Final Report Summary - OMSAMA (Optimisation of Multiscale Structures with Applications to Morphing Aircraft)
Flight, and the design of aircraft, has been a great success story. Early pioneers were inspired by the natural world, and early aircraft, such as the Wright Flyer, twisted a compliant wing for roll control. The demand for higher payloads and faster cruise speeds required stiffer wing structures. Controlling the aircraft by deforming the wings was replaced by discrete aerodynamic surfaces. However, modern aircraft wings are a compromise that allows the aircraft to fly at a range of flight conditions, but the performance at each condition is inevitably sub-optimal. The ability of a wing surface to change its geometry during flight has interested researchers and designers over the years as this reduces the design compromises required. Concepts based on mechanisms, for example variable sweep, have been successful, but concepts based on the compliance of the structure have met with limited success. Such compliant concepts, often termed morphing aircraft, are the subject of the ERC project entitled “Optimisation of Multi-scale Structures with Applications to Morphing Aircraft”.
The design of efficient morphing aircraft requires advances in system level modelling and performance assessment, innovative and novel structural concepts, and improved components such as compliant skins. All of these aspects were considered in the project and some highlights are summarised below.
The key requirement for the adoption of morphing technology is the demonstration of the potential performance benefits. This requires a system level analysis that considers not only the aerodynamics of the aircraft, but also the sizing and weight estimation for both the structure and actuators, and how the vehicle will be operated. For example, detailed analysis has been performed on aircraft with variable span for combined dash and loiter missions, to determine if the improved aerodynamic performance is able to offset the weight penalty.
Novel configurations investigated include the biologically inspired FishBAC compliant variable camber device, consisting of a chordwise spine with stringers to support a pre-tensioned elastomeric skin. A significant improvement in aerodynamic efficiency (the ratio of lift to drag) has been demonstrated in simulation and wind tunnel testing, for a relatively small increase in weight. A novel span extension concept with a compliant skin has been designed and extensively modelled.
The structures that comprise a morphing aircraft must be understood to enable the system level performance optimisation. Equivalent models are used to capture their characteristics at the system level and must allow for changes in dimensions and geometry. Skins are vital components, and are typically anisotropic to combine stiffness to support the aerodynamic loads, and flexibility to enable deformation. Corrugated and reinforced elastomer skins have been a particular focus within the project.
The design of morphing aircraft continues to be a huge challenge, and this project has made significant advances in understanding the key requirements in the design process. However, modern aircraft are lightweight and highly optimised, and more research is required before morphing can be routinely considered as a design option for commercial aircraft.
The design of efficient morphing aircraft requires advances in system level modelling and performance assessment, innovative and novel structural concepts, and improved components such as compliant skins. All of these aspects were considered in the project and some highlights are summarised below.
The key requirement for the adoption of morphing technology is the demonstration of the potential performance benefits. This requires a system level analysis that considers not only the aerodynamics of the aircraft, but also the sizing and weight estimation for both the structure and actuators, and how the vehicle will be operated. For example, detailed analysis has been performed on aircraft with variable span for combined dash and loiter missions, to determine if the improved aerodynamic performance is able to offset the weight penalty.
Novel configurations investigated include the biologically inspired FishBAC compliant variable camber device, consisting of a chordwise spine with stringers to support a pre-tensioned elastomeric skin. A significant improvement in aerodynamic efficiency (the ratio of lift to drag) has been demonstrated in simulation and wind tunnel testing, for a relatively small increase in weight. A novel span extension concept with a compliant skin has been designed and extensively modelled.
The structures that comprise a morphing aircraft must be understood to enable the system level performance optimisation. Equivalent models are used to capture their characteristics at the system level and must allow for changes in dimensions and geometry. Skins are vital components, and are typically anisotropic to combine stiffness to support the aerodynamic loads, and flexibility to enable deformation. Corrugated and reinforced elastomer skins have been a particular focus within the project.
The design of morphing aircraft continues to be a huge challenge, and this project has made significant advances in understanding the key requirements in the design process. However, modern aircraft are lightweight and highly optimised, and more research is required before morphing can be routinely considered as a design option for commercial aircraft.