Joined-wing test bed UAV

The future green aircraft will be required to meet demanding constraints, including weight reduction, high energy and aerodynamic efficiencies and high performance, to be compliant with pollutant emissions and noise generation regulations. The joined-wing concept is considered a trade-off variant for a green aircraft design with a lower cruise drag and lower structural weight. In addition, the requirements for low pollution and noise could be met using an all-electric aircraft. Hence, the aim of the present study is to design and produce a joined-wing unmanned aircraft test bed or flight laboratory. The basic design incorporates tip-joined front and rear wings with wing-tip vertical joints. The airframe is mainly composed of carbon and glass fibre composite materials. The power plant consists of an electric ducted fan, speed controller and Li-Po batteries. The aircraft integrates the Piccolo II Flight Management System, which offers a state-of-the-art navigation and flight data acquisition. Prior to production and flight testing of the prototype, aircraft aerodynamics and flight dynamics were analysed. Potential models with wind tunnel tests have been used to determine aircraft aerodynamics. One of the major problems found during simulation and flight experiments is the Dutch roll effect. This is thoroughly discussed in the paper. Some problems that concern autopilot tuning are also described. © 2014, Deutsches Zentrum für Luft- und Raumfahrt e.V.