Infrared Signatures of Low-Flying Aircraft and Their Rear Fuselage Skin's Emissivity Optimization

Abstract

This paper analyzes the main contributors of infrared (IR) signature in a typical aircraft on a low-altitude mission. Various computational models are used to predict IR radiation from the aircraft. The bands within IR spectrum in which aircraft are susceptible to a typical IR-guided surface-to-air and air-to-air missile, for typical cases of tactical relevance, are identified. Lock-on range for aircraft against a typical missile is also computed. The feasibility of a low-altitude mission against a ground-based IR-guided threat is analyzed. The technique of emissivity optimization of aircraft rear fuselage skin, for reducing its infrared signature, is introduced and compared with other IR signature suppression techniques. The effectiveness of this technique in enlarging the safe flight envelope of aircraft, with respect to threat from heat-seeking missiles, for both surface-to-air and air-to-air missiles, is demonstrated. It is found that earthshine reflected off the aircraft surface plays a crucial role in the effectiveness of this technique against a surface-to-air missile (SAM) in 8‐12 μm band. Nomenclature A = area, m 2 H = spectral irradiance, μW/μm · m 2 h = aircraft altitude, km I = spectral radiant intensity, W/Sr · μm · m 2 J = spectral radiance: comprising emission and earthshine, W/Sr · μm · m 2 L = length, m M = Mach number N = number of discretized elements NEI = noise equivalent irradiance, W/m 2 Rma = distance separating missile and aircraft, km