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High-speed vehicle structures have been of interest since the earliest days of aviation. Every since that fateful day at Kittyhawk, North Carolina, the quest for speed has been inseparable from the world of aviation. Some of the advances in structures technology are explored specifically for hypersonic flight vehicle structures during the first century of aviation. In particular, those advances pointing toward the next century hypersonic vehicles are examined.

The degree of space-use overlap among adjacent individuals is a central focus of many wildlife investigations. We studied the comparability of minimum convex polygon and fixed-kernel home-range overlap indices and Volume of Intersection (VI) scores using simulated data. We simulated pairs of point patterns to represent telemetry locations of adjacent individuals and varied the amount of potential overlap in the simulation region (100%, 50%, and 10%) and the point distribution (random, loosely clumped, and tightly clumped). We created 1,000 pairs of point sets (60 points in each individual set) for each of the 9 potential overlap and point distribution combinations. In all 9 treatment combinations, VI scores were highest followed by kernel and then polygon estimates. Raw differences among estimates within a treatment were greatest when there was 50% potential overlap, and overlap indices decreased as the degree of clumping increased. The relative differences among overlap indices within a treatment were affected most by potential overlap; differences generally were greatest at 10% and least at 100%. Correlation between index values was lowest for random point patterns, and highest for loosely clumped and tightly clumped point patterns. Although the VI tended to indicate the most overlap and minimum convex polygon the least, there was no consistent correction factor among techniques because of the interacting effects of the overlap index, distribution pattern, and potential overlap. Interpretation of overlap measures requires careful consideration of assumptions and properties of animals under study.

The finite element method is used to study double diffusive convection in a rectangular box containing a porous medium. The porous medium is described by means of the Darcy-Brinkman model. The problem solved is the Benard problem in the box. It is found that the stability of the flow is dependent on a combination of thermal Rayleigh number, buoyancy ratio, and Lewis number. This combination for the onset of cellular motion can be written as Ra (1+ N.Le )=4π π 2 . This criterion holds for all combinations of Ra, N, and Le whether the thermal and solutal gradients are aiding or opposing each other. Numerical results are presented in the form of flow, temperature, and concentration fields and average Nusselt and Sherwood numbers.

The properties of the numerical solution of turbulence equations are examined using the finite element method. The set of equations used is the q-f turbulence equations, instead of the commonly used k-e equations. It is found that from a purely numerical point of view, the former has several desirable features over the latter in that the coupling between the equations is quite weak, and the signs of diffusivities, sources and sinks are independent of the sign of q and f. An algorithm for solving the q-f equations is presented using Galerkin's finite element method. Several numerical examples verifying the robustness and stability of the algorithm are presented.

This paper provides an overview of the evolution of structures and materials technology approaches to survive the challenging extreme environments encountered by earth-to-orbit space transportation systems, with emphasis on more recent developments in the USA. The evolution of technology requirements and experience in the various approaches to meeting these requirements has significantly influenced the technology approaches. While previous goals were primarily performance driven, more recently dramatic improvements in costs/operations and in safety have been paramount goals. Technologies that focus on the cost/operations and safety goals in the area of hot structures and thermal protection systems for reusable launch vehicles are presented. Assessments of the potential ability of the various technologies to satisfy the technology requirements, and their current technology readiness status are also presented

The Structures and Aeromechanics Divisions of the Flight Dynamics Directorate, Wright Laboratory, Wright‐Patterson Air Force Base, Ohio have a long history of activities in transatmospheric vehicle (TAV) technology development. Included in these activities were research and development efforts in thermal protection systems (TPS), cryogenic fuel tanks, and hot structures. Additional efforts existed in the aerodynamics, aerothermodynamics, and performance of transatmospheric, hypersonic, and lifting reentry vehicle configurations. High payoff TAVresearch and development activities in the Flight Dynamics Directorate continue today and are planned for the future.

Natural convection heat transfer around a cylinder embedded in a porous medium is studied numerically using the penalty finite-element method. To model fluid flow inside the porous medium, the Brinkman and Brinkman-Forschheimer equations are used. Numerical results are obtained in the form of streamlines and isotherms. The Rayleigh number values range from 0.04 to 200. Calculated values of average heat transfer rates agree reasonably well with values reported in the literature.