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Recently, there has been a strong emphasis on aerodynamic and aeroacoustic wind tunnel testing of automobiles. While significant level resources have been spent on investigating aerodynamics, the methodology has not changed appreciably since the beginning of aerodynamics as a science. Over the past decade, a number of global flow diagnostic techniques have been developed that drastically increase the quality and quantity of data from wind tunnel testing. One of these technologies is the use of pressure sensitive luminescent coatings, known as pressure-sensitive paint, a method which has matured considerably since its inception and is now used extensively in aerospace applications with good results. The goal of this research is to implement this technology in the full scale testing of high performance automotive vehicles. This paper discusses the details of a preliminary test, such as technique, paint formulation, camera and lighting hardware, and data reduction and analysis.

Pressure Sensitive Paint (PSP) has been used for several years by the aircraft industry in transonic wind tunnel testing where the oxygen concentrations are low and the luminescence of the paint is easily recorded. Extending PSP to slower speeds where the oxygen concentrations are closer to atmospheric conditions is much more challenging. For the past few years, work has been underway at both Wright Patterson Air Force Base and Ford Motor Company to advance PSP techniques for testing at slower speeds. The CRADA (Cooperative Research and Development Agreement) provided a way for comparisons to be made of the different PSP systems that were being investigated. This paper will report on PSP tests conducted as part of the CRADA.

This paper describes research and development for reducing the aerodynamic drag of heavy vehicles by demonstrating new approaches for the numerical simulation and analysis of aerodynamic flow. Experimental validation of new computational fluid dynamics methods are also an important part of this approach. Experiments on a model of an integrated tractor-trailer are underway at NASA Ames Research Center and the University of Southern California (USC). Companion computer simulations are being performed by Sandia National Laboratories (SNL), Lawrence Livermore National Laboratory (LLNL), and California Institute of Technology (Caltech) using state-of-the-art techniques.

An experimental investigation of the flow over the rear end of a 0.16 scale notchback automobile configuration has been conducted in the NASA Langley Basic Aerodynamics Research Tunnel (BART). The objective of this work was to investigate the flow separation that occurs behind the backlight and obtain experimental data that can be used to understand the physics and time-averaged structure of the flow field. A three-component laser velocimeter was used to make non-intrusive, velocity measurements in the center plane and in a single cross-flow plane over the decklid. In addition to off-body measurements, flow conditions on the car surface were documented via surface flow visualization, boundary layer measurements, and surface pressures.

This paper describes research and development for reducing the aerodynamic drag of heavy vehicles by demonstrating new approaches for the numerical simulation and analysis of aerodynamic flow. In addition, greater use of newly developed computational tools holds promise for reducing the number of prototype tests, for cutting manufacturing costs, and for reducing overall time to market. Experimental verification and validation of new computational fluid dynamics methods are also an important part of this approach. Experiments on a model of an integrated tractor-trailer are underway at NASA Ames Research Center and the University of Southern California. Companion computer simulations are being performed by Sandia National Laboratories, Lawrence Livermore National Laboratory, and California Institute of Technology using state-of- the-art techniques, with the intention of implementing more complex methods in the future.

Hover and ground-effect tests were conducted with the Lockheed-Martin Large Scale Powered Model (LSPM) during June-November 1995 at the Outdoor Aerodynamics Research Facility (OARF) located at NASA Ames Research Center. This was done in support of the Joint Strike Fighter (JSF) Program being lead by the Department of Defense. The program was previously referred to as the Joint Advanced Strike Technology (JAST) Program. The tests at the OARF included: engine thrust calibrations out of ground effect, measurements of individual nozzle jet pressure decay characteristics, and jet-induced hover force and moment measurements in and out of ground effect. The engine calibrations provide data correlating propulsion system throttle and nozzle settings with thrust forces and moments for the bare fuselage with the wings, canards, and tails removed. This permits measurement of propulsive forces and moments while minimizing any of the effects due to the presence of the large horizontal surfaces.

Noise is a barrier issue for penetration of civil markets by future tiltrotor aircraft. To address this issue, elements of the NASA Short Haul (Civil Tiltrotor) [SH(CT)] program are working in three different areas: noise abatement, noise reduction, and noise prediction. Noise abatement refers to modification of flight procedures to achieve quieter approaches. Noise reduction refers to innovative new rotor designs that would reduce the noise produced by a tiltrotor. Noise prediction activities are developing the tools to guide the design of future quiet tiltrotors. This paper presents an overview of SH(CT) activities in all three areas, including sample results.

This paper summarizes the results to date of an on-going research program being conducted by NASA in conjunction with the FAA vertical flight program office. The goal of the program is to reduce pilot workload and increase safety for rotorcraft category A terminal area procedures. Two piloted simulations were conducted on the NASA Ames Vertical Motion Simulator to examine the benefits of optimal procedures, cockpit displays, and alternate cueing methods. Measures of performance, handling qualities ratings and pilot comments indicate that such enhancements can greatly assist a pilot in handling an engine failure in the terminal area.

The need for highly accurate measurements of velocity, temperature, pressure and density has required the development of new experimental techniques. While the majority of these development efforts at NASA Langley are focused toward applications for aeronautical programs such as the High-Speed Civil Transport, Advanced Subsonic Transport, and the National Aero-Space Plane, a number are applicable to other fields. The intent of this paper is to review recent instrumentation developments and applications at NASA Langley Research Center that may have applications in automotive testing. Five experimental techniques are described along with recent results obtained in NASA facilities.

An automatic trim system for reducing the control forces after an engine failure on a light twin has been investigated on the Langley General Aviation Simulator. The system schedules open-loop trim tab deflections as a function of differential propeller slipstream dynamic pressure and freestream dynamic pressure. The system is described and the airplane-system static and dynamic characteristics are documented. Three NASA research pilots evaluated the effectiveness of the system for takeoff and landing maneuvers. A variety of off-nominal system characteristics were studied. The system was judged to be generally beneficial, providing a 2 to 3 point improvement in pilot rating for the tasks used in the evaluations.