Ist Julp.
"ENGINEERING" of the 6th of} May last devotes a considerable amount of its space to the progress that is being male. in the eubetitution of Parsons' Turbines for reciprocating engines for the propulsion of steam vessels, In the ordinary, or reciprocating, engine, with which we are all familiar, the shaft on which the yaddlewheels or screw propeller are fixed is actuated by a piston which is continually driven to and fro in its cylinder by the pressure of the steam, and there must be a loss of power in this constant reciprocation. Some years ago, the Hon, Charles Parsons adapted the turbine, in which the shaft is continuously driven in the same direction by the direct pressure of the steam, to the driving of dynanio machines; and seven years ago he adapted his turbine to marine purposes ina small craft which he called the Turbinia, and which made a great sensation at the Diamond Jubilee Naval Review. He then built a destroyer, the Cobra, which was bought by the Government and mysteriously wrecked on her way round from the north of England to Portsmouth. The frab practical application of the turbine engine in a commercial ship was in the King Edward in 1901. The success of this ship—it must be understood that we are quoting largely from " Engineering "—resulted in a second vessel being ordered; and credit for enterprise in this direction is due not only to the Hon. Charles Parsons, but to Messrs. Denny's firm, and to Captain John Williamson, who has for so many years been closely identified with the Clyde passenger traffic. The King Edward and the Queen have given good results, but there was some doubt still in the minds of naval architects as to whether the turbine-driven propeller was sufficiently large in diameter or area to give efficiency in a heavy seaway. The Midland Railway Company, however, arranged to build four steamers for a new service between Heysham and Ireland; and on the advice their naval architects, Messrs. Biles, Gray & Ca, they decided to furnish two of them with turbines and two; with reciprocating-engines. The four vessels are otherwise exactly alike in size and design, and thus a unique opportunity is' being offered for thoroughly testing the comparative economy of the two systems.
The space occupied by the two types of propelling machinery is the same, but the turbine engine-rooms are not so crowded with machinery as the others, and the weights are lower in the ship. The propellers are smaller in the turbine vessels and project less beyond the line of the ship, rendering them less liable to damage. In the first turbine steamers there was great difficulty about going astern, but this is being got over. In the King Edward the go-astern power was comparatively small; in the Queen it amounted to one-half of the full go-ahead power of the engines; in the two Midland steamers, the Londonderry and Manxman, it will be about sixty per cent. The cost of manufacture can hardly be compared with that of reciprocating machinery, as the turbine production is in its infancy. All the years of effort which have been put into cheapening the cost of reciprocating engines have yet to come to the turbine. Yet even with this disadvantage the turbine is not appre-dably more costly than its rival, In the case of the Londonderry the extra cost is less than two per cent of the total cost of the vessel. There is every reason to believe that the cost of the upkeep of turbines will be very moderate, and they are cheaper to run, as they require two men less in the engine-room. The question of coal consumption is expected to be solved by the four Midland steamers when they are in regular work, The British Government are building a cruiser with turbine engines, and it has been stated that the Allan line are putting turbines into two 10,000-ton steamers that they are building for the Atlantic trade; but the greatest step forward that the new mode of propulsion has made is in its adoption for the two Atlantic flyers, costing about 24 millions sterling, that are being built, with the assistance of the Government, for the Cunard line.. These vessels are to maintain a speed of 25 knots at sea they are to have a length of 760 feet, and a beam of 88 feet, and their displacement, with no cargo on board, will be between 82,000 and 33,000 tons. To get the required speed, they will have to develop some 66,000 to 70,000 horse-power, and their coal consumption will exceed 1,000 tons a day. But what makes these monster ships most interesting is that they are' to be driven b Parsons' steam turbines. hero will be four shafts in each vessel, each with one powerful go-ahead turbine, side shafts, so as to enable the ehafy the high-pressure units being on the to be as near the shell of the ship possible, while the low pressure units will be on the inside shafts, These latter will extend much further aft than the wing shafts, and the propellers will take the place of the ordinary twin-screws, with the deadwood of the ship between them cut away. The lines of the ship afe will be specially fine, so that although the wing propellers are well forward from the stern, the blades will not preiest beyond the vertical line of the hull. The number of revolutions is to be 140 a minute, so that the propellers will be of sufficient size to ensure efficiency in a heavy Atlantic seaway, The inner shafts will also be fitted with go-astera turbines, It may be added that one of these great ships is to be built by Messrs, John Brown Ca, at their Clydebank works, and the other by Messrs, Swan & Hunter, on the Tyne. These vessels, it is hoped, will recover for the British flag the championship of the Atlantic as far as speed is concerned.
Text read from the printed page and cleaned; old type leaves the occasional error.