Investigation of the Effects of UAV Nozzle Configurations on Aircraft Lock-on Range

Abstract

The infrared lock-on range of target aircraft plays a critical role in determining the aircraft survivability. In this investigation, the effects of various UAV engine nozzle configurations on the aircraft lock-on range were theoretically analyzed. A virtual subsonic aircraft was proposed first, based on the mission requirement and the engine performance analysis, and convergent-type nozzles were then designed. After determining thermal flow field and nozzle surface temperature distribution with the CFD code, an additional analysis was conducted to predict the IR signature. Also, atmospheric transmissivity for various latitude and seasons was calculated, using the LOWTRAN code. Finally, the lock-on and lethal envelopes were calculated for different nozzle configurations, assuming the sensor threshold of the given IR guided missile. It was shown that the maximum 55.3% reduction in lock-on range is possible for deformed nozzles with the high aspect ratio.

Analysis of Plume Infrared Signatures of S-Shaped Nozzle Configurations of Aerial Vehicle

“…The lock-on range is the measure of aircraft susceptibility to IR-guided missiles and can be determined primarily by the IR emissions of target aircraft and the detection capability of IR sensor [13,26]. When atmospheric transmissivity is taken into account, the lock-on range R LO may be expressed as…”