| The landing gear,as a relatively independent device component in the overall structure of the aircraft,plays an extremely important role in buffering and releasing energy during the main accidents of the aircraft such as takeoff,landing and ground roll.Therefore,the performance of the landing gear device is an important factor that affects the safe takeoff and landing of the aircraft.This article takes S/VTOL fixed-wing UAVs as the object,and sets the landing gear layout based on many factors such as weight,stability,crash resistance and UAV characteristics,and determines it by calculating the design conditions such as focus,center of gravity and bearing ratio The main landing gear position.Then,according to the high-speed cruising characteristics of S/VTOL fixed-wing UAV,in order to avoid aerodynamic loss,a set of retractable mechanism that meets the requirements of retractable space was designed.In order to meet the requirements of the width of the fuselage and the main wheelbase of the main landing gear,by increasing the angle between the main shaft of the main landing gear and the horizontal line of the extension,the main landing gear is stored in the chord direction,and the support members such as the buffer pillar Move towards the inside of the fuselage,and through the reasonable design of the wheel rotation mechanism,the large angle between the wheel and the fuselage of the aircraft is avoided without adding a power source.The rear landing gear adopts a half-rocker configuration,and the installation method is coaxial with the full-motion fin rotation shaft.The fin is divided into two parts:the main rudder surface and the follow rectification surface,and the follow rectification surface connected to the rear landing gear wheel axis Part of the load-bearing process is retracted in the inner ring of the main rudder surface of the ventral fin through the chute to reduce the weight of the rear landing gear as much as possible.Since the target prototype is a small verification machine.Due to the limitations of weight and space,there is no independent center of gravity adjustment system in the body.Therefore,in response to the large center of gravity changes caused by landing gear retracting and other processes,as well as the small amplitude and high-frequency secondary center of gravity changes caused by factors such as fuel oil level changes,The longitudinal dynamic model of the S/VTOL fixed-wing UAV was established,and the trimming conditions of the S/VTOL fixed-wing UAV were obtained through the Nelder-Mead Simplex optimization algorithm modified based on the homotopy continuity principle,and based on this A robust control method based on angular acceleration estimation and compensation is presented.According to the above design scheme,this article completed the establishment of a three-dimensional digital model of the S/VTOL fixed-wing UAV landing gear system based on the established landing gear movement and dynamics model,and established a load that includes the simulation of the aircraft equivalent aerodynamic lift caused by the load change.The dynamic analysis model of the main landing gear with damping and buffer strut friction is analyzed by joint simulation with digital prototypes established by ADAMS and CATIA to solve the dynamic characteristics of the earthquake.Finally,in view of the strong multi-field coupling interference between the S/VTOL fixed-wing UAV rotor wake and the airframe components during the ground roll phase,a complex ground-effect coupling flow field was formed,such as rotor/wing,rotor/machine Aerodynamic coupling models such as body,rotor/tail,and integration of the aerodynamic models of each component by combining the body dynamics equations to obtain a complete nonlinear six-degree-of-freedom dynamic model,which can be used to slide S/VTOL fixed-wing UAVs More detailed modeling was carried out during the running phase. |
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