When testing airfoils, propellers and aircraft with vertical take-off (VTOL) and landing systems, the incoming air flows at the tested objects at large angles of attacks, which leads to a large deflection of the airflow. Therefore, for the needs of VTOL testing, we designed a closed return wind tunnel with an open test section, where the influence of a large downwash flow is not as big as in a closed test section. The closed return wind tunnel was designed in a confined space, determining the maximum possible diameter of the air duct system. The air duct system was divided into two parts and installed in a movable steel structure. Wind tunnel was equipped with measuring equipment for measuring temperature, humidity, static and total pressure. For the designed wind tunnel, we calculated the parameters to achieve similarity between the model and the prototype. We drew a scheme of a wind tunnel, workshop and components drawings of the air duct system and a wind tunnel mounted in a steel structure.