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The Aerospace Systems Design Laboratory at the Guggenheim School of Aerospace Engineering, Georgia Institute of Technology, has recently created the “Collaborative Design Environment” (CoDE), a next-generation design facility supporting efficient, rapid-turnaround conceptual design. The CoDE combines cost-effective, off-the-shelf information technology with advanced design methodologies and tools in a customized, user-centered physical layout that harnesses the power of creative design teams. The CoDE will enable researchers to develop, test and apply new approaches to conceptual design, and to improve modeling and simulation fidelity. It will also support sponsored design projects as well as student teams participating in national design competitions.

This paper attempts to assess the benefits of a unique distributed propulsion concept, known as the Multi-Gas Generator Fan (MGGF) system, over conventional turbofan engines on civilian vertical takeoff and landing (VTOL) applications. The MGGF-based system has shown the potential to address the fundamental technical challenge in designing a VTOL aircraft: the significant mismatch between the power requirements at lift-off/hover and cruise. Vehicle-level performance and sizing studies were implemented using the Grumman Design 698 tilt-nacelle V/STOL aircraft as a notional personal air vehicle (PAV), subjected to hypothetical single engine failure (SEF) emergency landing requirements and PAV mission requirements.

Heterogeneous physical systems can often be considered as highly complex, consisting of a large number of subsystems and components, along with the associated interactions and hierarchies amongst them. The simulation of a large-scale, complex system can be computationally expensive and the dynamic interactions may be highly nonlinear. One approach to address these challenges is to increase the computing power or resort to a distributed computing environment. An alternative to improve the simulation computational performance and efficiency is to reduce CPU required time through the application of surrogate models. Surrogate modeling techniques for dynamic simulation models can be developed based on Recurrent Neural Networks (RNN).This study will present a method to improve the overall speed of a multi-physics time-domain simulation of a complex naval system using a surrogate modeling technique.

The accepted paradigm in aerospace systems design was to design systems sequentially and iteratively to maximize performance based on minimum weight. The traditional paradigm does not work in the rapidly changing global environment. A paradigm shift from the norm of “design for performance” to “design for affordability and quality” has been occurring in recent decades to respond to the changing global environment. Observations were made regarding new tenets needed to bridge the gap from the old to the new. These tenets include new methods and techniques for designing complex systems due to uncertainty and mulit-dimensionality, consideration of the life cycle of the system, and the methods needed to assess breakthrough technologies to meet aggressive goals of the future. The Technology Identification, Evaluation, and Selection method was proposed as a possible solution to the paradigm shift.

Several approaches to robust design have been proposed in the past. Only few acknowledged the paradigm shift from performance based design to design for cost. The incorporation of economics in the design process, however, makes a probabilistic approach to design necessary, due to the inherent ambiguity of assumptions and requirements as well as the operating environment of future aircraft. The approach previously proposed by the authors, linking Response Surface Methodology with Monte Carlo Simulations, has revealed itself to be cumbersome and at times impractical for multi-constraint, multi-objective problems. In addition, prediction accuracy problems were observed for certain scenarios that could not easily be resolved. Hence, this paper proposes an alternate approach to probabilistic design, which is based on a Fast Probability Integration technique.

One the most critical barriers to the advancement of Personal Air Vehicles in today's market environment is that the technological capabilities can never seem to outweigh the risks associated with financing such an endeavor. To address such a need, a system dynamics approach with the capability to model the uncertainties in the supply chain is presented in this paper. The overall modeling framework is first presented and the modeling process of the various relevant elements, such as demand prediction and manufacturer analysis, is then described. The aim of this research is ultimately to assess the viability of a next-generation aircraft program beyond the static confines of a net present value approach, through the inclusion of dynamic events and uncertainties that can occur throughout the life-cycle of the aircraft.

A solid business case is highly dependent upon a strategic technology research and development plan in the early phases of product design. The embodiment of a strategic technology development plan is the identification and subsequent funding of high payoff technology programs that can maximize a company’s return on investment, which entails both performance and economic objectives. This paper describes a technique whereby the high payoff technologies may be identified across multiple platforms to quantitatively justify resource allocation decisions and investment opportunities. A proof of concept investigation was performed on a fleet of subsonic, commercial aircraft.

A technique is proposed for examining complex behaviors in the “pilot - vehicle - operational conditions” system using an autonomous situational model of flight. The goal is to identify potentially critical flight situations in the system behavior early in the design process. An exhaustive set of flight scenarios can be constructed and modeled on a computer by the designer in accordance with test certification requirements or other inputs. Distinguishing features of the technique include the autonomy of experimentation (the pilot and a flight simulator are not involved) and easy planning and quick modeling of complex multi-factor flight cases. An example of mapping airworthiness requirements into formal scenarios is presented. Simulation results for various flight situations and aircraft types are also demonstrated.

Current robust design methods rely heavily on meta-modeling techniques to reduce the total computational effort of probabilistic explorations to a combinatorially manageable size. Historically most of these meta-models were in the form of Response Surface Equations (RSE). Recently there has been interest in supplementing the RSE with techniques that better handle non-linear phenomena. One technique that has been identified is the Gaussian Process (GP). The GP has fewer initial assumptions when compared to the linear methods used by RSEs and, therefore, fewer limitations. The initial implementation and employment techniques proposed in current literature for use with the GP are barely modified versions of those used for RSEs. A better, more tailored technique needs to be developed to properly make use of the nature of the GP, and minimize the effect of some of its limitations. Such a technique would allow for rapid development of a reusable, computationally efficient and accurate GP.

One of the major impetuses for the development of modern, robust design methodologies is the need for affordable aerospace systems. Because the affordability of a system is directly tied to the economics of developing, manufacturing, operating, and disposing of that system, it has become common practice to perform an economic analysis of a potential system to evaluate its viability. Additionally, as needs for improved modeling, analysis, and evaluation capability have arisen, several techniques which have proved themselves popular in economics have been adopted. While adopting these techniques has improved the capabilities of the designer/engineer, they do not proceed far enough. That is aerospace systems design, and consequently all complex systems design, could actually be considered an exercise in economics. All of the players, i.e. designers, firms, end users, and the systems themselves can be considered microeconomic entities.

Creation and utilization of accurate drag polars is essential in the aircraft sizing and synthesis process. Existing sizing and synthesis codes are based on historical data and cannot capture the aerodynamics of a non-conventional aircraft at the conceptual design phase. The fidelity of the aerodynamic analysis should be enhanced to increase the designer’s confidence in the results. Hence, there is need for a physics-based approach to generate the drag polars of an aircraft lying outside the conventional realm. The deficiencies of the legacy codes should be removed and replaced with higher fidelity meta-model representations. This is facilitated with response surface methodology (RSM), which is a mathematical and statistical technique that is suited for the modeling and analysis of problems in which the responses, the drag coefficients in this case, are influenced by several variables. The geometric input variables are chosen so that they represent a multitude of configurations.

A design process is formulated and implemented for the taxonomy selection and system-level optimization of an Efficient Multi-Mach Aircraft Current Technology Concept and an Advanced Concept. Concept space exploration of taxonomy alternatives is performed with multi-objective genetic algorithms and a Powell’s method scheme for vehicle optimization in a multidisciplinary modeling and simulation environment. A dynamic sensitivity visualization analysis tool is generated for the Advanced Concept with response surface equations.

The preparation of manned space exploration missions beyond Earth orbit requires precursor activities such as integrated space mission simulations at dedicated Earth-based analog facilities. In recent years, the Mars Society, with the support of private donors, has built several of these facilities. The lessons learned by the crews simulating planetary exploration activities on board those stations are generating a body of knowledge that can make a significant contribution to the design and operation of future planetary bases, as well as improve the next generation of such simulation facilities. Drawing from the author’s first-hand experience as a crewmember during the 2003 field season at the Flashline Mars Arctic Research Station, the Mars Society’s analog simulation facility on Devon Island in the Canadian High Arctic, this paper provides a compilation and first analysis of the crew’s experience.

The challenge of designing next-generation systems that meet goals for system effectiveness, environmental compatibility, and cost has grown to the point that traditional design methodologies are becoming ineffective. Increases in the analysis complexity required, the number of objectives and constraints to be evaluated, and the multitude of uncertainties in today’s design problems are primary drivers of this situation. A new environment for design has been formulated to treat this situation. It is viewed as a testbed, in which new techniques in such areas as design-oriented/physics-based analysis, uncertainty modeling, technology forecasting, system synthesis, and decision-making can be posed as hypotheses. Several recent advances in elements of this multidisciplinary environment, termed the Virtual Stochastic Life Cycle Design Environment, are summarized in this paper.

An integrated, multidisciplinary environment of a tactical aircraft platform has been created by leveraging the powerful capabilities of both MATLAB/Simulink and Numerical Propulsion System Simulation (NPSS). The overall simulation includes propulsion, power, and thermal management subsystem models, which are integrated together and linked to an air vehicle model and mission profile. The model has the capability of tracking temperatures and performance metrics and subsequently controlling characteristics of the propulsion and thermal management subsystems. The integrated model enables system-level trade studies involving the optimization of engine bleed and power extraction and thermal management requirements to be conducted. The simulation can also be used to examine future technologies and advanced thermal management architectures in order to increase mission capability and performance.

An evolved version of the Technology Identification, Evaluation, and Selection (TIES) method is presented that provides techniques for quantifying technological uncertainty associated with immature technologies. Uncertainty in this context implies forecasting. Forecasting the impact of immature technologies on a system is needed to provide increased knowledge to a decision-maker in the conceptual and preliminary phases of aircraft design. The increased knowledge allows for proper allocation of company resources and program management. The TIES method addresses the milestones encountered during a technology development program, the sources of uncertainty during that development, a potential method for bounding and forecasting the uncertainty, and a means to quantify the impact of any emerging technology. A proof of concept application was performed on a High Speed Civil Transport concept due to its technically challenging customer requirements.

The success of business jets like the Citation X, the fastest civil aircraft in use after the Concorde, highlights the need for speed to improve business and globalization. Currently, developing a supersonic business jet has many technical and economical impediments. These obstacles include sonic boom, emissions and noise requirements problems that are easily meet or do not exist for subsonic aircraft. A baseline aircraft, defined by an optimization process, is the starting point for this study. However, this baseline aircraft does not meet the sonic boom, emissions and noise requirements, which are very strict. Companion studies to this one indicate that it may be possible to meet emissions and noise requirements, but it is clear that technology infusion is necessary for the future viability of this aircraft concept to succeed.

A method to identify the topology of an aerospace system’s requirements space, specifically the location and type of the discontinuities that occur at the boundaries of the available technology and the physics of the system, allows the designer to make decisions as to the desirability of a specific solution state. Additionally, since a given set of requirements may produce multiple solutions the designer can compare his/her solution to other potential solutions. This allows an assessment of the requirements risk associated with a specific design. This paper addresses the need to visualize and understand the topology of the requirements space for a Rapid Response Strike System.

To allow for the assessment of synergistic subsystem interactions during the conceptual design phase of manned spacecraft and space stations, an existing software tool was improved to permit integrated modeling and simulation of a space station's life support system and attitude and orbit control system. This facilitates early estimation of potential reductions in resupply mass - and life-cycle cost - as well as the assessment of increases in operational flexibility through incorporation of synergisms into the conceptual design. The created interactive tool is based on a user-friendly graphical programming language and can therefore be used by conceptual designers and engineering students alike.

Understanding the factors influencing crew performance under conditions of long-term isolation, confinement, high workload and elevated risk is an important prerequisite to the manned space exploration missions beyond low-Earth orbit that are planned under the new National Space Policy of the United States. Quantitatively tracking the performance of crews affected by those stressors is therefore crucial both during actual space missions and as part of precursor activities on the ground, such as those taking place at planetary-analog simulation facilities. During the summer of 2003, an experiment was carried out tracking the cognitive performance of the crew on board such a facility, the Mars Society’s “Flashline Mars Arctic Research Station” in the Canadian High Arctic. In addition to the self-administered computer-based testing, the crew’s daily activities were logged to enable the identification of external factors that might affect the observed performance.