SAE J1252_201207

The scope of this SAE Recommended Practice is sufficiently broad that it encompasses the full range of full-scale medium and heavy duty vehicles represented as either full-scale or reduced-scale wind tunnel models. The document provides guidance for wind tunnel testing to support current vehicle characterization, vehicle development, vehicle concept development, and vehicle component development. Wind tunnel testing of heavy vehicles has evolved in the past thirty years with new facility types, new ground simulation techniques, and more robust methods for estimating aerodynamic force and moment coefficients. References have been added for support of the narrative and emphasize the common elements between automotive and heavy vehicle testing, and thus avoid duplication of material. The origin of the US average annual wind speed was not disclosed in the original document and is now supported by references and calculations performed by the revision task force. The derivation of the wind averaged drag coefficient and a sample calculation have been added for completeness. Uncertainty bounds are a required element for any contemporary wind tunnel test report and a suggested uncertainty analysis method has been added for the first time with an included sample calculation.