Synthesis of and Experiment on a Morphing Nose Cone Driven by a Biomimetic 4-3R1U&3R Parallel Mechanism

Abstract Aircraft have received much attention because of their capability to adapt to various flight environments and complex missions. The nose cone is one of the key elements in optimising the aerodynamic shape of aircraft. A morphing nose cone (MNC) driven by a biomimetic 4-3R1U&3R sparallel mechanism is proposed in this study. Based on screw theory, the parallel mechanism’s configuration is determined, and the structure’s full-cycle degrees of freedom are concurrently confirmed. Examples in the paper demonstrate the viability of the structure by configuration synthesis, and diagrams also show the chains. This MNC is modelled after the structural design of the cicada’s abdomen and can be extended, contracted and bent. It can actively adjust its shape in response to change in the flight environments, thereby aerodynamic performance and enhancing the aircraft’s multi-mission capabilities. A scaled-down prototype is created to verify the deformation capacity of the MNC meeting the engineering requirements. Results show that the extension ratio is 36.7%, and the bending angle is 21.7°, which is better than expected. The relative error value is within a reasonable range and the extension process is incredibly stable. This research proposes new perspectives for the design of MNCs.