Full scale lightning generation techniques for aircraft susceptibility evaluations

Abstract

There are numerous laboratory tests that simulate aircraft/lightning interactions to assess aircraft survivability and vulnerability. One such test uses a high voltage capacitor bank to generate a high current pulse that is applied to an actual aircraft or a geometrically similar structure. The current pulse is similar in peak magnitude and shape to lightning return strokes present in a lightning flash. The test technique described here uses an aluminum cylinder to simulate an aircraft. The cylinder is representative in size and construction of a fighter-type aircraft fuselage. The objective is to assess the susceptibility of aircraft electrical circuits to the electromagnetic effects of the lightning current. When the current pulse is applied, measurements are made on electrical circuits inside the cylinder to determine the magnitude of voltages and currents induced as a result of electromagnetic fields created by the lightning current flowing on the cylinder surface. The high voltage capacitor bank used to generate the pulse is described along with details of the test circuit. The characteristics of the generated current waveshape and the limitations of pulse generators to simulate the complete lightning flash threat are presented. In addition, the total electrical circuit, which includes the capacitor bank, cylinder and return leads has been modeled. Through computer analysis, the waveshapes of the total surface current are calculated and compared to empirical values for the cylinder test configuration.