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ABCD - An Improved Coast Down Test and Analysis Method
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English
Abstract
An improved coast down method that incorporates the input of data measured with an onboard anemometer into the governing equation of motion is used to evaluate models representing the aerodynamic and mechanical drag characteristics of a wide variety of vehicles. Results from the application of the improved technique are presented to demonstrate the repeatability and precision of the analyzed aerodynamic drag coefficients, to address the merits of different wind tunnel blockage correction methods, to illustrate the method's usefulness in the study of tractor-trailer and light truck-travel trailer aerodynamic drag, to evaluate the influence of floor blowing in wind tunnel studies of the effects of various changes to the underbody of an automobile, and to compare track and dynamometer determinations of the variation of mechanical drag with speed on a vehicle equipped with a four-speed automatic transmission.
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Authors
Citation
Buckley, F., "ABCD - An Improved Coast Down Test and Analysis Method," SAE Technical Paper 950626, 1995, https://doi.org/10.4271/950626.Also In
References
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- White, R. A. Korst, H. H. “The Determination of Vehicle Drag Contribution from Coast-Down Test” SAE Paper 720099 1972
- Yasin, T. P. “The Analytical Basis of Automobile Coastdown Testing” SAE Paper 780334 1978
- Walston, W. H., Jr. Buckley, F. T., Jr. Marks, C. H. “Test Procedures for the Evaluation of Aerodynamic Drag on Full-Scale Vehicles in Windy Environments” SAE Transactions 85 September 1976
- Buckley, F. T., Jr. Walston, W. H., Jr. Marks, C. H. “Analysis of Coast-Down Data to Assess the Aerodynamic Drag Reduction on Full-Scale Tractor-Trailer Trucks in Windy Environments” SAE Transactions 85 September 1976
- Hamabe, K. Kitoh, K. Ogata, H. Kobayashi, T. “An Estimation of Aerodynamic Drag Coefficient of a Passenger Car by Coast-Down Tests in Windy Environments” JSAE Review 114 April 1985
- Passmore, M. A. Jenkins, E. G. “A Comparison of the Coastdown and Steady State Torque Methods of Estimating Vehicle Drag Forces” SAE Paper 880475 1988
- SAE Recommended Practice J1263 “Road Load Measurement and Dynamometer Simulation using Coastdown Techniques” June 1979 June 1991
- Young, H. D. Statistical Treatment of Experimental Data McGraw-Hill New York, NY 1962 07-072646-9
- Hackett, J. E. Wilsden, D. J. “Estimation of Wind-Tunnel Blockage from Wall-Pressure Signatures” AIAA Tenth Annual Aerodynamic Testing Conference San Diego, CA April 1978
- Buckley, F. T., Jr. Sekscienski, W. S. “Comparisons of Effectiveness of Commercially Available Devices for the Reduction of Aerodynamic Drag on Tractor Trailers” SAE Transactions 84 September 1975
- SAE Recommended Practice J1252 “Wind Tunnel Test Procedure for Trucks and Buses” August 1979
- Buckley, F. T., Jr. “Aspects of Over-the-Road Testing of Truck Drag Reducing Devices” SAE Transactions 91 September 1982