Form Approved
REPORT DOCUMENTATION PAGE
OMB No. 0704-0188
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1. AGENCY USE ONLY (Leave blank)
2. REPORT DATE
3. REPORT TYPE AND DATES COVERED
March 1995
4. TITLE AND SUBTITLE
5. FUNDING NUMBERS
Motion Resistance of Wheeled Vehicles in Snow
PR: 4A762784AT42
TA: CS
WU: M04
6. AUTHORS
Paul W. Richmond
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)
8. PERFORMING ORGANIZATION
REPORT NUMBER
CRREL Report 95-7
U.S. Army Cold Regions Research and Engineering Laboratory
72 Lyme Road
Hanover, N.H. 03755-1290
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)
10. SPONSORING/MONITORING
AGENCY REPORT NUMBER
Office of the Chief of Engineers
Washington, DC 02314-1000
11. SUPPLEMENTARY NOTES
12a. DISTRIBUTION/AVAILABILITY STATEMENT
12b. DISTRIBUTION CODE
Approved for public release; distribution is unlimited.
Available from NTIS, Springfield, Virginia 22161
13. ABSTRACT (Maximum 200 words)
Before vehicle mobility in snow can be reliably predicted, a complete understanding of motion resistance in snow
is required. This report examines several aspects of wheeled vehicle motion resistance using results obtained with
the CRREL instrumented vehicle. Resistances of leading and trailing tires are examined. Limited data are presented
for undercarriage drag, and third and fourth wheel passes in the same rut are initially analyzed, as is how snow
deforms around a wheel. For the CRREL instrumented vehicle, a trailing tire has a resistance coefficient of about 0.017
for snow depths less than about 22 cm. For deeper snow, the disruption of the snowpack caused by a preceding wheel
causes snow to fall into the rut, resulting in higher trailing tire coefficients. For larger vehicles, which in some cases
have trailing tires carrying larger loads than preceding tires, the trailing tire coefficients are on the order of 0.048 and
0.025 for second and third trailing wheels respectively. Since there are no trailing tire data available for these larger
vehicles, these values are based on nonlinear regression analysis, which includes a prediction of the leading tire
resistance. The results and observations of this study are applied in a reanalysis of the towed resistance data obtained
during the U.S. Army's Wheels vs. Tracks study. An improved algorithm is presented for predicting wheeled vehicle
motion resistance caused by snow.
14. SUBJECT TERMS
15. NUMBER OF PAGES
Instrumented vehicles
Snow
Vehicles
47
Mobility predictions
Snow strength
Trafficability
16. PRICE CODE
Motion resistance
Vehicle traction
Off road mobility
17. SECURITY CLASSIFICATION
18. SECURITY CLASSIFICATION
19. SECURITY CLASSIFICATION
20. LIMITATION OF ABSTRACT
OF REPORT
OF THIS PAGE
OF ABSTRACT
UNCLASSIFIED
UNCLASSIFIED
UNCLASSIFIED
UL
Standard Form 298 (Rev. 2-89)
NSN 7540-01-280-5500
Prescribed by ANSI Std. Z39-18
298-102
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