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Emerging advanced controls technology will allow future generation fighter aircraft to aggressively maneuver at high angles-of-attack. Currently there is a need to develop flight-validated design methodologies and guidelines to effectively integrate this technology into future aircraft. As part of the NASA High-Alpha Technology Program (HATP), advanced controls technology is being developed in ground-based research and demonstrated using the High-Alpha Research Vehicle (HARV) as a flying testbed. Efforts are in progress to develop flight validated control law design methodologies and design guidelines which could be used to effectively exploit the capabilities provided by advanced controls at high angles of attack. This paper outlines this research effort and summarizes the design process and preliminary methodologies and guidelines developed to date.

This paper describes the analysis and performance testing of a uniquely designed external heat exchanger. The heat exchanger is attached externally to an aircraft and is used to cool a laser system within the fuselage. Estimates showed insufficient cooling capacity with a conventional staggered tube array in the limited space available. Thus, a non-conventional design was developed with larger tube and fin area exposed to the ram air to increase the heat transfer performance. The basic design consists of 28 circular finned aluminum tubes arranged in two parallel banks. Wind tunnel tests were performed to simulate air and liquid flight conditions for the non-conventional parallel bank arrangement and the conventional staggered tube arrangement. Performance comparisons of each of the two designs are presented. Test results are used in a computer model of the heat exchanger to predict the operating performance for the entire flight profile.

The design and analysis of the National Aerospace Plane (NASP) depends heavily on developing critical technology areas through the Technology Maturation Program (TMP). The TMP is being completed almost entirely in government laboratories with technology dissemination to all prime NASP contractors immediately upon completion of any portion of the technology development. These critical technology areas span the entire engineering design of the vehicle; included are structures, materials, propulsion systems, propellants, propulsion/airframe integration, controls, subsystems, and aerodynamics areas. There is currently a heavy dependence on Computational Fluid Dynamics (CFD) for verification of many of the classical engineering tools. Quite often the design of an aircraft uses wind tunnel tests for much of this verification, but for NASP, this task is almost impossible from a practical standpoint.

Results of a recent low-speed wind-tunnel investigation conducted to define the forebody flow on a 16% scale model of the NASA High Angle-of-Attack Research Vehicle (HARV), an F-18 configuration, are presented with analysis. Measurements include force and moment data, oil-flow visualizations, and surface pressure data taken at angles of attack near and above maximum lift (36° to 52°) at a Reynolds number of one million based on mean aerodynamic chord. The results presented identify the key flow-field features on the forebody including the wing-body strake.

One of the factors needed to describe the wear behavior of the Space Shuttle Orbiter main gear tires is their behavior during the spin-up process. An experimental investigation of tire spin-up processes was conducted at the NASA Langley Research Center's Aircraft Landing Dynamics Facility (ALDF). During the investigation, the influence of various parameters such as forward speed and sink speed on tire spin-up forces were evaluated. A mathematical model was developed to estimate drag forces and spin-up times and is presented. The effect of prerotation was explored and is discussed. Also included is a means of determining the sink speed of the orbiter at touchdown based upon the appearance of the rubber deposits left on the runway during spinup.

A method for thermally analyzing convectively cooled flight experiments is presented in this paper. A three-dimensional fluid flow analysis code was used to optimize air circulation patterns and predict air velocities in thermally critical areas. A comparison between a fan flow analysis using this code and the performance characteristics of a typical isothermal free jet was made. The velocity profiles and radial distribution agree well for downstream mixing of the flow. Predicted air velocities from the fluid analysis were used to calculate forced convection coefficients for the flight experiment. These convection coefficients were used in a finite difference thermal analysis code to describe the response of air temperature and heat loss for the LIDAR Atmospheric Sensing Experiment (LASE) during transient flight profiles. The performance of the existing thermal design is described and the analytical techniques used to arrive at this design are presented.