As NASA continues to make plans for future robotic precursor and eventual human missions to Mars, the need to characterize and develop designs for entry vehicles capable of delivering large masses to the surface of Mars will persist. In combination with this, NASA has recognized that the current heritage technology for Mars’ Entry Decent and Landing (EDL) does not have the capability to land the required payload masses. Both the Thermal Protection System (TPS) and the Descent/Landing systems require new design approaches. Because of these needs, NASA has performed an Entry, Descent and Landing Systems Analysis (EDL-SA) study for high mass exploration and science missions to identify key enabling technology areas for further investment. One key technology area identified includes rigid aeroshell shapes for aerodynamic performance and controllability.

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In this investigation, a system optimization study of alternative aeroshell shapes for Mars exploration class payloads of approximately 40 metric tons has been conducted. This system optimization is accomplished using a Multi-disciplinary Design Optimization (MDO) framework which accounts for the aeroshell shape, trajectory, thermal protection system, and vehicle subsystem closure along with a Multi Objective Genetic Algorithm (MOGA) for the initial shape exploration. This is accomplished using a combination of engineering analysis and higher-fidelity physics based tools along with optimization methods and engineering judgment. The results of this process have shown that a proposed family of optimized mid lift-to-drag aeroshell shapes exhibit a significant improvement to the current reference entry rigid aeroshell configuration. Furthermore, a trade-off between the vehicle TPS and structural mass is identified for this class of aeroshell shapes and their corresponding trajectories. Balancing this trade-off can yield an overall decrease in the total vehicle mass or corresponding increase in landed payload, as compared to the current reference configuration.

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The paper describes the development of a mul-tidisciplinary design optimization framework for con-ceptual design of truss-braced wing configurations. This unconventional configuration requires specialized analysis tools supported by a modular and flexible framework to accommodate different configurations. While the previous framework developed at Virginia Tech was a monolithic Fortran-77 code, the need for more flexibility for com-plex truss-braced wing configurations was addressed by the development of this new framework, which is based on Phoenix Integration ModelCenterTM environment. The framework uses updated structural and aerodynamic de-sign modules that enable a more general geometry defini-tion. The new framework, thus, provides a foundation for future design concepts, especially multi-member truss-braced wing configurations. The fuel saving potential of these truss-braced wing configurations is presented by com-paring different truss designs with gradually increased level of complexity.

This paper documents the development of a conceptual level integrated process for design and analysis of efficient and environmentally acceptable supersonic aircraft. To overcome the technical challenges to achieve this goal, a conceptual design capability which provides users with the ability to examine the integrated solution between all disciplines and facilitates the application of multidiscipline design, analysis, and optimization on a scale greater than previously achieved, is needed. The described capability is both an interactive design environment as well as a high powered optimization system with a unique blend of low, mixed and high-fidelity engineering tools combined together in the software integration framework, ModelCenter. The various modules are described and capabilities of the system are demonstrated. The current limitations and proposed future enhancements are also discussed.

The objective of this paper was to provide an update on NASA’s current tools for design and analysis of hybrid wing body (HWB) aircraft with an emphasis on Vehicle Sketch Pad

(VSP). NASA started HWB analysis using the Flight Optimization System (FLOPS). That capability is enhanced using Phoenix Integration’s ModelCenter®. Model Center enables multifidelity analysis tools to be linked as an integrated structure. Two major components are linked to FLOPS as an example; a planform discretization tool and VSP. The planform discretization tool ensures the planform is smooth and continuous. VSP is used to display the output geometry. This example shows that a smooth & continuous HWB planform can be displayed as a three-dimensional model and rapidly sized and analyzed.

The Air Force Institute of Technology is studying a new upper-stage rocket engine architecture: the dual-expander aerospike nozzle. The goal of this research is to provide the maximum thrust-to-weight ratio in an engine that delivers a minimum of 50,000 lbf vacuum thrust with a vacuum specific impulse of 464 s. Previous work focused on developing an initial design to demonstrate the feasibility of the dual-expander aerospike nozzle architecture. That work culminated in a design exceeding the requirements, delivering an estimated 57,000 lbf thrust with a specific impulse of 472 s by using an oxidizer-to-fuel ratio of 7.03, a total mass flow of 121 lbm=s, and an engine length of 38 in. These results were computed in a numerical model of the engine. Current work expands the model in preparation for optimizing its thrust-to-weight ratio. The changes to the model are designed to support running automated parametric and optimization studies. Parametric studies varying oxidizer-to-fuel ratio, total mass flow, and chamber

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length show that a dual-expander aerospike nozzle engine can achieve 50,000 lbf vacuum thrust and 489 s vacuum Isp with an oxidizer-to-fuel ratio of six, a total mass flow of 104 lbm=s (a reduction of 14%), and an engine length of 27.9 in. (a reduction of over 25%), which should equate to a significant weight savings over the original design.

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Fully Constrained Design (FCD) is a new method for discrete sizing optimization of steel frames. Based on the optimality criteria approach, FCD features a distinct approach to constraint handling and the generation of new designs that makes the method scalable to large problems and applicable when the problem objective and/or constraint functions are discontinuous. FCD is tested on several truss structures and compares favorably to optimality criteria and heuristic methods in terms of solution quality and computational efficiency, respectively. A successful industry application of the method is presented to demonstrate the scalability of the method and its suitability for industry application.

In the development of complex systems, a large gap exists between systems engineering activities and domain-level engineering analysis. This gap limits the use of accurate disciplinary and multidisciplinary engineering analysis, resulting in failures to meet system requirements and cost overruns. An integrated toolset was developed that bridges the gap through the integration of a SysML tool and a process integration and design optimization framework. The integrated capability enables engineers to quickly evaluate system configurations using realistic analysis models. This ability was combined with requirements conformance analysis techniques, which automatically highlighted unsatisfied requirements.

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It allows the design team to rapidly respond to inevitable changes in requirements and gives

them the ability to perform continuous analysis, simulation, and trade-studies throughout

the design process.

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This paper describes ongoing research to develop a flexible 3D hullform design process and modules with associated performance models, and integrate these modules into an existing ship synthesis model (SSM) in a multi-objective optimization approach to perform Naval Ship Concept and Requirements Exploration (C&RE). Effectiveness is initially based on seakeeping indices and resistance, and then extended to a multi-objective genetic optimization of an Offshore Patrol Vessel (OPV) total ship design.