An adaptive wing tip concept was developed to enable controlled wash-in and wash-out throughout the entire flight envelope. The concept is based upon adaptive stiffness structures enables control of the aeroelastic deflections, and also facilitates gust load alleviation. Furthermore, a mathematically based design tool was developed making use of Reduced Order Models (ROMs) of the wing structure and aerodynamics such that an inverse approach can be employed to determine the required sizing of the internal aircraft structure, and also the position and sizing of any adaptive structural components and actuators. The adaptive structural concept and the inverse ROM approach was demonstrated and evaluated on two real-size aircraft test cases.
Adaptive wing tip concepts have been considered to enable controlled wash-in and wash-out throughout the entire flight envelope. The concepts, based upon adaptive stiffness structures, enable control of the aeroelastic deflections to optimise the aerodynamic performance along with the use of changing the leading edge and trailing edge camber shape. A mathematically based design tool was developed, making use of Reduced Order Models (ROMs) of the wing structure and aerodynamics, so that an inverse approach can be employed to determine the required sizing of the internal aircraft structure, and also the position and sizing of any adaptive structural components and actuators. The adaptive structural concept and the inverse ROM approach will be demonstrated on a regional jet aircraft test case.
Initial studies using panel based aerodynamics were performed to determine the desired aerodynamic shape of the wing at different points in the flight envelope, and these were then used to optimise the internal structure so that the desired aeroelastic deflections were achieved subject to a number of structural constraints; further work considered the use of Euler based CFD.
Three types of adaptive structure-based solution were considered: rotating spars, moving spars and moving spar caps designed to enable the required wing-tip deflections through changes in the bending and torsional stiffness along with the position of the shear centre. The rotating spar concept had the greatest effect upon the stiffness characteristics of the wing cross-section.
Inclusion of the device showed that it is possible to achieve the required aerodynamic shapes at all parts of the flight envelope including the extreme low speed Mach 0.25 case; however the least amount of morphing required was when both the adaptive stiffness and leading/trailing edge camber stiffness concepts were used together.
The effect of uncertainty in both the aerodynamics and structural models was assessed using both Polynomial Chaos Expansion and Bayesian methods, and it was found that the morphing performance was most sensitive to the structural stiffness and aerodynamic parameters (speed and air temperature).
Further work is required to validate the concept using a more detailed aerodynamic and structural model.