Propwash rotation effects on spray drift

by

 Steven J. Thomson, A. R. Womac, J. Mulrooney, S. Deck

Contact: Steven J. Thomson  email:  sthomson@ars.usda.gov

Summary:

In this study, boom and propeller wash direction effects were investigated.  When aerially applying chemical near field boundaries, switching off one boom might reduce the likelihood of off-target drift, although there is some question whether this or the direction of propwash rotation is the major factor contributing to spray drift.     The testing showed that, to minimize drift, it is best to fly the airplane so that propwash spirals upwind. So, for a wind coming from the south, the plane should be flown east to west for a clockwise propeller rotation; the opposite for a counterclockwise rotation.  Although the effect of which boom is spraying was small, using the upwind boom to spray indicated slightly less drift (left boom for a clockwise propeller rotation).

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