Keywords: Helicopter spraying on sky.jpg Helicopter spraying in flight http //www public-domain-image com/public-domain-images-pictures-free-stock-photos/transportation-vehicles-public-domain-images-pictures/helicopters-public-domain-images-pictures/helicopter-spraying-on-sky jpg Jahons Brad E U S Fish and Wildlife Service Not given Transferred by Fæ on 2013-03-01 PD-author Jahons Brad E U S Fish and Wildlife Service Images uploaded by Fæ Public-domain-image com Hughes Model 269 Public-domain-image com check needed Lift-induced vortices Toroidal vortices Flow visualization |