SEADROMES

Evening Star, Issue 21931, 18 January 1935, Page 11

SEADROMES

USE IN TRANSATLANTIC AIR SERVICE Fifteen .years ago Edward Armstrong, a well-known American inventor, conceived the idea of a marine structure that would have certain unique properties (writes Nigel Tangye in the ‘ Manchester Guardian ’). This structure he termed a seadrome. The inventor saw in a floating vessel that remained steady without any tendency to roll or pitch, whatever the state of the sea, a number of important uses. In this article I am going to deal solely with the possibilities of such a structure with regard to floating airEorts, and in particular those that ave been designed by the inventor for use on the North Atlantic? airway. For some years we have heard of the idea of floating islands across the Atlantic on which aircraft could land to fuel, and thus overcome the otherwise insuperable difficulty of bridging the Atlantic and at the same time carrying an economic payload. Many pilots have proved that the Atlantic can be crossed, but to do this they have had to carry such a huge load of petrol that there was no room for anything else. Indeed, it is generally considered that > range of 500 miles is about the limit for an air liner running a commercial service.

The idea of a string of floating airports at intervals of 450 miles across the Atlantic would therefore solve this difficulty, provided that these airports Were possible from an aeronautical, marine, and economic viewpoint. I personally _ always regarded this idea as fantastic until I was given the opportunity of studying the claims of the seadrome in detail. The result of the preliminary investigations of the past few weeks that I have carried out with the assistance of the official representative of the Seadrome Ocean Dock Corporation of America leaves no doubt in my mind that a 24-hour London-New York service is capable of immediate operation from every point of view. PLAN OF THE SEADROME. The suggested scheme is to moor five seadromes at 450-mile intervals along the thirty-eighth parallel of latitude. These seadromes consist of a flight deck 1,500 feet in length and 300 feet in width, supported on thirty-two streamline telescopic pillars, 103 feet above sea level. When in position these pillars are sunk to a depth of 208 feet below the surface, and ballast and buoyancy tanks are so arranged in them that the centres of buoyancy and gravity of the whole seadrome structure are well below the agitated surface of the sea. The seadrome is therefore at all times floating in suspension in still water. The supporting pillars are of such size, construction, and shape that they offer practically no resistance to waves, and so do not bar their passage. No energy is therefore released from the waves to be absorbed by the pillars as impact force. The prospect of the seadrome being damaged by a storm, as so often happens to Atlantic liners, need not therefore be considered. The liner is floating in , the agitated water, is constantly breaking waves, and thus absorbing their energy. The seadrome is floating in suspension beneath this agitated surface, and the .waves pass

through the pillars undisturbed, as they do through those of a seaside pier. OFFICIAL EXPERIMENTS. I have seen films depicting the official experiments with models of the seadrome in one of the United States Navy Dockyard basins. The claims of the inventor with regard to the unique stability of the seadrome in stormy weather were here justified in every way. I saw one model about 15ft long alongside one of the Majestic to the same scale. The manufactured waves were of such a size that the Majestic was shipping them over her funnels. It would have been impossible for her_ to have survived such a storm in real life. Throughout the demonstration, however, no .movement could be detected in the seadrome. I saw another model which was over 30ft high being subjected to waves coming from all angles off the walls of the basin. Alongside was a gentleman in a rowing boat having an, acutely uncomfortable time, but the seadrome remained quite steady. These experiments led the United States Navy Department to satisfy themselves entirely with regard to the stability of the seadrome in the roughest Atlantic storms. And this stability makes in itself the problem of anchoring the structure much easier. The chief difficulty with regard to the anchoring of ships in storm conditions lies in their movements produced by wind and waves. This problem does not arise in the case of a seadrome, as it remains perfectly steady._ There were other problems involved in mooring a 60,000-ton structure in three to four files’ depth of water, but all of them have been overcome.

Only the briefest of descriptions can be made, in this article, but let me add weight to them by saying that the United States Navy Department has given, its unqualified approval to tho practicability of tho whole system. The anchor is of a novel type designed for the great depth that it will lie and for the nature of the bottom that it will encounter. It has a rounded top and a flat Jjottom, and weighs 1,600 tons. Special buoyancy chambers enable it to be floated to tho desired position, where seacocks are opened electrically, and the anchor sinks to the bottom. Its speed is checked by means of water brakes, and the landing shock should not exceed 15 per cent, of the anchor’s weight. The cable to be used is of the type used on suspension bridges. This is because the stoutest chain cable ever made would break from its own weight at, a depth of 13,000 ft. The suspension type cables have ample strength for them to reach a theoretical depth of 60,000 ft before breaking. This cable is to be attached to a seadrome structure buoy, which in turn is attached to the seadrome itself. There is, therefore, never a direct pull on the anchor.

In the worst conditions of wind and tide ever known on the route to be used the maximum pull by the seadrome will be 100,0001 b. The mooring system is designed to withstand a pull of six times this, and in addition the seadrome has motors that can relieve the strain, if necessary. On each seadrome will ho accommodation for a crew of 43 and an hotel for 500 passengers ly day and 100 by

night. Full meteorological, wireless, and workshop equipment will also be on each.

The whole system will cost approximately six millions sterling to lay down. By charging a toll of only £l4 per passenger, 7d per pound for parcels, and 2}d per letter, and presuming only 5 per cent, of existing first-class traffic is diverted to the airway in the first ten years of operation, the initial loan would be repaid, and all costs of maintenance, including insurance and depreciation, would be covered in that period. The United States Department of Public Works, after examining the economics of the’ project in great detail, and after receiving the technical report from the Navy Department, have recommended that an initial appropriation of £1,700,000 be made. This will in all prabability be done at the next session of Congress next January. A seadrome will then be built and placed in service on the New York-Bermuda route. It is vitally important that Great Britain should study the question of the seadrome with the greatest care. At present she is perched on a position of no importance on the fringe of a vast network of air lines serving hundreds of millions of people. If she should gain the monopoly of transatlantic traffic she instantly becomes a centre of the world’s air commerce.