Morphing aircraft

overcoming the limitations of traditional fixed configurations

represents a critical direction in aircraft development. Their core principle lies in adjusting the airframe configuration to achieve optimal aerodynamic profiles for diverse operational environments

thereby significantly enhancing flight performance. After years of development

morphing aircraft exhibits the following characteristics: (1) Evolution from rigid deformation to flexible continuous deformation; (2) Progression from low-speed to high-speed applications; (3) Transition from single-medium to cross-medium flight; (4) Expansion of operational domains from singular airspace to integrated airspace domains. Deformable structures constitute a key enabling technology for morphing aircraft

primarily encompassing skins

supporting structures

and actuation systems. Skin technology has evolved from rigid to flexible skins. Moving beyond the initially employed metal skins

contemporary developments include composite material skins

smart skins based on shape memory polymers and piezoelectric responsive materials

multi-medium adaptive reconfigurable skins

and thermal protectiondeformable integrated skins. This flexible skin system not only grants adaptive surface deformation capabilities but also maintains the continuity of the airframe surface. Structural design is shifting from hinge-based mechanisms towards continuous deformation structures. Hinge-based wing morphing systems enable large-angle adjustments of aerodynamic surfaces. In contrast

continuous deformation structures not only possess substantial deformation capacity but also achieve precise aerodynamic profile matching while preserving airframe continuity. This capability

coupled with space deployment mechanisms

enables multi-medium transition capabilities

such as switching between underwater navigation and aerial flight. Actuation systems for morphing aircraft are transitioning from traditional motor-hydraulic actuators towards smart actuation

realized through the integration of active deformation units like dielectric elastomers

piezoelectric stack actuators

and shape memory alloys. This paper reviews the morphing configurations and research progress on deformable structures

focusing on their applications in unmanned aerial vehicles (UAVs)

cross-medium vehicles

civil airliners

and aerospace vehicles. Building on this foundation

it outlines future development directions and primary challenges

aiming to provide a reference for innovative research in morphing aircraft technology.