NOTABLE developments in 1928 that have greatly increased interest in lighter-than-air craft were the transatlantic flight of the Graf Zeppelin as an experiment in commercial transoceanic air-service, the ordering by the United States Navy Department of the construction in this Country of two rigid airships larger than any yet built or under construction, the development and construction of two British airships for long-distance passenger and mail transportation, the starting of erection of the world's largest airship factory and dock at Akron, Ohio, and the construction and operation in this Country of a number of non-rigid airships to be used for commercial purposes.
Each of these developments is dealt with in order. General dimensions, major characteristics, and unique features of the Graf Zeppelin, the new Navy airships, and the projected large transoceanic commercial airships are given. Alternative lifting-gas and fuel-gas cell arrangements are shown, means of water recovery from the combustion of liquid fuel to compensate for weight loss as the fuel is consumed are discussed, and the advantages of helium as a lifting gas are pointed out. Use of this non-inflammable gas makes possible the placing of engines and passenger quarters inside the hull. Another unique feature of the projected American airships is the use of swiveling propellers that can be swung through an arc of 90 deg. and used to elevate or depress the ship. Main transverse rings of the hull are described as being of built-up triangular section with longitudinal corridors that give the crew ready access to all parts of the hull for inspection.
The dock in which the new ships will be built is of special design, and actual distribution of wind pressures has been taken into account.
Brief descriptions are given of the British 5,000,000-cu. ft. hydrogen airships to be completed this summer, and of the two non-rigid passenger-airships, the Pilgrim and the Puritan, which have demonstrated the advantages of their type for both commercial and military purposes.
Conceding the importance of the airplane for high-speed mail and passenger transportation over medium distances, the author emphasizes the utility of lighter-than-air craft for long range, large-capacity mail, passenger and freight air-service.