Document ID: chunk:federal_register_of_legislation:F2024L00446:reg:10:p9
Version: federal_register_of_legislation:F2024L00446
Segment Type: reg
Provision Reference: reg 10 (pt 9/32)
Character Range: 1293766–1296956

procedure is not satisfied, the approval of the alternative method is regarded as invalidated.
              3.2.3.2.2.3.3. Application of aerodynamic influence on the individual vehicle
              is the difference in the product of the aerodynamic drag coefficient multiplied by frontal area between an individual vehicle and test vehicle L due to options and body shapes on the vehicle that differ from those of test vehicle L, m2;
              These differences in aerodynamic drag, Δ(CD×Af), shall be determined with an accuracy of ±0.015 m².
              Δ(CD×Af)ind may be calculated according to the following equation maintaining the accuracy of ±0.015 m² also for the sum of items of optional equipment and body shapes:
              where:
                      is the aerodynamic drag coefficient;
                      is the frontal area of the vehicle, m2;
                      is the number of items of optional equipment on the vehicle that are different between an individual vehicle and test vehicle L;
                      is the difference in the product of the aerodynamic drag coefficient multiplied by frontal area due to an individual feature, i, on the vehicle and is positive for an item of optional equipment that adds aerodynamic drag with respect to test vehicle L and vice versa, m2.
              The sum of all Δ(CD×Af)i differences between test vehicles L and H shall correspond to Δ(CD×Af)LH.
              3.2.3.2.2.3.4. Definition of complete aerodynamic delta between test vehicles L and H
              The total difference of the aerodynamic drag coefficient multiplied by frontal area between test vehicles L and H shall be referred to as Δ(CD×Af)LH and shall be recorded, m².
              3.2.3.2.2.3.5. Documentation of aerodynamic influences
              The increase or decrease of the product of the aerodynamic drag coefficient multiplied by frontal area expressed as Δ(CD×Af) for all items of optional equipment and body shapes in the interpolation family that:
                  (a) Have an influence on the aerodynamic drag of the vehicle; and
                  (b) Are to be included in the interpolation,
                     shall be recorded, m².
              3.2.3.2.2.3.6. Additional provisions for aerodynamic influences
              The aerodynamic drag of vehicle H shall be applied to the whole interpolation family and Δ(CD×Af)LH shall be set to zero, if:
                  (a)  The wind tunnel facility is not able to accurately determine Δ(CD×Af); or
                  (b)  There are no drag-influencing items of optional equipment between the test vehicles H and L that are to be included in the interpolation method.
              3.2.3.2.2.4. Calculation of road load coefficients for individual vehicles
              The road load coefficients ,  and  (as defined in Annex B4) for test vehicles H and L are referred to as ,  and ,and ,  and  respectively. An adjusted road load curve for the test vehicle L is defined as follows:
              Applying the least squares regression method in the range of the reference speed points, adjusted road load coefficients  and  shall be determined for  with the linear