Preliminary Design And Optimization Of Coaxial Unmanned Helicopter

The application of helicopter preliminary design,aerodynamic analysis,trimming,flight performance analysis and multi-disciplinary optimization technology on the preliminary optimization design of coaxial unmanned helicopter are researched in this thesis.Firstly,based on the existing data of coaxial unmanned helicopter,the preliminary parameter determination method in the preliminary design stage is established by statistical analysis method,forming the preliminary design of the aircraft;Secondly,the aerodynamic interference factor is introduced to solve the coaxial rotor aerodynamic interference problem,and the first-order harmonic form static non-uniform inflow model is adopted to establish the coaxial double-rotor inflow model.Combining the blade element-momentum theory,the load calculation model of coaxial rotor is established.Adding the aerodynamic calculation model of the fuselage,flat tail and vertical tail,a full-machine stable flight balance model can be established and the state balance solution and power needed can be obtained,which are the basis for aerodynamic performance and flight performance analysis;Referring to the flight performance analysis method of single-rotor helicopter,the hovering and forward flight performance analysis model of coaxial unmanned helicopter can be established;The effectiveness of the aerodynamic model and performance model established in this paper are proved by analyzing the balance calculation analysis and flight performance of a sample coaxial unmanned helicopter;Integrating the disciplines of gravity,aerodynamics,and flight performance,a multi-disciplinary optimization model of preliminary parameters is established by multi-objective genetic algorithm,the effectiveness of the optimization model is verified by optimizing the preliminary design that was originally formed.In conclusion,the systematic preliminary optimization design on coaxial unmanned helicopter was formed.