Military and Commercial Aircraft

In the United States, scientific research in space weather is funded by several Government Agencies including the National Science Foundation (NSF) and the National Aeronautics and Space Agency (NASA). For commercial purposes, space weather forecast is made by the Space Weather Prediction Center (SWPC) of the National Oceanic and Atmospheric Administration (NOAA). Observations come from the network of groundbased observatories funded via various sources, as well as from the instruments on spacecraft. Numerical models used in forecast are developed in the framework of individual research projects. Later, the most promising models are selected for additional testing at SWPC. In order to increase the application of models in research and education, NASA in collaboration with other agencies created Community Coordinated Modeling Center (CCMC). In mid-1990, US scientific community presented compelling evidence for developing the National Program on Space Weather, and in 1995, such program has been formally created. In 2015, the National Council on Science and Technology issued two documents: the National Space Weather Strategy [1] and the Action Plan [2]. In the near future, these two documents will define the development of Space Weather research and forecasting activity in USA. Both documents emphasize the need for close international collaboration in area of space weather.

Team performance in space crews: Houston, we have a teamwork problem

Microgravity research results and experiences from the NASA/MIR space station program

After previous years had seen a number of landmark breakthroughs in climate and energy policy, optimism and elation gave way to a more sober assessment of actual developments in 2006. In January, for instance, climatologists at the National Aeronautics and Space Agency (NASA) reported that the previous year had seen the highest global annual average surface temperature on record, affirming that ‘rapid warming gives urgency to discussions about how to slow green-house gas emissions ‘. A study released in early 2006 by the Tyndall Centre for Climate Change Research even concluded that greenhouse gas emissions must ‘end completely ‘ by the end of the next century if global warming is to be kept within a safe range.

On several occasions during the years 1968–1971 artists Robert Irwin and James Turrell, an experimental psychologist named Ed Wortz, and a number of UCLA student volunteers spent hours depriving themselves of light, sound and human contact. They were engaged in a series of experiments involving an anechoic chamber used for psycho-physical experimentation by the Garrett Corporation, a contractor to the National Aeronautics and Space Agency (NASA). The interior of the chamber was soundproofed, suspended to minimize the effects of the earth’s rotation and utterly darkened. Self-projected sounds like speech were deadened. Sitting in these reduced surroundings was exhausting; rather than depriving the subject of the senses of sight and hearing, the lack of focal markers proved to heighten them, causing the subject to strain his eyes and ears, searching for something upon which to focus his attention. Most startling were the effects upon leaving the chamber when the body re-adjusted to the overwhelming array of stimuli in daily life and the world became intensely bright, loud and noticeable.

The concept and reduction to practice of the Hazard Analysis and Critical Control Point (HACCP) system was directly related to the Pillsbury Company’s projects in food production and research for the space program. The basics were developed by the Pillsbury Company with the cooperation and participation of The National Aeronautics and Space Agency (NASA), the Natick Laboratories of the U.S. Army, and the U.S. Air Force Space Laboratory Project Group.

Aircraft thermal management is increasingly important to the safe and efficient design and operation of commercial and military aircraft due to the continually increasing heat loads from expanded avionic functionality, more electrical systems architectures, and the greater temperature sensitivity of composite material systems relative to traditional metallic designs. Military aircraft designers face the additional challenges of removing the waste heat from advanced weapon systems. This article provides an overview of the multiple thermal design issues faced in maintaining an acceptable temperature environment for the flight crew, passengers, cargo, and airplane structure and systems on a modern commercial aircraft.

Combustion of oxygen rich fuel vapors in aircraft fuel tanks can lead to explosions and fires. This was demonstrated unfortunately on July 17, 1996 with a Boeing 747 exploding in mid-air due to heated, highly explosive fumes in the center fuel tank. Sloshing of fuel, lightning and static discharge, and, for military aircraft, enemy ground fire can pose significant risks to the fuel tanks when the oxygen content is greater than 9%.Given the importance of fuel safety for both military and commercial aircraft, improved fuel inerting systems are needed that make these fuel tank ullage vapors non-explosive. This is often done by adding a nitrogen-rich gas stream to the fuel tank to reduce the oxygen content to less than 9%, a level that mitigates combustible explosive mixtures. On-board inert gas generating systems (OBIGGS) have been used on aircraft where engine bleed air is used as a pressurized air source flowing through a zeolite adsorption bed to separate oxygen and nitrogen molecules. The resulting enriched nitrogen stream fills the tank ullage lowering the oxygen content to non-explosive limits, however, this occurs at the expense of engine power.For certain military aircraft such as the V-22, the use of compressed engine bleed air to drive the separation process is not desirable, especially in landing zones that throttle back the compressor. For this reason, an electrochemically driven inerting system was developed by Reactive Innovations using a collection of membrane and electrode assemblies to remove the oxygen from the fuel and air mixture. The operating principle behind the separation process is to electrochemically reduce the oxygen in the fuel-air mixture to a water molecule that migrates via diffusion across a polymer ion-exchange membrane. On the opposing anode side, this water molecule is oxidized releasing protons that migrate to the cathode maintaining the separation process. This process is shown in Figure 1.The separator cell consists of a 5 mil thick Nafion membrane that is catalyzed with platinum on the cathode surface and catalyzed with a platinum/iridium oxide mixture on the anode. Air or a mixture of fuel and air flows over the cathode surface while an imposed voltage is applied to drive the process. The resulting current is measured over time while the cathode and anode outlet streams are sent individually to a gas chromatograph to measure the constituent concentrations.To avoid introducing or using external water with this separator that could affect the fuel quality, the separation process uses the internal hydration state of the membrane to facilitate the electrochemical separation process. This requires that the diffusive water flux from cathode to anode is balanced by the electro-osmotic drag of water from anode to cathode. Operating the separator at too fast of a separation rate causes regions of the membrane separator to dry out lowering the transport rate. This behavior is shown in Figure 2 where an applied voltage of 1 to 2.5 volts was used to drive the process. Stable current profiles were obtained up to about 1.75 volts with higher applied voltages causing the current profiles to decay.Cascaded operation was examined with one or two separators in series showing that the oxygen content in the tank ullage could be reduced to less than 9% as shown in Table 1. This indicates that the separator can be sized accordingly to extract the oxygen from the fuel-air mixtures.Acknowledgment: This work was supported by Navy Contract No. N68335-11-C-0397.

Involute spline couplings are commonly used in aircraft to transmit power to gearboxes, generators, pumps, and other engine driven accessories. Spline driven accessories which are cantilever mounted on an aircraft engine are of special concern to the user as these interface splines characteristically exhibit extremely poor reliability. To compound the problem, replacement of splines is difficult and costly due to their inaccessibility. Whereas the engine driven accessory may demonstrate a mean time between failures (MTBF) of 2000 hr., the spline coupling typically fails within 500 hr. Consequently, the degree of maintenance demanded by spline wear conflicts with the operational requirements of military or commercial aircraft. Failures can also compromise flight safety. This paper reviews recent spline research directed at understanding the characteristics and problems of conventional involute splines. It also discusses the design, development, and application of the circular spline coupling (MS14169) which was developed to solve spline wear problems being experienced in military aircraft.

The Wright brothers' first flight took place in 1903, and for the next 60 years flight was purely a mechanical activity. This all changed in the early 1960s, when computers first began to find their way onto airplanes. The first onboard computers were hybrid electromechanical devices and made use of very specialized and limited instruction sets. There was a substantial lag between the appearance of digital technology in military aircraft and those flown in civilian applications. Although many people view aviation as an extremely high technology field, there is often a lag in technology adoption, particularly in the airborne segment of civil aviation. This lag is the result of conservatism due to safety concerns as well as a need to constrain both the weight and the cost of onboard systems. While slow to embrace the digital age, aviation‐related applications of software engineering are now at the forefront of this new science. Software applications are now found in all phased of aviation and include among the many, aircraft design, flight safety, air traffic control, maintenance, etc. Ever greater levels of automation onboard aircraft and in ATC systems require highly complex designs while demanding the utmost reliability and dependability of the software and the hosting hardware. Time and experience has shown that such reliability is the result of disciplined, well‐planned, thorough development processes. Current regulatory guidance for airborne systems containing software invokes DO‐178B/ED‐12B as the design assurance standard of choice to ensure safe software. Where software blends with hardware to produce firmware in the form of application‐specific integrated circuits and programmable logic devices, a new standard, DO‐254/ED‐80, has been introduced to extend design assurance to this area of software engineering for airborne systems. The software engineering approaches and techniques discussed here are a result of ongoing debate and consensus among the industry, regulators, and researchers. There is much engineering judgment in the techniques described, although there is no empirical basis or measurement of how best these techniques can eliminate safety‐related problems. Models have been developed to predict the latent fault density by correlating the maturity of the development process. Such models have not yet been applied and tested in the aviation industry. It should be noted that as the amount of software has steadily risen in commercial aircraft, the fatal accident rate has steadily fallen over the same time period. While a direct cause–effect relationship has yet to be established between the design assurance approaches discussed in this article and overall system safety, the trends provide significant confidence in our modern aerospace infrastructure.

From that memorable day in December, 1903, when Orville Wright made the first power driven flight, aeronautical engineers have directed continuous efforts towards improving the range of aircraft. The distance covered on that first flight was about 120 yards. At the present time the record for distance flown in a straight line stands at 5,012 miles, and as for duration, some unfortunate Americans recently succeeded in staying in the air for nearly 27 days and nights without landing. This latter record has little value beyond that of an endurance test of the engine, and possibly the physiological effects on the occupants of the aircraft. The long distance record, however, has a direct influence upon the design of both military and commercial aircraft.

Military and defense-related procurement has been an important source of technology development across a broad spectrum of industries that account for an important share of U.S. industrial production. This book focuses on six general-purpose technologies: interchangeable parts and mass production, military and commercial aircraft, nuclear energy and electric power, computers and semiconductors, the Internet, and the space industries. It addresses three questions that have significant implications for the future growth of the U.S. economy: Will changes in the structure of the U.S. economy and of the defense-industrial base preclude military and defense-related research, development, and procurement from playing a role in the future comparable to the role it played in the past? Will public support for commercial research and development become an important source of new general purpose technologies? Will a major war, or the threat of major war, be necessary to mobilize the scientific, technical, and financial resources necessary to induce the development of new general-purpose technologies? It argues that when the history of U.S. technology development over the next half century is written, it will focus on incremental rather than revolutionary changes in both military and commercial technology. It will also be written within the context of slower productivity growth than the relatively high rates that prevailed in the U.S. through the 1960s or during the information technology bubble that began in the early 1990s.

The Fly-By-Light Advanced Systems Hardware (FLASH) program is developing Fly-By-Light (FBL) and Power-By-Wire (PBW) technologies for military and commercial aircraft. FLASH consists of three tasks. Task 1 is developing the fiber optic cable, connectors, testers and installation and maintenance procedures. Task 3 is developing advanced actuators. Task 2, which is the subject of this paper, focuses on integration of fiber optic sensors and data buses with cable plant components from Task 1 and PBW, smart and thin wing actuators from Task 3 into complete centralized and distributed flight control systems. Laboratory demonstrations will show applicability to widebody transport and tactical aircraft. Products include high throughput processors, neutral network applications to maintenance diagnostics and reconfiguration, hardware upset recovery, active sidestick controllers and application of the SAE AS-1773A protocol to the flight control system bus. This paper overviews the requirements, objectives, key technologies and demonstrations for each of the FLASH flight control system developments. Companion papers provide additional description of the Tasks 1 and 3 as well as further details on the individual developments within Task 2.

Numerical simulation of jet noise

The Nation's economic prosperity and military security depend heavily on development and commercialization of advanced materials. Materials are a key facet of many technologies, providing the key ingredient for entire industries and tens of millions of jobs. With foreign competition in many areas of technology growing, improvements in materials and associated processes are needed now more than ever, both to create the new products and jobs of the future and to ensure that U.S. industry and military forces can compete and win in the international arena. The Federal Government has invested in materials research and development (R&D) for nearly a century, helping to lay the foundation for many of the best commercial products and military components used today. But while the United States has led the world in the science and development of advanced materials, it often has lagged in commercializing them. This long-standing hurdle must be overcome now if the nation is to maintain its leadership in materials R&D and the many technologies that depend on it. The Administration therefore seeks to foster commercialization of state-of-the-art materials for both commercial and military use, as a means of promoting US industrial competitiveness as well as the procurement of advanced military and space systems and other products at affordable costs. The Federal R&D effort in Fiscal Year 1994 for materials science and technology is an estimated $2123.7 million. It includes the ongoing R&D base that support the missions of nine Federal departments and agencies, increased strategic investment to overcome obstacles to commercialization of advanced materials technologies, interagency cooperation in R&D areas of mutual benefit to leverage assets and eliminate duplicative work, cost-shared research with industrial and academic partners in critical precompetitive technology areas, and international cooperation on selected R&D topics with assured benefits for the United States. The materials R&D program also supports the Administration's specific technological objectives, emphasizing development of affordable, high-performance commercial and military aircraft; ultra-fuel-efficient, low-emissions automobiles that are also safe and comfortable; powerful yet inexpensive electronic systems; environmentally safe products and processes; and a durable building and transportation infrastructure.