Research in Adaptive Combination and Separation Fixed-Wing Aircraft: Wingtip-Connected Conceptual Design and Flight Endurance Performance

This paper has investigated wingtip-connected conceptual design and flight endurance performance for the fixed-wing aircraft. Firstly, starting from the requirements of communication, surveillance and reconnaissance functions, and cluster capabilities, the task requirement analysis was completed for adaptive combination and separation flight of unmanned aerial vehicle (UAV). A conceptual design strategy was proposed to adopt to wingtip-connected of two unit UAV. Secondly, based on the wingtip connection mode combined electromagnetic adsorption and bolt connection, the flight profile of wingtip-connected UAV was charted for determine the typical application scene and operation method. The conceptual design of wingtip connection and separation of two unit UAV was carried out to achieve obtain design results of aerodynamic configuration, mass distribution of full aircraft and mechanism scheme of wing folding. Thirdly, according to the based Reynolds-stress model, a robust solution procedure for the numerical method is described and a verification study is presented. The lift-drag and longitudinal-lateral stability performance of the unit UAV was analyzed by numerical method. And then, aerodynamic performance of docking interference and wingtip-connected aircraft of two unit UAV was evaluated. The flight performance of the unit and wingtip-connected aircraft were compared. Their lift-drag ratio, cruise endurance factor, and stability of longitudinal and lateral flight were analyzed respectively. It is most important that the rolling stability characteristics of the wing tip connected aircraft was able to determine. Finally, based on aerodynamic performance and flight profile, the evaluation indicator of flight endurance capability has been improved. The enhancement results of flight endurance performance have been gained for the wingtip-connected aircraft. The research shows that the flight endurance performance of the two unit wingtip-connected aircraft is increased by more than 35% compared to a unit aircraft. The cruise lift-drag ratio and endurance factor of the wingtip-connected aircraft respectively increases over 30% by two unit wingtip-connecting. It has good longitudinal and lateral stability of flight endurance. The longitudinal stability is about 10%, and roll stability is similar to a unit aircraft. The two unit wingtip-connected aircraft and its design strategy have excellent application prospect. They can provide the adaptive combination-separation flight new concept aircraft design strategy for the satisfaction of multi-role functions and cluster capabilities, which are able to complete intelligent-emerged missions.