IMPROVED LANDING-GEAR DESIGN FOR FLEXIBLE AIRPLANE

Landing dynamic simulation and landing-gear optimization design are used to improve the landing-gear design for a flexible airplane. Landing response is simulated by using velocity-squared damping, polytropic exponential air-compression spring, tire force power function characteristics, and an equivalent three-mass system.Optimization of landing-gear parameters is performed considering the maximum displacement of the landing-gear shock stroke, the maximum landing-gear force and the maximum deformation of the wingtip in the landing impact. Resutls show that landing-gear design parameters have an important influence on the structural flexibility of the airplane. And the landing performance of the landing-gear can be improved by the optimized metering pin type landing-gear.

Impact of Ground Effect on Airplane Lateral Directional Stability during Take-Off and Landing

Computational simulations of aerodynamic characteristics of the Common Research Model (CRM), representing a typical transport airliner are conducted using CFD methods in close proximity to the ground. The obtained dependencies on bank angle for aerodynamic forces and moments are further used in stability and controllability analysis of the lateral-directional aircraft motion. Essential changes in the lateral-directional modes in close proximity to the ground have been identified. For example, with approach to the ground, the roll subsidence and spiral eigenvalues are merging creating the oscillatory Roll-Spiral mode with quite significant frequency. This transformation of the lateral-directional dynamics in piloted simulation may affect the aircraft responses to external crosswind, modify handling quality characteristics and improve realism of crosswind landing. The material of this paper was presented at the Seventh European Conference for Aeronautics and Space Sciences EUCASS-2017. Further work is carried out for evaluation of the ground effect aerodynamics for a high-lift configuration based on a hybrid geometry of DLR F11 and NASA GTM models with fully deployed flaps and slats. Some aspects of grid generation for a high lift configuration using structured blocking approach are discussed.

IAP's Solar-Powered Unmanned Surface Vehicle Actively Passes through the Center of typhoon Sinlaku(2020)

The solar-powered marine unmanned surface vehicle(USV) developed by the USV team of the Institute of Atmospheric Physics is a rugged, long-duration, and autonomous navigation vessel designed for the collection of longrange, continuous, real-time, meteorological and oceanographic measurements, especially under extreme sea conditions(sea state 6–7). These solar-powered USVs completed a long-term continuous navigation observation test over 26 days.During this time, they coordinated double-USV observations and actively navigated into the path of Typhoon Sinlaku(2020) before collecting data very close to its center during the 2020 USV South China Sea Typhoon Observation Experiment. Detailed high temporal resolution(1 min) real-time observations collected by the USV on the typhoon were used for operational typhoon forecasting and warning for the first time. As a mobile meteorological and oceanographic observation station capable of reliable, automated deployment, data collection, and transmission, such solar-powered USVs can replace traditional observation platforms to provide valuable real-time data for research, forecasting, and early warnings for potential marine meteorological disasters.

Compatible Design of the System to Detect Ships and Airplanes with a Ground Wave Over-the-horizon Radar

This paper provides a design method based on a time-shared form, which obtains the compatibility of signal and the system for detecting both ships and airplanes. Then, it gives the structure diagram of the system and the chart diagram of signal processing. Finally, the continuity problem of signal modulation for ship detection is discussed.

Analysis of Airplane Precipitation Operation on Embedded Convective Clouds in Hunan Province

Based on NCEP 1°×1° reanalysis data, ground encryption houdy precipitation, FY-2E stationary satellite and Doppler radar data, the structural characteristics of precipitation clouds in Hunan Province and the effects of airplane precipitation operation were analyzed. The results show that under the effects of low-pressure system and southwest monsoon, Hunan was rich in water vapor, which was beneficial to the maintaining of precipitation clouds. During the process of the artificial precipitation operation over Hunan Province, convection developed vigorously, and precipita- tion was strong in the south of the province; embedded convective clouds were dominant and precipitation was weak in the east of the province. Cloud optical thickness correlated with ground precipitation positively. After catalyzing, echo at high altitudes responded firstly, and the echo intensi- ty increased gradually; the response of low-altitude echo lagged behind that of high-altitude echo. It shows that catalysis could lead to increase of upper precipitation particles in size and quantity. As time goes on, upper precipitation particles descended to low altitudes, so that echo intensity in- creased at low altitudes. It is clearly seen that catalysis could lead to increase of echo intensity and prolong the lifetime of target clouds to improve the area of strong echo zone, showing obvious positive catalytic effect. At the same time, houdy average precipitation in the affected region tended to increase stably and was obviously more than that of the contrast region where hourly average precipitation reduced gradually with time. The changing trend of hourly average precipitation in the affected region correlated positively with the response of radar echo.

Cost Comparision of Airplane Parking Methods at Apron of Maptuto International Airport

Three known designs for parking, frontal, angled and parallel, were presented. Aircrafts at aprons can be parked either by towing equipment （push-back） or by its own power （serf-powered parking）. The costs of these two methods for Maputo International Airport were investigated. Based on airplane parking design theory, formulas to calculate the annual maintenance cost at aprons were proposed. Calculation results indicate that self-powered parking is preferable, justified by the fact that this airport has low traffic volume. The system of aircraft parking adopted by this airport saves significantly the cost for purchase and subsequent maintenance of push-back.

Effect of airplane transport of donor livers on post-liver transplantation survival

AIM To evaluate the effect of long haul airplane transport of donor livers on post-transplant outcomes. METHODS A retrospective cohort study of patients who received a liver transplantation was performed in Perth, Australia from 1992 to 2012. Donor and recipient characteristics information were extracted from Western Australian liver transplantation service database. Patients were followed up for a mean of six years. Patient and graft survival were evaluated and compared between patients who received a local donor liver and those who received an airplane transported donor liver. Predictors of survival were determined by univariate and multivariate analysis using cox regression.RESULTS One hundred and ninety-three patients received alocal donor liver and 93 patients received an airplane transported donor liver. Airplane transported livers had a significantly lower alanine transaminase(mean: 45 U/L vs 84 U/L, P = 0.035), higher donor risk index(mean: 1.88 vs 1.42, P < 0.001) and longer cold ischemic time(CIT)(mean: 10.1 h vs 6.4 h, P < 0.001). There was a weak correlation between CIT and transport distance(r2 = 0.29, P < 0.001). Mean follow up was six years and 93 patients had graft failure. Multivariate analysis found only airplane transport retained significance for graft loss(HR = 1.92, 95%CI: 1.16-3.17). One year graft survival was 0.88 for those with a local liver and was 0.71 for those with an airplane transported liver. One year graft loss was due to primary graft non-function or associated with preservation injury in 20.8% of recipients of an airplane transported liver compared with 4.6% in those with a local liver(P = 0.027). CONCLUSION Airplane transport of donor livers was independently associated with reduced graft survival following liver transplantation.

Robust Speech Endpoint Detection in Airplane Cockpit Voice Background

A method of robust speech endpoint detection in airplane cockpit voice background is presented. Based on the analysis of background noise character, a complex Laplacian distribution model directly aiming at noisy speech is established. Then the likelihood ratio test based on binary hypothesis test is carried out. The decision criterion of conventional maximum a posterior incorporating the inter-frame correlation leads to two separate thresholds. Speech endpoint detection decision is finally made depend on the previous frame and the observed spectrum, and the speech endpoint is searched based on the decision. Compared with the typical algorithms, the proposed method operates robust in the airplane cockpit voice background.

To Understand Why Airships Lost the Sky to Airplanes Take a Look at the Network on the Ground

Zeppelins and airplanes went into a commercial competition during the 1920s and 1930s. The Zeppelin was a very costly and high-scale technology which operated with a number of devices less than fingers a hand has. Airplanes, however, were cheap both in investment and operation and improved their cost-effectiveness rapidly during the times. Therefore, it was clear from an economic point of view to develop a fast growing net of commercial airports serving an even fast growing number of passengers. This was self-energizing. Zeppelins, however, focused on one, later two point-to-point services only, justified by a lack of capital and permanent economic losses.

Asia's Largest Airplane Workshop

The four-airplane repair workshop built and put into operation in May 1996 by the Beijing Airplane Maintenance Engineering Co. Ltd is the largest one in Asia at present. At the 1990s world advanced level, it marks the fact that the maintenance facilities and technology of China’s civil aviation have entered the world’s advanced rank.

An Inteduction to the NO.605 Airplane Institute

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舰船综合电力系统研究进展与应用建议

该文概述舰船综合电力系统(integrated power system,IPS)的原理、组成、分类、特点与技术难点,介绍国内外工程研制情况,综述集成设计、大容量直流源及其并联组网控制、大容量直驱式电力推进、直流大电流开断保护、电力电子静止电源、高密度储能、智能化能量管理等7项共性技术及我国技术研究突破情况。针对IPS在民用新能源船舶、电动及混动飞机、轨道交通、海上能源高效利用等推广应用实际需求,给出系统推荐方案,并提出各应用场景下还需重点研究的内容,旨在为IPS在多领域推广应用提供参考。

基于变刚度复杂曲面模糊路径策略的飞机座舱自动化磨抛

飞机座舱罩作为典型的复杂曲面弱刚性薄壁零件,是军用与民用飞机的重要部件,其安全与否直接关系到飞机和飞行员的安全。针对飞机座舱盖研磨抛光过程的曲面形状复杂以及刚性弱等问题,本文基于机器人自动化磨抛系统提出了一种基于自适应阻抗控制策略的复杂曲面模糊路径的生成方法,并对磨抛过程的接触力进行建模与分析,引进主被动相结合的磨抛方法,对某型飞机座舱盖进行了仿真及磨抛试验分析。试验结果表明,所提出的主被动相结合的磨抛方法结合自适应阻抗控制策略能较好的适应复杂曲面模糊路径的磨抛过程,力控制精度可达±1N;提出的复杂曲面模糊路径能够满足某型飞机座舱罩的自动化磨抛工艺需求,在保证磨抛结果一致性的同时提高了磨抛效率。

民用飞机发动机舱灭火剂浓度测试研究

国际民航史上曾因发动机舱着火而多次发生空难事故,为确保飞行安全,找出对发动机舱灭火剂浓度影响的各种因素、采用精准的改装手段以及建立有效的飞行测试方法就显得尤为重要。分析了通风流量、飞行速度、环境温度等因素对发动机舱灭火剂浓度的影响,给出了测试设备、采样管敷设、采样点布置等改装方法,提出了发动机舱灭火剂浓度测试的飞行试验方法,对试验结果裕度进行了分析,为其它民用飞机发动机舱灭火剂浓度测试合格审定试飞提供了参考。

Tree‑Inspired Structurally Graded Aerogel with Synergistic Water,Salt,and Thermal Transport for High‑Salinity Solar‑Powered Evaporation

Solar-powered interfacial evaporation is an energy-efficient solution for water scarcity.It requires solar absorbers to facilitate upward water transport and limit the heat to the surface for efficient evaporation.Furthermore,downward salt ion transport is also desired to prevent salt accumulation.However,achieving simultaneously fast water uptake,downward salt transport,and heat localization is challenging due to highly coupled water,mass,and thermal transport.Here,we develop a structurally graded aerogel inspired by tree transport systems to collectively optimize water,salt,and thermal transport.The arched aerogel features root-like,fan-shaped microchannels for rapid water uptake and downward salt diffusion,and horizontally aligned pores near the surface for heat localization through maximizing solar absorption and minimizing conductive heat loss.These structural characteristics gave rise to consistent evaporation rates of 2.09 kg m^(-2) h^(-1) under one-sun illumination in a 3.5 wt%NaCl solution for 7 days without degradation.Even in a high-salinity solution of 20 wt%NaCl,the evaporation rates maintained stable at 1.94 kg m^(-2) h^(-1) for 8 h without salt crystal formation.This work offers a novel microstructural design to address the complex interplay of water,salt,and thermal transport.

“双碳”目标下竹制航模技术探索

“双碳”目标是我国基于推动构建人类命运共同体的责任担当和实现可持续发展的内在要求而作出的重大战略决策,为了实现“双碳”目标,需要国家、社会、个人各个层面从小到大做出具体性措施,作为高校学子,西北工业大学民航学院“航育”团队在田薇老师的带领下,结合学校三航特色及学生专业性技能,自主研发制作了一种新型环保型航模,团队取材于西北工业大学定点帮扶地区——广西壮族自治区“毛竹之乡”融水,利用当地丰富的毛竹资源,探讨了竹材料在各向的力学性能,并针对传统型航模的短板,制作出一种更环保更实惠的航模,与当地特色苗族文化进行交融,在乡村振兴战略下为“双碳”目标作出自己的贡献。

Airworthiness engineering and practices of COMAC C919 airplane

This paper systematically summarizes the basic philosophy and principles of airworthiness that COMAC follows in the process of developing C919 large passenger aircraft.It carries out type certification along with the aircraft development process,and plans and implements compliance activities for airplane design features.Targeting the airworthiness requirements,COMAC has also established an airworthiness management system,including design assurance system and continuing airworthiness system,to ensure that aircraft are designed in accordance with airworthiness requirements,to show compliance with airworthiness requirements and to continuously ensure the airworthiness of airplane by dealing with continuing airworthiness events in service.

喷气式飞机尾喷管及尾焰红外辐射特性测量分析

用3~5μm中波、8~12μm长波红外热像仪对某喷气式飞机侧飞状态的红外辐射特性进行了测量,得到该飞机尾喷管及尾焰的红外辐射亮度分布。结果表明,该状态下尾焰中波、长波辐射呈现对称包络分布,随着距离的增加,尾焰喷气束逐渐扩散,辐射亮度逐渐减弱。相同情况下,中波波段尾焰长度为长波的3.5倍左右、面积为6.3倍左右;尾喷管为该飞机辐射亮度最高的部位,中波辐射亮度对比度达到了20.1,长波辐射亮度对比度达到了8.2。

飞机螺旋桨数字化测量路径规划研究

针对某型飞机螺旋桨快速扫描测量几何形状的要求,对螺旋桨的扫描路径进行规划和研究。介绍了由工业机器人和三维激光扫描仪为核心的螺旋桨自动化扫描测量系统,研究了螺旋桨空间自由曲面离散的算法原理,并提出将螺旋桨待测点按照截面分组并以矩形包围,生成满足扫描设备约束的扫描测量路径点规划的方法,研究了能够以最短路径遍历所有空间扫描路径点的算法。对扫描测量路径进行了仿真分析与试验,结果证明效果良好,为螺旋桨数字化测量提供了有效方法。