The four-engine plane

Sikorsky had built the first four-engine plane, the Bolsche of 1913. As long as a single aircraft engine could not generate much more than 1,000 horsepower, multiple engines became the only way to gain the total amount of power necessary to lift the large loads of fuel needed for long journeys. When Pan American sought to open a service from Alameda (Oakland),Calif., to Manila and China, it faced a 2,400-mile maximum stage between the San Francisco Bay area and Honolulu. Only a four-engine plane could lift enough fuel to make such a “jump.” A further constraint entered the planning: such large planes and the fuel load they would carry could not lift off the ground on the landing strips then available. Only landing on the surface of sheltered waters would provide the thousands of feet required. The Germans in attempting to establish a transatlantic airmail route experimented with artificially calmed stretches of ocean, but the operation was far too risky ever to be used in passenger service. Only through the use of insular stepping-stones properly spaced, such as the Americans controlled west of Honolulu, could an ocean crossing be obtained. In 1932 Pan American signed a contract with Sikorsky to build a four-engine flying boat capable of carrying mail and passengers across the Pacific and a second contract that same year for an even larger flying boat, weighing 26 tons, to be built by Glenn Martin. On Nov. 22, 1935, the first airmail flight left Alameda for Manila using the Martin M-130 (the China Clipper), with a wingspan of 130 feet (equal to the Boeing 727 of a generation later). Passengers were added to the service in 1936, when the first long transoceanic flight began.

The success of these huge flying boats greatly whetted the appetite of American airline operators because it demonstrated the advantages that might be hoped for from four-engine planes, particularly in raising the ceiling on normal commercial flight so that airlines might “fly above the weather.” To do so, it was necessary to artificially pressurize plane cabins above 6,000 to 8,000 feet. Half the weight of the atmosphere is normally found below 18,000 feet, and most of the turbulence is located there. Early experimental flights had shown that as an aircraft rises in the atmosphere it tends to encounter less stormy conditions; most of the “weather” is found below 4,000 feet. If planes could operate at such higher altitudes, flights would be more comfortable and there would be less resistance to forward movement, allowing the same input of power to move the plane at a greater speed. The first hurdle came in securing an airtight cabin, but success in this operation had to be accompanied by better engines, as was done in the Boeing Stratoliner introduced in 1940. Capable of flying at 14,000 feet and at a speed of 200 mile/h, the Stratoliner had just begun service when war in Europe broke out; development of this pioneering four-engine plane was taken over by the government for the duration of the war. It was the only commercial aircraft to be able to fly directly from Newfoundland to Northern Ireland during World War II. With its powerful supercharged engines the Stratoliner could navigate not only above weather but over rather than around mountains. Thus routes could be chosen because they formed parts of great circles on the Earth's surface and were thereby the shortest possible distances between two points.

A second four-engine plane was designed just before World War II when the general configuration of the DC-3 was transformed into a four-engine size. Unlike the Stratoliner, this was not a pressurized plane, so it represented the last phase of one line of advance more than the beginning of a postwar design. The enlarged DC-4 was flown throughout the war, becoming the main transatlantic aircraft, in the form of the United States Army's C-54 troop transport.

Essential vocabulary:

1. constraint - ограничение
2. strip - полоса
3. surface - поверхность
4. sheltered – скрытый, укрытый
5. to provide – снабжать, обеспечивать
6. to require - требовать
7. available - доступный
8. to attempt - пытаться
9. to establish - устанавливать
10. artificial - искусственный
11. calm – спокойный, тихий
12. stretch - протяженность
13. insular - островной
14. stepping-stone – камень, положенный для перехода через речку
15. airmail - авиапочта
16. wingspan – размах крыльев
17. whet – точить (зд. разжигать, усиливать)
18. ceiling - потолок
19. to encounter – сталкиваться с
20. altitude - высота
21. resistance - сопротивление
22. input - вклад
23. secure – безопасный, защитный
24. hurdle - барьер
25. airtight -герметический
26. to accompany - сопровождать

I. Work in pairs. Discuss which sentence in B best continues the sentence in A:

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