MAHA LPS 3000, Руководство по эксплуатации, Страница: 34 / 115

34
BA052301-en
2.9 Calculation Basis
2.9.1 Road Load
Equation
m a
v
3,6 P
v
v 3,6 P
v
v 3,6 P
F
ref
Roll
2
ref
Flex
3
ref
2
Air
x
 +

+
 
+
 
=
with
•
v
ref
Reference speed for resistance performance values - normally 90
km/h.
•
v Driving speed
•
P
air
Air resistance performance [kW]
•
P
flex
Flex performance [kW]
•
P
Roll
Roll resistance performance [kW]
•
a.m Vehicle mass
Air resistance power P-Air [kW]
The air resistance power is proportional to the surface
of the vehicle front and air resistance coefficient c
w
.
v ) v (v A c 0,5 P
2
0 Front W Air
 +     =

with e.g.
•
Air density

(rho) =
1.1 kg/m 3
•
air resistance coefficient
c
W
= 0.38
•
Front surface
(VEH-width x Height)
A
Front
= 1.7 m · 1.47m = 2.5 m 2
•
Driving speed v = 90 km/h = 25 m/s
•
Head wind speed
v
0
= 0 m/s
results:
•
P
air
= 0,5 · 1,1 · 0,38 · 2,5 · 25 2 · 25 = 8.164 kW at 90 km/h
Flex power P-Flex [kW]
Flex power or resistance is defined as the power loss
which occurs due to the flexing of the tire on the road
surface and/or roller.
v g m P
w Flex
   =

Generally speaking the flex power does not have a relevant influence on the test results due to
the minimal flex resistance coefficient.