Research On The Horizontal Backward Launch Dynamics Of Airborne Missiles

The arsenal plane and the fifth-generation stealth fighter fighting side by side will greatly compensate for the latter’s problem of Insufficient bomb load,and become an important part of the future air combat for its great air strike capability.In order to solve the related dynamic problems of the missile’s horizontal backward launch of the arsenal plane,an effective and reliable simulation system of weapon launch is necessary for the study on the launch process.In this paper,a horizontal backward emission method suitable for large spans and long rails was studied.The vibration of the launch paltform,the initial disturbance of missile and the safety problems in separation were researched systematically,which has important reference values and engineering significance for the parameter selection and safety improvement of the missile launch.The main contents of this paper are as follows:(1)The basic concepts of launch dynamics related to the research content were described.The multibody system of missile separation was analyzed,and the dynamic equations of motion of a rigid body with six degrees of freedom of a rigid body with six degrees of freedom of a rigid body with six degrees of freedom were derived.The fluid control equations,constructed using the N-S equations based on the continuous medium assumption and the single equation turbulence model “SA model” based on the Boussinesq viscosity assumption,were solved with the finite-volume method to obtain the numerical solution of the flow field.This part provides important theoretical support for the establishment of the launch platform longitudinal vibration model,the missile separation dynamic model and the missile-plane separation flow field model.(2)An unsteady wind field model at high altitude was established with the power spectral density function,which was based on the Von Karman model as continuous gust model in calculation of atmospheric disturbance response.The equations of aircraft motion with wind disturbance were deduced,and the mathematical model for the longitudinal vibration of the airborne launch platform under the wind disturbance was established.By solving the equations,the theoretical calculation results of the longitudinal vibration of the airborne launch platform were obtained.The three-dimensional flow field model of the aircraft under the unsteady wind field was established,and then the simulation results of the longitudinal vibration of the airborne launch platform under the disturbance of continuous gust were obtained.Comparising the two results,the effectiveness of the model was verified,and the longitudinal vibration of the airborne launch platform under gust load were analyzed,which provides an important input for the study of initial disturbance.(3)The basic concepts of the horizontal backward launch,the composition of the launch system,and the movement characteristics of the missile off-rail process were described.Considering the characteristics of the horizontal backward launch of airborne missile,the calculation formula of the contact force was derived and the contact friction model during missile’s separating was established based on the contact analysis theory of finite element method.Analyzing the boundary conditions and the excitation loads in the missile’s off-rail process,the finite element model was established of missile separating from the rails under the condition of large spans and long rails,and then the results of the missile’s initial disturbance were obtained by numerical calculation.And compared with the ground ejection test results,the correctness of the model was verified.Through analyzing the off-rail process under longitudinal vibration of launch platform,the influence of the ejection velocity and launching angle on the initial disturbance of the missile was obtained,which provided initial input for the study of the separation safety of the off-rail missile.(4)The three-dimensional flow field around the carrier was established,and the flow field characteristics of the longitudinal section and the cross section of the carrier’s tail were analyzed through simulation calculations.According to the characteristics of the initial stage of external ballistics of the airborne missile launched at horizontal backward direction,the factors affecting the missile-plane separation safety were analyzed comprehensively.With the initial disturbance of the missile as the input,the simulation model of the missile-plane separation is established,and the changing law of the motion attitude of the missile in the initial stage of the external ballistic was calculated,and the influence of the missile ejection velocity and the launching inclination angle on the separation safety is obtained.