The Airship for the British Navy

Abstract

THE leading article in Engineering for February 17 gives some account of the airship for the British Navy built by the Vickers Company at Barrow. Trials were conducted on Tuesday, February 14, in presence of the Government's Advisory Committee on Aëronautics, these being analogous to the basin trials of a warship, and have proved to be quite satisfactory. The structure for accommodating the hydrogen reservoirs or balloons is 512 feet in length and 48 feet in diameter. It is in the form of a decagon in section, and the. ten sides are built up of' longitudinal lattice-girders, with vertical intercostal girders, the top and bottom boom in each case being formed of angles or tees of duralumin. Each bay has diagonal wire bracing. The form is whale-like, with a bluff entry, and a sweet run aft to a point, where, at the bottom, there is a big fin, increasing in depth aft according to the upward rise to the point of the stern. Aluminium was first tried, but the girder structure of this metal collapsed under stress. The metal adopted—duralumin—is one of the magnesium alloys of aluminium, and contains 91 per cent, of aluminium. It has a specific gravity between 2.77 and 2.84, a melting point of about 650° C., a yield point varying from 12 to 16 tons per square inch according to the hardness, and a breaking resistance from 22 to 29 tons per square inch. The elongation varies from 23 to 18 per cent., and the contraction of area from 34 to 26 per cent. It will thus be seen that, despite its lightness, it bears comparison with mild steel.