Fuel Model		Coverage Level (gal/100 sq. ft)	Description
National Fire Danger Rating System (NFDRS)	Fire Behavior
A,L,S	1	1	Annual and perennial western grasses, tundra
C	2		Conifer with grass
H,R	8	2	Shortneedle closed conifer; summer hardwood
E,P,U	9		Longneedle conifer; fall hardwood
T	2		Sagebrush with grass
N	3		Sawgrass
F	5	3	Intermediate brush (green)
K	11		Light slash
G	10	4	Shortneedle conifer (heavy dead litter)
O	4		Southern rough
F,Q	6	6	Intermediate brush (cured), Alaska black spruce
B,O	4		California mixed chaparral, high pocosin
J	12	Greater than 6	Medium slash
I	13		Heavy slash

The results of drop tests allow managers to estimate the drop speed and height that provide the retardant coverage level required for a given fire intensity represented by the applicable fuel model. Table 2 or Figure 4 can be used to estimate the air speed of a water drop required to obtain the maximum line length of the desired coverage level. Table 3 or Figure 5 can be used to estimate the air speed of a foam drop to obtain the maximum line length of the desired coverage level. Table 4 or Figure 6 can be used to estimate the air speed of a gum-thickened retardant drop to obtain the maximum line length of the desired coverage level.

Table 2—Water tests producing the longest line at various levels.

Coverage Level (gal/100 sq. ft)	Airspeed (knots)	Line Length (feet)
0.5	80	2008
1	86	1659
2	72	1189
3	58	1046
4	58	791
6	39	457
8	39	265
10	25	229

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Figure 4—Use this graph to estimate the drop speed needed
to produce the maximum line length of water at various coverage levels.

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Table 3—Foam tests producing the longest line at various levels.

Coverage Level (gal/100 sq. ft)	Airspeed (knots)	Line Length (feet)
0.5	80	2031
1	80	1764
2	80	1268
3	45	926
4	45	638
6	19	352
8	19	305
10	19	237

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Figure 5— Use this graph to estimate the drop speed needed to
produce the maximum line length of foam at various coverage levels.