Research On Unsteady Aerodynamic Characteristics Of Low Aspect Ratio Flying Wing

As the development trend of UCAV in the future,every country is developing its own flying-wing UCAV.In this context,the research of flying-wing layout UCAV has important practical significance.This paper focuses on the research of aerodynamic characteristics and aerodynamic mathematical modeling of low aspect ratio flying wing.Firstly,based on the wind tunnel test data,the static aerodynamic characteristics of the aircraft are analyzed and the rudder efficiency is simply analyzed.The results show that the aircraft with low aspect ratio has good lift-drag characteristics and lateral static stability.The static course stability is poor,mainly due to the elimination of the vertical tail.The aircraft has good lift-drag characteristics,which is conducive to cruise.The single deflection of the trailing flap does not increase the static stability of pitch.The single deflection of wingtip rudder has an influence on the static stability of yaw and roll.The single deflection of wingtip rudder has an effect on the static stability of transverse direction.Secondly,the effects of the motion frequency and yaw-roll coupling ratio on the dynamic aerodynamic characteristics of the vehicle are discussed.The frequency of motion will affect the damping characteristics of pitch and roll motion,and the amount of aerodynamic force will increase with the increase of frequency.The coupling ratio has great influence on the aerodynamic damping characteristics,especially at high angle of attack.Finally,the unsteady aerodynamic model based on the yaw-roll coupled motion wind tunnel experiment is established,and the practicability of the model,dynamic derivative model and hybrid model in reflecting the unsteady aerodynamic characteristics of aircraft at high angle of attack is compared,and the accuracy and practicability of the model are verified by calculation.