This proposal presents the design study now carrying-out on the unmanned air vehicles (UAVs).There are several existing UAVs in the market with various configurations and built for a designated function. These vehicles may carry visual, acoustic, chemical or biological sensors for such missions as traffic management, hostage situation surveillance, rescue operations and a few more. In this report, the concept of rotary wing UAV was selected for our design study. The concept was selected mainly due to its hover capability and stability during maneuvers. Hover capability for UAV is desired in order to provide constant observation of designated targets as well as operating near obstacles, such as trees or buildings. Combined with fast cruise, such an UAV would be suitable for a variety of missions, for both civilian and military applications. The Tri-copter project is aimed at the design of a hover-capable rotary wing UAV that could perform such missions. The key principle is: VTOL, More and smaller motors with equal higher redundancy. The tri-copter should be able to land safely even if a motor or propeller fails. Other benefits are lower thrust per motor, even at higher payloads, resulting in less vibration. In this case the payload needs to be more than 2000 grams in order to carry a camera with high Definition imaging capacity.