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Aviation History
1937
1937 - 1974.PDF
68 FLIGHT. JULY 15, 1937. '' Bradshaw'' Crossings by Imperial Airways and Pan-American Airways Boats : The Story of the Historic Experimental Flights : Interesting Features of the Sikorsky S.4.2B Revealed on Inspection ATLANTIC ROUTINE AT 11 a.m. (B.S.T.) on Tuesday, July 6, Caledonia put down at Botwood, Newfoundland, thirteen minutes after the Pan-American Airways' Sikorsky S.42B had touched the water off Foynes. Each had travelled the 1,900-odd miles across the Atlantic, their skippers treating the affair as one of routine interest only. The fact that the eyes of the world were upon them pro vided, apparently, the only real cause for nervousness. In last week's issue of Flight there appeared an article explaining the major navigation problems involved in such a crossing, outlining the general Atlantic position and briefly stating the facts of success. Later in this article is a description of the successful Pan-American boat, with some comments on the navigational methods employed by her crew. Caledonia, in her general design and primary structure, is identical with the Short boats of the Empire class. A detailed description of the class appeared in Flight of October 29, 1936, but it may be of interest to recall some outstanding features. Each machine is an all-metal four- engined cantilever monoplane, with a two-stepped hull. Stability on the water is obtained by two outboard floats. Each Bristol Pegasus Xc engine is rated at 740 b.h.p. at 3,500ft., a total of 2,960 h.p. These units each give 910 b.h.p. for take-off, with the De Havilland v.p. airscrew turning at 2,475 r.p.m. An interesting point is that the Pegasus Xc was the first unit operating on 87-octane fuel to go into service with a British air line. The Short boats are of 114ft. span and 88ft. length. The wing area is 1,500 sq. ft. Caledonia differs from her sisters mainly by reason of the fact that luxurious cabin equipment has been omitted and the interior is of a strictly utilitarian character. A greater gross weight has been permitted, 45,000 lb , compared with the 40,500 lb. of the other boats. Extra tanks have been installed in the wings, thereby increasing the fuel and oil load from 4,960 lb. to 18,750 lb. With this fuel and oil load the Caledonia has a range of 2,500 miles against a head wind of 40 m.p.h. when cruising at an airspeed of 160 m.p.h. To show how efficient, from an engineering point oi view, is the structure of the Caledonia, it may be pointed out that the machine weighs, bare but with the extra fuel and oil tanks, 23,200 lb. As the gross weight is 45,000 lb. the ratio of gross to tare weight is 1.94, which is merely another way of saying that the machine carries as dis posable load 94 per cent, of its own bare weight. This is an unusually good ratio, especially for such a large air craft. The special equipment of the machine accounts for a weight of 1,450 lb., and this leaves 1,600 lb. for crew and pay load. With a crew of four there is thus available
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