Tgross
R
R
= R terrain + R internal
S
ws v
lip = s
vs
0.1
0.2
Figure 17. Idealized tractionslip curve in snow.
Slip
1.0
Loose Sandy Soils
0.8
Dense Sandy Soils
0.6
0.4
Shallow Snow
0.2
Ice
0
Figure 18. Generalized tractionslip curves for
0
20
40
60
80
100
different surface materials.
Slip (%)
The maximum traction in snow occurs at
respectively. We recommend that this velocity cor-
about 20% slip, and
rection be applied before other effects are taken into
The tractionslip curve is nearly linear be-
account. Generalized tractionslip curves for differ-
tween 0 and 20% slip (Fig. 17),
ent materials are shown in Figure 18. These varia-
we claim that the slip when operating in snow
tions will need to be considered when or if the full
can be calculated from the following equation:
traction curves are incorporated into future mobil-
ity models.
0.2 (Rterrain + Rinternal )
Slipsnow =
(29)
Tgross
INTERNAL MOTION
RESISTANCE
for Tgross ≥ Rterrain + Rinternal.