Distributed versus concentrated flexibility in shape control of lifting surfaces: The "belt-rib" concept

Kurzfassung

The „mechatronic“ way of dealing with the issue of structure geometry control, based on mechanical systems with hinges, bearing and discrete actuators, cannot easily cope with the strict requirements of aircraft design. In this paper a “structronic” concept for airfoils with variable camber is presented, in which the desired geometry changes are achieved through structural flexibility and no moveable parts are needed. A short introduction to the “structronic” approach to structure adaptation in general and to airfoil shape control in particular opens the paper, with some emphasis on the role of solid-state actuators. The description of the new structural concept (the belt-rib concept) follows, with the application to the case of a landing flap with variable camber. Some results of FEM simulations as well as of experimental tests on different prototypes – one of them equipped with shape memory wires as actuators – are also included in the paper. The results provide a first feasibility proof of the new concept and encourage further work.