TRANSITION PHASE ANALYSIS OF A QUADCOPTER BIPLANE TAILSITTER UAV USING COMPUTATIONAL FLUIDS DYNAMICS

• Main Author: Widhi Dyatmika, Wahyu
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67684
• Institution: Institut Teknologi Bandung

Several large corporations begin to use unmanned aerial vehicles (UAVs) to deliver items to their customers, especially for last-mile deliveries. UAV is preferred for last-mile cargo delivery because of its reachability and accessibility. Tailsitter is a novel UAV configuration that can be used for the last-mile delivery of cargo. This configuration enables the aircraft to land on its tail, take off in rotary-wing mode, and then switch to the fixed-wing mode for cruising. In the transition phase, in which the aircraft changes from fixed-wing to rotary-wing lets the aircraft into a stall condition. Thus, understanding the stall performance, as well as the propeller and wing interaction during stall, is critical for creating the optimum tailsitter design. However, the stall performance of an aircraft is difficult to obtain because of the unpredictability of the flow. In this research, the performance of a quadcopter biplane tailsitter during the transition phase is analyzed. Two different analysis is used for gathering data. First, the freestream and propeller rotational velocities are obtained in an analytical model using the force equilibrium equation. The second analysis is numerical computation, which is used as verification and obtaining more realistic data. CFD is utilized for the numerical computation, with SST K-? used for low angles of attack and Spalart-Allmaras for high angles of attack. The two analyses were then repeated in four iterations to ensure the convergence of the result. This analysis is under the assumption of steady transition, meaning that the angle of attack will always be the same as the angle of pitch. Overall, the performance result is converged after four iterations, though differences between numerical and analytical results are present. During a high angle of attack, there is an abrupt change of performance. The investigations of flow patterns show that the propeller slipstream creates adverse effects during high angles of attack. The accelerated, rotating flow from the propeller decreases lift, increases drag, and decrease the overall stability of the aircraft.