How mechanical engineering issues affect avionics design

Environmental questions that involve temperature and heat dissipation are discussed. A description is given of work on passive (no machinery to move coolant) cooling techniques, which can replace active (machinery-powered) cooling systems, and studies to ascertain the effect of temperature on equipment reliability. The following conclusions are reached. Passive cooling techniques can produce temperatures approximately equivalent to those of active cooling. Heat transfer enhancement techniques can extend the application of passive cooling. Geometry and arrangement are important for achieving good heat transfer with passive cooling. Active cooling can incur high prices beyond the immediately visible costs of the active cooling systems alone. System configuration decisions can continue into future or derivative programs because of nontechnical considerations, making careful thought in early stages essential. 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.<>