A Stadium with an Air Supported Roof. (Compressed Air Magazine, Vol. 50, No. 7.)--Serious consideration is being given to the construction in Baltimore, Md., of a covered all-purpose stadium with a roof of sheet aluminum supported entirely by air pressure. The project calls for a structure large enough to seat Ioo,ooo persons and suitable for year-round use. It is proposed to designate it as a state and city war memorial and to appoint for its administration a nonpartisan commission representing the religious, educational, business, political, sports, and cultural interests of Maryland. A General Stadium Committee of 78 leading citizens, divided into eight subcommittees for investigation of the various phases of the scheme, made a final favorable report on the project to Mayor Theodore R. McKeldin on May I. This report will be supplemented later by additional engineering data and recommendations regarding the site.
Present plans are for a structure that will inclose an area 900 feet in diameter and cover thirteen acres. The continuous exterior wall will be of concrete and will rise well above the highest of the seating stands. On top of this wall will be a compression ring for the attachment of the aluminum roof, with provisions for an airtight seal. Internal air pressure will flex the roof upward to form a dome, with its center I7O feet above the playing-field level. This will give sufficient clearance for baseball, football, and all other forms of sport. There will be 93,000 fixed seats arranged in the conventional banks and in the shape of an oval, plus 7,000 portable seats that can be moved about as desired, depending upon the spectacle that is being staged. When not in use they will be stored under the permanent stands. Underneath the concrete seating structure will be ample space for the necessary operating machinery, offices,locker rooms, assembly rooms, a gymnasium, stables, kitchens and dining rooms, firstaid stations, toilets, etc.
Because steel sheets are vulnerable to attack by corrosion, it is proposed to use aluminum, which has the added advantage of being lighter. It has been computed that a pressure of only 9 pounds per square foot (approximately I ounce per square inch) would in that case suffice to support the huge roof' of the stadium, as compared with 20 pounds for the same expanse if made up of steel sheets. That pressure is so low that it would have no physiological effect upon persons in the enclosure; in fact, they would not be aware of it. It could be induced by ordinary fans of the ventilator type.
R. H. O.