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Experts estimate that in the second part of the 21st century we will go by rocket from New York to Tokyo in 30 minutes. We will be able to reach any point on the globe from any other point through tunnels deep in the earth. The prospect is adventurous and exciting.

It's possible, that within the next two or three decades we will be riding in remote-controlled electronic cars.

Trips through metropolitan areas will be made on quiet, swift buses travelling on separate express lines of city streets. Helicopters may carry whole buses loaded with passengers from point to point above city traffic. "Flying crane" helicopters soon may help solve the complicated problem of getting passengers from the centre to the airport and back again.

Most of the advances in air transportation will materialize within the next few years. The largest airplane ever designed for commercial service, capable of seating nearly 500 passengers, is already being built.

Mankind has entered an age of high speeds, pressures and temperatures that could be generated and withstood only with the help of new and hitherto unknown materials.

In the 1920s the top speed of an airplane was not more than 200 kilometres per hour, the load per square metre of the wing area was about 50 kilograms. The main construction material was wood. In our day, the speed of aircraft, even passenger planes, is approaching 3,000 kilometres per hour, loads may be as high as 600 kilograms per square metre of wing. The turbine that drives such an aircraft is not only a miracle of design, it is also a miracle of materials strength. Its blades, for example, rotate at a tremendous speed and at the temperature greater than 1,000° Centigrade. The given examples are sufficient to indicate the complexity of materials studies today and the extent to which progress in the near or more distant future depends on them.

Of tremendous importance is the creation of new materials. Chemists engaged in polymer research have produced the world's best synthetic materials.

Metallurgists studying a new class of aluminum alloys have produced a very durable alloy, which is being used in aircraft and rocket engineering. The alloy helps reduce the weight of apparatus substantially, thereby effecting a considerable saving of materials.

Plastics are employed in a number of aircraft engine applications and have successfully displaced metals in jet turbine impellers where the high fatigue resistance of the material is of great importance. If suitable higher temperature plastics were developed, it is quite feasible that turbines will one day be all of plastic construction.





Дата публикования: 2015-04-06; Прочитано: 444 | Нарушение авторского права страницы | Мы поможем в написании вашей работы!



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