study. Resistance in shallow snow was studied fur-
ment to obtain the resistance due only to the deform-
ther in an experimental program in 1993, also in
able snow (or other terrain). The experimental values
Houghton, Michigan, documented in Richmond
of rolling resistance presented here are only the por-
(1995). The data from these studies are given in Ta-
tion of the resistance due to the deformation of the
ble 11. The majority of these data were collected us-
terrain (snow).
ing Michelin XCH4 tires except where a different
CRREL has a large database of vehicle measure-
radius is noted. This database was used to develop a
ments in snow. For comparison to model data, most
semi-empirical performance model for mobility on
of the field measurements were taken from a study of
snow, which was incorporated into the NATO Refer-
wheeled and tracked vehicle performance in snow
ence Mobility Model (NRMM II) (Richmond et al.
that was performed in Houghton, Michigan, in 1988
1995, Ahlvin and Shoop 1995). Both the original data
and 1989 and documented in Blaisdell et al. (1990)
and the predictive algorithms were compared to the
and Green and Blaisdell (1991). Motion resistance
tiresnow finite element model.
measurements formed a significant portion of this
Table 11. Measured sinkage and resistance in snow. All
tires are the same (radius = 38 cm), except for the last four
measurements.
Snow depth
Sinkage
Resistance
Snow density
(kg/m3)
(m)
(m)
coefficient
0.13
0.10
0.05
160
0.16
0.12
0.06
160
0.15
0.12
0.05
170
0.19
0.15
0.08
170
0.16
0.13
0.07
160
0.17
0.14
0.06
160
0.18
0.15
0.06
170
0.19
0.16
0.07
170
0.21
0.17
0.07
220
0.21
0.17
0.10
220
0.20
0.16
0.07
220
0.21
0.17
0.12
220
0.20
0.16
0.07
220
0.21
0.16
0.09
220
0.18
0.14
0.07
220
0.19
0.16
0.10
220
0.21
0.16
0.06
220
0.22
0.17
0.07
220
0.21
0.15
0.07
220
0.18
0.13
0.05
220
0.18
0.13
0.06
220
0.20
0.15
0.07
220
0.21
0.16
0.07
220
0.22
0.17
0.08
220
0.22
0.17
0.06
220
0.22
0.17
0.05
220
0.14
0.10
0.02
110
0.13
0.90
0.03
110
0.17
0.14
0.03
110
0.16
0.12
0.04
110
0.18
0.15
0.03
110
0.16
0.12
0.06
110
0.16
0.13
0.14
230
0.38
0.33
0.19
220
0.38
0.31
0.19
160
0.36
0.31
0.21
160
0.32 (r = 35 cm)
0.26
0.17
190
0.28 (r = 33 cm)
0.25
0.10
120
0.26 (r = 33 cm)
0.22
0.16
170
0.25 (r = 33 cm)
0.23
0.12
120
45
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