Showing papers by "Nandan K. Sinha published in 2014"

Aircraft Design Using Constrained Bifurcation and Continuation Method

Abstract: A novel approach for conceptual aircraft design using constrained bifurcation and continuation method is presented in this paper. To demonstrate the approach, vertical tail sizing problem of a generic six seater, light, business transport airplane is addressed here. For sizing the vertical tail, stability analysis of the aircraft lateral-directional modes in straight and level, symmetric flight trims is carried out using constrained bifurcation analysis and continuation methodology. A full six degrees-of-freedom nonlinear mathematical model is used for modeling the rigid body flight dynamics of the aircraft; aerodynamic stability and control derivatives required for stability analysis are estimated using standard empirical relations available in aircraft design textbooks. Effects of center-of gravity change and altitude variation are also incorporated to cover a typical flight envelope for analysis. Stability parameters of lateral-directional modes, as characterized by the corresponding eigenvalues obtained from bifurcation analysis, are examined and compared with flying qualities specifications to arrive at an optimal vertical tail size that meets the handling qualities requirements.

An assessment of thrust vector concepts for twin-engine airplane:

Abstract: Thrust vector nozzles are finding place on modern fighter airplanes because of the benefits they provide and also due to diminishing weight penalty of such nozzles. They offer additional benefits in the case of a twin-engine airplane. Different vectoring configurations such as multi-axis vectoring, single-axis pitch vectoring and single-axis vectoring with canted nozzles have been studied with respect to twin-engine airplane configuration. Modeling and integration of thrust vector nozzles with rigid airplane six-degrees-of-freedom equations of motion have been carried out in this article. Using the integrated model, a comparative study is carried out to summarize the capabilities and limitations of various nozzle configurations with respect to performance of an airplane in velocity vector roll and in Herbst maneuvers. The airplane model used in this work is the F-18/HARV and all simulation results have been produced using a nonlinear dynamic inversion controller developed in Matlab/Simulink environment. Results show that a multi-axis thrust vectoring provides additional benefits as compared to single-axis vectoring with canted nozzles in high angle of attack velocity vector roll and in Herbst maneuvers. The single-axis pitch only vectoring has roll control power and lacks in yaw control power, to execute the velocity vector roll maneuver.

Key factors that affect the performance of flares against a heat-seeking air-to-air missile

Abstract: Deploying flare decoys against heat-seeking threats involves various parameters such as flare timing, flare ejection velocity, direction of ejection and the number of flares used. In this study, an...