• 한국군사과학기술학회지
• /
• 제22권1호
• /
• pp.81-92
• /
• 2019

Stealth means the reduction of all signature including the reflection/emission of radar, infrared, visible light and audio signals. Stealth aircraft can significantly improve the penetration capability, the combat survivability and the mission effectiveness. This paper presents the basic concept, the key elements and the application examples of stealth aircraft technology. Also it briefly describes the effect of the modern stealth aircraft on the future air warfare.

• International Journal of Aeronautical and Space Sciences
• /
• 제17권1호
• /
• pp.101-108
• /
• 2016

The RCS characteristics of stealth modified three-surface aircraft are analyzed in this paper. Prototype A is built with CATIA software and the three-dimensional digital models of modified stealth three-surface B and C are also designed based on carrier-based aircraft Su-33; the numerical simulation of RCS characteristics of three-surface aircraft is conducted with RCSAnsys software based on physical optics method and the method of equivalent currents; The following results are obtained by comparative analysis and mathematical statistics: (1) by the use of physical optics method and equivalent electromagnetic current method, the scattering intensity for each part of the model and RCS characteristic of the aircraft can be analyzed efficiently and accurately; (2) compared with model A, the mean RCS value of model B is reduced to 14.1% in forward direction and 48.1% in lateral direction; (3) compared with model A, the mean RCS value of model C decreases to 11.4% in forward direction and 21.6% in lateral direction. The results are expected to provide theoretical basis and technical support to the conceptual design of aircraft and stealth technology research.

• 한국군사과학기술학회지
• /
• 제18권4호
• /
• pp.369-375
• /
• 2015

In this paper, transparent circuit analog radar absorbing structure with angular stability for stealth aircraft canopy was proposed and designed. To obtain wideband electromagnetic absorption, optical transparency and smaller thickness, we proposed the novel FSS(Frequency Selective Surface) for X-band and implemented the resistive FSS and PEC(Perfect Electric Conductor) plane using ITO(Indium Thin Oxide) coating with optical transmissivity of 90 %. Reflection loss characteristics for different incident angles of both TE(Transverse Electric) and TM(Transverse Magnetic) polarizations are presented through simulations. We then fabricated the proposed structure to verify the simulation results. The comparisons between the simulation and measured results show good agreements. The results also show that the proposed radar absorbing structure can provide better frequency stability for different incidence angles and polarizations as well as optical transparency. We can apply this proposed structure to the canopy of stealth aircraft and other stealth applications for visible transparency.

• 한국군사과학기술학회지
• /
• 제17권6호
• /
• pp.764-772
• /
• 2014

The stealth performance of supersonic aircraft in recent air battlefield is one of the most significant feature for latest fighters. Especially, as the technology is advancing, the IR stealth capability becomes more important because of its passive characteristic. To design an aircraft with stealth capability, we must know how much the IR signature is generated from the aircraft. Also, predicting the IR signature of enemy's aircraft is tactically crucial. In this study, we calculated MWIR and LWIR infrared signature of $5^{th}$ generation supersonic aircraft against air-to-air and surface-to-air threat using IR simulation code and CFD coupled procedure.

• 한국진공학회지
• /
• 제17권6호
• /
• pp.501-510
• /
• 2008

비행체를 레이더의 시야에 들어나지 않도록 하기 위한 은신 (stealth) 기술은 일반적으로 비행체 표면에 특수도료를 도포하는 방식을 사용하여 실현하고 있지만 요즈음 플라즈마의 전자기파 흡수 능력을 이용하려는 연구가 활발히 진행되고 있다. 대기압 플라즈마가 은신기술에 응용될 수 있는가 우선 물리적인 타당성을 알아보기 위해 이 논문에서는 대기층에서 비행하는 비행체 표면을 어떤 정도의 플라즈마로 얼마나 덮어야 원하는 은신 기능을 나타낼 수 있는지 판단할 수 있도록 비 자장, 비 균일, 평판 플라즈마 모델을 사용하여 계산한 결과를 제시하고 논의한다.

• International Journal of Aeronautical and Space Sciences
• /
• 제15권3호
• /
• pp.309-319
• /
• 2014

This paper mainly focuses on the conceptual design and stealth performance of the three-surface military aircraft. A three-dimensional (3-D) digital mock-up of the three-surface strike fighter with stealth feature was designed and the schemes of carrying missiles were analyzed in CATIA. Based on physical optics principle and the Method of Equivalent Currents (MEC), a numerical simulation of the RCS feature of the aircraft was carried out with RCSPlus which is a software designed by Beihang University. The paper contributes to the RCS feature analysis of the whole plane and different parts on X-band, S-band and UHF-band and a comparison of RCS feature to Su-37 and T-50 military aircraft is drawn. On X-band, the pitch angle of the incident wave was $0^{\circ}$, and the result shows: (1) Compared with Su-37 aircraft, the forward scattering RCS of the three-surface strike aircraft was reduced to 14.9%, the side scattering RCS to 9.6% and the back scattering RCS to 40.2%. (2) Compared with T-50 aircraft, the forward scattering RCS was reduced to 38.61%, and the side scattering RCS to 67.26%. This paper should be useful for researchers in conceptual design and stealth technology of the military aircraft.

• 한국군사과학기술학회지
• /
• 제17권4호
• /
• pp.463-470
• /
• 2014

Stealth technology of combat aircraft is most significant capability in recent air battlefield. As the detector of IR missiles is being developed, IR stealth capability which is evaluated by IR signature level become more important than it was in previous generation. Among IR signature of aircraft from various sources, aerodynamic heating dominates in long-wavelength IR spectrum of $8{\sim}12{\mu}m$. Skin temperature change by aerodynamic heating which is derived by effects of Mach number and structure. The 4th and 5th generation aircraft are selected for calculation of the skin temperature, and its height and velocity in numerical conditions are 10,000 m and Ma 0.9~1.9 respectively. Aircraft skin temperature is calculated by computing convection of fluid and conduction, convection and radiation of surface. As the aircraft accelerates to higher Mach number, maximum skin temperature increases more rapidly than average temperature and temperature distribution changes in more sharp, interactive ways. The 4th generation aircraft whose shape is more complex than that of the 5th generation aircraft have complicated temperature distribution. On the other hand, the 5th generation aircraft whose shape is relatively simple shows plain temperature distribution and lower skin temperature in terms of both average and maximum value.

• 한국군사과학기술학회지
• /
• 제25권3호
• /
• pp.251-258
• /
• 2022

Infrared stealth technology used in aircraft is applied to reduce the infrared signal by controlling surface temperature and emissivity using internal heat sink, low emissivity material or metamaterial. However, there is one part of the aircraft where the use of this technology is limited, and that is the radome. Especially, radome should have transmittance for the specific radio frequency, therefore, common stealth technology such as emissivity control surfaces cannot be applied to radome surface. In this study, we developed metal nano-coating for infrared stealth which is applicable to radome surface. We designed slot-type pattern for frequency selective transmission in X-band, and also controlled thickness of metal nano-coating for long wavelength infrared emissivity control. As a result, our infrared stealth surface for radome has 93.2 % transmittance in X-band and various infrared emissivities from 0.17 to 0.57 according to nano-coatings thickness. Also, we analyzed infrared signature of radome through numerical simulation, and finally reduced contrast radiant intensity by 97.57 % compared to polyurethane surface.

• 한국추진공학회지
• /
• 제25권4호
• /
• pp.28-35
• /
• 2021

열 추적 미사일로부터 항공기를 보호하기 위한 적외선(IR: InfraRed) 스텔스 기술은 군용 항공기 개발에 있어 매우 중요한 요소이다. 본 연구에서는 항공기에서 발생하는 다양한 적외선 신호 중 엔진 후류에서 발생하는 적외선 신호를 관측하고 이를 측정 각도별로 확인하여 신호 강도를 비교하였다. 실제 항공기에 적용된 제트 엔진을 모사하기 위해 소형 터보젯 엔진을 구성하였으며, 측정 각도에 따른 파장별 적외선 신호 특성을 확인하였고 파장별 신호를 적분하여 측정 범위 내 전체 적외선 radiance를 도출하였다. 본 연구를 통해 항공기 적외선 스텔스 성능 향상을 위한 기초 데이터를 제시하고자 한다.

• 한국전산구조공학회논문집
• /
• 제29권5호
• /
• pp.455-461
• /
• 2016

적외선을 이용한 무기체계의 발달로 인해 항공기의 생존은 큰 위협에 직면해 있다. 따라서 항공기의 생존성 향상을 위해서 적외선 스텔스 기술이 매우 중요하다. 본 논문에서는 수치해석을 통해 실제 비행환경에서의 항공기 표면온도 및 주위 배경에 따른 적외선 신호를 분석하고 이를 바탕으로 적외선 스텔스를 위한 항공기 표면 구조체 방사율의 가이드라인을 제시하고 그 성능을 검증하고자 한다. 수치해석 결과, 주위 배경에 따라서 항공기 표면 방사율을 최적화한다면 항공기와 배경간의 복사대비강도를 감소시킬 수 있음을 확인하였다.