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. = equivalent area C L = lift coefficient dp/p = (the calculated pressure -the ambient pressure)/(the ambient pressure) EXTR = extraction ratio FPR = fan pressure ratio L/D = lift to drag ratio nmi = nautical miles OPR = overall pressure ratio OML = outer mold line SFC = specific fuel consumption T 3 = compressor exit temperature, °R T 4 = combustor exit temperature, °R TTR = throttle ratio V app = approach velocity, kts V jet = jet velocity, ft/s

This paper documents a mixed-fidelity approach for the design of low-boom supersonic aircraft as a viable approach for designing a practical low-boom supersonic configuration. A low-boom configuration that is based on low-fidelity analysis is used as the baseline. Tail lift is included to help tailor the aft portion of the ground signature. A comparison of low-and high-fidelity analysis results demonstrates the necessity of using computational fluid dynamics (CFD) analysis in a low-boom supersonic configuration design process. The fuselage shape is modified iteratively to obtain a configuration with a CFD equivalent-area distribution that matches a predetermined low-boom target distribution. The mixed-fidelity approach can easily refine the low-fidelity low-boom baseline into a low-boom configuration with the use of CFD equivalent-area analysis. The ground signature of the final configuration is calculated by using a state-of-the-art CFD-based boom analysis method that generates accurate midfield pressure distributions for propagation to the ground with ray tracing. The ground signature that is propagated from a midfield pressure distribution has a shaped ramp front, which is similar to the ground signature that is propagated from the CFD equivalent-area distribution. This result confirms the validity of the low-boom supersonic configuration design by matching a low-boom equivalent-area target, which is easier to accomplish than matching a low-boom midfield pressure target. * NomenclatureA e = equivalent area dp/p = (the calculated pressure -the ambient pressure)/(the ambient pressure)

There are several research papers on how to design a supersonic configuration that has desirable low-boom characteristics as determined by the Seebass-George-Darden boom minimization theory (SGD theory). The low-boom signatures predicted by the SGD theory could be realized by wing-fuselage configurations. However, for a given low-boom signature generated by the SGD theory, it is still an open question whether one could develop a feasible aircraft configuration with nacelles and tails that has a similar low-boom ground signature as that predicted by the SGD theory.Past attempts indicated that no feasible aircraft configuration with nacelles and tails would have a total equivalent area distribution matching one of the equivalent area distributions corresponding to the low-boom ground signatures determined by the SGD theory. There are essentially three alternative methods for generating a supersonic concept with a shaped boom ground signature: (i) use a direct optimization method that minimizes numerical figures of merit for low-boom characteristics, (ii) construct new "realizable" target equivalent area distributions (or near-field pressure distributions) that result in shaped boom ground signatures, and (iii) develop new tools to help designers find acceptable low-boom configurations. There were many attempts, with mixed results, using the first two methods to obtain supersonic configurations that have shaped boom ground signatures.This paper introduces a tool called BOSS (Boom Optimization using Smoothest Shape modifications). BOSS utilizes interactive inverse design optimization to develop a fuselage shape that yields a low-boom aircraft configuration. The paper also demonstrates how BOSS could be used to help design realistic aircraft concepts with low-boom ground signatures. A fundamental reason for developing BOSS is the need to generate feasible low-boom conceptual designs that are appropriate for further refinement using CFD-based preliminary design methods. BOSS was not developed to provide a numerical solution to the inverse design problem. Instead, BOSS was intended to help designers find the "right" configuration among infinitely many possible configurations that are equally good using any numerical figure of merit.BOSS uses the smoothest shape modification strategy for modifying the fuselage radius distribution at 100 or more longitudinal locations to find a smooth fuselage shape that reduces the discrepancies between the design and target equivalent area distributions over any specified range of effective distance. For any given supersonic concept (with wing, fuselage, nacelles, tails, and/or canards), a designer can examine the differences between the design and target equivalent areas, decide which part of the design equivalent area curve needs to be modified, choose a desirable rate for the reduction of the discrepancies over the specified range, and select a parameter for smoothness control of the fuselage shape. BOSS will then generate a fuselage shape based on the designer's inputs in a matter ...

This paper documents an integration of engine, plume, and computational fluid dynamics (CFD) analyses in the conceptual design of low-boom supersonic aircraft, using a variable fidelity approach. In particular, the Numerical Propulsion Simulation System (NPSS) is used for propulsion system cycle analysis and nacelle outer mold line definition, and a low-fidelity plume model is developed for plume shape prediction based on NPSS engine data and nacelle geometry. This model provides a capability for the conceptual design of low-boom supersonic aircraft that accounts for plume effects. Then a newly developed process for automated CFD analysis is presented for CFD-based plume and boom analyses of the conceptual geometry. Five test cases are used to demonstrate the integrated engine, plume, and CFD analysis process based on a variable fidelity approach, as well as the feasibility of the automated CFD plume and boom analysis capability.

A tool with an Excel visual interface is developed to generate equivalent-area (A e ) targets that satisfy the volume constraints for a low-boom supersonic configuration. The new parametric A e target explorer allows users to interactively study the tradeoffs between the aircraft volume constraints and the low-boom characteristics (e.g., loudness) of the ground signature. Moreover, numerical optimization can be used to generate the optimal A e target for given A e volume constraints. A case study is used to demonstrate how a generated lowboom A e target can be matched by a supersonic configuration that includes a fuselage, wing, nacelle, pylon, aft pod, horizontal tail, and vertical tail. The low-boom configuration is verified by sonic-boom analysis with an off-body pressure distribution at three body lengths below the configuration.

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There are several research papers on how to design a supersonic configuration that has desirable low-boom characteristics as determined by the Seebass-George-Darden boom minimization theory (SGD theory). The low-boom signatures predicted by the SGD theory could be realized by wing-fuselage configurations. However, for a given low-boom signature generated by the SGD theory, it is still an open question whether one could develop a feasible aircraft configuration with nacelles and tails that has a similar low-boom ground signature as that predicted by the SGD theory.Past attempts indicated that no feasible aircraft configuration with nacelles and tails would have a total equivalent area distribution matching one of the equivalent area distributions corresponding to the low-boom ground signatures determined by the SGD theory. There are essentially three alternative methods for generating a supersonic concept with a shaped boom ground signature: (i) use a direct optimization method that minimizes numerical figures of merit for low-boom characteristics, (ii) construct new "realizable" target equivalent area distributions (or near-field pressure distributions) that result in shaped boom ground signatures, and (iii) develop new tools to help designers find acceptable low-boom configurations. There were many attempts, with mixed results, using the first two methods to obtain supersonic configurations that have shaped boom ground signatures.This paper introduces a tool called BOSS (Boom Optimization using Smoothest Shape modifications). BOSS utilizes interactive inverse design optimization to develop a fuselage shape that yields a low-boom aircraft configuration. The paper also demonstrates how BOSS could be used to help design realistic aircraft concepts with low-boom ground signatures. A fundamental reason for developing BOSS is the need to generate feasible low-boom conceptual designs that are appropriate for further refinement using CFD-based preliminary design methods. BOSS was not developed to provide a numerical solution to the inverse design problem. Instead, BOSS was intended to help designers find the "right" configuration among infinitely many possible configurations that are equally good using any numerical figure of merit.BOSS uses the smoothest shape modification strategy for modifying the fuselage radius distribution at 100 or more longitudinal locations to find a smooth fuselage shape that reduces the discrepancies between the design and target equivalent area distributions over any specified range of effective distance. For any given supersonic concept (with wing, fuselage, nacelles, tails, and/or canards), a designer can examine the differences between the design and target equivalent areas, decide which part of the design equivalent area curve needs to be modified, choose a desirable rate for the reduction of the discrepancies over the specified range, and select a parameter for smoothness control of the fuselage shape. BOSS will then generate a fuselage shape based on the designer's inputs in a matter ...

This paper documents a mixed-fidelity approach for the design of low-boom supersonic aircraft as a viable approach for designing a practical low-boom supersonic configuration. A low-boom configuration that is based on low-fidelity analysis is used as the baseline. Tail lift is included to help tailor the aft portion of the ground signature. A comparison of low-and high-fidelity analysis results demonstrates the necessity of using computational fluid dynamics (CFD) analysis in a low-boom supersonic configuration design process. The fuselage shape is modified iteratively to obtain a configuration with a CFD equivalent-area distribution that matches a predetermined low-boom target distribution. The mixed-fidelity approach can easily refine the low-fidelity low-boom baseline into a low-boom configuration with the use of CFD equivalent-area analysis. The ground signature of the final configuration is calculated by using a state-of-the-art CFD-based boom analysis method that generates accurate midfield pressure distributions for propagation to the ground with ray tracing. The ground signature that is propagated from a midfield pressure distribution has a shaped ramp front, which is similar to the ground signature that is propagated from the CFD equivalent-area distribution. This result confirms the validity of the low-boom supersonic configuration design by matching a low-boom equivalent-area target, which is easier to accomplish than matching a low-boom midfield pressure target. * NomenclatureA e = equivalent area dp/p = (the calculated pressure -the ambient pressure)/(the ambient pressure)