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Lightning Field Spectra Obtained from Airborne Measurements
AIR FORCE WRIGHT AERONAUTICAL LABS WRIGHT-PATTERSON AFB OH
A WC-130 aircraft was used as an airborne platform for broadband electric and magnetic field sensors to measure the surface fields on the airframe from lightning strikes in the 7 - 35 km range. The waveforms were recorded digitally, with a sample interval of 20 nsec and a time window of 164 microseconds. Since the aircraft was above 15,000 feet, and the lightning source was relatively nearby, the effects of ground propagation were minimized. Spectra have been obtained for the stepped leader, first return stroke, and subsequent return stroke over the frequency range 100 kHz to 20 MHz. These spectra are compared to published data of lightning field spectra obtained from ground-based measurements. With airframe resonances and field enhancement effects removed, the data have two primary applications 1 To add to the data base for the nearby lightning strike threat and 2 To infer characteristics of the stepped leader, first return stroke, and subsequent return stroke processes. Recommendations for these applications are presented.
This article is from 'International Aerospace and Ground Conference on Lightning and Static Electricity (8th): 'Lightning Technology Roundup,' held at Fort Worth, Texas on 21-23 June 1983,' ADA135100, p47-1 thru 47-8.
Approved for public release; distribution is unlimited.