Development and demonstration of atmospheric electricity hazards protection

An Advanced Development Program (ADP) to develop and demonstrate effective Atmospheric Electricity Hazards Protection (AEHP) for the fighter, transport/bomber, helicopter and cruise missile classes of air vehicles is being conducted under an Air Force Wright Aeronautical Laboratories (AFWAL) contract with Boeing Military Airplane Company (BMAC). Other Government agencies are also supporting the ADP. The parameters characterizing the lightning threat have been defined for moderate and severe flashes ; e.g., 200 kA peak and 200 kA/microsecond rise rate for the severe threat lightning current. The attachment of lightning flashes to aircraft has resulted in many losses of aircraft in the past. The losses have been caused by both physical damage to the aircraft frame or structure, and electrical effects to aircraft flight critical elements and systems. The losses associated with upset and/or damage may increase with the advent of sensitive integrated circuitry being used in flight critical applications, and the use of composite material in these airframes and structures thereby reducing its electromagnetic shielding effectiveness. Protection concepts ; e.g., circuit and system shielding, terminal protection, conducting floors and cable protection ; may be used to prevent damage. A design methodology considering airframe characteristics, and circuit and system characteristics and criticality, which will lead to identification of balanced protection schemes is presented. Incorporation of AEHP is expected to enhance the operational flexibility of air vehicles through increased confidence of all-weather operational integrity. The effectiveness demonstration phase of the AEHP ADP using a modified F-14 airframe with advanced avionic and power systems is described. An ACAP helicopter is also to be used as a testbed. The testbeds will be subjected to low-level continuous wave (CW), moderate-level pulse, and severe-level pulse current injection. This method evaluates the safety margin of the generic protection design. Revue Phys. Appl. 21 (1986) 795-801 DÉCEMBRE 1986,