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Over the past few years, modern aircraft design has experienced a paradigm shift from designing for performance to designing for affordability. This paper contains a probabilistic approach that will allow traditional deterministic design methods to be extended to account for disciplinary, economic, and technological uncertainty. The probabilistic approach was facilitated by the Fast Probability Integration (FPI) technique; a technique which allows the designer to gather valuable information about the vehicle's behavior in the design space. This technique is efficient for assessing multi-attribute, multi-constraint problems in a more realistic fashion. For implementation purposes, this technique is applied to illustrate how both economic and technological uncertainty associated with a Very Large Transport aircraft may be assessed.

The projection of aeroelastic constraints in the design space has long been a want in the design process of vehicles. These properties are usually not established accurately until later phases of design. The desire is to bring another interactive constraint to the conceptual design phase and allow the designer to see the impact of design decisions on aeroelastic characteristics. Even though a number of analysis and optimization tools have been developed to support aeroelastic analysis and optimization in the flight vehicle design process, the toolbox is far from being complete. The results often cannot be obtained in a manner timely enough and the natural division of the engineering team into specialty groups is not supported very well by the aerodynamic-structures monolithic codes typically in the above toolbox. The monolithic codes are also not amenable to the use of concurrent processing now made available by computer technology.

In this paper, a brief overview is given of the different alternatives to an integrating computational framework. A new framework will be introduced, which incorporates the latest computational techniques and more importantly a mind-set emphasizing flexibility, modularity, portability and re-usability. This introduction will include a thorough review of the fundamental design decisions that went into developing this new integrated computational framework. Distributed object computing extends an object-oriented system which allows objects to interact across heterogenous networks and interoperate as a unified whole. Integrated computing frameworks are discussed, together with data transport techniques such as Extensible Markup Language (XML) and Simple Object Access Protocol (SOAP) to achieve platform, code and meta-model independent integration.

A family of Very Large Transport (VLT) concepts were studied as an implementation of the affordability aspects of the Robust Design Simulation (RDS) methodology which is based on the Integrated Product and Process Development (IPPD) initiative that is sweeping through industry. The VLT is envisioned to be a high capacity (600 to 1000 passengers), long range (∼7500 nm), subsonic transport. Various configurations with different levels of technology were compared, based on affordability issues, to a Boeing 747-400 which is a current high capacity, long range transport. The varying technology levels prompted a need for an integration of a sizing/synthesis (FLOPS) code with an economics package (ALCCA). The integration enables a direct evaluation of the added technology on a configuration economic viability.

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.

Several unique aspects of the design of hypersonic aerospace systems necessitate a truly multidisciplinary approach from the outset of the program. These coupled with a vague or changing requirements environment, provide an impetus for the development of a systematic and unified approach for the exploration and evaluation of alternative hypersonic vehicle concepts. The method formulated and outlined in this paper is founded upon non-deterministic conceptual & preliminary design formulations introduced over the past decade and introduces the concept of viewing system level requirements in a similar manner. The proposed method is then implemented for the concept exploration and design of a Hypersonic Strike Fighter in the presence of ambiguous open and/or evolving requirements.

A multidisciplinary design study considering the impact of Active Aeroelastic Wing (AAW) technology on the structural wing weight of a lightweight fighter concept is presented. The study incorporates multidisciplinary design optimization (MDO) and response surface methods to characterize wing weight as a function of wing geometry. The study involves the sizing of the wing box skins of several fighter configurations to minimum weight subject to static aeroelastic requirements. In addition, the MDO problem makes use of a new capability, trim optimization for redundant control surfaces, to accurately model AAW technology. The response surface methodology incorporates design of experiments, least squares regression, and makes use of the parametric definition of a structural finite element model and aerodynamic model to build response surface equations of wing weight as a function of wing geometric parameters for both AAW technology and conventional control technology.

The Conceptual Aerospace Systems Design and Analysis Toolkit (CASDAT) provides a baseline assessment capability for the Air Force Research Laboratory. The historical development of CASDAT is of benefit to the design research community because considerable effort was expended in the classification of the analysis tools. Its implementation proves to also be of importance because of the definition of assessment use cases. As a result, CASDAT is compatible with accepted analysis tools and can be used with state-of-the-art assessment methods, including technology forecasting and probabilistic design.