Lock-on range of infrared heat seeker missile

The lock-on range, R, of infrared (IR) heat seeker missile has been studied in details. An analytical expression form of R has been derived in term of target (assumed as aircraft hot metal tailpipe), atmosphere and infrared (IR) detector parameters. The R is represented in term of ldquoLambert W functionrdquo and as a function of target temperature, T, and atmosphere extinction coefficient, alpha. Assuming clear sky background, the simulation results show: firstly, R increases as the target temperature increases. High value of R is achieved when the temperature of aircraft engine is high especially in takeoff case where the engine thrust is large. Secondly, R can be decreased by (1) increasing the attenuation coefficient of the propagation medium, i. e. by cooling the aircraft hot engine or any other obscurants that absorb or scatter the IR radiation (2) or by decreasing emissivity , epsiv, of the target surface which depends on the applied coatings / paintings. The decreasing of R will increase the probability of aircraft survivability assuming effective aircraft early warning system where the detecting range of the latter should be larger than the missile lock-on range.