Lightning Transient Research on an F-111E Aircraft
Final rept. Jun-Dec 1976
AIR FORCE FLIGHT DYNAMICS LAB WRIGHT-PATTERSON AFB OH
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A simulated lightning test was conducted on an F-111E aircraft SN 67-116A to field test improved measurement techniques and to record and evaluate induced transient voltages on selected electrical circuits to determine their susceptibility to lightning. Technical improvements included 1 a pneumatic system to trigger the simulated lightning current-producing capacitor bank, 2 a change in configuration of current return leads, 3 specially designed breakout boxes and cables, 4 a fiber optics measurement system, and 5 a Tektronix transient digitizer data recording system. The standard 2 x 50 microsecond current pulse was applied to the aircraft nose-to-tail and induced voltages were measured and recorded both in the time and frequency domains on 17 different circuits with power off in the aircraft. The magnitude of the current pulse was varied from 0.5 to 5.5 kiloamperes, but most measurements were made at 2.5 kiloamperes. Measurements were made on flight critical circuits of the Altitude-Vertical Speed amplifiers, the Yaw and Roll computers, and the Roll Rate Gyro in the Feel and Trim assembly, on the tail light and right and left wing position light circuits, on the fuel indication circuits, and on the pitot heater circuit with and without a transient suppressor device. Power-on measurements made on four damper servo circuits resulted in substantially higher induced voltage amplitudes than with power off. Changing aircraft ground points did not affect the magnitude or waveshape of induced transients.
- Atmospheric Physics
- Test Facilities, Equipment and Methods