combined than subsonic aircraft, particularly with regard to APSE effects and sonic boom, as already discussed. Stringent requirements for component performance (with attendant development, manufacturing, cost, and operational issues), coupled with the economic and environmental challenges faced by commercial supersonic aircraft, leave little room for inefficiencies in the design of the airframe, engine, flight controls system, or other performance-critical systems.

Design integration tools should allow design teams to interact in the design of complex systems where technical and other factors (including cost) can be appropriately traded; to compress the design cycle time by concurrently considering all critical constraints and disciplines; to adapt quickly to changes in design and manufacturing processes; to easily accept new and improved tools; and to provide databases with levels of complexity appropriate to each task.

Fortunately, a substantial national investment has been made in tools for integrated design, including system engineering methods, multidisciplinary optimization methods, detailed discipline methods and interfaces, and design-integration frameworks. The aircraft design and manufacturing industry is heavily committed to improving such tools. Universities and the government also have critical roles in advancing the state of the art in many of these areas. NASA and the Department of Defense have both made significant investments in the development of advanced integration environments and tools, although NASA’s flagship program in this area, the Integrated Synthesis Environments Initiative, was recently cancelled.

Despite the progress that has been made, important work remains to be done. Existing tools cannot model some key technologies (e.g., active controls), nor do they have sufficient model validity in all important disciplinary areas. At the broad technical scale, it is extremely important to begin with a full understanding of the design objectives and constraints, such as payload, range, takeoff gross weight (TOGW), noise, sonic boom, and cost, and to identify all the critical disciplines. This will prevent suboptimization and the debilitating effects of discovering, too late, that a first-order design driver (such as APSE in the HSR Program) has not been fully appreciated or adequately addressed. Many existing design schemes do not fit well with integration/ optimization algorithms, and user-friendly frameworks that accommodate such schemes are not available. Off-the-shelf software and interface mindsets are needed. Faster mechanisms for geometric modeling are required for improved efficiency at both the conceptual and detailed design levels. For design teams that might be geographically dispersed, mechanisms for sharing the geometric models are lacking. Indeed, the management and sharing of information and data are themselves first-order issues, as is reducing the time for each design cycle. Very large quantities of data must be transferred; presently, both modeling and data management are much too labor-intensive. Analytical design tools, such as computational fluid dynamics and finite element modeling, have been greatly improved, but they often take so long to run that they are impractical in an iterative design context, and they are not robust enough to be fully integrated into a design framework. Other important issues for the development of advanced integrated tools are associated with uncertainties: how they propagate through a design and how to develop calibration and validation processes that quantify them. Too often, even after an optimization calculation has been made, new designs can be evaluated only by comparing them against a previous baseline rather than by making an absolute measurement of expected performance and comparing it against a validation metric.

Major benefits could be realized from the development and effective use of advanced design and integration tools, but there are significant barriers to achieving these benefits. On the nontechnical front, NASA could help by creating a new culture of collaboration, which is required for the most effective utilization of university, government, and industry talent in the realm of integration tools. NASA also has the charter and opportunity to provide much of the technology that is needed to enable viable supersonic aircraft designs.

First, it will be vital to develop advanced, high-fidelity methodologies and tools for intradiscipline analysis in areas such as computational fluid dynamics and finite element modeling for structures. Interdisciplinary and multidisciplinary tools are also crucial for integrated design of complex systems and entire vehicles. Particular attention should be given to (1) integrating the design of mechanical systems with the design of electrical systems and software development and (2) factors such as computational speed and robustness that will increase the utility of new tools in an integrated design context. Speed should come naturally with advances in computer hardware capability, but algorithms must be tailored to take advantage of the massively parallel computing environment.

Second, to realize the potential for design improvements through advanced tools, substantial new efforts must be focused on the automation of integration and validation. Today, design processes can require weeks to a couple of months to set up and compute the aerodynamic, weight, stability and control, aeroelastic, and other performance characteristics resulting from a configuration change. Optimizing in any context takes a number of such cycles. While multidisciplinary optimization techniques can reduce the optimization time dramatically, the setup time for the basic configuration is still counted in weeks and the validation of designs resulting from multidisciplinary optimization techniques, at least in the usual context of experimental verification, is extremely difficult because of the highly integrated nature of the process (it typically involves the use of sophisticated analyses to check design calculations). There is, as a result, a great need for focused research on how to validate highly integrated design capabilities. Clever combinations of analytical, computational, and experimental approaches

Front Matter (R1-R12)

Executive Summary (1-5)

1. Introduction (6-9)

2. Technology Challenges (10-16)

3. New Opportunities for Research on Critical Supersonic Technologies (17-26)

4. Areas Needing Continued Technical Development (27-40)

5. Findings, Conclusions, and Recommendations (41-44)

Appendix A. Biographies of Committee Members (45-49)

Appendix B. Participants in Committee Meetings (50-50)

Appendix C. Acronyms and Abbreviations (51-52)