Study Of The Carrier Aircraft To Achieve Vertical Takeoff And Landing Of Fixed Wing Aircraft In A Dual Aircraft Compound

Since the birth of the aircraft,only a relatively small number of fixed-wing aircraft have been able to achieve vertical takeoff and practical applications,including the British Harrier,the Soviet Union's Yak-141,and the U.S.F35 B with its power system to achieve vertical takeoff.Although the development process of vertical takeoff aircraft has achieved a large number of research results.But in the process of vertical takeoff of fixed-wing aircraft are impossible to avoid the consumption of large amounts of fuel,and can not achieve the maximum load takeoff.At the same time,after the aircraft takeoff is completed,the lift engine has been in a non-functional state,becoming a dead weight that is not conducive to aircraft flight.In this paper,we propose a vertical takeoff and landing scheme using an aircraft with vertical takeoff capability(the carrier aircraft)to carry a traditional delta-wing fixed-wing aircraft(the target aircraft)and call this scheme a composite vertical takeoff and landing scheme,which does not consume its fuel during the vertical takeoff phase compared with the vertical takeoff of a single aircraft,and the carrier aircraft's carrying capacity ensures that the target aircraft has a larger carrying capacity during the vertical takeoff phase,thus achieving a longer flight distance or loading capacity.The compound vertical takeoff and landing scheme is also divided into compound vertical takeoff and compound vertical landing for key technology studies.Firstly,the compound vertical takeoff is studied based on the computational fluid dynamics methods.The aerodynamic parameters of the compound flight process are theoretically calculated and the dynamic separation process is simulated and evaluated using the aerodynamic profiles of the two designed aircraft(the aerodynamic profile of the carrier aircraft and the aerodynamic profile of the traditional delta-wing aircraft,respectively).The aerodynamic data under different installation parameters(installation altitude,installation angle)and flight states(flight angle of attack,flight speed,flight altitude)are obtained.Through further analysis of the obtained relevant data,the feasible domain satisfying the separation conditions can be obtained,and the dynamic simulation of the separation process of the target aircraft in the feasible domain is successfully realized,which theoretically verifies the feasibility of the analysis method and scheme.Secondly,design an unmanned carrier aircraft and modify a fixed-wing aircraft with Su-35 aerodynamic shape for compound vertical takeoff experiments.We completed the dynamic layout and dynamics modeling of the unmanned carrier aircraft,the structural design and finite element analysis of the airframe,the machining and assembly of the unmanned carrier aircraft,the design and manufacture of the connection and separation mechanism,and the design and debugging of the control system.In addition,the aerodynamic coupling between the propellers of the unmanned carrier aircraft and the aerodynamic shape of the Su-35 was studied through computational fluid dynamics,and the aerodynamic forces(including lift,drag,torsional moment,and speed of five propellers)of the two aircraft under different installation parameters and flight speeds were obtained,and the data results of the numerical calculations were analyzed to obtain the installation parameters and separation speed intervals that can satisfy the separation of the two aircraft.By analyzing the data,the installation parameters and the speed range of the two aircraft to satisfy the separation were obtained.In the actual several experiments of vertical takeoff,air hover,horizontal acceleration,and air separation of unmanned carrier aircraft carrying fixed-wing aircraft,not only the feasibility and reliability of the scheme and technical route are successfully proved through experiments,but also the reference scheme with practical engineering significance is provided for further design of the unmanned carrier aircraft.Finally,the key technology in the compound vertical landing,the air for docking technology,is studied.The proposed scheme is based on visual navigation to autonomously dock two aircraft in the vertical direction in flight.The aircraft is affected by airflow disturbances and its own control during flight,resulting in small changes in the position and attitude of the two aircraft during the docking process in the air.To overcome this changes,a targeted navigation docking scheme is designed: the camera is fixed at an angle to the carrier aircraft,and the position and attitude of the target aircraft's landing gear relative to the chasing aircraft are solved by collecting and identifying the center pixel coordinates of the target aircraft's three sets of landing gear tires and the P3 P algorithm.The position and attitude of the target aircraft landing gear relative to the chasing aircraft are solved by calculating the coordinates of the center point of the tires.The docking is completed by planning the path and docking speed of the chaser platform.To test the feasibility of this navigation docking scheme,the docking experiment was conducted when the position component and attitude component of the target aircraft were generated multi-degree-of-freedom motion,and the dynamic docking between the chaser platform and the landing gear of the target aircraft was also successfully achieved,which proved that the navigation docking scheme is feasible.In this article,the compound vertical takeoff phase and the compound vertical landing are investigated separately.The theoretical study,simulation evaluation,and experiments of the vertical takeoff phase verify the feasibility of the compound vertical takeoff scheme.The docking experiment for the vertical landing phase verifies the feasibility of the automatic docking scheme using monocular visualization.Through the research of this paper,it is expected to provide a general solution for the realization of vertical takeoff and landing of fixed-wing aircraft in the future,and to contribute to the realization of vertical takeoff of fixed-wing aircraft in China.