Document ID: chunk:federal_register_of_legislation:F2024L00446:reg:16:p21
Version: federal_register_of_legislation:F2024L00446
Segment Type: reg
Provision Reference: reg 16 (pt 21/108)
Character Range: 942638–945801

the flat belt or chassis dynamometer at reference speed j, N;

              fj is the measured force at reference speed j, N;

                  K0 is the correction factor for rolling resistance as defined in paragraph 4.5.2. of this annex, K-1;

                  K1 is the test mass correction as defined in paragraph 4.5.4. of this annex, N;

                  T is the arithmetic average temperature in the test cell during the measurement, K.

              6.7.2. Calculation of the aerodynamic force

              The calculation in paragraph 6.7.2.1. shall be applied considering the results of both wind speeds. However, if the difference of the product of the drag coefficient and frontal area measured at the wind speeds vlow and vhigh is less than 0.015 m², the calculation in paragraph 6.7.2.2. may be applied at the request of the manufacturer.

              6.7.2.1. The aerodynamic force of each wind speed F0wind, Flow, and Fhigh shall be calculated using the equation below.

               where:

                     is the product of the drag coefficient and frontal area measured in the wind tunnel at a certain reference speed point j, if applicable, m²;

                    ρ0 is the dry air density defined in paragraph 3.2.10. of this Regulation, kg/m³;

                    Fw is the aerodynamic force calculated at wind speed w, N;

                    vw is the applicable wind speed, km/h.

                    w is the reference to the applicable wind speed "0wind", "low" and "high";

                    F0wind is the aerodynamic force at 0 km/h, N;

                    Flow is the aerodynamic force at vlow, N;

                    Fhigh is the aerodynamic force at vhigh, N.

              The aerodynamic force coefficients f1a and f2a shall be calculated with a least square regression analysis using F0wind, Flow, and Fhigh and the equation below:

              The final result for the aerodynamic force FAj shall be calculated with the equation below at each reference speed point vj. If the vehicle is equipped with velocity-dependent movable aerodynamic body parts, the corresponding aerodynamic force shall be applied for the reference speed points concerned.

              6.7.2.2. The aerodynamic force shall be calculated using the equation below, where the final (CD × Af) of that wind speed shall be used that is also used for determination of optional equipment within the interpolation method. If the vehicle is equipped with velocity-dependent movable aerodynamic body parts, the corresponding (CD × Af) values shall be applied for the reference speed points concerned.

              where:

                     FAj is the aerodynamic force calculated at reference speed j, N;

                      is the product of the drag coefficient and frontal area measured in the wind tunnel at a certain reference speed point j, if applicable, m²;

                     ρ0 is the dry air density defined in paragraph 3.2.10. of this Regulation, kg/m³;

              vj is the reference speed j, km/h.

              6.7.3. Calculation of road load values

              The total road load as a sum of the