Wind tunnel tests of the pusher propeller : an assessment of accuracy

A pusher propeller is one of popular types of the airplane propulsion. It is applied especially in light sport aircrafts and in the UAVs (Unmanned Aerial Vehicles). Its main advantage is that the engine with the pusher propeller does not affect the visibility from the cockpit and allows placing an electronic equipment in the front part of the UAV’s fuselage. The main disadvantage of the pusher propeller is that its performance may be worse than the tractor propeller, because of a stream distortion caused by the fuselage. It should be taken into account during propeller tests. The most accurate way is to investigate the pusher propeller in the presence of the complete airplane, as a part of airplane wind tunnel tests. However, this approach is possible in a late stage of the airplane design, when the geometry of the airplane is fixed. In the paper, an alternative, innovative approach for the propulsion tests has been presented. The propeller was investigated in a wind tunnel in a presence of the aft part of the fuselage, including a root part of the wing. A typical propeller and a ducted fan have been investigated. The results has been compared with the results of the wind tunnel tests of the complete airplane (with powered propulsion) to evaluate the accuracy of this methodology. The investigated propulsion was designed for a joined wing UAV, ILX-32 MOSUPS.