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Aviation History
1948
1948 - 0271.PDF
FEBRUARY 20TH, FLIGHT Transports To-day angd To-morrow . .... is manifestly another development of the old "C" Class design of 1934, ar*d is closely akin to the Sunderland and Seaford military variants. It is, in fact, a civil Seaford, and must not be considered as an example of what might have materialized had Short Brothers been given a free hand to produce the most efficient solution to B.O.A.C.'s requirements. The calibre of the Solent and of its imme- diate predecessors (both of which remain in service) can be gauged from the following abridged specifications: Engines... RangeGross weight ... Max. speedPassenger capacity Sunderland Conversion 4 Pegasus(3,920 h.p.) 1,410 sea miles56,000 Jb 182 kt40 Sandringham 4 Pegasus(3,920 h.p.) 1,790 sea miles66,000 lb 185 kt21- and 45- seat versions Solent 4 Hercules(6,700 h.p.) 2,000 sea miles75,000 !b 240 kt30 The relatively low speeds are largely attributable to the age of the basic design and to unavoidable concessions to military requirements. Even the Shetland, the basic design of which is much more recent, is a modified Service type, though its performance and capacity are appreciably superior. Comparative data are: Engines, four Centaurus (10,000 h.p.) ; range, 4,000 sea miles ; gross weight, 130,000 lb ; max. speed, 230 kt; passenger capacity, sixty. It will thus be seen that the SR/45 is the first British flying boat of recent years in the design of which civil needs have been given prior consideration. This epitome of British conviction, skill •? i and eight units of 5,000 h.p. each would doubtless havebeen preferred could these have been developed in time. Flying-boat construction in America has in the past beenprincipally in the hands of the Boeing, Sikorsky, and Martin concerns. Now only Martin remains as a potentialproducer, in the immediate future, of large marine air- craft for commercial operation, and only one type of flyingboat—the Mars—is at present available. The U.S. Naval Air Transport Service is successfully operating militaryversions of the Mars on the Alameda-Honolulu run, but there is little likelihood that the Mars, already ageing indesign, will be adopted by any commercial airline. •-•••.•••'•--•• A Civil Mars A projected civil version of the Mars, announced overtwo years ago, was to have been a considerable improve- ment over the military versions, and it was claimed thatfully 52^ per cent of its 87^-ton gross take-off weight could be devoted to useful load on the cargo version and 48.1per cent on the all-passenger model. Pratt and Whitney Wasp Major engines were specified, and, at f power, themachine was to carry 50,550 lb of payload for 2,076 miles at 204 m.p.h. ; 36,700 lb for 3,000 miles at 208 m.p.h. ; or12,690 lb for 4,650 miles at 213 m.p.h. Interest in the Mars was revived recentlyby a statement made before the President's Air Policy Commission by Mr. Langdon P.•iMarvin, Jr., formerly the Chairman of the Inter-departmental Air Cargo PrioritiesCommittee, who discounted as imprac- ^ a suggestion for building a fleet of "height aircraft for the military services and'' putting them in moth- balls" until needed in anemergency. A more suitable method of developing '' aMerchant Marine of the air " and hope has been designed to have the range and speed required for a direct London-New York service against a continuous headwind of 60 m.p.h. and to be suitable for medium, long and extreme-stage services in any part of the world. Briefly, the "45" can be described as a high-wing monoplane of 220ft span with a 146ft hull of relatively small " double-bubble," or, more descriptively, "cottage loaf" section. For the first time, perhaps, the dimensions of the hull have been governed primarily, not by water clearance or seaworthiness, but (as is the size of a land- ~lane's fuselage) by considerations of per- formance and stowage space. The cross-section was dictated by pressurizing requirements, and with the addition of a planing bottom, chines and upswept stern section, appears to give a much less favourable aerodynamic form than that selected for the fuselage of the Brabazon. Preliminary performance data, however, sug- gest that the hull shape is aerodynamically more efficient than might at first be supposed, though in considering the estimated cruising speed of " over 350 m.p.h." it must be remem- bered that the SR/45 is to be powered with no fewer than ten Bristol Proteus airscrew tur- bine units, whereas the Brabazon, of somewhat larger dimensions, (though of lower all-up weight) will have • " • m ' The second Short Shetland, powered by four Bristol Centaurus engines, on an early flight from the Med- way. On this occasion the Shetland was not flying at its maximum weight of 130,000 Ib. Frontal aspects of the Short Solent top) and the Sounders-Roe SR/45, showing that the sectional area and depth of the hull have not increased in proportion to overall size. would, in Mr. Marvin's view, be the promotion of a domestic, and especially international, air trade, whereby aircraft might earn their salt in peacetime. They could, he claimed, be kept busy flying commercial cargo and thus would be useful if America remained at peace and ready,if she went to war. It was necessary, he claimed, to find a formula to combine both military and commercial interests—to design a '' combination sword and The par- and only eight. choice of this ticular type number of power plants was governed by availability of airscrew turbines, \\
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