The particular unmanned aircraft system design is an emergency service vehicle capable to detect accident victims buried in avalanches or landslides. The idea behind the concept is to equip an unmanned VTOL with optical equipment, and sensors to detect accident victims covered by snow and /or debris or even immersed in water to direct emergency service personnel to the respective sites. However, if a hover endurance is a primary design factor, then better understanding of propeller interactions and ground effects are needed for designing VTOL UAV. A novel UAV layout was proposed at the University of Arizona MAV laboratory in 2016-2018 [ 10 , 11 ] combining hovering and VTOL capabilities like multi-copters and the cruise flight ...