Deployable Mechanism Design For Span Morphing Wing Aircraft

Compared with traditional aircrafts,the span morphing wing aircraft can change its span according to different flight conditions and missions in order to improve flight performances,also,it has advantages in storage and transportation.Most of the mechanisms designed for span morphing wing are multi-degree-of-freedom(MDOF),the structures of MDOF mechanisms are usually complex.Additionally,during the changing process of the span,the power required for the actuators to work coordinately may be tremendous.To solve the above problems,a single-degree-of-freedom(SDOF)overconstrained mechanism based on Sarrus linkages is required for span morphing wing aircraft.As the deployable mechanism is SDOF and overconstrained,the mechanism can be driven by a single actuator and the morphing wing is of higher rigidity.In this paper,the design scheme of the span morphing wing aircraft is introduced firstly.Followed by the working principles of three types of SDOF deployable mechanisms as well as brief kinematics analyses on them,and 3D models are set up for the mechanisms.Then,the most suitable mechanism among the three is selected for optimal design according to conditions and requirements.The finite element methods are used to investigate the performance of the mechanism.Furthermore,two generations of prototype aircraft with morphing wing mechanism installed are designed and manufactured.Computational Fluid Dynamics(CFD)simulations carried out on the span morphing wing model plane show the deployable mechanism generates slight influence on the drag coefficient while having a relatively strong influence on the lift coefficient and lift to drag ratio.Finite Element Model(FEM)methods were used to analyze mechanical proper-ties of the mechanism during flight,the results indicate that maximum stress 45.5 MPa occurs at the link connected to the base link.A series of flight experiments were conducted to prove that the mechanism enables the span change smoothly and improves flight performances effectively.