EMPIRE AIRSHIPS

Evening Star, Issue 19768, 19 January 1928, Page 12

EMPIRE AIRSHIPS

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The titst of U.c two new 5,000,000 cubic led capacity an snips oruered lor f.iupuc use will bo complete., about next .April, uiul to-Uay an oppoiiumu was given me at the aii'suips woihS lo ko tue advanced stage const!action Inis now reached (writes an expert correspondent of ‘ 'l.'nc Times This blnp, KIUO, u being built to a contract lor £3aU,Ot)U by tbo Anslny Guarantee Company, the inspiration of which is Commander Burney, wno has fought consistently and cogently m i'aiTiaineni and out for a detinue airship policy, wi.en tew people had any interest in tno lighter-llmn-air vessel. This and a sister ship under construction at the Itoyul Airship Works, Curdington, are designed to a specilication calling for a gross lift of 150 tons a structure weight not exceeding 90 tons, and a speed of 70 miles an hour.

This ship is so far advanced now that it is a complete framework, except for nose and tail, and is suspended from the huge shed roof towering 140 ft or more from the giotmd, while its three internal decks to accommodate 100 passengers and crew of 40 are already taking shape within the hull. So far no technical details have been available, and more than ordinary interest Therefore attached to tho complete examination possible to-day, though Commander Burney asked that only general features should, he described. He informed me that lie and bis chief technical associates, Major I’. L. Teed and Mr B. N. Whllis, had bettered the specification, in that, with a gross lift of 156 tons, the structure weight was only ,B.'? tons, with a top speed of 83 miles an hour and a cruising speed of 75, miles an hour for 4,500 miles in still air, taking as full load 100 passengers and their supplies. FACTORS OF SAFETY. Further, he claims that the factors of safely are double those laid down by the airworthiness panel, and assume as the worst condition a vertical gust of 4,000 ft velocity per minute striking the ship when moving at full speed. The constructional principles used, it was apparent, are based on simplification of stresses and. economy in production, and represent striking technical advances on the earlier types of airships. Unlike the Fiate airship, in which stainless steel is largely used for the girders, 11100 remains faithful to duralumin, but it is used iu a radically different way from Zeppelin practice. The main members of tho triangular girders are of duralumin sheet wound into a helical tube ana riveted along the continuous overlap; this enables cleaner metal to bo secured, facilitates inspection of the raw material, and improves uniformity. A machine produces readily this tube, and tho cross bracings of the triangular girder are also made from dural sheet by stamping out tho shapes from the flat strip. Each girder is fitted with a screwed end, and all girders at each transverse frame connect to a framework called a spider web. This is a built-up component of dural sheet and tube fitted also with screwed ends. A screw collar pulls the spider web and each girder into contact on the principle of the turnbuckle, with its left and righthand threads. Standard end fittings are used throughout tho ship; thus cost is reduced and replacement simplified. Radical bracing wires from each spider web in each frame run to tho centre of the circle, and the centre of each circle is tied to the next, by an axial girder running tho length of the ship. The gas bag encircles this gilder, which is in sections, and its main purpose is to reduce side pressure on the radial wires if any one bag bulges out. Each bag, and tho largest will have a capacity of 500,000 cubic feet, is enclosed! in a not, and so anchored to the spider webs as to prevent any bending strains being put on the girders. These important considerations in efficient design have been wen red, and I was informed that very considerable simplification of strength problems has been attained by designing for all loads in tho girders lo be pure tension or compression. Throughout the store, too, a system of grading the girders and shear wires has been followed, the strength, and therefore weight, of each girder varying according to the intensity of tho local strains in that particular area. SAVING OF WEIGHT. In the bow, where the mooring strains are concentrated, tho girders are uniform and in fact reinforced, but in the centre bay the principal stresses to be met are due to " hogging i.c., the ship trying to hump its buck. Here the lower longitudinal girders are stronger to resist compression than tho topmost girders, wliich have to take mamly loads in tension. The same principle applied throughout tiro ship has resulted in considerable saving of weight without reduction in safety. Tho fins and tail planes are fixed to the hull by a new method by means of girders shaped like a cross, the centre of which is a much strengthened aerial girder, the whole being tied once again to tho spider webs. 'Similarly tho passenger unit, with its two and four-berth cabins, its lounge, dining rooms, verandahs, etc., is suspended as it were iu the ship, and does not rest on any girder or frame. Tho only projections outside the clear lines of the hull are the three engine nacelles and the commander’s control cabin, wliich is sunk through the underside of the vessel amidships. The engines to be used are six Rolls-Royce condor units of 700 h.p. each, and this is a regretted departure from the proposal to eliminate petrol aa a fuel, necessitated by the fact that the alternative engines, burning hydrogen and kerosene or crude oil, are not yet available. Tho length of the ship is 709 ft, and tho greatest diameter is 130 ft, with the transverse frames so spaced that no one gas bag between frames takes more than 10 per cent, of the total lift. Commander Burney is satisfied that his ship will withstand all weathers, and certainly, if human skill and foresight can accomplish that end, Commander Burney and his associates have reason. for optimism. His view is that for Empire operation the airship must be able to weather the worst conditions, hence _ his insistence of meeting vertical gust conditions of tho severity named. PHANS FOR BIGGER AIRSHIPS.

: Already ho is satisfied, from the knowledge gained in building this ship, that he can go to larger sizes; in fact, he has such plans in hand for an ail-ship capable of operation bei.ivceu Europe and America, which, he said, would represent as big an advance on RIOO as she is on the wartime ships. Such a ship should carry out the trip from London to Neiv York in forty-eight hours, at an average fare of £IOO per passenger. The initial cost per ship, he thought, would be about £450,000. He insisted that the success of the commercial operation of. airships lay in private and not State enterprise, and not unjustifiably he is apprehensive of the position next April, when, with his ship completed and no immediate prospect of more work, the trained staff now gathered at Howden will become an unremuneralive burden or be dispersed. So far as can be seen at present, the trials of the ship are to wait until the second shed at Cardington is completed. This may moan that not until the summer will any practical flying bo possible, and it. is obvious that most exhaustive trials of gradually increasing severity must bo undertaken before the wider our.s cf Empire airship communication can oven he considered from a practical standpoint.