Long wave infrared signature of swept back leading edges in aircraft frontal aspect
Aircraft Engineering and Aerospace Technology
ISSN: 0002-2667
Article publication date: 18 January 2024
Issue publication date: 7 March 2024
Abstract
Purpose
In recent years, increased use of all-aspect infrared (IR)-guided missiles based on the long-wave infrared (LWIR; 8–12 µm) band has lowered the probability of aircraft survival in warfare. The lock-on of these highly sensitive missiles is difficult to break, especially from the front. Aerodynamically heated swept-back leading edges (SBLE), because of their high temperature and large area, serve as a prominent LWIR source for aircraft detection from the front. This study aims to report the influence of sweep-back angle (Λ, based on the Mach number [M∞]) on aerodynamic heating and the LWIR signature of SBLE.
Design/methodology/approach
The temperature along SBLE is obtained numerically as radiation equilibrium temperature (Tw) by discretizing the SBLE length into “n” number of segments, and for each segment, emission based on Tw is evaluated. IR radiance due to reflected external sources (sky-shine and Earthshine) and radiance due to Tw are collectively used to determine the IR contrast between SBLE and its replaced background in the LWIR band (icont-SBLE,LWIR).
Findings
The results are obtained for low subsonic turboprop aircraft (Λ = 3°, M∞ = 0.44); high subsonic strategic bombers (Λ = 35°, M∞ = 0.8); fifth-generation stealth aircraft (Λ = 40°, M∞ = 1.6); and aircraft with supercruise/supersonic capability (Λ = 50°, M∞ = 2.5). The aircraft with supersonic capability (Λ = 50°, M∞ = 2.5) reports the maximum LWIR signatures and hence the highest visibility from the front. The results obtained are compared with values at Λ = 0° for all cases, which shows that increasing Λ significantly reduces aerodynamic heating and LWIR signatures.
Originality/value
The novelty of this study comes from its report on the influence of Λ on the LWIR signatures of aircraft SBLE in the frontal aspect for the first time.
Keywords
Acknowledgements
The authors are grateful to research project no. RI/0100–10000483 (PGRDFI00009 Personal Research Development Fund of Prof. Shripad P. Mahulikar at IIT-Bombay) for the partial sponsorship. The authors also thank the Ministry of Human Resource Development, Govt. of India, for the financial support in the form of Teaching Assistantship to Kajal Vinayak (Roll no. 194010007 – IIT-Bombay).
Since submission of this article, the following author has updated their affiliation: Shripad P. Mahulikar is at the Escuela de Ingeniería de Bilbao (Departamento de Ingeniería Energética), University of the Basque Country UPV/EHU, Bilbao, Spain.
Citation
Vinayak, K. and Mahulikar, S.P. (2024), "Long wave infrared signature of swept back leading edges in aircraft frontal aspect", Aircraft Engineering and Aerospace Technology, Vol. 96 No. 2, pp. 205-214. https://doi.org/10.1108/AEAT-02-2023-0056
Publisher
:Emerald Publishing Limited
Copyright © 2024, Emerald Publishing Limited