Structural Batteries in Aviation: A Preliminary Sizing Methodology

A significant research effort in aviation is currently focused on the integration of electric or hybrid-electric power-trains onboard aircraft in an effort to improve efficiency and environmental friendliness. New designs incorporating these novel propulsion systems face the issue of penalizing battery characteristics, especially in terms of limited energy and power density performance, in turn imposing a toll on the inert weight of the machine. A possible solution to this issue is that of structural batteries. These are similar in structure to carbon fiber composites, where the matrix features dielectric characteristics, making the structure capable of storing electric energy while retaining the capability to withstand mechanical loads. The adoption of this technology, currently under advanced development, shall enable significant weight savings; yet it also raises relevant issues concerning aircraft sizing procedures that need to be conceived taking into account the specific characteristics of such multifunctional materials. This paper faces the new problem of aircraft initial design in presence of structural batteries. First, it presents a method for aircraft preliminary weight sizing, where the double effect of structural batteries on both structural mass and energy storage mass is considered. Subsequently, a procedure to size an airframe structure with the adoption of structural batteries in key components is shown, based on a weight-optimal approach. The complete sizing procedure is illustrated through an award-winning test case in the General Aviation category.