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60 number, Reynolds number, and size for the aerodynamic configuration, and mixing studies needed up to Mach number 10. A facility is needed to generate detailecl experiments for compu- tational validation and engineering design data for complex configur- ations, under conditions where the effects of cold walls, roughness, and flow field disturbance charac- teristics can be evaluated. Such a facility could provide the connec- tion between the stratospheric disturbance field (yet to be measured and modeled) with the wind tunnel data shown to be sensitive to this parameter. 4) We recommend that the highest priority be placed on the design, construction, and operation of a "quiet" wind tunnel in the Mach number range of 10, with a scale and Reynolds number capability to permit flight simulation. An expeditious approach may be the conversion of an available facility with the required operating condi- tions, such as the AEDC Gas Dynamics Facility. 3.4.2 High Hypersonic Speeds (M > 10) 5~ For these conditions, the require- ment is a simulation of BOTH the aerodynamics (viscous and flow field described at low M) and the real gas effects including chemical non-equilibrium effects. High Reynolds number continuum flow to the high free molecular region must be understood and predicted. 6) No current facility or facilities can cover the complete range of flow parameters with the flow quality (mean distribution, constituent and density determination, and flow field disturbance field) needed, and HYPERSONIC TECHNOLOGY FOR MILITARY APPLICATION this lack will be an important detriment to the generation of engineering design data. Existing and proposed facilities, such as arc tunnels, MHD acceler- ators, shock tunnels, and flight ranges, each have some potential to generate the required data, but all have significant limitations. S) CFD needs validation data, but it appears that it must be done in elements since no full simulation of high hypersonic speeds is available or within sight in ground test facilities. For this reason, flight tests will be necessary for full validation of CFD codes. 9) The full characteristics of the flow fields generated by present facil- ities are incomplete and not yet matched to the requirements of CFD for specific validation exper- iments, although the technology is, in many cases, within reach. 10) We recommend a combined CFD experimental program focused on key hypersonics aerodynamic elements to provide validated units for combination into realistic configurations at flight conditions that can be reached by ground facilities. 1 1 ) We recommend that the field of low density flows be given special attention with regard to direct simulation of particulate flows and experimental validation. This would provide much needed information on high altitude, high Mach number flight conditions where continuum Navier-Stokes computations are of uncertain accuracy. The applica- tion of the aerodynamic studies, both computational and ground- based, will require detailed knowledge of the characteristics of the stratosphere to translate the