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ВАРИАНТ 4

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РЕМ Fuel Cells

''The proton exchange membrane cell, which was developed by General Electric for NASA's Gemini space program nearly four decades ago, is the favored technology for auto applications because it is compact, runs at a low operating temperature, permits an adjustable power output, and can be started relatively rapidly. Innovations made in the 1980s at Los Alamos National Laboratories made the РЕМ cell more practical by substantially cutting the amount of precious metal catalyst needed to coat the cell's ultra-thin polymer membrane.

Ballard's prototype fuel-cell units, which are used by DaimlerChrysler, Ford, Honda, and Nissan (and others yet unacknowledged), comprise a series of carbon plate/PEM electrode assemblies. "Each assembly includes five main components," explained Paul Lancaster, Vice President, Finance at Ballard. "At either end is an electrode made of a carbon material with a coating of platinum-family catalyst that ionizes hydrogen on one side of the unit and oxygen on the other. In the middle is a thin proton exchange membrane, which is a rubbery hydrophilic polymer electrolyte with solid sulfonic acid sites bonded onto it. These sites allow protons to be transported selectively through the membrane."

Although the latest enhancements to fuel cells are rather recent, researchers at Ballard and presumably GM have worked out most of the technical problems, boosting the stack's power density by determining how to keep the membranes moist but not flooded, and by optimizing the flow lines that transport hydrogen, oxygen, and water through the stacks. Ballard, which has obtained nearly 400 patents in РЕМ technology, intends to have a car-sized power unit ready to go within four years at prices comparable to 1С engines, according to Lancaster.

Clearly, fuel cells provide some advantages over 1С engines: they are more efficient in extracting energy from fuel; they are quieter; and they could form the basis of a zero- or very-low-emissions engine that runs on a renewable fuel. It should be noted that some engineers expect practical fuel-cell vehicles to be hybridized with batteries, ultracapacitors, or other energy storage devices to allow them to be run at lower power output levels and, thus, at higher efficiencies. "Fuel-cell stacks operate at 50 to 70% efficiency in the current power load of interest - about 60% in around-town driving," explained Byron McCormick, Co-director of GM's Global Alternative Propulsion Center.

Getting the Cost Out

Until recently, building a fuel cell sufficiently powerful to run a car was costly - even more than a vehicle powered by electrochemical batteries or a hybrid drive. To attain the power levels of a standard-issue 1С engine in a midsize sedan, a fuel cell needs to produce from 60 to 90 kW. When NASA first started using fuel-cell technology in space, a PEM fuel cell cost about $500,000 per kW. Today that price has dropped to around $500 per kW - but that means that a fuel-cell engine still costs about $25,000, which is around seven times the price of a typical 1С engine (about $3500).

Working for several years with specialists from Ford and Daimler-Chrysler, Ballard researchers studied the automotive industry's needs for low-cost, high-volume fuel-cell stack manufacturing and specifically designed the Mark 900 unit to accommodate them. "The key to developing an efficient supply chain," explained Lancaster, "is to choose low-cost, readily available materials and cheap, scaleable, automated manufacturing processes. We did an actual commercial plant study for the annual production of 300,000 vehicle equivalents, considering the building, logistics and other crucial details.

Facing the challenge of making economical fuel-cell units, Ballard worked with Ford and DaimlerChrysler to optimize its latest stack design for production. Said Lancaster, "Whereas the Mark 700 systems were basically hand-crafted units that needed carbon plates that were individually machined for two hours from blanks costing $ 100, the Mark 90 unit is made using a carbon sheet material called Graf oil which is supplied by U.S. Carbon Graftek. This soft, natural graphite material comes in rolls. The sheet is first roller-embossed, die-cut, then impregnated, and heat-treated. Now each plate costs a few dollars." The manufacturing process also reportedly employs other high-volume production processes such as injection molding. Each PEM fuel-cell stack comprises hundreds of these identical plates sandwiched between polymeric membranes.

Aircraft Collection

During the 1960s aircraft preservation continued to develop; both national and commercial museums flourished and aircraft preservation - and the practice of building replicas in the absence of the original -became an important aspect of the business.

Today, the preservation and use of vintage and historical aircraft can be summarized as follows: Museums may exhibit the original remains of an aircraft or a renovated model, either capable of flying or purely for display purposes. Privately owned aircraft may be used for private or pleasure flying, air shows, or air racing.

There are now some 700 museums and aircraft collections worldwide. While some specialize, others offer a broader interest, often combining other aspects. Either way, it can be said that they generally provide interest as well as education, even for those who thought they were not air-minded.

CONCORDE

More than two decades after its first flight, Concorde remains the only successful supersonic transport aircraft in the world. Two prototype and two pre-production aircraft were built which, despite the considerable interest initially shown by the world's major airlines, led to a production run of just 16 aircraft, seven each being purchased by British Airways and Air France. Both airlines started operations simultaneously on 21 January 1976, with services from London to Bahrain and Paris to Rio de Janeiro respectively. The first prototype made its maiden flight on 2 March 1969 from Toulouse, France, followed by the British prototype, Concorde 002, on 9 April from Filton near Bristol. Twin assembly lines were set up at Toulouse and Filton while major airframe sections were made at other factories in the two countries.

Concorde 002 spent its life at the manufacturer's Flight Test Centre at Fairfield, where it was used for aerodynamic and engine development trials until its withdrawal from service in March 1976.

The aircraft was acquired by the Science Museum, who at that time had no suitable location where it could be displayed. The Fleet Air Arm Museum took the aircraft on loan and, stripped out and with its undercarriage locked down, 002 made its last flight to the museum's Yeovilton home base in the southwest of England.

Now situated in its own museum building, Concorde 002 is displayed with some of the research aircraft that were built as part of the research and development programme.