Stealth Considerations for Aerodynamic Configurations Design of Missiles

The aerodynamic design of a strategic weapon is of interest, especially when the radar signatures are included in the conceptual design phase. The basics of stealth configurations and stealth mechanisms for missiles are reviewed. The Radar Cross Sections （RCS） of some generic missiles are predicted and compared to analyze the trade-offs involved between low RCS and aerodynamic performance. The consideration of RCS prediction in the conceptual design phase gives a quick insight into the stealth performance prior to detailed design.

Finocyl Grain Design and Optimization Using Sequential Quadratic Programming

Design technique of 3D Finocyl grain configuration for Solid Rocket Motors, including its performance prediction and optimization is discussed. In doing so, the design objectives and constraints are set, geometric parameters of Finocyl grain are identified, and performance prediction parameters are calculated, thereafter the preliminary design is completed and optimal design is reached. For every grain design, it is necessary that the minimum possible mass of propellant is used to produce the required thrust within a certain limit of burning time. By using this technique of design and optimization, the vital parameter of propellant mass is optimized to its minimum value, yet vital parameter of thrust is attained in the required burning time with the fixed length and diameter of motor. Especially a geometrical model of grain configuration is developed by using various combinations of ellipsoid, cone, cylinder, sphere, torus and inclined plane. With the diameter of the motor fixed, the Finocyl Grain geometry totally depends on sixteen independent variables. Each of these variables has a bearing on explicit characteristic of Finocyl grain design and optimization. Changing the value of each of these variables brings significant effects on the performance. Due to such attributes of Finocyl grain configuration, compromises will result. Overall optimal design is ensured through assigning and analyzing a suitable range of geometric parameters satisfying the requirements of minimum mass of propellant and ensuring sound values for internal ballistic parameters while remaining within the design constraints of thrust, burning time, length and diameter of chamber case.

Multidisciplinary Design and Optimization of Multistage Ground-launched Boost Phase Interceptor Using Hybrid Search Algorithm

This article proposes a multidisciplinary design and optimization （MDO） strategy for the conceptual design of a multistage ground-based interceptor （GBI） using hybrid optimization algorithm, which associates genetic algorithm （GA） as a global optimizer with sequential quadratic programming （SQP） as a local optimizer. The interceptor is comprised of a three-stage solid propulsion system for an exoatmospheric boost phase intercept （BPI）. The interceptor＇s duty is to deliver a kinetic kill vehicle （KKV） to the optimal position in space to accomplish the mission of intercept. The modules for propulsion, aerodynamics, mass properties and flight dynamics are integrated to produce a high fidelity model of the entire vehicle. The propulsion module com- prises of solid rocket motor （SRM） grain design, nozzle geometry design and performance prediction analysis. Internal ballistics and performance prediction parameters are calculated by using lumped parameter method. The design objective is to minimize the gross lift off mass （GLOM） of the interceptor under the mission constraints and performance objectives. The proposed design and optimization methodology provide designers with an efficient and powerful approach in computation during designing interceptor systems.

A Hybrid Optimization Approach for SRM FINOCYL Grain Design

This article presents a method to design and optimize 3D FINOCYL grain （FCG） configuration for solid rocket motors （SRMs）. The design process of FCG configuration involves mathematical modeling of the geometry and parametric evaluation of various independent geometric variables that define the complex configuration. Virtually infinite combinations of these variables will satisfy the requirements of mass of propellant, thrust, and burning time in addition to satisfying basic needs for volumetric loading fraction and web fraction. In order to ensure the acquisition of the best possible design to be acquired, a sound approach of design and optimization is essentially demanded. To meet this need, a method is introduced to acquire the finest possible performance. A series of computations are carried out to formulate the grain geometry in terms of various combinations of key shapes inclusive of ellipsoid, cone, cylinder, sphere, torus, and inclined plane. A hybrid optimization （HO） technique is established by associating genetic algorithm （GA） for global solution convergence with sequential quadratic programming （SQP） for further local convergence of the solution, thus achieving the final optimal design. A comparison of the optimal design results derived from SQP, GA, and HO algorithms is presented. By using HO technique, the parameter of propellant mass is optimized to the minimum value with the required level of thrust staying within the constrained burning time, nozzle and propellant parameters, and a fixed length and outer diameter of grain.