Computational Zoning Assessment of Unconventional Aircraft

Abstract

The protection of aircraft from lightning strikes, both triggered and intercepted, is an essential component in the aircraft development process. In the past, lighting strikes to aircraft have caused catastrophic accidents that have prompted studies into the mechanisms behind lightning effects and their mitigations. These recommendations have led to protective measures in the form of wire mesh and diverter strips on nonmetallic surfaces, removing sources of spark-triggered ignition in fuel system, and route management to avoid thunderstorms.

While significant progress has been made in understanding these phenomenon, much of what we know about lightning strikes to aircraft comes from historical experience and testing. This knowledge is currently used to drive requirements for new aircraft designs, which may not conform to the same assumptions under which models for existing aircraft are valid.

As the aviation industry has evolved, so too has our ability to predict the onset of aircraft triggered lightning. At present, computational tools are used extensively in lightning protection scenarios to adapt old models to new designs. Specifically, computational zoning analysis predicts points on the aircraft at which a lightning leader will likely initiate.

In this work, a new pipeline for the computational zoning assessment of novel aircraft using free, open source software is developed. This methodology is discussed and compared with other zoning techniques that have been used in the past.

The zoning methodology presented here predicts positive and negative leader attachment points for arbitrary orientations of the ambient electric field. Additionally, analysis of the optimal aircraft charge, allowing the aircraft to sustain higher fields, is presented.

The details of the software, which uses an implementation of the three dimensional Galerkin finite element method, is covered. Analysis examples of the MIT D8 DoubleBubble, a Blended Wing Body, and a conventional transport aircraft are presented.