Document ID: chunk:federal_register_of_legislation:F2012C00283:reg:21:p35
Version: federal_register_of_legislation:F2012C00283
Segment Type: reg
Provision Reference: reg 21 (pt 35/39)
Character Range: 353710–357411

direction: t2.
              5.1.1.2.5. Take the average T of the two times t1 and t2.
              5.1.1.2.6. Repeat these tests several times such that the statistical accuracy (p) of the average

           is not more than 2 per cent (p ≤ 2 per cent)

               The statistical accuracy (p) is defined by:

 Where:
 t       =  coefficient given by the following table,
 n       =  number of tests,
 s       =  standard deviation,

n  4    5     6     7     8     9     10    11    12    13    14    15
t  3.2  2.8   2.6   2.5   2.4   2.3   2.3   2.2   2.2   2.2   2.2   2.2
   1.6  1.25  1.06  0.94  0.85  0.77  0.73  0.66  0.64  0.61  0.59  0.57

              5.1.1.2.7. Calculate the power by the formula:

 Where:
 P          is expressed in kW,
 V       =  speed of the test in m/s,
 ΔV      =  speed deviation from speed V, in m/s as specified in paragraph 5.1.1.2.3. of this appendix,
 M       =  reference mass in kg,
 T       =  time in seconds (s).

              5.1.1.2.8. The power (P) determined on the track shall be corrected to the reference ambient conditions as follows:
         PCorrected  =  K · PMeasured

 Where:
 RR      =  rolling resistance at speed V,
 RAERO   =  aerodynamic drag at speed V,
 RT      =  total driving resistance = RR + RAERO,
 KR      =  temperature correction factor of rolling resistance, taken to be equal to 8.64 x 10-3/°C, or the manufacturer's correction factor that is approved by the authority,
 t       =  road test ambient temperature in °C,
 t0      =  reference ambient temperature = 20 °C,
 ρ       =  air density at the test conditions,
 ρ0      =  air density at the reference conditions (20 °C, 100 kPa).

               The ratios RR/RT and RAERO/RT shall be specified by the vehicle manufacturer based on the data normally available to the company.
               If these values are not available, subject to the agreement of the manufacturer and the technical service concerned, the figures for the rolling/ total resistance given by the following formula may be used:

 Where:
 M       =         vehicle mass in kg and for each speed the coefficients a and b are shown in the following table:
         V (km/h)  a                                                                                                 b
         20        7.24 · 10-5                                                                                       0.82
         40        1.59  ·10-4                                                                                       0.54
         60        1.96 · 10-4                                                                                       0.33
         80        1.85 · 10-4                                                                                       0.23
         100       1.63 · 10-4                                                                                       0.18
         120       1.57 · 10-4                                                                                       0.14

              5.1.2. On the dynamometer
              5.1.2.1. Measurement equipment and accuracy
               The equipment shall be identical to that used on the road.
              5.1.2.2. Test procedure
              5.1.2.2.1. Install the vehicle on the test dynamometer.
              5.1.2.2.2. Adjust the tyre pressure (cold) of the driving wheels as required by the dynamometer.
              5.1.2.2.3. Adjust the equivalent inertia of the dynamometer.
              5.1.2.2.4. Bring the vehicle and dynamometer to operating temperature in a suitable manner.
              5.1.2.2.5. Carry out the operations specified in paragraph 5.1.1.2. above