MAV Takeoff : 2012

Photograph by

Phred Petersen

About this image

Schlieren image showing the downwash from the rotors of a model helicopter. This technique visualises changes in the refractive index of a gas, in this case because of changes in air density. In this instance, alcohol vapour has been added to emphasise density variations as air is forced downward by the rotors. As the air stream hits the ground it moves outward in all directions with a turbulent, billowing motion. Studies such as this investigate the occurrence of recirculation, or how the billowing outward-moving ground air is pulled back toward the rotors. In the real world this can cause significant damage to the rotors and engines from debris. The image was captured using a 300mm Z-configuration schlieren system with a three-colour filter over the electronic flash source. School of Media and Communication, RMIT University, Melbourne, Australia