This post describes the steps to perform lightning initial attachment for zoning. Lightning zoning for aircraft involves separating each aircraft outer surface area into a specific category based on its likelihood for lightning attachment, lightning sweep and lightning hang-on. The steps required are detailed s in SAE ARP 5414A: Aircraft Zoning. The task is divided into two sections:
- Determination of the initial attachment locations
- Zoning based on the ARP guidance using the attachment locations and the vehicle operating speeds at various altitudes
EMA has applied its Finite-Difference Time-Domain (FDTD) solver of Maxwell’s equations (EMA3D) in the determination of primary attachment regions on air vehicles previously. The approach is to model a lightning leader in proximity to the vehicle with a time-domain buildup of charge for which the simulation can be run to steady-state. At steady-state, the distribution of the surface normal electric field over the vehicle is characterized.
Regions of high electric field become of interest as the potential primary attachment points for the vehicle in the E-field modeling approach. It is possible to take advantage of the time-domain nature of the solution as it approaches steady-state to characterize the rate of increase in electric field (and charge) in the regions of interest. Those areas building to a peak charge most rapidly are considered likely candidates for early streamer formation and as primary attachment locations.
This post describes step-by-step how to perform the lightning initial attachments for zoning. You can download all the files needed to try this example here. If you would like to try a demo of the EMA3D Framework, contact us.
After the initial attachment points have been assigned, EMA3D CADfix is used to easily label each zone by color on a 3D model of the aircraft. It is exportable in a variety of formats, including 3D PDF. Contact EMA if you have any questions about how you can do this, or to hire EMA analysts to perform a zoning for your aircraft.