non-linear terms along with extensions in the range of flight conditions [31]. [PERSON] and [PERSON] [32] developed a procedure to determine the single generic global aerodynamic model structure that could be applicable to various aircraft. The analysis was carried out by applying multivariate-orthogonal-function modeling on wind-tunnel aerodynamic databases of different aircraft over a wide range of angles, rates, and deflections of control surfaces.Drela et al. [33] investigated the aerodynamic benefit from ingestion of boundary layer of a transport aircraft. The power balance method was developed based upon the mechanical power required and streamwise forces acting on the aircraft. The results showed an increase in efficiency of up to 9% at low cruise power conditions. [PERSON] and [PERSON] [34] developed a generic nonlinear aerodynamic model based upon multivariate orthogonal function. The model accurately predicted the global and local dynamic behavior and trim solutions over a range of large amplitude excitations. [PERSON] et al. [35] and [PERSON] et al. [36] performed aerodynamic analysis of an aircraft wing using computational fluid dynamics. The variation of velocity and pressure distribution on the wing was captured by using ANSYS Fluent package. The coefficients of lift and drag were estimated based upon data obtained at different boundary conditions. [PERSON] and [PERSON] [37] provided the guidelines in the design and optimization of transport aircraft. MATLAB algorithm was developed to determine the aerodynamic coefficients. The panel code solver was used to optimize the geometrical shapes. The procedure helped to import and modify geometries by interpolation of curves and surfaces.Nicolosi et al. [38] presented a method to determine the aerodynamic performance of aircraft fuselage. During the study, the contribution of the fuselage to overall stability and its interactions with the wings and tail were investigated. Numerical simulations were carried out based upon CFD techniques and aerodynamic coefficients were estimated. [PERSON] et al. [15] performed the stability analysis of a blended-wing-body aircraft. The static and dynamic stability and flying quality analysis was carried out in a flight envelope by applying aircraft synthesis and integrated optimization methods. The flight envelope was created and the TORNADO program was used to estimate the aerodynamic coefficients of aircraft.