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Trial of Turbinia

steam, speed, turbine, blades, knots, shaft, row, power, tons and engines

TRIAL OF TURBINIA.

Time on the mile, first trial, 109t sec.; second trial. 110 sec.

Corresponding speed in knots, first trial, 32.79; second trial, 32.73.

Mean speed in knots, 32.76.

Revolutions per minute, of high pressure and intermediate shaft, 2,230.

Revolutions per minute of low-pressure shaft, 2,000.

Steam pressure in boiler by gauge, 210 pounds per square inch.

Steam pressure on admission to high-pressure turbine, 157 pounds per square inch.

Greatest pressure in stokehold by water gauge, 71 inch.

The speed reached during this trial, 32.76 knots, in the mean was the highest recorded for any vessel. It is greatly in excess of the speed hitherto reached for a boat so small as the Turbinia. It is clear that the exceptional speed developed in the Turbinia has been achieved without sacrifice to economy, and that the substitution of turbines driving high-speed screws in place of reciprocating engines driving screws of much more moderate speed is not attended with increased consumption of steam so far as fast running is concerned?' The Viper Destroyer.— The success of the Turbinia led to the construction in 1899 of a naval atorpedo-boat destroyer," Viper, and this craft, only 210 feet in length, of 375 tons dis placement, developing 11,000 horse power, on 15,000 square feet of heating and 376 feet of grate surface, in water-tube boilers, with steam at 175 pounds by gauge; at 1,050 revolutions of the turbines, made over 37 knots, above 43 miles an hour. The contract speed was 35 knots. The turbines were two high and two low pressure, each driving a separate shaft car rying two propellers. The turbines were 35 and 50 inches in diameter. No vibration was produced by the engines, and the engine-room was so quiet that it was hardly possible to realize the presence of engines developing over 10,000 horse power. Here, as in all craft of the sort, the extraordinary performance in power production, once all is understood, is that of the boilers; that of a horse power for each one and one-half square feet of heating surface, and from each square foot of grate about 30 net horse power. This is probably the most extraor dinary phenomenon in this or any other ex ample of marine engineering. For warships of the destroyer class the absolute maximum of possible speed is the first thing to be desired, and the expenditure necessary to secure the extra speed is a matter of comparatively small importance.

The Turbine Passenger-Steamship.— In 1901 the turbine for passenger steamships was first adopted on the King Edward VII, a pas senger steamer of a type in common use on the Clyde, built . by William Denny Brothers of Dumbarton, Scotland. The builders, the Par sons Turbine Company and a captain of long experience in the Clyde passenger trade and the steamers by which it is carried, were all equally interested in the venture. To insure that accu rate data on which the performance of the tur bine might be obtained, the King Edward was modeled as nearly as possible of the same size and same general design as the paddle steamer Duchess of Hamilton, one of the crack steamers running on the route for which the King Edward was designed. The latter is, however, of slighter greater draft and more displacement. The weight of the motors, con

densers, steam pipes, auxiliaries connected with the propelling machinery, shafting, propellers, etc., is 66 tons; which works out at about half the weight per indicated horse power of the engines required for paddle steamers of the same type. Another advantage secured to the boat by the adoption of the turbine engines is increased deck space for passengers.

Steam is raised in a double-ended Scotch boiler of the ordinary type, 20 feet long by 16 feet 6 inches in diameter. There are four fur naces at each end, made to work under forced draft with closed stokehold. For purposes of comparison, the capacity of the boiler under these conditions might be set down roughly at about 3,000 indicated horse power. It is, how ever, in the steam-turbine — the first engine to realize the dream of a perfect steam-driven ro tary engine — that the chief interest in the craft is centred. The principle of the turbine is fortunately simple enough to make it easy of explanation. Inside the cylinder to which the steam from the boiler is led is a drum or hollow shaft studded with row upon row of blades or vanes, all set at an angle to the flow of the steam as the sails of a windmill are set to the breeze. It is apparent that the rush of steam deflected from its course by the first row of blades would not reach the next in such a directtion as would allow it to do its work effectively. To meet this difficulty there are, between each row of the working blades, a row of guide-blades fixed to the inside of the cylinder casing and set at the reverse angle. These blades are stationary and their sole pur pose is to again alter the direction of the flow of the steam and bring it back to the straight course from end to end of the cylinder before it meets the next succeeding row of working blades. The tops of the revolving blades reach nearly to the outer casing of the cylinder and the stationary blades project inward until they almost scrape the revolving shaft or drum. A series of turbine wheels on one shaft are thus constituted, each one complete in itself, like a parallel-flow water-turbine; but, unlike a water-turbine, the steam, after performing its work in each turbine, passes on to the next, preserving its longitudinal velocity without shock, gradually falling in pressure on passing through each row of blades, and gradually ex panding. There is no rubbing friction and no wearing parts except the bearings on which the main shaft or drum revolves.

Following are the net results of the compara tive trials: Duchess of Hamilton King Edward Coal, 1,758 tons, 13 cwt. 1,429 tons, 16 cwt.

Mileage, 15,604 12,116 Miles per ton, 8.87 8.47 Number of days run, 111 79 Daily average consumption 15 tons. 17 cwt. 18 tons, 2 cwt.

Average speed, 164 knots. 184 knots.

The success of the King Edward was so pronounced that arrangements were at once made to construct other vessels of the same type, to be engined also with the steam-turbine. Larger and yet larger ocean-going vessels are being built and equipped with turbine engines, which have demonstrated their many advan tages. See also STEAM VESSELS; STEAM-EN GINES