The Development of Airship Construction

Abstract

AMONG the important papers read last week at the Institution of Naval Architects was one on airship construction by Mr. C. I. R. Campbell, who has been responsible at the Admiralty for the design of our airships. In British practice it is assumed for design purposes that the gas has a lift of 68 lb. per 1000 cubic ft. The author gives a curve showing the average lift per unit volume of gas at various altitudes as a percentage of the lift at ground-level. A dominating requirement in design is the provision of the longitudinal strength necessary to withstand the longitudinal shearing forces and bending moments, and the different means adopted to meet this requirement divide airships into three main types, viz. non-rigids, semi-rigids, and rigids. Particulars of three non-rigid airships are given in the paper, having gross lifts of 4690 lb., 14,100 lb., and n tons respectively; the disposable lifts when full are 1669 lb., 4655 lb., and 5 tons. For airships larger than 500,000 cubic ft. the non-rigid type can be, and has been, used, but its efficiency tends to compare less favourably with the semi-rigid type as size is increased. The author deals with questions of the gas pressures required to enable the envelope of the non-rigid ship to maintain its form under the distorting forces due to weights, and with the means for supporting the bow against the external air pressure in flight. He considers that non-rigid ships form a class of great utility, which can be given speeds of 45 to 60 miles per hour, with disposable weight percentages from 33 to 45 per cent. They are particularly suitable for short-distance flights and for patrol duties. Their chief merits are simplicity, ease and cheapness of production, and low cost of maintenance.