In the process of airfoil optimization, it is required to represent an with parameters, and goal arbitrary airfoils less parameters. this paper, a new parameterization method proposed, called IGP method, which realized camber-thickness decoupling so that camber thickness could be constructed respectively fewer parameters compared previous methods. Also featured clear physical meaning consecution parameter domain. The mathematical model introduced. With definition domain control was...

To find a trajectory with low radar detection probability for stealth aircraft under the assumption of 2D space, performing rapid turning maneuver is useful way to reduce an by changing azimuth angle rapidly time high cross-section (RCS) exposure radar. However, in real flight, not only does change but elevation also changes rapidly, and significant this process. Based on premise, paper established planning method based sparse A* algorithm 3D complex, dynamic environment, called method,...

With the continuous improvement and development of armed helicopters, research on their stealth characteristics has become more in depth. In order to obtain complex effect caused by high-speed rotation rotor-like components, a dynamic scattering method (DSM) is presented. Rotation speed, azimuth, elevation angle, pitching rolling angle are studied discussed detail. The results show that electromagnetic main rotor tail periodic. This period characteristic related speed attitude rotor. radar...

Abstract In order to reduce the radar cross section (RCS) of unmanned aircraft while suppressing its infrared signature, a comprehensive design method (CDM) based on sorting factor Pareto solution is presented. The physical optics and diffraction theory are used evaluate electromagnetic scattering characteristics aircraft, Monte Carlo ray tracing radiation intensity exhaust system. CDM screen each individual in offspring, parameters sub-models system continuously improved. results show that...

For modern stealth aircraft, it is important to analyze the influence of Radar Cross Section (RCS) peak exposure on penetration for guiding design and trajectory planning, which needs reflect RCS statistical uncertainty difference with change incident angle. Based characteristics typical this paper established a simplified dynamic fluctuation model parameters log mean standard deviation. According detection probability algorithm in radar signal processing field, built based model. The...

This paper describes the design, parametric study, and IR signature analysis of plume a slit-shaped exhaust nozzle. Circular-shaped nozzles are generally used to get essential thrust necessary for an aircraft flight. However, Infrared (IR) emanating from these is very high, missile can easily lock hit aircraft. In this paper, compressible flow CFD model using realizable k-ε turbulence study characteristics nozzle with different aspect ratios. The exit cross-section kept elliptical up maximum...

Most existing studies on aerodynamic shape optimization have not considered longitudinal trim under control surface deflection, typically achieving self-trim through a constraint of zero pitching moment or adjusting the optimized configuration for trim. However, adjustments to might introduce additional drag, reducing overall benefits. In this paper, novel approach incorporating deflection in is proposed. Firstly, an computation program based high-order panel method was developed,...

In this paper, two typical stealth aircraft concepts (wing fuselage blended and flying-wing) were designed. Then three gradually changed surface distribution models with the same planform for each concept created. Based on multilevel fast multipole algorithm (MLFMA), vertical polarization transmitting/vertical receiving (VV) horizontal transmitting/horizontal (HH) radar cross section (RCS) characteristics simulated five frequencies between 0.1 1.0 GHz. The influences mechanisms of...

With the development of coaxial rotors and high-speed helicopters, electromagnetic scattering characteristics helicopters have gradually become a research hotspot. In order to deal with Radar Cross-Section (RCS) rotating or main rotors, Dynamic Scattering Method (DSM) based on dynamic process simulation grid coordinate transformation is presented. Instantaneous from solved using Physical Optics (PO) Theory Diffraction (PTD). Important factors are analyzed discussed in detail, including...

The development of quantum radar technology presents a challenge to stealth targets, so it is necessary study the detection probability. In this study, an analytical expression cross section (QRCS) for complex targets presented. Based on QRCS expression, calculation method probability creatively proposed. Moreover, self-designed flying-wing aircraft adopted obtain distributions conventional and in different directions. As revealed by result probabilities are significantly different, has...

A 1019 bit Legendre code was evaluated for use in digital ionosondes. Experimental testing done using the Canadian Advanced Digital Ionosonde (CADI). Theoretically, autocorrelation function of this new sequence has very low peak sidelobe level −32.6 dB, and system signal‐to‐noise‐ratio (SNR) will be improved by 30 dB compared with a single pulse code. Field experiments were near London, Ontario, Canada, two CADIs bistatic arrangement 20 km spacing. The experimental results agreed theoretical...

With the continuous advancement of rotor dynamic electromagnetic scattering research, radar cross-section (RCS) turbofan engines has attracted more and attention. In order to solve characteristics a biaxial multirotor engine, method (DSM) based on simulation grid transformation is presented, where static RCS engine its components calculated by physical optics theory diffraction. The results show that periodic when working stably, while rotors such as fans turbines are main factors affecting...

To study the Radar Cross-Section (RCS) characteristics of tilt-rotor aircraft, a dynamic calculation approach that takes into account rotor rotation and nacelle tilt is presented. Physical optics physical theory diffraction are used to deal with instantaneous electromagnetic scattering target. The RCS aircraft in helicopter mode, fixed-wing mode transition analyzed. results show blade has weaker deflection effect on head incident wave horizontal plane. improves plane, while it increases...

In this paper, the aerodynamic characteristic of a ducted tail rotor in hover has been numerically studied using CFD method. An analytical time domain formulation based on Ffowcs Williams-Hawkings (FW-H) equation is derived for prediction acoustic velocity field and used as Neumann boundary condition rigid scattering surface. order to predict noise, hybrid method combing computational aeroacoustics with an thin-body element proposed. The results calculated sound pressure levels (SPLs) are...

Purpose This study aims to the radar cross-section (RCS) of an intermeshing rotor with blade pitch. Design/methodology/approach The variation pitch is designed into three modes: fixed mode, linear mode and smooth mode. dynamic process two crossed rotors simulated, where instantaneous RCS calculated by physical optics theory diffraction. Findings Increasing angle in can reduce average at given head azimuth. curve helicopter will have a large peak side direction moment. Although generally...

To study the electromagnetic scattering characteristics of a morphing aircraft with Z-folding wings, method hybrid grid matrix transformation (HGMT) is presented. The radar cross-section (RCS) in four modes calculated and analyzed. When considering deflection outer wing separately, RCS under head side azimuth shows obvious dynamic characteristics, while peak fluctuation range are quite different. mid deflected upwards together, positive direction could be significantly reduced. deflects...

The main acoustic noise source of helicopters is supposed to be the rotor blades, but scattering effect helicopter fuselage sometimes cannot ignored. For accuracy prediction and research on affections fuselage, an FWH–BEM Method (FBM) based convective FW–H equation boundary element method (BEM) presented for effects approach calculation a helicopter’s field. In this paper, different models are adopted comparisons scattered by types fuselages. According discovery that fuselages with sharp...