Advancements in I.R. Suppressors for Helicopters

In recent military engagements, the threat of heat seeking missiles to helicopters has proven to be formidable. I.R. missiles have effectively hit their targets by sighting the infrared signal emitted from the exposed hot metal exhaust parts of turbine engines. Initial efforts to counter the missile threat involved hiding the hot engine parts from direct viewing by using bent tail pipes, bulb center body tail pipes, or others. The parts of the tail pipes contacting the hot exhaust gas were cooled with air. It is now established that the more advanced missiles have the ability to lock on to the turbine engines hot exhaust plume. Presented in this paper are the advances made in I.R. suppressors to effectively attenuate the I.R. signal from exhaust plumes. Particular attention is given to helicopter aircraft where protection at hover or at relatively low flight speeds is required. In this case the potential use of ram air for exhaust plume dilution is lost. Discussed is the initial design and testing of the plume attenuating suppressors and the subsequent modifications made to the suppressor to minimize aircraft system penalties such as suppressor size, weight, and power drain.