Lightweight unmanned aerial vehicle for emergency medical service – Synthesis of the layout

Abstract

The article presents the innovative unmanned aerial vehicle project for emergency medical services. Designed unmanned aerial vehicle combines vertical takeoff and landing characteristics with fast forward flight capability that are vital to perform such an emergency medical mission. The main purpose of the designed unmanned aerial vehicle is to deliver the necessary medical package to the place where access is difficult, and estimated arrival time of conventional ambulance is too long. The cost of the support of such unmanned aerial vehicle could be significantly lower than in case of medical helicopter, which is not necessary in some cases. Designed unmanned aerial vehicle can also be used for fast delivery of essential medical substances (e.g. blood). The selection of configuration was the first and crucial step of the design. After analysis of many different copter configurations, together with selected crash reports analysis, the coaxial quadcopter configuration crossed with conventional airplane was selected. All power units for VTOL capability are electric, and they are doubled for redundancy purposes, with maximum T/W ratio about 2.0. Such configuration allows to sustain a stable flight (vertical phases) in case of one motor failure. Two versions of the vehicle are designed: fully electric (power units for the forward flight and vertical takeoff and landing are electric) and mixed where forward flight unit is a small piston engine. The final layout was the result of conceptual investigation and preliminary research, MDO and trade-off analysis, where as many aspects as possible were considered. The main problem was to meet the vertical takeoff and landing capabilities, relatively long range and endurance, expected payload (3 kg) and the requirement not to exceed 25 kg of maximum take-off weight. Paper presents the design process from initial requirement to the final configuration accepted to be manufactured.