Abstract:Regional freight UAVs provide a more economical and efficient transportation mode for freight in remote areas, mountains, plateaus, islands and cities, and play an important role in emergency rescue and supplies at wartimes. This paper reviews the development of regional freight UAVs, compares the competitive advantages between regional freight UAVs, human aircraft, and land traffics, and discusses the relatively safe running mode of freight UAVs under the current technical status, which is “the pipeline flight of point to point”. Finally, Key technologies of regional freight UAVs are analyzed, including: the technology of airworthiness, aircraft platforms, data link, navigation and autonomous take-off and landing technology and so on. The application of regional freight UAVs need to carry out systematic construction, pay attention to operational risk, and Laws and regulations for UAVs, airspace management, flight management, airport facilities and other construction work must also be attached importance, in addition of aircraft platforms.

Abstract:Energy crisis promotes the development of more electric aircraft, and environmental control system is the high energy consumption system of aircraft. Therefore, electric environmental control system has become an important direction of aviation technology development. This paper introduces the composition of Boeing 787 environmental control system, discusses the architecture design and trade-off analysis of the environmental control system, and introduces the research status of the key technologies of the main components of the environmental control system of the more electric aircraft, so as to provide reference for the research and development of the domestic electric environmental control system.

Abstract:For the design of variable camber wing of long range wide-body civil aircraft, the trimmed configurations with flap and spoiler deflecting were researched, which can fully consider both the impact on trim characteristic and the feasibility of variable camber wing. The Reynolds averaged Navior-Stokes equations were solved to predict the drag precisely and the Response-surface models were built based on these results. The drag reduction optimizations were carried for multi-conditions with different lift coefficients and Mach numbers. The optimization results show that at cruise mach number, the camber variation can lead drag reduction except at lower lift condition, and at lower mach number the drag can also be reduced by camber variation. The optimal angles of flap for each flight condition are different. Based on the above-mentioned work, the requirement of camber variable manipulation and the general drag reduction were researched by numerical simulation. The results show that two camber settings can lead drag reduction in a large range of lift. The camber designed for cruise condition can still obtain drag reduction at lower mach number. The general profit of cruise efficiency was evaluated based on Breguet equation. When cruising at a fixed altitude of 10km, 1.9 cts of drag reduction and 0.72% increase of flight time and endurance can be obtained during the whole cruise phase. When cruising at stepped altitudes of 8km and 10km, 2.9 cts of drag reduction and 1.19% increase of flight time and endurance can be obtained.

Abstract:It is popular to feature a tadpole fuselage for modern light general aviation(GA) airplanes. Computational fluid dynamics software was utilized to analysis the aerodynamic characteristics for a typical GA airplane, with the presentation of drag bucket. We investigated the aerodynamic effects of different rear-fuselage contractions on the simplified geometry. It is found that 29.76% reduction can be achieved for the pressure drag of the tadpole fuselage, leading to 6.34% increment of maximum lift-to-drag of the simplified geometry.

Abstract:The shipboard helicopter is in a harsh environment and its rotor tip is prone to over-swing and collision with the body. The research on the aeroelastic response on the ship surface of the helicopter can prevent such accidents. In this paper, CFD method is used to obtain the data of ship flow field. Combining with blade dynamic model, a comprehensive calculation and analysis method of rotor aeroelastic response is proposed and the aeroelastic response of the rotor under different inflow speed, hovering position and wind direction is studied. The results show that the method used in this paper is correct. The maximum response of rotor tip increases with the increase of ship inflow speed. When the speed changes from 20m/s to 40m/s, the response amplitude increases by 8.35%; The hovering position mainly affects the distribution of tip displacement response along the azimuth angle of the rotor disc. The change of inflow wind direction angle significantly affects the aeroelastic response of the rotor. The maximum flapping displacement of the blade tip is related to the vertical velocity distribution of the ship"s wake flow field. The greater the change gradient, the greater the maximum flapping of the blade tip.

Abstract:In order to study the problem of UAV search and rescue task allocation in the collaborative search and rescue of UAVs and general aviation, a UAV task allocation model was established on the basis of previous research, and multi-objective optimization was considered. In previous studies, only search and rescue efficiency was considered. On the basis, the search and rescue cost, the number of drones used, and the balance of drone tasks are used as the objective function, and environmental factors such as terrain, wind, and the constraints of the drone battery capacity are considered in the model; in the algorithm for solving the model , Using the excellent NSGA-II algorithm to obtain the Pareto solution, which also uses the method based on opposite learning to increase the diversity and scale of the population, and finally analyze the sensitivity of the obtained solution, and give the actual result according to the result. Give reasonable suggestions on how to take different solutions in rescue scenarios.

Abstract:The existing research on aviation equipment support lacks the exploration of the influencing factors of military civilian cooperative support strategy selection. Based on the limited rationality，the evolutionary game model of cooperative support between local aviation enterprises（institutions）and military aviation equipment users based on knowledge sharing with the participation of the Equipment Development Department is constructed. With the participation of the Equipment Development Department，the strategy selection of aviation equipment cooperative support between the military and the civilian is analyzed，and the numerical simulation analysis of the tripartite strategy selection is carried out on the basis of the theoretical model. The results show that the initial willingness of the equipment development department，policy-making，capital investment，the cost and benefit coefficient of military and civilian cooperative support in the context of knowledge sharing，the opportunity benefit of one party and the degree of penalty for breach of contract have an important impact on the strategic choice of civil-military cooperative support.

Abstract:In aviation mission planning system, the accuracy of aircraft air-to-ground attack route solution, route generation quality and route calculation speed are important indicators to measure the capability of mission planning system. Aircraft air-to-ground attack route design is a typical multi constraint complex maneuver in aircraft route planning. In the process of design and use, it is subject to multi-dimensional constraints from time, space and aircraft body, which puts forward high requirements for flight dynamics modeling and track optimization. This paper uses object-oriented thinking to model the aircraft"s side-slip dynamics model, and realizes the design and optimization of the complex maneuvering process by the way of route maneuvering splicing and segmental optimization. After simulation analysis, it is proved that the route optimization design can realize the multi-constrained trajectory design and planning function of the aircraft in terms of ideas and methods. The iterative optimization algorithm has good convergence, and the model and algorithm can meet the requirements of aviation mission planning.

Abstract:Aiming to improve the endurance of solar-powered UAV in low altitude in a mission cycle, a high-efficiency propeller design method is proposed. According to the flight span curve of the solar-powered UAV, the climb and main cruise altitudes are selected as the design points. Firstly, based on the Betz minimum energy loss design criteria and the strip theory and its reverse derivation, the chord length and pitch under each design point are calculated Angular distribution, and then assign weights to the calculation results of each design point according to the flight span curve to obtain the final design chord length and pitch angle distribution. Finally, based on the CFD numerical simulation technology, the designed propeller is simulated and calculated on the basis of the verification algorithm. The results show that compared with the conventional propeller, the efficiency of the propeller designed in this paper is within the flight envelope of the entire mission cycle under the allowable power range. The interior has been significantly improved to meet the design requirements.

Abstract:The crack in adhesives is one of the common damage patterns in composite adhesive structures, which will affect the integrity of composite structures. In this paper, the single-lap bonded composite joints which are the common adhesive structures in aircrafts were chosen as the study object. The three-dimensional numerical model was established with the bilinear cohesive constitutive relation characterizing the static crack propagation, and then the static model was extended to fatigue crack propagation model. The distribution of stress and strain, crack propagation and failure mechanism were studied by combing the experiment and numerical methods. The results have shown that the strain of single-lap adhesive joints varies nonlinearly under static and fatigue loadings because of the eccentric tension. Due to the stress concentration, fatigue cracks appear on both ends of the lapped area firstly, and then extend to the central area until cover the whole lapped area. The static failure mode is cohesive failure, and the interface debonding failure is observed in fatigue fracture.

Abstract:The landing gear buffer strut was disassembled for repair, it was found that the nut thread of the plunger assembly was occluded and deformed, which was difficult to disassemble. In order to analyze the cause of the fault, the fault analysis and improvement research were carried out. According to the structural characteristics and usage of the plunger assembly, the fault tree of the nut thread occlusion deformation was constructed. Based on the historical test data, residual strength analysis and products status, the bottom events of the fault three which was analyzed and verified. It was concluded that the design defects of the nut and the nut was not assembled in place could lead to the thread occlusion deformation. In addition, based on residual strength analysis of nut thread, when the thread pitch was 1.5mm, the residual strength was 0.76, while the thread pitch changed to p=2mm, the residual strength was 1.4. Based on the problem that the nut was difficult to be disassembled , the method of bidirectional fixing of the plunger assembly and design of the double sleeve type special tooling was adopted to effectively solve the problem. The research results were great significance to the design improvement and disassemble,assembly quality of nut.

Abstract:There are no detailed design criteria and methods for the Integrated design of micro turbojet engine. In this paper, a integrateddesign method and evaluation of 9kg ~ 80kg micro turbojet enginesare carried out by using the size and weight design method. The intergated design parameters database of micro turbojet engine is established, and the intergrated design criteria of micro turbojet engine is extracted. Using this criterion, the Integrated design of 16KG micro turbojet engine is completed. The results show that: using the intergrated design method for the micro turbojet engine, the obtained design criteria are highly reliable, and the overall scheme design of the micro turbojet engine can be carried out.

Abstract:Ram air turbine(RAT)system is a kind of aircraft emergency energy, which provides emergency hydraulic source and / or emergency power supply for key systems of aircraft in case of loss of main and auxiliary power, so as to maintain the maneuverability of aircraft, which is significant for aircraft to deal with emergency. Referring to AP-21-AA-2011-03-R4 about aircraft life cycle certification process division and certification activities, combined with the development process of a certain type of civil aircraft RAT system, this paper determines the workflow and method of civil aircraft RAT system airworthiness engineering technology. Starting from identifying the certification basis, transform the clauses into requirements, which are implemented into product design; the compliance methods and verification ideas of clauses are clarified, and finally the airworthiness compliance matrix is formed. The workflow has been preliminarily verified by the development of a certain type of civil aircraft RAT system, which provides a reference for the development and certification process of domestic civil aircraft airborne system.

Abstract:Under the development trend of multiple/full electrification of aircraft and integrated electromechanical management, the door actuator gradually replaced the traditional hydraulic and mechanical actuation by electromechanical actuation. Aiming at the current situation where the cabin doors of civil aircrafts are controlled separately, chaotically, and scattered, a centralized control scheme for electrically actuated cabin doors is proposed. Under the centralized control scheme, how to realize the servo control of the motor, the parallel control of the hatch, and the modification of the proximity sensor sensing distance value were designed, and the simulation device of the hatch actuation system and the motor loading experiment platform were built. The control structure and motor servo have been experimentally verified. The research results show that the centralized control scheme of electrically actuated hatch can greatly reduce the number of hatch cables, reduce the complexity of the hatch system, and improve the reliability and maintainability of the system.

Abstract:In order to resolve the continued exhaust fault of safety valve which installed on the integrated pressure reducer, the test is designed and performed according to the configuration and operational principle and analysis of fault phenomenon and fault tree. The test and simulation result show that the damp properties of reducer of reducer valve is mismatch with safety exhaust flow is primary reason lead to this fault. Under the large flows condition, the reducer valve will be in the vibrate state which result in the valve worn and lead to the output pressure is increased slowly and finally over the open pressure of safety valve. Because of the exhaust flows of safety valve is more than the rated output flows, reducer valve loss the function of pressure regulation until gas of cylinder is entirely exhaust. The fault is resolved by change the damp characters of valve.

Abstract:The use of power compensation system can greatly reduce the burden of pilot control, and can improve the dynamic response speed and control accuracy. This article focuses on the research of two carrier-based aircraftpower compensation control systems. Firstly, based on the Hdot command, the two approach power compensation systems of angle of attack and speed control were designed. Secondly, the simulation analysis was carried out for the two approach power compensation control systems, and the approach dynamic compensation response of the two compensation systems in the case of airwake disturbance was further analyzed, and their basic principles were analyzed through the simulation results: The ability of the angle of attack power compensation system to stabilize the angle of attack is greater than that of the constant speed, and the trajectory control is also faster than the constant speed power compensation system.

Abstract:The economic target for the civil aircraft WWS is partly contributed by the system weight load during the flight. To reduce the system weight load and improve the system economy, this document does a research on the water fill requirement according to the flight course accounting data, and then comes to a calculation method of the needed water volume. The comparison between the calculation result and the data of other aircraft water tanks shows that the calculation method is effective. According to the distribution characteristic of the flight hour in our country, the pre-selection water fill function which is based on the flight time and attendants numbers has been studied. The research shows that the the pre-selection water fill function could reduce the flight weight effectively. The study in the document could be used in the civil aircraft water and waste system research and the optimization design.

Abstract:With the increasing number of multi runway airports in China, it is of great significance to study the optimal design and evaluation method of taxiway operation scheme in maneuvering area of multi runway airport for promoting the intensive and efficient utilization of airport surface resources. The "fixed, one-way, forward and circular" ,which is the design principle of taxiway operation scheme in maneuvering area of multi runway airport is given, as well as the design paradigm of "one-sided operation" and "two-sided operation" taxiway operation scheme for isolated operation scenario of parallel runway; Based on the "flight alternative taxiing path library" and the given basic principles and paradigms of taxiway operation scheme design, it is comprehensively working out to optimize the taxiway operation scheme in the maneuvering area. Taking Chengdu Tianfu International Airport as an example, three alternative operation schemes of taxiway in maneuvering area are designed, and AirTOp software is used for simulation and quantitative analysis for typical daily flight sorties. The results show that the design method of taxiway operation scheme in maneuvering area of multi runway airport is helpful to alleviate flight taxi delay, taxi conflict waiting time and taxi conflict proportion, The simulation evaluation method is suitable for the comparison and demonstration of surface operation schemes under large flight volumn.

Abstract:In order to research the influence of the flow field around the large-scale flexible airship on its modal performance, the air around the airship was assumed as compressible potential fluid, the influence of air with structure vibration is considered as additional mass was added to the capsule structure. The modal test of the internal pressure of the 1:60 main airbag at 2kpa、4kpa、6kpa、8kpa and 10kpa was completed, the virbrometer based on the principle of laser vibration measurement was applied to measure the first three modes of the main airbag. Also the wet modal analysis method based on the additional mass was used to analyze the first 3 modes of the main airbag under 5 different internal pressure. The test and calculation results prove that the wet modal analysis method on the additional mass can be used for modal analysis for large flexible structure.

Abstract:In response to the issue of reducing satellite constellation backup costs while meeting constellation availability metrics. This paper studies the impact of different spare strategies on the performance of a Low Earth Orbit satellite constellation and select the best spare strategy that takes into account both the performance and economic efficiency of the constellation. First and foremost, a constellation availability model with degraded operation is developed. Secondly, the Markov process is used to solve this model. Last but not least, the availability of the constellation with different spare strategies at different constellation levels is calculated based on the operation data of a real LEO satellite constellation. The results of the analysis prove that deploying two backup satellites in each orbit can make the constellation with the lowest spare cost while meeting the availability requirement. The spare strategy proposed in this paper has a certain reference value for the construction of LEO satellite constellations and can provide guidance for the accurate configuration of spare satellites with reasonable cost reduction.