Research On Conceptual Design Of Quad-Tilt Rotor Aircraft

Conceptual design is the first step of aircraft design and the basis of overall design.The task of conceptual design is to find one or more initial solution that meets the design requirements and the design specifications,as well as their main parameters and aerodynamic configuration,and is a design process from scratch.The quad-tilt rotor aircraft is novel in concept,lacking in design and experience data,and statistical analysis in traditional conceptual design is not suitable for quad-tilt rotor aircraft.Therefore,this paper presents a conceptual design method of general parameters and aerodynamic layout based on optimization method,which can be used to design the overall design plan.In this paper,based on the estimated weight model of tiltrotor aircraft and considering the characteristics of quad-tilt rotor aircraft,a weight model suitable for the quad-tilt rotor aircraft is established.Based on XV-15,the weight model verification and parameter sensitivity analysis are conducted.According to the configuration of the quad-tilt rotor,the calculation methods of the required power in helicopter mode and airplane mode are established respectively,and the flight performance calculation methods of various flight modes are proposed.Finally,XV-15 is taken as an example to verify the model and method.In this paper,the design method of the general parameters of quad-tilt rotor based on the optimization design is proposed.First of all,according to the performance requirements of the mission,the ratio of fuel method is used to initially determine the empty weight and fuel quality of the aircraft.Based on this,the overall parameters such as rotor radius,rotor solidity,wing area and aspect ratio are preliminarily determined.Then,the weight model and the flight performance model are integrated,and the genetic algorithm is used to optimize the overall parameters.At the same time,according to the requirement of the center of gravity of the quad-tilt rotor and the aerodynamic characteristics of the configuration itself,the internal layout,the transmission system and the aerodynamic layout of the quad-tiltrotor are completed.In this paper,the stability analysis of quad-tilt rotor is conducted.Firstly,the aerodynamic model of the rotor is established by BEMT theory,and then the aerodynamic interference of the wake of the rotor to the wing is considered.The wing part is modeled with the slipstream and the non-slipstream.Combined with other parts of the aerodynamic model,the flight dynamics model is completed.Then,the stability analysis of the aircraft in helicopter mode,transition mode and fixed-wing mode is completed to verify the feasibility of the general parameters on this configuration.