Design, flight mechanics and flight demonstration of a tiltable propeller VTOL UAV

Abstract

This paper presents the design, flight mechanics and flight demonstration studies of a novel tiltable propeller VTOL UAV. The aircraft, discussed in this study, consists of a forward-swept fixed wing, two pairs of counter rotating tiltable propellers placed on both wing tips and a pair of counter rotating propeller placed between the tail booms. The aircraft has a capability of vertical take-off and landing as well as conventional take-off and landing. Both wing tip counter rotating propellers have been designed with a capability of tilting about ninety degrees around y-axis of the aircraft. The early design studies and the and the unexpected experimental results about ducted propeller systems have been summarized. The weight estimation approach has been discussed and initial sizes of the aircraft have been tabulated. After describing the general equation of motion, the trim condition calculations have been derived for hover, transition and cruise flight modes. The longitudinal stability characteristics for hover, transition and cruise flights have been analyzed via state space representation. The control strategies for all three flight modes have been evaluated and a control algorithm has been prepared. The construction studies of the test frames and the prototype aircraft have been summarized. Several flight demonstrations have been performed and the obtained results have been compared with the design calculations