Calculation and Analysis on Stealth and Aerodynamics Characteristics of a Medium Altitude Long Endurance UAV

Abstract

This paper seeks to calculate and analyze the stealth and aerodynamics characteristics of a medium altitude long endurance (MALE) UAV. Firstly, geometry model of the UAV was established according its technical parameters by three-dimensional modeling software. In terms of electromagnetics analysis, the physical optics (PO) and the method of equivalent currents (MEC) were used as the numerical computation method, and its feasibility was verified by experiment. The main radar scattering source, scattering characteristics, polarization characteristics and RCS level were analyzed by the computation of the main components and the whole UAV under the electromagnetic bound S (3GHz) and bound X (10GHz). In terms of fluid analysis, the finite volume method was used to solve Navier-Stokes equations and the Spalart-Allmaras (S-A) turbulence model was applied to simulate the turbulence. The aerodynamics characteristics of lift, drag and pitch in the cruise state were calculated. The final result shows: the aerodynamic layout of high aspect ratio and approximate straight wing has good aerodynamic performance of high lift-drag ratio. The high aerodynamic efficiency of UAV makes for investigation or carrying out other tactical assignment with long endurance; however, the aerodynamic layout has the disadvantage in the stealth performance. Big leading edge radius of the low-speed aero foil and low sweptback angle of wing (and empennage) has mirror reflection, which make up of the important scattering source in the front direction of UAV. Large radius of curvature surface and small angle plane of fuselage has high scattering level in the side direction of UAV. These results may help the stealth design and research of UAV.