Where:
F = the mean force measured during the coastdown for each speed interval and inertia setting, expressed in lbf and rounded to four significant figures.
I = the dynamometer's inertia setting, in lbf·s2/ft.
vinit = the speed at the start of the coastdown interval, expressed in ft/s to at least four significant figures.
vfinal = the speed at the end of the coastdown interval, expressed in ft/s to at least four significant figures.
t = coastdown time for each speed interval and inertia setting, accurate to at least 0.01 s.
Example:
I = 2000 lbm = 62.16 lbf·s2/ft
vinit = 25 mi/hr = 36.66 ft/s
vfinal = 15 mi/hr = 22.0 ft/s
t = 5.00 s
F = 182.3 lbf
Fact, to the corresponding Fref to determine values for coastdown force error, Ferror, using the following equation:
Example:
Fref = 192 lbf
Fact = 191 lbf
Ferror = 0.5%
Example:
Fref = 192 lbf
Ferrormax = 1.14%
40 C.F.R. §1066.270