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Develop and document an aerodynamic constant speed procedure for heavy vehicles that can accurately calculate the aerodynamic performance through the typical expected yaw angles during operation at highway speeds.

This document describes a rigorous-engineering fuel-consumption test procedure that utilizes industry accepted data collection and statistical analysis methods to determine the change in fuel consumption for trucks and buses with GVWR of more than 10,000 pounds. The test procedure may be conducted on a test track or on a public road under controlled conditions and supported by extensive data collection and data analysis constraints. The on-road test procedure is offered as a lower cost alternative to on-track testing but the user is cautioned that on-road test may result in lower resolution (or precision) data due to a lack of control over the test environment. Test results that do not rigorously follow the method described herein are not intended for public use and dissemination and shall not be represented as a J1321-Type II test result.

This document describes a rigorous-engineering fuel-consumption test procedure that utilizes industry accepted data collection and statistical analysis methods to determine the change in fuel consumption for individual trucks and buses with GVWR of more than 10000 pounds. The test procedure may be conducted on a test track or on a public road under controlled conditions and supported by extensive data collection and data analysis constraints. The on-road test procedure is offered as a lower cost alternative to on-track testing, but the user is cautioned that on-road test may result in lower resolution (or precision) data due to a lack of control over the test environment. Test results that do not rigorously follow the method described herein are not intended for public use and dissemination and shall not be represented as an SAE J1321-Type II test result.

This procedure incorporates test cycles that produce relative fuel economy data relating to long haul, short haul, and local driving patterns, or any combination of these and to those components developed to improve fuel economy for these patterns. The tests conducted on a specific vehicle are to reflect that vehicle's general mode of operation. The procedure is intended to be used under controlled, warmed-up conditions on a test tract or on suitable roads. A minimum of two vehicles running simultaneously is required. Test condition recommendations are provided for undertaking this engineering test. If it is necessary to conduct a test outside of these test conditions, the purpose of the test and the variant conditions should be recorded and noted whenever the results are reported.

This document outlines general requirements for the use of CFD methods for aerodynamic simulation of medium and heavy commercial ground vehicles weighing more than 10 000lbs. The document provides guidance for aerodynamic simulation with CFD methods to support current vehicle characterization, vehicle development, vehicle concept development and vehicle component development. The guidelines presented in the document are related to Navier-Stokes and Lattice-Boltzmann based solvers. This document is only valid for the classes of CFD methods and applications mentioned. Other classes of methods and applications may or may not be appropriate to simulate the aerodynamics of medium and heavy commercial ground vehicle weighing more than 10 000lbs.

This document outlines general requirements for the use of CFD methods for aerodynamic simulation of medium and heavy commercial ground vehicles weighing more than 10 000lbs. The document provides guidance for aerodynamic simulation with CFD methods to support current vehicle characterization, vehicle development, vehicle concept development and vehicle component development. The guidelines presented in the document are related to Navier-Stokes and Lattice-Boltzmann based solvers. This document is only valid for the classes of CFD methods and applications mentioned. Other classes of methods and applications may or may not be appropriate to simulate the aerodynamics of medium and heavy commercial ground vehicle weighing more than 10 000lbs.

This document outlines general requirements for the use of CFD methods for aerodynamic simulation of medium and heavy commercial ground vehicles weighing more than 10000 pounds. The document provides guidance for aerodynamic simulation with CFD methods to support current vehicle characterization, vehicle development, vehicle concept development, and vehicle component development. The guidelines presented in the document are related to Navier-Stokes and Lattice-Boltzmann based solvers. This document is only valid for the classes of CFD methods and applications mentioned. Other classes of methods and applications may or may not be appropriate to simulate the aerodynamics of medium and heavy commercial ground vehicle weighing more than 10000 pounds.

This recommended practice provides minimum requirements for testing components or systems of the type which can be switched from one truck to another with relative ease; i.e., aerodynamic devices, clutch fans, radial tires, and the like. The test utilizes in-service fleet vehicles, operated over representative routes. The relative fuel effectiveness of the component or system under test is determined as a percentage improvement factor. This factor is calculated using the relative fuel usage of like vehicles operating with and without the specific component or system under evaluation. Accuracy capability employing this test technique is either ±1% or ±2%, depending upon the method of fuel measured. (See paragraph 7.4.)

This recommended practice provides minimum requirements for testing components or systems of the type which can be switched from one truck to another with relative ease; i.e., aerodynamic devices, clutch fans, radial tires, and the like. The test utilizes in-service fleet vehicles, operated over representative routes. The relative fuel effectiveness of the component or system under test is determined as a percentage improvement factor. This factor is calculated using the relative fuel usage of like vehicles operating with and without the specific component or system under evaluation. Accuracy capability employing this test technique is either ±1% or ±2%, depending upon the method of fuel measurement. (See paragraph 6.4.)

The test utilizes two medium to heavy duty in-service vehicles operated over interstate type highways. The relative fuel economy of the component, system, or vehicle under test is expressed as a percentage improvement or as a percentage of fuel saved. This factor is calculated using relative fuel consumption while operating with and without the test component, system, or vehicle under evaluation. Accuracy obtained from the use of this test procedure can be ±% when properly executed. This procedure is not intended to replace SAE J1264 OCT86, Joint RCCC/SAE Fuel Consumption Test Procedure or SAE J1321 OCT86, Joint TMC/SAE Fuel Consumption Test Procedure Type II, but will enhance a fleet's or manufacturer's ability to do a wide variety of fuel consumption tests on highway. The following basic rules must be applied to this procedure to ensure valid test results: a A single test is inconclusive. A single test result may be an indicator.

This recommended practice provides a standardized test procedure for comparing the in-service fuel consumption of two conditions of a test vehicle or of one test vehicle to another when it is not possible to run the two or more test vehicles simultaneously. An unchanging control vehicle is run in tandem with the test vehicle(s) to provide reference fuel consumption data. This procedure is especially suitable for testing components which require substantial time for removal and replacement or modification, such as engines, transmissions, tag-axles, and cab sheet metal. This procedure may also be used for comparison of entire vehicles and for easy-to-change components (those referenced in the Type I test described in SAE Recommended Practice, SAE J1264). The test may utilize fleet vehicles operating over representative routes.

This recommended practice provides minimum requirements for testing components or systems of the type which can be switched from one truck to another with relative ease; i.e., aerodynamic devices, clutch fans, radial tires, and the like. The test utilizes in-service fleet vehicles, operated over representative routes. The relative fuel effectiveness of the component or system under test is determined as a percentage improvement factor. This factor is calculated using the relative fuel usage of like vehicles operating with and without the specific component or system under evaluation. Accuracy capability employing this test technique is either ±1% or ±2%, depending upon the method of fuel measured. (See paragraph 7.4.)

This document describes a fuel-consumption test procedure that utilizes industry accepted data collection and statistical analysis methods to determine the difference in fuel consumption between vehicles with a gross vehicle weight of more than 10000 pounds. This test procedure can be used for an evaluation of two or more different vehicles but is not to be used to evaluate a component change. Although on-road testing is allowed, track testing is the preferred method because it has the greatest opportunity to minimize weather and traffic influences on the variability of the results. All tests shall be conducted in accordance with the weather constraints described within this procedure and shall be supported by collected data and analysis. This document provides information that may be used in concert with SAE Recommended Practices SAE J1264, SAE J1252, SAE J1321, and SAE J2966, as well as additional current and future aerodynamic and vehicle performance SAE standards.

This document describes a fuel-consumption test procedure that utilizes industry accepted data collection and statistical analysis methods to determine the difference in fuel consumption between vehicles with a gross vehicle weight of more than 10,000 pounds. This test procedure can be used for an evaluation of two or more different vehicles but is not to be used to evaluate a component change. Although on-road testing is allowed, track testing is the preferred method because it has the greatest opportunity to minimize weather and traffic influences on the variability of the results. All tests shall be conducted in accordance with the weather constraints described within this procedure and shall be supported by collected data and analysis. This document provides information that may be used in concert with SAE Recommended Practices J1264, J1252, J1321, and J2966 as well as additional current and future aerodynamic and vehicle performance SAE standards.

The scope of this recommended practice is sufficiently broad that it can encompass the full range of current heavy duty vehicles, vehicle modifications, and prototype configurations. The test procedure describes methods for examination of the vehicle’s flow field using surface pressures and flow visualization.

The scope of this SAE Recommended Practice is sufficiently broad that it can encompass the full range of current heavy duty vehicles, vehicle modifications, and prototype configurations. The test procedure describes methods for examination of the vehicle’s flow field using surface pressures and flow visualization.

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.

This information report is a companion document to SAE Recommended Practice J1376, Fuel Economy Measurement Test (Engineering Type) for Trucks and Buses. It provides background information and explanations to better understand the measurement procedure and its use. It also provides references and data which were developed by the SAE/DOT Program in support of the particular limitations or parameters selected for the various items in the test procedure. The format used in this document is similar to the recommended practice so that corresponding topics can be found under the same headings.

The testing techniques outlined in this SAE Recommended Practice were developed as part of an overall program for testing and evaluating fuel consumption of heavy-duty trucks and buses. The technique outlined in this recommended practice provides a general description of the type of equipment and facility which is necessary to determine the power consumption of these engine-driven components. It is recommended that the specific operating conditions suggested throughout the test be carefully reviewed on the basis of actual data obtained on the specific vehicle operation. If specific vehicle application is not known, see SAE J1343, “Information Relating to Duty Cycles and Average Power Requirements of Truck and Bus Engine Accessories,” Section 3, Air Brake Compressors and Section 5, Air Conditioning Compressor.

The testing techniques outlined in this SAE Recommended Practice were developed as part of an overall program for testing and evaluating fuel consumption of heavy-duty trucks and buses. The technique outlined in this document provides a general description of the type of equipment and facility which is necessary to determine the power consumption of these engine-driven components. It is recommended that the specific operating conditions suggested throughout the test be carefully reviewed on the basis of actual data obtained on the specific vehicle operation. If specific vehicle application is not known, see SAE J1343.