Abstract:To reasonably and efficiently guide the safe, reliable and economical operation of civil aircraft, we investigate the main contents and explore the application in operational reliability analysis and feedback of S5000F, i.e., international specification for in-service data feedback, which is organized by AeroSpace and Defence Industries Association of Europe (ASD). The compilation background and purpose of S5000F specification are first elaborated, and the main contents and the relevant business processes in the S5000F specification were then introduced. We finally discussed the application of S5000F specification in the operational reliability analysis and feedback of civil aircraft. In this paper, the S5000F specification is comprehensively interpreted, and its application in the operational reliability of civil aircraft is studied. In this case, we further extend this specification to the design phase and service phase of civil aircraft. The efforts of this study provide effective guidance for the life cycle management of civil aircraft.

Abstract:High Altitude Long Endurance (HALE in short ) UAV has made great development since its birth and participation in war. With the expansion of combat mission to high-risk confrontation battlefield, HALE fly-wing UAV has become a hotspot in the world today. In this paper,the requirements of HALE fly-wing UAV for turbofan engine are described, effect of key design parameters on the performance of turban engine is analyzed based on the basic principle of aero engine, the key problems and research progress of HALE fly-wing UAV are summarized. This paper has important reference value of the selection of turbofan engine for HALE fly-wing UAV and the improvement of its adaptability design.

Abstract:Due to the complex interference between the front and rear rotor of the tandem helicopter, the flow field analysis of the aerodynamic interference between the two rotors is carried out in this paper. Firstly, a numerical research method based on momentum source model and N-S (Navier-Stokes) equation is established. The k-ω SST two-equation turbulence model is selected, and the pressure-based implicit solver is used. The established solution method is verified with examples. Subsequently, the numerical simulation of the front and rear rotor flow fields of the tandem helicopter in the hovering state, the forward inflow state and the backward inflow state is carried out, and combined with the calculation results and the flow field characteristics, the aerodynamics generated by the interference flow field are carried out.The results show that for the example in this paper, the rotor performance is reduced for the front and rear rotor in hover, and the rear rotor has a great influence on the performance of the front rotor. The rear rotor lift loss is greater than that in hover in the case of forward flow, and the rotor lift loss is more obvious in the case of backward flow, and the max loss is nearly 50%.

Abstract:The propeller slipstream passed through the rotor plane when the autogyro was flying forward, in order to study the unsteady aerodynamic interference of propeller slipstream on the autorotating rotor, based on the RANS equations (Reynolds averaged Navier-Stokes), a computational analysis method for the aerodynamic interference flow field of autorotating rotor-propeller was established by using the moving overset grids method, and the model was simulated. The unsteady aerodynamic characteristics and flow field characteristics of the isolated and combined autorotating rotor at low speed were analyzed. The effects of different velocities and propeller positions on the aerodynamic characteristics of the spinning rotor were studied. The results showed that the propeller slipstream affected the lift-drag characteristics of the autorotating rotor at all azimuths, and caused the distortion of the rotor wake near 0° azimuth. Under the same rotor thrust, the larger the inflow velocity, the smaller the rotor tilt angle, and the smaller the influence of propeller slipstream on the autorotating rotor. Increasing the pitch between the propeller and the autorotating rotor can reduce the aerodynamic interference of the propeller slipstream on the rotor..

Abstract:Ari-launch can significantly improve rocket payloads, reduce the number of rocket launch sites and the high maintenance funds, and shorten the launch cycle. In this paper, the influence of the initial state of air-launch on the payload of the launch vehicle is studied, and the mathematical model of the rocket flight is first established by the model of the flight orbit, and then the influence of the launch height and the firing velocity on the payload of the rocket after entering the orbit is analyzed quantitatively. The results show that if the emission height and emission velocity are increased, the payload will increase obviously, and the basic emission height and emission velocity are linearly related to the payload respectively. Relative to ground launches, if the initial height reaches 30-kilometer, the payload is increased to 1.63 times, and if the initial height reaches 30-kilometer and the initial speed reaches 1000 meters per second (about Mach 3), the payload will be 5.43 times the traditional ground launch. From the point of view of initial height and speed, the effect of initial emission velocity on the increase of payload is more significant, so we should pay more attention to the increase of launch speed when designing the launch platform under the consideration of economy.

Abstract:To predict the degradation of engine maneuvering characteristics, transient process based gas path analyses were conducted. Sequential Operating Points Analysis (SOPA), which extracts more information from a limited number of gas path sensors as well as eliminate the systematic error introduced by the averaging effect of multiple operating points approach, was applied to the estimation of a large number of health parameters. To solve the convergence problem of health parameter estimating calculation with considerable deviations, indirectly recursive Newton-Raphson method enhanced non-dominated sorting differential evolution algorithm was introduced. Applications to a dual-spool separated flow turbofan engine indicated that the proposed approach was able to predict a large number of health parameters with considerable deviations, using transient measurements provided by a very limited number of gas path sensors, efficiently and accurately.

Abstract:The dynamic planning of the training airspace is of great significance for improving the utilization rate of the airspace, improving the efficiency of military training, and alleviating the contradiction between military and civilian air. In this paper, the spatial dynamic programming problem is processed in stages, and the total occupation time is minimized by the optimal scheme of each stage. Aiming at the dynamic programming problem in each stage, on the basis of analyzing the complexity of the problem, the spatial planning model is constructed, and the genetic-discrete particle swarm optimization algorithm is proposed. By integrating the crossover and mutation ideas in the genetic algorithm, the DPSO algorithm"s ability to get rid of the local optimal solution is improved, and the convergence speed and accuracy of the algorithm are improved. In order to ensure the diversity of the population, the adaptive crossover operator and mutation operator are designed. Finally, the gantt chart is used to represent the whole airspace planning process. Compared with the genetic algorithm, the improved gpso is applied to the numerical example

Abstract:The core algorithm to prevent unmanned aircraft system（UAS）from flying out of the designated airspace or flying into the restricted airspace is the goe-fence violation detection algorithm of UAS. In order to improve the accuracy of cross-border detection of UAS geo-fence and ensure the safety of low-altitude UAS flight, this paper improves the ray cast algorithm by adding buffer distance to solve three special cases that cannot be solved by the traditional ray cast algorithm, and it is verified by simulation under Matlab environment, and the detection function of crossing the boundary is realized. Three factors that affect the running time of the improved algorithm are found out, and in-depth analysis and discussion are carried out. Simulation results show that the proposed goe-fence violation detection algorithm based on improved ray cast algorithm improves the accuracy of UAS detection without affecting the running time.

Abstract:Electric aircraft is booming in the field of general aviation domestic and international, and affects the future development direction of aviation. Using electric propulsion technology to transform UAV can greatly improve the safety, reliability and maintainability of UAV and reduce the use cost. SW1 UAV was took as the object of electric transformation, the electric transformation scheme was proposed, the main parameters of motor and lithium battery pack in the electric propulsion system were calculated and analyzed in detail, and the feasibility of the transformation of the UAV was analyzed from the weight, center of gravity, performance and the installation form of the electric propulsion system. The results showed the electric transformation of SW1 UAV was feasible,and the problems that need to be paid attention to the subsequent transformation were put forward.

Abstract:High Altitude Long Endurance (HALE) solar powered unmanned aerial vehicle has the design characteristics of low Re number which makes a great challenge to the propeller aerodynamic design. Based on the main design of a UAV, a solar powered propeller is design in this paper. Multi variables optimization method is used to design the blade element. With proper blade width and pitch distribution, the propeller works efficiently in low Re number. The propeller aerodynamic characteristics are validated in BEM method. The calculation shows the propeller has a high efficiency of over 85% in cruise.

Abstract:In the process of missile design, the aerodynamic characteristics of missile as an important factor directly affect the dynamic quality of missile flight. In the case of severe nonlinearity of aerodynamic characteristics in subsonic and transonic regions, the aerodynamic calculation accuracy provided by engineering estimation and CFD numerical calculation method is limited, which leads to low identification accuracy of rudder efficiency characteristics. It is necessary to calculate aerodynamic parameters accurately by wind tunnel test method to determine the rudder efficiency of missiles. In this paper, the influence of Mach number of missile flight on aerodynamic characteristics of missile in subsonic and transonic speed is studied by means of wind tunnel test method. The results show that the aerodynamic characteristics of the missile are basically the same at subsonic speed, and there are drastic non-linear changes at transonic speed. The pitch rudder efficiency of the missile increases first and then decreases, while the roll rudder efficiency decreases first and then increases. The conclusion has reference value for the design of missile control law and the subsequent development of engineering models.

Abstract:Based on the development of amphibious aircraft at home and abroad, this paper prospects the future applications of amphibious aircrafts. From the perspective of Flight Performance and Characteristics, Structure and Load as well as Avionics System, this paper generalizes the similarities and differences of several existing airworthiness certification regulations, and analyses their insufficiencies. Finally, suggestions on China"s existing airworthiness regulations including items in the field of take-off characteristics, structure safety, cockpit integration system, water tightness and Anti-corrosion, are proposed to match with the practical structure and task model of the light amphibious aircrafts.

Abstract:In order to get a wide range of angles of attack, pre-bending support joints were used in rotary balance test. The pre-bending support joint was located in the model wake region at low angle of attack. The pre-bending support joint can cause interference with aerodynamic force and aerodynamic moment of model. The test was carried out by installing the pre-bending support joint at a symmetrical negative angle and rotating the model by 180 degrees. The test results show: the aerodynamic characteristic of the SDM model were interfered by the pre-bending support joint, when the pre-bending support joint was located in the model wake region at low angle of attack. But the interference of pre-bending support joint mainly caused the translation of the aerodynamic characteristic curve, and the interference of pre-bending support joint had little effect on the rotation derivative. The interference correction method proposed in this paper is very simple, which can provide a convenient and fast test method for the research of interference correction of the pre-bending support joint in rotary balance test.

Abstract:With the development of new theory, new technology and new material for weapon system, rocket sled is more and more widely used. In this paper, a dynamic analysis model of sled-pulley system is established for two-track rocket sled system. An optimization method is established for simplifying the three-dimensional sled model. The dynamic equations of rocket sled considering damping, rail clearance and irregularity are derived and solved. The results obtained by the proposed simulation method are basically consistent with the experimental results, which verifies the rationality of the proposed method. The proposed method is of great theoretical and practical significance for the calculation of sled dynamic characteristics, sled design and load prediction.

Abstract:Due to the lack of the right outer wing part of the test piece, the many and complicated butt joint, and the large test load, which brings great difficulty to the application of the wing load. Therefore the independent loading clamp is designed for the three sets of joints. The actual load of the front and middle joint is reduced by extending loading force line spacing. According to the opposite loading position of the upper and lower joints, different loading joint connection forms are designed to ensure the deformation freedom of the actual butt joint of the aircraft. The rear joint load is adjusted by coordinate conversion, and the test site is conveniently implemented. The method can ensure to transmit the accurate load to the joint, avoid the rigidity matching problem between the joints, and is convenient to install and meet the test requirements. The use of local restraint device effectively avoids the generation of harmful damage at the joint and protects the joint in real time.

Abstract:Based on the numerical simulation, the influence of total pressure probes of four different structures (type A, type B, type C, type D) on the flow field and their own total pressure measured values under different near-wall distances was studied, then verifies the numerical simulation results with the experimental results. The results show that: the smaller relative near-wall distance c/d is, the larger error of the airflow deflection angle of the front end of the total pressure probe is, the larger measurement error of the total pressure probe is, and the maximum value of total pressure loss coefficient is less than 1%. When c/d>3, the total pressure loss coefficient is close to 0, indicating that the wall effect fails when the near-wall distance is greater than 3 times the outer diameter of the probe. Influence of wall effect to measured values of the total pressure probes of the four structures are sequentially increased in the same condition. the uniformity of the measured flow field is reduced, and the velocity uniformity is the smallest behind the total pressure probe support rod.

Abstract:Based on the airworthiness specification, the geometry, mass and initial attitude characteristics of two foreign objects: the hail and ice cube, are analyzed and determined. The aerodynamics and trajectories of the foreign objects in engine inlet and bypass duct of turboprop aircraft have been simulated by coupling the Computational Fluid Dynamics (CFD) and six degrees of freedom methods. In view of the possible collision phenomenon in the movements, we further develop a reasonable and effective method combined with LS-DYNA software. The method is verified through a turboprop. The results indicate that once the foreign objects collide with the inlet or bypass duct, they lose their kinetic energy and can be broken into very small pieces, then these foreign objects do less harm to the engine and can be considered to exclude from the bypass duct. However, the ice cubes on the lower wall of the inlet may directly move into the main engine, and cause serious consequences, which should be carefully noted and researched.

Abstract:As technique of integrated modular avionics developing, requirement of large data transfer requirement is increasingly clear. Methods currently used either need to modify existing architecture or need specific functional support from operating system, which limits their application in different avionics systems. In order to solve this problem, a multiple window protocol as well as its implementation is proposed in this thesis. This protocol applies extra resource to keep transferring multiple windows and remains high stability and efficiently while working in unstable airborne networks. Therefore, it can meet the requirement of efficiency and stability of large data transferring in avionics system. And also, this protocol can be implemented at application level; there is no need to modify existing system architecture. This character makes it have a wild range of application.

Abstract:In order to explore the influence of phenolic resin on the properties of aramid paper honeycomb, two different phenolic resins were used to prepare aramid paper honeycomb core materials, and the compression properties and shear properties of the prepared honeycomb core material were tested. Combining the observation of resin end face resin distribution and contact angle measurement, the reasons for the difference in performance of honeycomb core materials prepared by two kinds of resins were analyzed. The results show that the volatilization rate of solvent water in the resin and the surface tension between the resin and the aramid paper affect the resin distribution of the resin on the honeycomb wall,When the content of the honeycomb core resin is the same, the resin rubber column at the end of the joint is beneficial to increase the compressive strength of the honeycomb core material, but the accumulation of the resin at the end of the node reduces the wall thickness of the honeycomb, resulting in a decrease in the shear strength and modulus of the honeycomb.

Abstract:Safety Assessment on civil aircraft is one of the effective methods to realize the airworthiness of aircraft. In this paper, based on the principle and method of civil aircraft system safety design and assessment, a certain high lift system is taken as an example, and functional hazard analysis and fault tree analysis are carried out for the failure condition of ’flap asymmetry motion over limit’, the critical factor affecting safety design are gained. By improving the design method of the critical factor, the system scheme which can meet the safety object is finally obtained.