Systematic design methodology for development and flight testing of a variable pitch quadrotor biplane VTOL UAV for payload delivery

摘要

This paper discusses the conceptual design and proof-of-concept flightdemonstration of a novel variable pitch quadrotor biplane Unmanned AerialVehicle concept for payload delivery. The proposed design combines verticaltakeoff and landing (VTOL), precise hover capabilities of a quadrotorhelicopter and high range, endurance and high forward cruise speedcharacteristics of a fixed wing aircraft. The proposed UAV is designed for amission requirement of carrying and delivering 6 kg payload to a destination at16 km from the point of origin. First, the design of proprotors is carried outusing a physics based modified Blade Element Momentum Theory (BEMT) analysis,which is validated using experimental data generated for the purpose.Proprotors have conflicting requirement for optimal hover and forward flightperformance. Next, the biplane wings are designed using simple lifting linetheory. The airframe design is followed by power plant selection andtransmission design. Finally, weight estimation is carried out to complete thedesign process. The proprotor design with 24 deg preset angle and -24 deg twistis designed based on 70% weightage to forward flight and 30% weightage tohovering flight conditions. The operating RPM of the proprotors is reduced from3200 during hover to 2000 during forward flight to ensure optimal performanceduring cruise flight. The estimated power consumption during forward flightmode is 64% less than that required for hover, establishing the benefit of thishybrid concept. A proof-of-concept scaled prototype is fabricated usingcommercial-off-the-shelf parts. A PID controller is developed and implementedon the PixHawk board to enable stable hovering flight and attitude tracking.