Measurement of lightning strike current effects on an airplane fuselage test setup

During the investigation, an aluminum test cylinder, representative in size and construction of a fighter-type aircraft fuselage, was subjected to high current pulses, similar to lightning return strokes. The objective of this full scale test technique was to assess the susceptibility of aircraft electrical circuits to lightning. Tests were conducted to determine the magnitude of magnetic flux density inside the cylinder as a result of lightning current flowing on the cylinder surface. The initial phase of the investigation was the modeling of the entire experimental circuit in order to calculate the total surface current and compare it to the measured values. During the second phase, a new technique was developed for the measurement of the magnetic field distribution outside and inside along the test cylinder during the simulated lightning surges. An example is given: the measured ratio of the voltage outputs of two magnetic flux density probes at two test points, one outside and one inside the closed aluminum test cylinder, was about 4700.