Text 3. Runway orientation
The number, length and configuration of runways influence greatly the airport capacity.
In broad terms, runways should be oriented so that aircraft are not directed over populated areas and obstructions are avoided. They are oriented in the direction of the prevailing wind when it blows consistently from one direction.
As a general rule, the primary runway at an airport is oriented as close as practicable to the direction of the prevailing winds. When landing and taking off, aircraft can manoeuvre on a runway as long as the wind component at right angles to the direction of travel (defined as cross-wind) is not excessive. The maximum allowable cross-wind depends not only on the size of the aircraft but also on the wing configuration and the condition of the pavement surface. Transport aircraft can manoeuvre in cross winds as high as 30 knots, but it is a most difficult thing to do. Hence lower values are used for airport planning.
A sufficient number of runways is required to meet the forecast aircraft traffic demand, i.e. the number of aircraft, mixture of aircraft types and mixture of arrivals and departures per one hour during the busiest periods. At busy airports in addition to the primary runways, one or more secondary runways may be needed to accomodate aircraft traffic under strong cross-wind conditions. However, as cross-wind runways are to be used only under high head-wind components, their length can be considerably shorter than that of the main runways.
Упражнение 28. Поставьте ключевые вопросы к тексту 3.
Упражнение 29. Переведите на русский язык следующие словосочетания. Составьте предложения с ними.
Much better, still farther, far more efficient, a great deal longer.
Упражнение 30. Переведите письменно текст 4, обращая внимание на особенности перевода сравнительных конструкций, содержащих определенный артикль
the ... the.
Образец: the sooner the better - чем скорее, тем лучше
Text 4. Runway length
The length of the runway depends on many factors which may be grouped into three general categories: a) aircraft performance requirements; b) environment at the airport; c) those items which establish the operating take-off and landing gross weights for each aircraft type.
Certain conditions at the airport also influence runway length. The most important of these conditions are: 1) temperature, 2) surface wind, 3) runway slope, 4) altitude of the airport and 5) condition of the runway surface.
The higher the temperature, the longer the runway required because higher temperatures reflect lower air densities, resulting in much lower output of thrust. The greater the headwind down a runway the shorter the length, and, conversely, a tailwind increases the length of the runway required. An uphill gradient requires far more runway length than a downhill gradient. If all other factors are equal, the higher the altitude of the airport, the longer the runway required.
The runway and taxiway characteristics are the basis for airport classification which, under ICAO, is coded in letters A,B,C,D,E,F,G. Though the airport category or class depends also on some other factors, including aircraft operating characteristics, airport annual capacity, radio, light and air traffic control equipment available.
The class of an airport determines the aircraft types which can be accepted. Thus, large jet airplanes use only the airports with paved or hard surface runways, although smaller airplanes, like AN-2, for instance, can operate from grass or dirt strips.
Упражнение 31. Поставьте ключевые вопросы к тексту 4.