Aerosciences, Aero-Propulsion and Flight Mechanics Technology Development for NASA's Next Generation Launch Technology Program

Cockrell, Charles E.

doi:10.2514/6.2003-6948

Cited by 7 publications

(5 citation statements)

References 45 publications

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“…The NGLT program was aimed at developing technologies for reusable launch vehicles (RLV), including hypersonic airbreathing concepts. 5 A description of research and technology in the areas of aerodynamics, aerothermodynamics, aero-propulsion integration and flight mechanics is described in reference 5. Ground and flight technology demonstrations were also part of the program, such as the X-43C hypersonic flight demonstrator program, which was to be conducted as a joint program with the U.S. Air Force to demonstrate ramjet-to-scramjet transition in an airframe-integrated hypersonic configuration.…”

Section: B Flight Test Experiencementioning

confidence: 99%

Aerodynamics for Optimal Engine-Integrated Airbreathing Launcher Configurations

Lewis

Boyd

Cockrell

2004

40th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit

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An overview of some of the activities in hypersonic airbreathing aerodynamics and propulsion airframe integration is presented for the Space Vehicle Technology Institute. The Institute is a multi-university joint NASA-DoD program that was created as a center for research and education in future launch vehicle technologies. Perhaps more than any other type of flight vehicle, next generation space launchers will have to be analyzed as completely integrated aerodynamic-propulsion systems. Optimal aerodynamics will be vital to the development of efficient, engine-integrated launch vehicle forms, especially using airbreathing propulsion. To this end, inverse design approaches, design tradeoffs, and an understanding of relevant basic flow physics are all part of the Space Vehicle Technology Institute program. The relevance of these efforts to NASA activities is also described. I. IntroductionMONG the challenges in launch vehicle design is balancing the integrated requirements for practical propulsion with good volumeterics, structural efficiency, controllability, and heating survivability. For airbreathing vehicles, or those with extended reentry footprints, coupled aerodynamic performance is also vital. The degree of coupling and close integration raises many questions about practical aerodynamic designs for hypersonic flight.Of all future launch concepts, hypersonic airbreathers will have their own special propulsion-airframe integration challenges. For cruisers, it is well-known that the optimal propulsion system is one that maximizes the range by providing the highest product of specific impulse and lift-over-drag, L/D for a given fuel weight fraction. Airbreathers that consume large fractions of their weight are not strictly governed by the Breguet range equation, but the general trends of that simple formulation are still valid. 1 This will generally favor designs in which the engine contributes to lift, and where inlet efficiency is absolutely critical. 2 Lift-over-drag is as important as specific impulse for the performance of such vehicles. 3 Though accelerators are different than atmospheric cruisers, there are some analogies to be drawn.Accelerators, including airbreathing access-to-space vehicles, achieve maximum overall performance with greatest effective specific impulse, realized with the maximum difference between thrust and drag. This translates into the need to design efficient engine systems on low-drag airframes. Note that horizontal launchers, including airbreathing accelerators, will match lift to weight, and so must also have high L/D in horizontal flight.This need for high lift on horizontal vehicles stands in stark contrast to the requirements for vertical launch, especially with traditional rockets. In that case, drag represents a very small fraction of overall energy loss in flight to orbital speed, 7790 m/sec; the space shuttle velocity loss to gravity (1220 m/s) is over ten times greater than loses due to drag (118 m/s). In contrast, a horizontal launcher would have negligible gravity losse...

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Section: B Flight Test Experiencementioning

confidence: 99%

Aerodynamics for Optimal Engine-Integrated Airbreathing Launcher Configurations

Lewis

Boyd

Cockrell

2004

40th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit

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“…The disciplines which must be accounted for and integrated during the design are: trajectory optimization [4-6], guidance, navigation, and control (GN&C) technology [7,8], aerodynamics and aerothermodynamics [9][10][11], thermal-structural analysis [12][13][14], and thermal protection system (TPS) development [15][16][17][18][19]. Efforts have been made in developing a collaborative or a multidisciplinary optimization process that considers some of the disciplines of interest during an integrated design [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Multidisciplinary Design under Uncertainty for a Hypersonic Vehicle

Zhang¹,

He²,

Vlahopoulos

2010

13th AIAA/ISSMO Multidisciplinary Analysis Optimization Conference

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An integration environment has been developed for conducting multidiscipline design optimization analysis under uncertainty. It facilitates solution of multiple optimization problems in parallel with multiple sets of objectives and constraints originating from different design disciplines while simultaneously accounting for uncertainty during the optimization process.A seamless general purpose integration capability facilitates exchanging data between the optimization processes and the solvers which are used for evaluating the objective functions and the constraints. Metamodels can be developed and used instead of the actual solvers during the highly iterative optimization process in order to expedite the computations. Uncertainties are introduced in the optimization by considering the constraints which depend on any random variables and any random parameters as probabilistic. Satisfying the probabilistic constraints in the presence of uncertainty introduces sufficient conservatism in the solution and eliminates the need for further application of safety factors. The work presented in this paper considers trajectory, aerothermal, aerodynamic, thermal, and structural computations when performing the design optimization for the Thermal Protection System (TPS) and for the structure of a TSTO upper stage vehicle. Sixteen different sections are considered on the vehicle when designing the TPS. The trajectory bank angle schedule, the angle of attack schedule, the thickness of the sixteen different TPS sections, and twenty seven thicknesses associated with the structure are considered when reducing the overall weight of the vehicle while satisfying the imposed constraints. Uncertainties are considered in three control angles of the trajectory, in the material strength, the thrust load and the 2.5G loads. The results from the multi-discipline optimization without and with uncertainty are discussed, and a comparison between the deterministic and the probabilistic optimum is made.

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“…The physical difficulty of designing entry vehicles originates from the large degree of coupling between the various disciplines involved in the design [1][2][3]. The disciplines which can be accounted for and integrated during the design are: trajectory optimization [4][5][6], guidance, navigation, and control (GN&C) technology [7,8], aerodynamics and aerothermodynamics [9][10][11], thermal-structural analysis [12][13][14], and thermal protection system (TPS) development [15][16][17][18][19]. Efforts have been made in developing a collaborative or a multidisciplinary optimization process that considers some of the disciplines of interest during an integrated design [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Multi-Disciplinary Design Optimization under Uncertainty for Thermal Protection System Applications

Sun¹,

Zhang²,

Vlahopoulos

et al. 2006

11th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference

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This paper presents an approach for performing Multidisciplinary Design Optimization under Uncertainty (MDO-U) and an application for minimizing the thickness of the Thermal Protection System (TPS) for an entry vehicle configuration. Uncertainties due to material variability and the operating environment are considered. The value of considering uncertainty during the optimization process is demonstrated by comparing the performance of two optimal configurations, one identified through a deterministic approach and the other by considering uncertainty. Been able to account for uncertainty in engineering simulations and in product design is both important and challenging. In particular, during design optimization the performance of the optimized design typically lays closely to the boundaries of some of the constraints. Since variability alters the actual performance of a system, the optimal design can exhibit performance in the infeasible domain when the impact of the uncertainty has not been accounted properly during the optimization.

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Aerosciences, Aero-Propulsion and Flight Mechanics Technology Development for NASA's Next Generation Launch Technology Program

Cited by 7 publications

References 45 publications

Aerodynamics for Optimal Engine-Integrated Airbreathing Launcher Configurations

Aerodynamics for Optimal Engine-Integrated Airbreathing Launcher Configurations

Multidisciplinary Design under Uncertainty for a Hypersonic Vehicle

Multi-Disciplinary Design Optimization under Uncertainty for Thermal Protection System Applications

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