Research On The Overall Scheme Of A Tail-sitter UAV

By analyzing the advantages and disadvantages of different new configuration aircraft,aiming at the functional requirements for high-speed cruising and vertical take-off and landing,a general scheme of long-endurance tail-sitter unmanned aerial vehicle is proposed in this thesis.This aircraft can cruise at high speed as the fixed-wing UAV and also realize the vertical take-off and landing and the low-altitude stable flight as the tilt-rotor by tilting the rotors,which is capable of providing high-quality air support for combat forces.China has a vast land area,a long border defense line,and numerous mountain and plateau areas,which means there is an urgent demand for this new type of drone to adapt to increasingly complex tasks.Firstly,by analyzing the relevant characteristics and performance parameters of helicopter,flying wing layout fixed-wing aircraft and tilt-rotor,the thesis compares the existing and under-developed tail-sitter unmanned aerial vehicles.Then overall plan for flying-wing tail-sitter coaxial-rotor vertical take-off and landing drone is proposed for long-endurance,large combat radius,and carrier based technical and tactical requirements of high and low speed,the preliminary overall design is carried out.Considering different flight states in the entire flight envelope of the tail-sitter unmanned aerial vehicle,namely vertical flight mode,horizontal flight mode and transitional flight mode,combined with the particularity of the aircraft carrier environment,the overall layout design and aerodynamic layout design for the UAV is carried out in this thesis.The overall parameters,geometric parameters of the rudder,landing gear and other systems is also determined;based on the overall scheme proposed above,the aerodynamic characteristics of the UAV is calculated by using the engineering experience formulas,including resistance characteristics,maximum lift coefficient and cruise pole curve.The computational fluid dynamics is used to analyze and solve the shape of the UAV,and the lift coefficient and moment coefficient of the UAV at different flight altitudes,Mach numbers and pitch angles are obtained,and the conformity degree of the theoretical calculation is verified.Secondly,using the flight principles of fixed-wing aircraft and tail-sitter unmanned aerial vehicle,the flight performance of the designed prototype is calculated.The computational fluid dynamics is used to accurately calculate the aerodynamic characteristics,and the transition mode is also established to obtain the UAV transition corridor,verifying the feasibility of the transition mode and providing a basis for flight control design.Finally,because of different points for the horizontal flight mode and vertical flight mode,the flight performance model is converted into single-objective optimization problemwith multi-objective genetic algorithm and linear weighted processing to optimize the ove rall parameters.The optimal solution for the overall parameter is obtained based on the o ptimization model.