The design of this ship was prepared by Messrs. Vickers, Ltd., and as it was considered likely that owing to inexperience the ship would probably be roughly handled and that heavy landings might be made, it was considered that the keel structure and also the cars should be made very strong in case of accidents occurring. This, while materially increasing the strength of the ship, added to its weight, and coupled with the fact that modifications were made in the design, rendered the lift somewhat disappointing. The hull structure was of the "Zahm" shape as in No. 1, a considerable portion being parallel sided, while in transverse section it formed a 17-sided polygon. In length it was 526 feet with a maximum diameter of 53 feet. The hull framework was composed of triangular duralumin girders, both in the longitudinal and transverse frames, while the bracing was carried out by means of high tensile steel wires and duralumin tubes. Attached to the hull was a V-shaped keel composed of tubes with suitable wire bracings, and in it a greater part of the strength of the structure lay. It was designed to withstand the vertical forces and bending moments which resulted from the lift given by the gasbags and the weights of the car and the cabin. The keel also provided the walking way from end to end of the ship, and amidships was widened out to form a cabin and wireless compartment. The wiring of the transverse frames was radial and performed similar functions to the spokes of a bicycle wheel. These wires could be tightened up at the centre at a steel ring through which they were threaded and secured by nuts. In addition to the radial wires were the lift wires, which were led to the two points on the transverse frames which were attached to the keel; on the inflation of the gasbags, the bags themselves pressed upon the longitudinal girders on the top of the ship, which pressure was transferred to the transverse frames and thence by means of the several lift wires to the keel. In this way all the stresses set up by the gas were brought finally to the keel in which we have already said lay the main strength of the ship. The hull was divided by the transverse frames into seventeen compartments each containing a single gasbag. The bags were composed of rubber-proofed fabric lined with gold-beater's skin to reduce permeability, and when completely full gave a total volume of 890,000 cubic feet. Two types of valve were fitted to each bag, one the Parseval type of valve with the pressure cone as fitted in No. 1, the other automatic but also controlled by hand. To distribute the pressure evenly throughout the upper longitudinal frames, and also to prevent the gasbags bulging between the girders, nets were fitted throughout the whole structure of the hull.