Aviation Radio [A century of powered flight 1903-2003]

The following topics are dealt with: electron tubes; World War I efforts; post WWI radio advances; airmail; antenna developments; weather; and WWII and after.     

From Autopilot to Strapdown: Electrotechnology in Inertial Guidance and Control

Electrotechnology has been a significant factor in the evolution of guidance and control (G & C) over the last half century. Ship stabilizers that used rotating wheels for brute force control were electrically driven. However, the first pilotless aircraft, developed in World War I, was controlled primarily with pneumatic servos. Inertial guidance and electronic control systems surfaced at Peenemunde around World War II. Advances in fire control servos led to development of the floated gyro and ushered in precision inertial navigators. Digital electronics replaced analog designs, so that the level of G & C sophistication increased dramatically. As digital computers became smaller and more powerful their use proliferated. The manned space program in the 60's saw substantial improvements in electronics reliability and performance. The successful first launch of the Space Shuttle, with all its complexity, is a tribute to electronics progress. It is difficult to predict what G & C advances electrotechnology will bring in the next 50 years.     

Navigation and landing [A century of powered flight 1903-2003]

Navigation and landing for the first half century of aviation fundamentally relied on radio-based electronic aids. The military began serious investigation of radio navigation during World War I. Up until WW II map reading, dead reckoning, and various means of radio direction finding were the primary methods of determining aircraft position. Since WWII a number of other navigation techniques, such as Doppler radar, radio inertial, pure inertial, aided inertial, and today's integrated GPS inertial, have been developed. Most of the inertial systems evolved from the military ICBM and subsequent space programs.     

Aerospace High Voltage Development

High voltage has been used for electrical power system generation, transmission, and distribution for over 75 years and manufacturers have been designing x-rays, radios/television transmitters and receivers for many years with excellent success. High voltage usage in aerospace equipment initiated during World War II with the advent of high power communications and radar for airplanes. About 20 years ago the first high voltage components were built for spacecraft systems. This article is to provide some insight into the status of high voltage for aerospace equipment and the differences between terrestial and aerospace system functions and the attendant problems. What are the basic differences between terrestial/commercial and aerospace equipment? The aerospace environment is defined as that significantly above the Earth's surface: From 5000 feet altitude to deep space. The basic differences are the constraints placed on the user vehicle (airplane, missile, or spacecraft). Constraints include: Atmospheric pressure, temperature, lifting capability, electronic requirements, and volume. Early airplanes needed only radios and mechanical pressurization instruments. Today's sophisticted airplanes require transmitters, receivers, controls, displays, and in the military case, special electronics. The addition of electronic devices has increased the electrical power demand from a few watts (for early aircraft) to well over one megawatt for special applications. There is the need for compact packaging to reduce weight and volume. Spacecraft with booster limitations are ever more restrictive of weight and volume then airplanes while they must maintain complete electrical system integrity for mission durations of several months to years.     

Introduction [A century of powered flight:1903-2003]

The term Avionics is used loosely to identify that electronic equipment necessary to fly an aircraft. The term is nearly 50 years old with origins in military electronics. With the increasing dependence of aviation on electronics the amount of equipment that falls into this category has skyrocketed. This issue is intended to commemorate the Wright Brothers' Centennial of Powered Flight. It emphasizes aviation-related electrical/electronic advances for the years 1903 to 1953. The following paragraphs highlight some of the major topics discussed in this special issue.     

The Impact of Integrated Electronics on Aerospace Avionic Subsystems

Integrated electronics or microelectronics is one of today's major technical frontiers. Possibilities offered to the designer of avionics subsystems, for aerospace vehicles, by these techniques, are almost limitless, from the point of view of performance capabilities as well as reliability and maintainability. Application will change current engineering practices in avionics design. Some changes will be easy; in others, problems will appear. This paper discusses these changes, indicating potential gains to be expected as well as potential problem areas. The rise in the application of integrated electronics is expected to be high for the next 10 to 15 years. By 1980, integrated circuitry will have largely replaced the use of discrete components, and the rate-of-increase-of-application curves will level off.     

Advances in signal processing technology for electronic warfare

The denial of effective communications by enemy forces during hostile military operations has been a primary concern for military commanders since the inception of radio communications on the battlefield before World War II. Since then, the electromagnetic environment has been in a constant state of evolution toward more sophisticated jam-resistant and convert forms of modulation. For example, exotic modulation techniques employing spread spectrum (SS) signaling are routinely used by our adversaries to provide their communication links an advantage over US and Allied jammers. These same spread spectrum modulation techniques are being refined to provide convert, low probability-of-intercept (LPI) features to the unintended interceptor. The thrust of this paper focuses on developments in the theory and algorithms for detection, characterization, and exploitation of advanced waveforms using new mathematical signal processing tools. Specifically, quadratic time-frequency signal representations, wavelet transforms, and cyclostationary signal processing are introduced. This overview demonstrates the importance of these advanced techniques in a clear and concise manner. Applications and future research activities are described     

Trunking vs. conventional radio systems

Correctional Service Canada (CSC) has recently replaced the aging, out-of-date radio communications systems in all major CSC facilities with new conventional digital radio systems. Based on very specific and restrictive operational requirements coupled with developments in digital radio technology and the Associated Public Communications Officers (APCO) Project 25 digital radio standards, it was determined that digital radio communications would best meet CSC's needs. The CSC national radio replacement program was completed in March 2000. Switching to a digital radio communications system gave CSC an opportunity to consider changing the existing radio system from a number of conventional, single-site systems to a trunking system. Areas to be considered when determining the architecture for a radio communication network, whether radio trunking systems or conventional radio systems should be used, are presented, In addition, the paper will also outline the requirements and measures taken to keep the radio communication network active and operational while the equipment was converted from an analog technology to a digital one     

High Data Rate SHF Communication Receiver

This paper describes an SHF receiver capable of demodulating analog or digital information rates of up to 50 Mc/s. The receiver is a dual conversion superheterodyne design having a first IF of 1660 Mc/s and a second IF of 445 Mc/s. The model was developed as part of an Air Force contract to study and evaluate design techniques aimed at increasing reliability of aerospace SHF communication equipment. Semiconductor circuitry is used throughout, in addition to numerous deposited thin film circuits for reliability enhancement. The second IF amplifier design is unique in that all circuit components, with the exception of the semiconductors, are deposited, whereas more conventional microelectronics approaches to date have employed externally connected, discrete-component, frequency-selective devices, such as tunable IF coils or filter networks.     

Achieving higher levels of electronic integration throughsystem-on-chip

All aerospace vehicles have the common constraint of limited space for the electronic systems. The challenge has always been how to pack effective electronic systems into the space available. Higher levels of electronic integration can give a competitive advantage; for example, by providing extra channels in a communications satellite thereby increasing revenue to the operator. Today's deep sub-micron manufacturing processes for integrated electronics offer an opportunity for a step change for electronic functionality that can be packaged in a given space. This technology makes possible, for the first time, a true system-on-chip approach to electronic systems, which is already being exploited by the commercial sector in products such as the mobile telephone     

Fibre reinforced composites in aircraft construction

Fibrous composites have found applications in aircraft from the first flight of the Wright Brothers’ Flyer 1, in North Carolina on December 17, 1903, to the plethora of uses now enjoyed by them on both military and civil aircrafts, in addition to more exotic applications on unmanned aerial vehicles (UAVs), space launchers and satellites. Their growing use has risen from their high specific strength and stiffness, when compared to the more conventional materials, and the ability to shape and tailor their structure to produce more aerodynamically efficient structural configurations. In this paper, a review of recent advances using composites in modern aircraft construction is presented and it is argued that fibre reinforced polymers, especially carbon fibre reinforced plastics (CFRP) can and will in the future contribute more than 50% of the structural mass of an aircraft. However, affordability is the key to survival in aerospace manufacturing, whether civil or military, and therefore effort should be devoted to analysis and computational simulation of the manufacturing and assembly process as well as the simulation of the performance of the structure, since they are intimately connected.     

The untold Pearl Harbor radar story

Ever wonder what happened to the radar set that detected the Japanese aircraft before the raid on Pearl Harbor? This article reveals the fate of that SCR-270 radar set; describes some of the radar development background; and includes typical results of a World War II command, control and communications system that used the SCR-270 as its backbone radar. The SCR-270 was a radio-echo detection and direction finding set for locating aircraft. It operated by transmitting a short-duration pulse of high frequency radio waves, which would be reflected or re-radiated by any metallic or conducting surface within the field of the directive transmitting antenna; therefore, one or more aircraft within the antenna field appeared as a source of reflected radio waves. Rotating the antenna which also served as the receiving antenna, provided a means for determining the azimuth or direction of aircraft. The system measured the time it took a blip or reflected return from the target to appear on a cathode ray tube indicator, to give the distance or range to the detected aircraft. The maximum range of the radar was about 250 miles up to 50,000 feet under all atmospheric conditions including rain, mist, smoke or fog, and during daylight or darkness. The azimuth and range data supplied by the set permitted the plotting of the location of detected aircraft on maps. Major performance characteristics of the radar are provided in the included table     

Making technology work in World War II

The role played during World War II by small band of airman, hidden from public knowledge in a remote part of China, in bringing about victory over Japan is examined. Their actions represented the first major uses of airborne radar by the United States. The ways in which the group dealt with the challenge of turning the new technology of radar, which had just emerged from the laboratory, into an unusually effective weapon, is described by an officer who was responsible for preparing for the first maintenance of the equipment, implementing the maintenance, and contributing the technical expertise to the planning and evaluation of the operation. The low-altitude radar bombsight, AN/APQ-5 (LAB), designed to provide an electronic analog to the Norden high-altitude optical bombsight, is also described     

Impact of aerospace on computers

Electronics and computers have long been associated with aviation, defense and aerospace. Many aerospace advances would have been impossible without digital computers, and digital computers would not have progressed as rapidly without aerospace. In some sense you may thank aerospace for the computer on your desk and Internet in your life. DoD and NASA programs drove computer technology for the first 25 years, but in the 80s the primary thrust transitioned to the commercial sector. Aerospace computation requirements have driven the development of many electronic components such as transistors, ICs and memory technology. Advances in memory technology progressed from delay lines to electrostatic tubes to magnetic cores and now solid-state memory. As the need for number crunching grew, computers transitioned from batch processing, time-sharing, real-time computing, networking to the ubiquitous PC and Internet. How far is it from your hand-held PDA to the nano computer?     

Recent advances in surrogate-based optimization

The evaluation of aerospace designs is synonymous with the use of long running and computationally intensive simulations. This fuels the desire to harness the efficiency of surrogate-based methods in aerospace design optimization. Recent advances in surrogate-based design methodology bring the promise of efficient global optimization closer to reality. We review the present state of the art of constructing surrogate models and their use in optimization strategies. We make extensive use of pictorial examples and, since no method is truly universal, give guidance as to each method's strengths and weaknesses.     

Impact Potential of New Power Electronic Technologies

New technological advances in the area of power electronics are having an increasing impact on the design of aerospace control systems. These next generation power components promise improved system performance through increased electronic efficiencies. Applying state-of-the-art packaging concepts as an integral part of the system design will allow these devices to be utilized in a space efficient and reliable manner. The first portion of this paper looks at two such next generation components. The first is a High Voltage Integrated Circuit (HVIC) that provides a bridge between the low voltage controller logic and the high voltage motor winding invertor. This device achieves size reduction and an increase in reliability through integration of low and high voltage logic networks on a single integrated circuit. The second is the Insulated Gate Transistor (IGT). This device provides a high voltage switch with MOS-like drive characteristics. The present and future expectations of these power devices are discussed. This paper then looks at new packaging techniques for power devices. The impact of parasitic circuit effects have significant impact on power circuit performance. Finally, this paper looks at an example control application. The design is that of a permanent magnet motor driven actuator. The drive motor uses 270 vdc for supply voltage. Within the intelligent system controller, is the capability to control the current demands of the motor. The new power electronics devices are making the design feasible in both thermal and volume efficiency. This topic includes projected controller sizing into the 1990s.     

World Space Congress: a vision quest

The World Space Congress (WSC) in October, 2002, brought together luminaries, aerospace engineers, students, and scientists to discuss strategies for reviving the world's space agency. WSC lectures and plenary sessions focused on future research in space. Among topics discussed are the use of the Hubble Space Telescope to scan for habitable planets and obtain data about the beginning of the universe, new weather satellites, planetary protection from comets or asteroids, exploration and establishment of colonies on the Moon and Mars, medical advances, the role of space exploration in the world economy.     

航天用复合材料压力容器的应用与发展

复合材料压力容器在航空航天、汽车、电子等领域具有广泛的应用,本文系统地分析了目前复合材料压力容器的材料和典型结构,阐述复合材料压力容器在航天工业的主要应用及发展方向。     

Mission/flight systems integration study: a long-term electronicsplanning project

The objective of the Mission/Flight System Integration Study (M/FSIS) is to identify the requirements and development objectives for electronics systems technologies and conceptual architectures in future weapon system applications (in and around the year 2005), based on analyses of future missions, threats, scenarios, aerospace system concepts, and technology trends. The products are substantiated requirements for future electronics functions, systems, and architecture; technology development objectives and roadmaps; and conceptual electronics architectures and functional definitions. The study outputs will serve to guide laboratory technology development planning and programs; guide weapon system program office long-range electronics planning; illustrate user needs in terms of electronics requirements; and guide air logistics center weapon-system master planning