US Department of Agriculture, USDA Forest Service, Technology and Development Program Banner with Logos.
Images from various aspects of the T&D Program.
HomeAbout T&DT&D PubsT&D NewsProgram AreasHelpContact Us
  T&D > T&D Pubs > Estimating Methods, Variability, and Sampling for Drop-Test Data T&D Publications Header
Table of Contents

Back | Next | Cover Page

Estimating Methods, Variability, and Sampling for Drop-Test Data

Results

Tabular

Six drop tests numbered 201 to 206 were made over the grid and the results collected on July 12, 2001. Table 4 shows the data collected and the calculated line lengths (longest continuous segment). The actual volumes for drops 201 and 202 were not measured. The measured volumes were obtained using a flow meter when the tank was being filled. There was no way to measure volume dropped or the actual flow rate. For this reason, percent recovery was not included in this table.

The flow rates shown are also a target. No usable flow-rate data were recovered from this drop test. The two numbers for height and speed were provided by the military. For height, one number is from a radar altimeter and the other is from the self-contained navigation system. For speed, one number is from a pitot tube and the other is from the self-contained navigation system. The Forest Service measured height and speed using video analysis.

Table 4—Results from six drop tests over the grid. Wind from 0° would be a head wind. GS is ground speed and RH is relative humidity. GTS-R is a fire retardant.
Drop Volume in tank (gallons) Time Target flow rate (gallons per second) Height1 (feet Forest Service) Height2 (feet military) GS1 (knots, Forest Service)
201 9004 10:31 a.m. 250 159 170/160 129
202 9004 11:08 a.m. 250 149 150/150 128
203 871 11:41 a.m. 250 167 160/160 132
204 877 12:17 p.m. 250 144 140/150 134
205 958 2:56 p.m. 500 Missed 160/150 Missed
206 821 3:37 p.m. 500 157 160/160 143
Table 4 Continued
GS3 (knots, military) Wind (miles per hour) Wind direction (0 degrees headwind) Temp (°F) Relative humidity (percent) Firefighting chemical Density (grams per cubic centimeter)
133/132 4 45 70 56 H2O 1.000
136/131 4 320 73 52 H2O 1.000
130/138 2 95 74 50 GTS-R 1.094
132/124 5 130 78 45 GTS-R 1.097
133/133 0 to 5 Missed Missed Missed GTS-R 1.096
138/131 4 130 89 29 GTS-R 1.095
1 The Forest Service measured height and ground speed using video analysis.
2 The military measured height using a radar altimeter (first value) and a self-contained navigation system (second value).
3 The military measured ground speed using a pitot tube (first value) and a self-contained navigation system (second value).
4 The actual volumes for drops 201 and 202 were not measured. The target volume was 900 gallons.
Length of the retardant line at specific coverage levels (in gallons per 100 square feet, gpc).
Drop 0.5 1 2 3 4 6 8
201 600 521 218 122 105 26 25
202 600 485 375 100 73 14 0
203 600 570 457 185 80 38 21
204 593 524 275 202 118 39 28
205 513 479 373 174 97 68 12
206 511 477 356 190 73 28 0

Graphical

Figures 9 through 14 show contour plots of the six drops after triangulation. The outer, dark contour represents the lightest coverage level of 0.5 gpc. The inner hachured contour indicates one of the heaviest coverage levels, 8 gpc.

Contour plot of drop 201 (10:31 a.m., July 12, 2001). Flight direction: north to south. Aircraft elevation: 160 feet. Windspeed: 4 miles per hour. Low-flow rate: 250 gallons of water per second. Water density: 1.00 grams per cubic centimeter.
Figure 9—Contour plot of drop 201 after triangulation.

Contour plot of drop 202 (11:06 a.m., July 12, 2001). Flight direction: north to south. Aircraft elevation: 150 feet. Windspeed: 4 miles per hour. Low-flow rate: 250 gallons of water per second. Water density: 1.00 grams per cubic centimeter.
Figure 10—Contour plot of drop 202 after triangulation.

Contour plot of drop 203 (11:43 a.m., July 12, 2001). Flight direction: north to south. Aircraft elevation: 160 feet. Windspeed: 2 miles per hour. Low-flow rate: 250 gallons of water per second. GTS-R density: 1.094 grams per cubic centimeter.
Figure 11—Contour plot of drop 203 after triangulation.

Contour plot of drop 204 (12:17 p.m., July 12, 2001). Flight direction: north to south. Aircraft elevation: 145 feet. Windspeed: 5 miles per hour. Low-flow rate: 250 gallons of water per second. GTS-R density: 1.097 grams per cubic centimeter.
Figure 12—Contour plot of drop 204 after triangulation.

Contour plot of drop 205 (2:56 p.m., July 12, 2001). Flight direction: north to south. Aircraft elevation: 155 feet. Windspeed: o to 5 miles per hour. Medium-flow rate: 500 gallons of water per second. GTS-R density: 1.096 grams per cubic centimeter.
Figure 13—Contour plot of drop 205 after triangulation.

Contour plot of drop 206 (3:38 p.m., July 12, 2001). Flight direction: north to south. Aircraft elevation: 160 feet. Windspeed: 4 miles per hour. Medium-flow rate: 500 gallons of water per second. GTS-R density: 1.095 grams per cubic centimeter.
Figure 14—Contour plot of drop 206 after triangulation.

Top

Back | Next | Cover Page