NOMENCLATURE
Symbols
a
Length of tire or track in contact with undisturbed snow (m)
Hard surface contact area for element i (m2)
Ai
b
Width of tire or track (m or in.)
bi
Undeflected tire width or track width (in.)
f
Traction multiplier for thawing soil
g
Resistance multiplier for thawing soil
h
Initial snow depth (cm)
hi
Tire unloaded section height (in.)
Li
Track length (in.)
n
Number of wheels on the axle
Ni
Normal stress under a wheel or track element i (kPa)
P
Maximum load for a given frost depth (MN)
p
Contact pressure (same as normal stress) (kPa)
Pfg
Fine-grain-soil pressure factor (psi)
r
Tire (wheel) radius (cm or in.)
r2
Correlation coefficient
RCI
Rating Cone Index
ri
Tire radius (in.)
Rinternal
Motion resistance due to resistance internal to the vehicle (also called
hard surface resistance) (N)
Rterrain
Motion resistance due to terrain (snow, soil, ice, etc.) (N)
Rthaw
Motion resistance of thawing soil (N or lb)
S
Thaw depth in soil (cm)
s
Slip in decimal form
t
Frost depth in soil (m)
Tgross
Total gross traction available on a specified terrain (N)
Tnet
Total net traction (N)
Tthaw
Gross traction available on thawing soil (N or lb)
Vs
Vehicle speed (mph or kph)
w
Weight on axle (lb)
Wi
Wheel or track load (lb)
Ws
Driven wheel speed (mph or kph)
z
Depth that a vehicle sinks into the terrain (sinkage) (cm)
zmax
Maximum vehicle sinkage (snow) (cm)
zsoil
Vehicle sinkage into soil (cm)
δi
Tire loaded deflection (in.)
ice
Traction coefficient for ice (ratio of tractive force to normal load)
θ
Angle between leading edge of a track and the ground surface
ρ0
Initial snow density (Mg/m3)
ρf
Theoretical critical density (Mg/m3)
Abbreviations
ALBE
Air Land Battlefield Environment
CAMMS
Condensed Army Mobility Model System
CIV
CRREL Instrumented Vehicle
HEMTT
Heavy Expanded Mobility Tactical Truck
HML
Hard Mobile Launcher
HMMWV
High Mobility Multipurpose Wheeled Vehicle
LAV
Light Armored Vehicle
NRMM
NATO Reference Mobility Model
SUSV
Small Unit Support Vehicle
USCS
Unified Soil Classification System
WES
U.S. Army Waterways Experiment Station
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