Document ID: chunk:federal_register_of_legislation:F2024L00446:reg:16:p2
Version: federal_register_of_legislation:F2024L00446
Segment Type: reg
Provision Reference: reg 16 (pt 2/108)
Character Range: 888770–891817

to paragraph 4.2.4. of this annex.
              4.3.2.1. Additional instrumentation for on-board anemometry
              The on-board anemometer and instrumentation shall be calibrated by means of operation on the test vehicle where such calibration occurs during the warm-up for the test.
              4.3.2.1.1. Relative wind speed shall be measured at a minimum frequency of 1 Hz and to an accuracy of 0.3 m/s. Vehicle blockage shall be accounted for in the calibration of the anemometer.
              4.3.2.1.2. Wind direction shall be relative to the direction of the vehicle. The relative wind direction (yaw) shall be measured with a resolution of 1 degree and an accuracy of 3 degrees; the dead band of the instrument shall not exceed 10 degrees and shall be directed towards the rear of the vehicle.
              4.3.2.1.3. Before the coastdown, the anemometer shall be calibrated for speed and yaw offset as specified in ISO 10521-1:2006(E) Annex A.
              4.3.2.1.4. Anemometer blockage shall be corrected for in the calibration procedure as described in ISO 10521-1:2006(E) Annex A in order to minimise its effect.
              4.3.2.2. Selection of vehicle speed range for road load curve determination
              The test vehicle speed range shall be selected according to paragraph 2.2. of this annex.
              4.3.2.3. Data collection
              During the procedure, elapsed time, vehicle speed, and air velocity (speed, direction) relative to the vehicle, shall be measured at a minimum frequency of 5 Hz. Ambient temperature shall be synchronised and sampled at a minimum frequency of 0.1 Hz.
              4.3.2.4. Vehicle coastdown procedure
              The measurements shall be carried out in run pairs in opposite directions until a minimum of ten consecutive runs (five pairs) have been obtained. Should an individual run fail to satisfy the required on-board anemometry test conditions, that pair, i.e. that run and the corresponding run in the opposite direction, shall be rejected. All valid pairs shall be included in the final analysis with a minimum of 5 pairs of coastdown runs. See paragraph 4.3.2.6.10. of this annex for statistical validation criteria.
              The anemometer shall be installed in a position such that the effect on the operating characteristics of the vehicle is minimised.
              The anemometer shall be installed according to one of the options below:
                  (a) Using a boom approximately 2 metres in front of the vehicle's forward aerodynamic stagnation point;
                  (b) On the roof of the vehicle at its centreline. If possible, the anemometer shall be mounted within 30 cm from the top of the windshield;
                  (c) On the engine compartment cover of the vehicle at its centreline, mounted at the midpoint position between the vehicle front and the base of the windshield.
              In all cases, the anemometer shall be mounted parallel to the road surface. In the event that positions (b) or (c) are used, the