Abstract
Recently, the unmanned aerial vehicle (UAV) is developed for aerial work. This study focused on unmanned helicopter that is one of UAVs. With the popularization of unmanned helicopter, some collision accidents between human body and its rotor blade happened. Now, we developed a new multi rotor helicopter which has 4 ducted-fans instead of non-covered rotors. We call this Quad Ducted-fan Helicopter. Ducted-fan's rotor blade is protected by duct. So, it clears up the risk of non-covered rotors.
