An Analysis of Dodge's Escape Fire on the 1949 Mann Gulch Fire in ...

Calculations <strong>of</strong> Flame Front Dimensions
Flame front residence time: 5-155
seconds for grass
Rate <strong>of</strong> fire spread: 360 ft/min or 6 ft/sec
Available fuel load: 1.56 tons/acre or 0.072 lb/ft 2
Mid-flame wind speeds: 15-20 mph
Flame depth = 5 sec x 6 ft/sec = 30 ft
to 15 sec x 6 ft/sec = 90 ft
Byram’s s (1959) <strong>Fire</strong>line Intensity =
Fuel Heat Content (7444 Btu/lb)
x 0.072 lb/ft2 x 6 ft/sec = 3333 Btu/sec-ft
Equivalent to a Flame Length <strong>of</strong> 19 ft
Nelson & Adkins (1986) Flame Height vs. Flame Length
and Mid-flame Wind Speed model prediction: 12.5 ft