How mechanical engineering issues affect avionics design

Environmental questions that involve temperature and heat dissipation in connection with avionics are discussed. The authors describe recent work on (a) passive (no machinery to move coolant) cooling techniques allowing deletion of active (machinery powered) cooling systems, and (b) studies to ascertain the effect of temperature on reliability. It is shown that passive cooling techniques can produce temperatures approximately equivalent to those of active cooling, and that heat-transfer-enhancement techniques can extend the application of passive cooling. In addition, it is noted that active cooling can incur high prices beyond the immediately visible costs of the active cooling systems alone. The influence of temperature as a failure accelerator in moderate temperature ranges cannot be readily confirmed. Passive cooling minimizes the interface definition for application of electronic equipment, thus simplifying use of a box in multiple applications