Air tanker drop patterns

Dominique Legendre (1) , Ryan Becker (2) , Elise Alméras (1) , Amélie Chassagne (1)

1 IMFT - Institut de mécanique des fluides de Toulouse
2 San Dimas Technology and Development Center (San Dimas, USA)

Ground patterns of liquid aerial drops for combating wildfires are considered. Based on a significant number of drop tests performed using different airplanes and helicopters, a simple model for the length, the width and the coverage distribution is presented. At first order both the length and the width of the drop pattern can be described using simple relations despite the significant difference between the conditions of the drop tests considered. These relations include factors that can be manipulated during aircraft and release system design, as well as during aerial firefighting operations. The liquid on the ground follows a Gaussian distribution that makes possible an original prediction of the maximum coverage level on the pattern centreline confirmed by the experiments. The difference between gravity systems and recent pressurised systems is also discussed. We show a clear difference between gravity systems and pressurised systems. The width is larger for pressurised systems, resulting in a smaller coverage for the same condition of drop.

Mots clés: Modelling; Drop pattern

Domaines: Ingénierie de l'environnement; Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]

Dominique Legendre, Ryan Becker, Elise Alméras, Amélie Chassagne. Air tanker drop patterns. International Journal of Wildland Fire, 2014, vol. 23 (n° 2), pp. 272-280. ⟨10.1071/WF13029⟩. ⟨hal-00961963⟩