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How
to Conduct Drop Tests of
Aerial Retardant Delivery Systems
The matrix was developed during planning for a helicopter bucket drop test. The objectives of the test were to quantify drop patterns at three different dumpvalve openings and at three different speeds, using water and retardant. Because helicopter availability was limited, all drops were made at 50 feet above the ground. To reduce costs, only two retardant drops were made, both at commonly used speeds and valve openings.
| Valve opening
(percent) |
Drop speed (knots per hour) |
Fluid |
|---|---|---|
| 100 | 40 | Water |
| 100 | 60 | Water |
| 100 | 60 | Retardant |
| 100 | 80 | Water |
| 60 | 40 | Water |
| 60 | 60 | Water |
| 60 | 60 | Retardant |
| 60 | 80 | Water |
| 30 | 40 | Water |
| 30 | 60 | Water |
| 30 | 80 | Water |
The test matrix was developed during planning for a constant-flow airtanker drop test. The objectives of the test were to:
| Load | Volume (gallons) | Coverage level | Flow rate (gallons per second) | Fluid | Evacuation (seconds) | Estimated pattern length (feet) | Repetitions |
|---|---|---|---|---|---|---|---|
| Full | 1,200 | 1 | 190 | Water | 6.3 | 1,390 | |
| Full | 1,200 | 1 | 190 | Retardant | 6.3 | 1,390 | |
| Full | 1,200 | 2 | 315 | Water | 3.8 | 840 | |
| Full | 1,200 | 2 | 315 | Retardant | 3.8 | 840 | |
| Full | 1,200 | 3 | 440 | Water | 2.7 | 590 | |
| Full | 1,200 | 3 | 440 | Retardant | 2.7 | 590 | 3 |
| Full | 1,200 | 4 | 560 | Water | 2.1 | 460 | |
| Full | 1,200 | 4 | 560 | Retardant | 2.1 | 460 | |
| Full | 1,200 | 6 | 640 | Water | 1.9 | 420 | 3 |
| Full | 1,200 | 6 | 640 | Retardant | 1.9 | 420 | 3 |
| Half | 600 | 1 | 170 | Water | 3.6 | 790 | 3 |
| Half | 600 | 1 | 170 | Retardant | 3.6 | 790 | 3 |
| Half | 600 | 4 | 560 | Water | 1.1 | 240 | |
| Half | 600 | 4 | 560 | Retardant | 1.1 | 240 | |
| One-third | 400 | 0.5 | 60 | Water | 6.6 | 1,450 | |
| One-third | 400 | 0.5 | 60 | Retardant | 6.6 | 1,450 | |
| One-third | 400 | 1 | 175 | Water | 2.3 | 500 | |
| One-third | 400 | 1 | 175 | Retardant | 2.3 | 500 | |
| One-third | 400 | 2 | 270 | Water | 1.5 | 330 | |
| One-third | 400 | 2 | 270 | Retardant | 1.5 | 330 |
A drop speed and altitude were selected that best represented “ typical” operational levels. Replicates were completed with low, medium, and high flow rates. During the test, additional drops were made at different drop heights and speeds to compare drop patterns of a gel product. These drops were made with the same low, medium, and high flow rates.
| USDA Forest Service, Technology and Development Last Modified: 10/15/2016 23:43:08 |
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