Accession Number : AD0910158

Title :   Lightning Effects Relating to Aircraft. Part III. Measurements of Lightning-Induced Voltages in an F4H-1.

Descriptive Note : Final rept. Nov 71-Jan 73,

Corporate Author : GENERAL ELECTRIC CO PITTSFIELD MA HIGH VOLTAGE LAB

Personal Author(s) : Plumer, J. A.

Report Date : MAR 1973

Pagination or Media Count : 122

Abstract : Measurements of possible lightning-induced voltages on several electrical circuits within an F4H-1 aircraft are reported. The measurements were made using the transient analysis technique in which simulated lightning currents identical in waveshape but reduced in amplitude from that of natural lightning are passed through the aircraft. The resulting induced voltages are than scaled upward in direct proportion to natural lightning amplitude. When scaled to a scale lightning stroke of 200,000 amperes as described in MIL-B-5087B, Para. 3.3.4.5, voltages induced in the measured circuits ranged between several millivolts and several thousand volts. Factors influencing the susceptibility of a particular circuit included circuit routing, function, electrical return path and exposure to direct contact with lightning currents at extremities such as NAV lights and pitot heaters. The circuits receiving the highest induced voltages include those in which associated components have been damaged as reported in actual F-4 lightning stroke incident reports. The results indicate that a combination of voltage limiting spark gap devices and lower voltage surge suppressors may be effective in limiting many of these voltages to safe levels, but the maximum transient voltage withstand levels of connected avionic and power system equipment should be determined before maximum safe voltage limits can be established. The advent of solid state avionics and nonmetallic structural materials in future aircraft will greatly aggravate the induced voltage problem unless positive steps are taken to establish coordinated protection levels and design in accordance therewith. (Author)

Descriptors :   (*LIGHTNING, JET FIGHTERS), (*JET FIGHTERS, ELECTRICAL EQUIPMENT), TRANSIENTS, DAMAGE ASSESSMENT, VOLTAGE, SIMULATION, ELECTRIC DISCHARGES, ELECTRONIC EQUIPMENT, COMPOSITE MATERIALS, CIRCUITS, INTERFERENCE, LIGHTNING ARRESTERS, ELECTROMAGNETIC COMPATIBILITY, ELECTROMAGNETIC PROPERTIES, SUPPRESSORS, HAZARDS, AVIATION SAFETY, LIGHTING EQUIPMENT, BOMBING COMPUTERS, PITOT TUBES, HEATERS, AIR TO AIR MISSILES.

Subject Categories : Attack and Fighter Aircraft
      Atmospheric Physics
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE