MEASUREMENT AND PREDICTION OF DEPOSITIONAL ACCURACY IN DISPERSANT SPRAYING FROM LARGE AIRPLANES

Abstract

ABSTRACT Aerial application of dispersants has progressed to include very large airplanes, such as the Hercules C-130, for which a portable spray unit has been developed. This unit, which can be rapidly placed in the cargo aircraft (without any mechanical alterations) was flight tested with spraying of a dispersant concentrate in 1982. The tests measured actual deposition of chemical under various conditions. The most definitive data were collected using a “deposition track,” positioned on the ground across the flight path of the airplane. The dyed dispersant was recovered from this track and the data converted to amount per unit area, and to percent of total pumped fluid on-target. The results led to correlation of depositional accuracy in terms of the air shear experienced by the sprayed fluid. The data has been further used to develop a mathematical prediction for design of dispersant treatment procedures using high-speed airplanes. Use of these considerations in operational planning can improve dispersant dosage control by preventing both under-treatment and wasteful off-target drift.