<div class="htmlview paragraph">Making use of advantages of ducted fan, i.e. compactness and approachability, ducted fan VTOL can be used for many purposes, such as construction and servicing of the tall structures, rescue, etc.. In this paper the development of a working platform which utilizes the ducted fan VTOL concept is tried. Two types of ducted fan VTOL research models are developed. One is driven by electric motors and the other by an engine. The aim of the development is to investigate the ability of the ducted fan VTOL as a platform for working tasks at a high position.</div> <div class="htmlview paragraph">One of the most important problems for the development of the working platform in air is the development of control system which enable precision hovering. In this paper mainly the automatic flight control system for ducted fan VTOL is investigated and the control problems are studied which will arise when the VTOL is utilized as a working platform. Among them are the application of two time scale control theory for the feedback control system design and application of Kalman filter theory to process sensor data.</div>