AIRSHIP SHEDS. Airship sheds or hangars are used to accommodate airships during construction, repair or docking. The increase in the cubic capacity of airships has necessitated a corre sponding increase in their housing accommodation until the mod ern hangar ranks amongst the biggest buildings of the world.
When the dirigible was in its infancy such funds as its protago nists commanded were needed for the construction of the ship it self and little could be ear-marked for its shelter ; but as the air ship emerged from the early experimental stages it became evident that accommodation was an important factor in development.
The first airship shed, built in a Paris suburb in i 903 at the time of Santos Dumont, had sides and a roof of canvas and was 165 feet long, 31 feet wide and 442 feet high. Modern airship docks, however, such as the Goodyear-Zeppelin hangar at Akron, Ohio, are marvels of construction engineering and can shelter two of the largest dirigibles at one time.
More than $2,000,00o was expended in construction in 1929 of the Akron base in which the ill-fated U.S. Navy zeppelins, "Akron" and "Macon," were built. The dock is 1,175 feet long, 325 feet wide, 2II feet high and has an interior space of 364,000 square feet. It is the largest building in the world without interior bracings, and its semi-paraboloid shell is so huge that its steel framework expands and contracts with changes in temperature. This "breathing" of the giant structure is of extremely minute pro portions and is counter-balanced by rollers on which the arches of the building are placed. The convex doors of the dock weigh 600 tons each, and roll open on tracks by electrical power.
Each door swings on a hinge pin, six feet long and 17 inches in diameter, located at the top of each end of the building. The pins do not sustain the weight of the doors. They rest on wheel trucks at the base. The hinges must be strong enough to keep the door from being pushed outward by a strong wind and must resist any sideways pressure on the door by wind or snow.
The semi-paraboloid shape of the Akron structure was decided upon following experiments whereby minimum interference from wind was established, cross-winds and giant drafts at open doors being important considerations in the movement of an airship to and from its shelter. Steel rails run the length of the dock, these tracks being used for the "side handling cars" which keep an air ship from swinging with the wind or surging upward as it is being made fast or released.
Aside from its great floor area and cubical capacity—the cubical content amounts to 45,o0o,00o feetTthe Akron dock has a helium storage plant, built underground and alongside the building with a total capacity of more than i,000,000 cubic feet of gas. Tunnels have been built under the concrete floors of the shed for other service facilities.
Previously the largest zeppelin hangars were those at Lake hurst, New Jersey, and Belleville, Illinois, respectively American Navy and Army lighter-than-air bases; the hangars at Friedrichs hafen, home of the Graf Zeppelin, and Potsdam; the French hangars at Orly and Toulon ; the Japanese hangar at Tokyo, and the British sheds at Cardington, Howden and Pulham in England, and at Karachi, India. Hangar space at Friedrichshafen was en larged in 1931, and a second U.S. Navy dirigible base was con structed in 1932 at Sunnyvale, California. Big ship activity at all these bases, however, excepting Friedrichshafen, suffered a practically complete cessation, at least temporarily, following the disaster to the British "R-Ioi" and the subsequent scrapping of the "R-Ioo" in England and the wrecking of the U.S. Navy's "Akron" and "Macon." (See AIRSHIPS.) (H. P. K.)