Propulsion system

The metal has recently found application in ion propulsion systems. Cesium is used in atomic clocks, which are accurate to 5 s in 300 years. Its chief compounds are the chloride and the nitrate. 

The procedures used for estimating the service life of solid rocket and gun propulsion systems include physical and chemical tests after storage at elevated temperatures under simulated field conditions, modeling and simulation of propellant strains and bond tine characteristics, measurements of stabilizer content, periodic surveillance tests of systems received after storage in the field, and extrapolation of the service life from the detailed data obtained (21—33). 

C. A. Detthng, ml 991JANNAF Propulsion Systems Ha ard Subcommittee Meeting, CPIA Pubhcation 562, Sandia National Labs, Albuquerque,... 

V. N. Huff and S. Gordon, Fables of Thermodynamics Functions forHnalysis ofHircraft-Propulsion Systems, Tech. No. 2161, National Advisory Committee... 

From the standpoint of commercialization of fuel ceU technologies, there are two challenges initial cost and reHable life. The initial selling price of the 200-kW PAFC power plant from IFC was about 3500/kW. A competitive price is projected to be about 1500/kW orless for the utiHty and commercial on-site markets. For transportation appHcations, cost is also a critical issue. The fuel ceU must compete with conventional mass-produced propulsion systems. Furthermore, it is not clear if the manufacturing cost per kilowatt of small fuel ceU systems can be lower than the cost of much larger units. The life of a fuel ceU stack must be five years minimum for utiHty appHcations, and reHable, maintenance-free operation must be achieved over this time period. The projection for the PAFC stack is a five year life, but reHable operation has yet to be demonstrated for this period. 

Appllca.tlons. The principal appHcations of nickel-base superalloys are in gas turbines, where they are utilized as blades, disks, and sheet metal parts. Abcraft gas turbines utilized in both commercial and military service depend upon superalloys for parts exposed to peak metal temperatures in excess of 1000°C. Typical gas turbine engines produced in the United States in 1990 utilized nickel and cobalt-base superalloys for 46% of total engine weight (41). However, programs for future aerospace propulsion systems emphasize the need for lightweight materials having greater heat resistance. For such apphcations, intermetallics matrix composites and ceramic composites are expected to be needed. 

R. L. WooUey, "Hydrogen Engine NO Control by Water Induction," NATO/ CCMS Fourth International Symposium on Automotive Propulsion Systems, Washington, D.C., 1977. 

As previously stated, uranium carbides are used as nuclear fuel (145). Two of the typical reactors fueled by uranium and mixed metal carbides are thermionic, which are continually being developed for space power and propulsion systems, and high temperature gas-cooled reactors (83,146,147). In order to be used as nuclear fuel, carbide microspheres are required. These microspheres have been fabricated by a carbothermic reduction of UO and elemental carbon to form UC (148,149). In addition to these uses, the carbides are also precursors for uranium nitride based fuels. 

Harmon, R., Alternative vehicle-propulsion systems. Mech. Eng. 105(4), 67-74. (March 1992). 

Mode Typical Capacity Propulsion System Customer Price/Speed lor Shipping (40 X 8 X 8 container size) Typical Speed in United States Mileage (ton-miles gallon) Energy Consumption (Btu/ton-mile) ... 

A major problem is the design of a propulsion system for a vehicle that has no contact with a guideway. The only reasonable choice is a linear motor that uses magnetic fields to propel the vehicle. The development of a linear motor and its control system is at least as formidable a challenge as the development of a maglev suspension system. 

The improvement of human control over inanimate forms of energy, put to use to military ends, has improved the logistics and coordination aspects of armies and navies, and increased the overall destructive capacity of humanity. Energy-efficient propulsion systems have reduced the costs and increased the ranges of various forms of transportation, both militai y and civilian. For the militai y, energy is both a blessing and a vulnerability, requiring ever-more-specialized soldiers and more expensive equipment to remain effective in the face of competition from other modern military forces. 

Wlienever anything is set in motion, there must be some type of propulsive force that moves it. Propulsion is a key element of many activities, including athletic events, recreation, transportation, weapons, and space exploration. This article explains the basic principles involved in any propulsion system, differentiates the types of propulsion systems, and discusses some practical aspects of propulsion. 

Propulsion generates kinetic energy to facilitate motion of spacecraft. Although propulsion is provided by various types of devices, the most common propulsion system of modern space technology is a rocket engine, a device that propels a rocket by a force... 

Table 2 compares some of the modern propulsion systems. 

New vehicles, propulsion systems, and fuels are on the horizon hybrid automobiles (combining an electric motor, batteries, and a gasoline or diesel engine), better electric cars, greater use of compressed natural gas (CNG) and propane for urban fleet vehi-... 

Plastics have found numerous uses in specialty areas such as hypersonic atmospheric flight and chemical propulsion exhaust systems. The particular plastic employed in these applications is based on the inherent properties of the plastics or the ability to combine it with another component material to obtain a balance of properties uncommon to either component. Some of the compositions and important properties of plastics are given in Tables 2-9 and 2-10 that have been developed over the years for use in flight vehicles and propulsion systems that are dependent upon chemical, mechanical, electrical, nuclear, and solar means for accelerating the working fluid by high temperatures. 

Since 1950, plastics have been development for uses in very high temperature environments. By 1954, it was demonstrated that plastic materials were suitable for thermally protecting structures during intense propulsion heating. This discovery, at that time, became one of the greatest achievements of modern times, because it essentially initially eliminated the thermal barrier to hypersonic atmospheric flight as well as many of the internal heating problems associated with chemical propulsion systems. 

Only chemical propulsion will be further discussed, and in particular, that associated with liquid, solid, and hybrid motors and engines. These motors and engines are uniquely different from other chemical propulsion systems in that they carry on board the necessary propellants, as contrasted to jet engines that rely on atmospheric oxygen for combustion of the fuel. 

Major Property of Interest Type of Polymer Propulsion System Application... 

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