Study on the Propeller Characteristics of a Vertical Takeoff and Landing Aircraft

The VTOL (Vertical Takeoff and Landing) aircraft are attractive because they combine the advantages of a helicopter and an airplane. It can hover, take off and land without a take-off strip like a helicopter and simultaneously fly forward at high speed as an aircraft. A notable example of such an aircraft is the Bell Boeing V22 Osprey, which utilizes tilt rotors to alter the aircraft's flight mode by rotating the rotors forward or upward. The Osprey's rotors can be likened to propellers/rotors, serving to generate thrust/lift. Thus, this work aims to explore the aerodynamic characteristics, explicitly focusing on the thrust-produced propeller of a UAV (Unmanned Air Vehicle) during the transition of VTOL from the helicopter to aircraft mode or vice versa, i.e., the effect of the propeller angle on the thrust produced in all three modes of flight viz, aircraft, transition and helicopter. To determine the aerodynamic characteristics of a propeller, an UAV propeller was selected and scanned using a 3D Scanner to get a propeller CAD model with actual twist distribution. Subsequently, computational fluid dynamics (CFD) analysis was conducted using the ANSYS Fluent software to predict the propeller's thrust. Parametric studies were conducted to check the propeller thrust for all three flight modes for different rpm and forward speeds. The simulated results were validated through comparisons with available analytical results. This comprehensive investigation sheds light on the propeller behavior for different flight modes, ultimately contributing to an enriched understanding of VTOL aircraft propeller characteristics.