Determination of Static and Dynamic Stability Derivatives Using Beggar
AIR FORCE INSTITUTE OF TECHNOLOGY WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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The static and dynamic pitch and roll stability derivatives of a finned, axisymmetric missile known as the Basic Finner were examined using a Computational Fluid Dynamics CFD approach. Stability derivatives are used to characterize vehicle motion, and knowledge of them is critical to the design of stable uncontrolled vehicles and control systems for controlled vehicles. Using CFD to characterize the motion of new munition designs has the potential to improve overall performance and reduce research and testing costs. The present analysis simulated forced oscillation and free oscillation of the Basic Finner model using the Air Force SEEK EAGLE Offices Beggar code. The pitch stability derivatives were determined at 0 degrees angle of attack for six Mach numbers from 1.58 to 2.50 and at Mach number equal to 1.96 for angles of attack from 0 to 20 degrees. The parameters defining the motion of the forced oscillation tests were the reduced pitch rate, amplitude, Newton iterations, iterations per oscillation, and total oscillations. Convergence studies on each of these parameters were performed to ensure both convergence and solution independence. Roll stability derivatives were determined through forced, constant rate rolling motion for six Mach numbers from 1.58 to 2.50 at an angle of attack of 0 degrees. The parameters defining the roll motion were reduced roll rate and iterations per revolution, which were chosen in the same manner as the pitch parameters. Good agreement was found between the different methods tested, previous CFD analysis, and experimental data.