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Conducting Aerial Drop Tests

[image] Graphic of the cover page for the How to Conduct Drop Tests of Aerial Retardant Delivery Systems report.The USDA Forest Service's aerial delivery project has developed procedures for conducting drop tests to quantify retardant drop patterns produced by rotary and fixed-wing airtanker retardant delivery systems. Drop testing serves as the most accurate means of measuring retardant ground patterns.

Basically, a grid of cups is laid out and the airtanker drops the retardant over the grid. Cups with retardant are capped and weighed, and the data collected during the weighing process are used to produce ground pattern contour plots and to calculate the coverage area. Examples of test matrices and grid setup instructions are provided in the report, along with a sample list of equipment used in a drop test.

Data from drop testing are used to quantify performance of retardant delivery systems, to define performance requirements set by the Interagency Airtanker Board, to establish a relationship between drop parameters (particularly flow rate) and drop pattern (coverage levels), and to compare the performance of different retardant delivery systems.

The report, How to Conduct Drop Tests of Aerial Retardant Delivery Systems (0457–2813–MTDC), describes the procedures for conducting drop tests.

For more information on aerial drop testing, contact Greg Lovellette, project leader (phone: 406–329–4815; e-mail:

USDA Forest Service and U.S. Department of the Interior Bureau of Land Management employees can view the report on the USDA Forest Service's internal computer network at:

Others can view the report over the Internet (username: t-d, password: t-d)

To order the report, contact Cailen Hegman, MTDC publications (phone: 406–329–3719; e-mail:

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