AIRSHIP AKRON

Rotorua Morning Post, Volume 2, Issue 253, 17 June 1932, Page 2

AIRSHIP AKRON

INTERESTING FACTS TYPE of CONSTRUCTION AND ADVANTAGES IT GIVES. UNlTED STATES NAVY ZEPPELIN Describing the giant Zeppelin Akron, recently completed by the Goodyear Zeppelin Corpoi\ation for the Uni'ted States Navy, Mr. H. D. Shilts, secretary of the Goodyear Corporation, made available to a "Morning Post" representative some very interesting facts regarding the construction of this huge airship. The modern design of the Zeppelin differs from the types in use during fhe war period, in that instead of being shaped like a lead pencil, it now shows a more curved profile, making the ship appear slightly shorter and thicker. Construction of Hull. The hull of the Akron is built on the triple-layer principle, having a' rigid metal framework to withstand the major stresses, has gas cells within to retain the lifting gas, and a taut fabric outer cover. The framework is composed mainly of transverse rings connected by longitudinal girders, which are made of a metal giving the required strength with the minimum of weight. Most of the rings are thirty-six sided polygons, with the longitudinal girders connected at the corners. The number of sides on the rings is reduced to 24 near the tail of the ship. A network of diagonal wires forms the bracing for the outside panels. The ring girders are of two types, main and intermediate, the former being constructed in the form of a triangle, a new feature in airship construction, which adds greatly to the strength. The main rings are spaced about 74 feet apart and the gas cells are placed between themThese are twelve in number in the Akron. Intermediate ring girders ' are of a single type and are spaced between the main girders, usually three to a compartment. The longitudinal girders connect the ring girders, forming the fore and aft ridges, which are discernible on the outside of the completed airship. Throughout most of the length of the Zeppelin extend three corridors or gangways, which are triangular in shape. One travels along the top centre line of the craft, while the other two are placed symmetrically in the lower part, about 45 degrees from the vertical. Over-pressure Gas Valves. As lifting gas expands and contracts with changes in temperatura and barometric pressure, valves are provided for the immediate release of any surplus expansion. These are located in the top gangway and as many as four are provided in the largest cells. They open automatieally to control the lift of the craft or they may be opened mechanically from the control cabin if necessary. The control surfaces by which the airship is steered are located in pairs near the stern of the craft. Fixed sections give the required stability, while hinged after-portions or rudders give altitude and direction control. The cabin from which the controls are operated is well forward and contains all the latest devices for navigation. The radio cabin and eommanding officers' quarters are directly over this central room, in the hull of the craft, and a number of rooms for the other officers and crew are located near the middle of the airship along each side gangway. Each sleeping room has four comfortable berths. Messrooms and a large galley are also provided. Power Plant. The use of non-inflammable helium gas as the lifting force allows of the housing of the motors inside the airship's hull instead of their being suspended in cars outside, as is the case when hydrogen is used. There are four engines on each side of the Zeppelin, and rigid drive shafts supported by outriggers deliver the power to the propellers outside the hull. A new innovation is that each propeller can be tilted on its axis through an angle of 90 degrees by means of a special bevel gear, making it possible to nse them in a vertical position for lifting or lowering the airship, instead of only for forward movement. The motors themselves are also reversible, so that the craft may be propelled either backwards or forwards. Definite loss of weight is experienced when liquid fuel is used in an airship and to avoid the necessity of valving off lifting gas to compensate for this, a system of condensers has been installed. These reeover the water given off from the exhaust gases of the motors and thus maintain the original weight. Provision is made for storage of five aeroplanes within the hull of the Zeppelin. This compartment is 75 feet long by fiO feet wide and the aeroplanes can be lowered or raised to and from it during flight by means of a trapeze operating through a Tshaped opening. The aeroplanes become detached from the trapeze with their engines running to commence a flight' and on their return can hook up again while the airship is flying at practically any speed. Safety of Airship. Among the safety factors in the Akron are the triple-layer hull, th'e ship's great structural strength, retention of gas in twelve separate cells, eight propulsion units, minimising of fire risk by use of non-inflammable helium gas, accessibility to all parts of the craft while in flight to enable repairs to be made, and the action of the hull framework as a Faraday cage to protect the airship from damage by lightning. The structural design of this naval airship permits it to be easily adapted for commercial worlc, in which case accommodation would be aVailahle for 100 passengers. It has a deck area of 12,000 squarei feet, with stater'ooms of 70 square feet and 900 feet of corridors five feet in width are also provided. Ample promenades, lonnges, dinihg rooms and smoking rooms could be installed.