Design of an image radiation monitor for ILS glide slope

The design of a monitor that measures changes in ground reflected image radiation is presented. This monitor is shown to be theoretically capable of determining the effects of snow cover and standing water in the vicinity of an Instrument Landing System (ILS) image-type glide slope, thereby reducing the number and length of outages. A discussion of errors and calibration are presented, along with an example of a practical design     

Calculating the Effect of Uneven Terrain on Glide Path Signals

A method for calculating the bends in the glide slope due to uneven terrain is presented. A computer program written for the purpose enables the calculation of the difference in depth of modulation (DDM) at any point, taking into account the effect of uneven terrain. Results are presented for a hypothetical case of a hill in front of the runway. The program enables us to predict the glide slope bends due to irregular terrain, so that proper selection of glide slope antenna location can be made.     

Application of Endfire Arrays at Contemporary Glide-Slope Problem Sites

The application of the endfire-type, compatible instrument landing system (ILS) glide slope is discussed in the context of providing increased capability to install facilities without requirements for extensive terrain modification. Costs of preparing a site for glide-slope operation can be reduced many times by eliminating the requirement for the usual image-forming ground plane. An example is given where the first endfire glide slope has been installed at an airdrome on a mesa giving a high quality path in space in spite of the limited real estate. Recent flight data from this glide slope are presented.     

Applications of slotted cable antennas in the instrument landingsystem

The use of slotted waveguides in the instrument landing system (ILS) is discussed, and applications of slotted cable antennas to the ILS localizer and glide slope are described. Examples are given of both existing and prospective designs intended to provide solutions for specific siting problems. Important applications are to the end-fire glide slope and category-III localizers     

F/A-18E/F全自动着舰飞行特性分析

以F/A-18E/F舰载机为对象,针对航迹精确控制和安全性要求,分析了舰载机全自动着舰飞行特性。首先,基于自动着舰控制系统,建立了全自动着舰飞行控制系统的动力学模型;然后,对下滑轨迹纠偏与控制能力、控制器指令响应特性、变换下滑道机动特性进行了仿真分析。仿真结果表明,在全自动着舰安全边界范围内,舰载机能在较短时间内将航迹控制在理想下滑线附近;控制器具有良好的高度变化率、俯仰角、俯仰角速度等状态指令响应特性及控制面指令响应特性;F/A-18E/F变换下滑道机动则需要配合油门完成,说明仅通过平尾控制实现该机动并非安全着舰的必要条件。     

Hybridizing contemporary glide slopes to provide vertical guidancefor GPS approaches

Vertical guidance for an instrument approach to landing during conditions of reduced visibility is a crucial element with respect to safety of flight. It is noteworthy that this vertical component-to be most useful and safe-must desirably provide the pilot with no more than several feet of uncertainty. Unfortunately, with GPS the vertical portion of the position information supplied the pilot by GPS signals is the least precise because of geometries involved. Augmentation for enhancement of accuracy is quite important and the assertion is that it is necessary for totally safe vertical guidance. Evidence from approximately 60 years of experience with electronic landing systems serving the public is that there has been no aircraft accident due to a defective vertical guidance signal. Visibilities as low as 600 feet horizontally can exist at certain airports and landings can still be accomplished. These landings, while not common, are being accomplished flawlessly by contemporary aircraft and equipment. Many aspects of the contemporary UHF glide slope have been studied during its half-century of use. This paper reports on advances, some of them quite recent, that make it realistic to claim that a glide slope can be sited for Category I operation at any runway that meets the physical requirements for this type of operation. For the UHF glide slope, siting imperfections are accommodated by using one of five available types of contemporary glide slope systems or derivatives thereof. This paper reviews how accommodations are achieved in practical cases. Results from earlier tests are identified which show hybridizing of UHF glide slopes and GPS can be used to provide good approach guidance to aircraft making fully automatic approaches to touchdown     

Comments on “Effect of wet snow an the null-reference ILSsystem”

The subject paper (July 1993) has raised some issues regarding the probability of the Instrument Landing System (ILS) radiating out-of-tolerance vertical guidance signals. An independent study has substantiated the findings of that paper and adds further concern regarding some FAA ILS snow procedures. The principal conclusions of this paper are: 1) an analysis, based on Walton's discovery of rare snow conditions that cause the null-reference ILS antenna image to disappear, indicates that these conditions can cause out-of-tolerance guidance signals, 2) operation without a monitor of the image radiation can result in signal-in-space guidance signal errors that are significantly beyond the intended limit values, and 3) the integrity of image glide path equipment in snow environments does not satisfy the ILS integrity requirements     

GTD Terrain Reflection Model Applied to ILS Glide Scope

The capability of calculating the reflection of electromagnetic signals from uneven terrain has many applications. One of these is the determination of instrument landing system (ILS) glide slope performance. For this application the wavelength is approximately 1 m, incidence angles are usually near grazing, and the fields are horizontally polarized, so that gross irregularities such as dropoffs and hills are more important than surface roughness. Past approaches used to calculate the ground reflections for this application have been three-dimensional physical optics models which were very cumbersome and time consuming and which neglected important diffraction and shadowing phenomenon; a two-dimensional physical optics model which was faster than the three-dimensional models but ignored many shadowing and transverse terrain variation effects; and a half-plane diffraction model which is applicable only to a specified type of terrain geometry. In this paper a terrain reflection model based on the geometrical theory of diffraction (GTD) is described which can accommodate any piecewise linear terrain profile, requires less computer time than the physical optics models, is capable of including transverse terrain effects, and determines the reflected fields with all important diffraction and blockage effects included.     

Computed Performance of Glide Slope Arrays on Sites with Limited Ground Plane

The computed performance of four different types of glide slope transmitting arrays sited over idealized ground planes consisting of one-dimensional perfectly conducting strips of various lengths in free space is presented. The idealized ground plane approximates the practical case of a site consisting of an expanse of relatively flat ground plane ending in a precipitous dropoff or in rough diffusely reflecting terrain. The computed results show several phenomena which have repeatedly been observed.     

ILS-past and present

Insight is provided into the evolution of VHF/UHF instrument landing system (ILS) equipment and the role of the US Civil Aeronautics and Federal Aviation Administrations in its development. The discussion covers the ILS localizer, glide slope (image arrays and nonimage arrays), marker beacon, reliability, and avionics     

结冰对民机飞行性能的影响研究

结冰是威胁民机飞行安全、影响飞行性能的主要因素之一。分析总结了飞机的结冰机理及影响冰型的主要因素，并着重研究了结冰对民机的主要飞行性能，包括起飞性能、爬升性能、飞行包线、续航性能、下滑性能以及着陆性能的影响。研究结果可为国内民用飞机的研制和现役民机的改进、改型提供参考。     

Half-Plane Scattering Applied to ILS Grading Criteria

A technique for calculating the derogation in the difference in depth of modulation (DDM) signal, used for aircraft glide slope guidance, due to slightly rough ground surfaces is developed. The contributions to the scattered signal from diffuse and specular scatter are treated separately. The diffuse derogation is calculated based on empirical data, and an average variation is presented. The specular contributions to the variation in the signal is calculated based on expanding the half-plane diffraction solution in terms of the ground roughness. A specular scattered deviation about the mean signal is then obtained by statistically averaging over normally distributed ground heights. Results of the analysis indicate that substantial relaxation in grading criteria can be effected.     

仪表着陆系统下滑信标台的场地保护——兼论《国家标准GB6364-86》的严密性

做好航空导航台站的电磁环境保护,是确保导航设备正常运行的一个重要手段,本文以仪表着陆系统的下滑信标台为例,论述了辐射信号的反射区、保护区场地平整及要求等。     

RF航段衔接ILS进近程序的最大下降角设计方法

RNP 程序的RF 航段与传统ILS 精密进近程序相结合能充分利用两类程序的优势,但两种程序的过渡阶段需要考虑最大下降角度的设计。本文分析过渡阶段程序的平面与剖面几何设计参数限制条件,以及从星基导航方式转为陆基无线电导航方式需要稳定截获航向信号与下滑台信号的运行限制条件;结合两种限制条件,设计一种可以从不同最后进近定位点（FAP）高度计算下滑道的偏离量与到最后航向截获点（FACF）的弧距离关系进行判断,从而确定最大下降角度的方法,并进行仿真验证。结果表明：该方法可以在不同过渡航渡长度与不同最后进近下降角度的限制下,根据给定最高程序假设温度计算得到符合两种限制条件的最大下降角,为RNP 程序与ILS 程序衔接过渡的下降剖面设计提供了一种基于理论基础且具有可行性的设计方法。     

微下冲气流对飞机着陆性能的影响

针对飞机在下滑着陆阶段穿越微下冲气流的问题,建立了微下冲气流影响下的飞机纵向运动数学模型。用数值方法计算了微下冲气流对空速、迎角和航迹的影响,结果表明,飞机在穿越微下冲气流时,空速、迎角、下滑航迹变化很明显,飞行员操纵和判断的难度会增大。特别是顺风阶段,航迹比正常偏低很多,对飞机的安全着陆影响很大。     

Analysis of optimal initial glide conditions for hypersonic glide vehicles

Hypersonic glide vehicles （HGVs） are launched by a solid booster and glide through the atmosphere at high speeds. HGVs will be important means for rapid long-range delivery in the future. Given that the glide is unpowered, the initial glide conditions （IGCs） are crucial for flight. This paper aims to find the optimal IGCs to improve the maneuverability and decrease the con- straints of HGVs. By considering the IGCs as experiment factors, we design an orthogonal table with three factors that have five levels each by using the orthogonal experimental design method. Thereafter, we apply the Gauss pseudospectral method to perform glide trajectory optimization by using each test of the orthogonal table as the initial condition. Based on the analytic hierarchy process, an integrated indicator is established to evaluate the IGCs, which synthesizes the indexes of the maneuverability and constraints. The integrated indicator is calculated from the trajectory opti- mization results. Finally, optimal IGCs and valuable conclusions are obtained by using range anal- ysis, variance analysis, and regression analysis on the integrated indicator.     

滑翔式空中靶标总体设计与弹道仿真

空中靶标作为一种消耗性的无人飞行器,在防空反导武器系统试验训练中具有不可或缺的重要作用,须统筹考虑其逼真性和经济性。为此,提出了滑翔式空中靶标系统发展思路与工作原理,设计了滑翔式空靶总体方案,并利用Datcom和Matlab对其滑翔供靶弹道进行了仿真分析。仿真计算表明,弹道性能满足亚音速俯冲类目标模拟供靶要求,系统具有高性能、低成本、使用安全等显著特点。     

多飞行器再入段时间协同弹道规划方法

提出了一种多飞行器再入段时间协同弹道规划方法。首先,在纵向平面内规划满足航程与终端约束的纵向标称轨迹。随后,在采用轨迹跟踪律跟踪纵向标称轨迹的同时,运用考虑初始横侧向状态的多边界航向偏差角走廊策略控制飞行器的横侧向机动,以满足到达时间约束与终端约束,进而实现单枚飞行器到达时间约束下的轨迹规划。在此基础上,完成了飞行器的到达时间分布与飞行能力分析,给出了最小与最大到达时间的分析计算方法,并根据多飞行器协同再入的任务需求完成了协同飞行时间决策。最后,多飞行器协同再入与扰动条件下的仿真结果表明,该方法能够规划出满足到达时间与终端约束的协同再入轨迹,具备良好的计算精度与鲁棒性。     

ILS-a safe bet for your future landings

An argument is presented in favor of the ILS (instrument landing system), the principal components of which are the localizer, which provides lateral guidance to the pilot, and the glide slope, which gives the vertical guidance. A pilot flying these signals precisely will end up over the hard surface runway with the ILS receiving antenna, wherever it is mounted on the aircraft, being about 20 ft above the touchdown point. The safety record and evolution of the ILS are examined, and a pilot's view of ILS (that of the author, an engineer who has worked with ILS since 1957 and a pilot who has used ILS safely for over 30 years) is given. System availability is discussed, and comments concerning future use are offered     

飞机下滑波束导引系统设计及仿真

下滑波束导引系统是飞机在自动着陆时所采用的一种重要无线电波束导引系统。首先,简要阐述了下滑波束导引系统的基本工作原理;然后,对导引系统的运动学环节及下滑耦合器进行分析,对飞机下滑波束导引系统结构进行设计;最后,在MATLAB平台下,对所设计的下滑波束导引系统进行大量仿真研究。仿真结果显示。所设计的下滑波束导引系统结构是合理的,其控制系统是稳定的,且其稳态性能也得到改善。