The Parsons Marine Turbine To the Editor of the SCIENTIFIC AMEBICAN: In your article in the current issue (February 15, 1908) on Turbines in the United States Navy, there is at least one statement that is contrary to fact, and several others which are misleading to anyone who has had no experience with steam turbines. The article seems to me to be unjustly derogatory to the Parsons turbine, and to give more credit than is due to the Curtis, a practically untried turbine for marine work. While wishing to see the American type prove superior to the English, still I feel that it unjust not' to give the Parsons turbine'credit for. the revolutionizing of marine engineering which it has brought about. Until data are given out as to the Creole's"' fuel and water consption, and until the scout cruiser Salem is given a trial, undue praise of the Curtis turbine should be withheld. Your statement that the length and dWplacement of the five 800-ton destroyers had to be increAsed to provide for Parsons turbine installation is contrary to fact. The writer personally worked on the designs which were accepted for two of the boats. Parsons turbine machinery, including the necessary cruising turbines, was fitted into the Department's hull, anel not only was it possible to shorten the engine-room ssce taken by the reciprocating engines, but leM space was taken up vertically, the center of gravity of the machinery was lowered, and the total weight of machinery was less. Hence your statement that the action of - the authorities in accepting Parsons turbine installation for these destroyers seems illogical in view of their refusal to accept Parsons turbines for battleships, is rather misleading. In the first place, as has been shown, Parsons turbines for this design 'were vastly superior to reciprocating engines. In the second- place, it does not follow that since the design of the South Dakota and Delaware was unsuited to Parsons turbines (about which more will be stated later), every battleship design will be. There was no trouble in fitting this turbine to the Dreadnought design. Also, no c'omparison between a battleship and a destroyer is possible or logical, since the conditions are radically different. While the initial cost of turbine machinery when cruising turbines art necessitated by low-speed requirements may be greater, still ' the saving in coal and water practically eliminates the initial cost consideration. We might as consistently argue that condensers are a disadvantage, since the installation would cost less were they omitted. Cruising turbines seem a positive necessity, and the makers of the Curtis turbine have yet to demonstrate that they can run at low speeds economically, i. e., that they themselves do not need cruising turbines. The economic speed of any turbine bears a certain ratio to the steam velocity. If the speed drops below this, the economy falls away. The economy of the cruising turbine really consists in providing for a more effective utilization of the low-pressure steam as expanded into the ordinary ahead turbines. Cruising turbines do not necessarily make an installation unwieldy and complicated, although there is a slight complication of connection and arrangement. To anyone who has seen a turbine engine-room when the machinery was in operation, with the freedom from noise, escaping steam, waste oil, flying cranks, piston rods, levers, etc., unwieldiness and complication seem terms applicable only to a reciprocating engine. Also, as stated above, a five-turbine, three-shaft Parsons turbine installation for high speeds occupies less space and weighs less than a, reciprocating engine installation of the same power. The extra shaft, if anything, is an advantage, since if one shaft were disabled, the vessel would stHl be able to make good speed with the other two shafts. It appears that outside of the face of the bids, one reason for not accepting Parsons turbine installation for the South Dakota and the Delaware was that the design would not accommodate the number of shafts necessary. It is to be hoped that it will not be found necessary to remodel the South Dakota when it becomes necessary to add cruising turbines on separate shafts to the Curtis installation, in order, to bring the coal consumption at slow speeds down to something reasonable. Having also seen something of the working of the Bureau system, it seems absurd that the action of the Japanese government in ordering two sets of Curtis turbines could have influenced the awards of the South Dakota and Delaware contracts. If it were the department's custom to accept advice from anyone, or to be influenced by the action of foreign govern.- ments, it would seem to be the consistent thing for them to ' follow the action of the English and the French governments, and adopt Parsons turbines. You rightly attribute the breaking of the transatlantic record !Jy the Lusitania to the use of Parsons turbines, and- rightly state that considerations of weight, and space occupied, are not of prime importance in a -merchant vessel.. But it has been shown that Parsons turbines require less space, and weigh lesl', than reciprocating engines of the same power. This is true of the Mauretania and the Lusitania. To bring the matter nearer home, each of the two Curtis turbines of the Salem weighs almost as mucl as all six of the Parsons turbines of the Chester. Furthermore, it has been shown that the problem of desigBing reciprocating engines for the Lusitania and her sister ship would have- been stupendous, if not' imposSible. Finally, Parsons turbines are now installed in torpedo boats, private yachts, merchant vessels, cruisers, and battleships, and have proved superior to reciprocating engines in many particulars. A few of these may be O interest. Fewer working parts; direct application of steam to the shaft; less danger of breakdown, since it is almost impossible for the small vanes to become damaged; less weight of machinery for same power; machinery: well down in vessel, hence a lower center of gravity; greater speed for the same consumption of coal at high speeds; practically no machinery v"V1:bration. To date, the Curtis turbine has been installed in but one small merchant vessel, the Creole,' ' ana. data as to the performance of the machinery of this vessel would be, if such data are obtainable, very gratefully: reeeivedl, ."lo, there will be an opportunity soon to publish comparative results of the performances of the Chester, Birmingham, and Salem. The Chester, equipped with Parsons turbines, has just . made, 26.52 knots on her official four-hour run, and has bettered her required coal consumption by 53 per cent. The writer tiad the privilege of being on board during the builders' trial, and too much praise can not be given to the Parsons turbine. The Curtis turbine has yet to prove its value for marine purposes. Bath, Me., February 20, 1908. V. H. PAQUET, S.B.
This article was originally published with the title "Correspondence" in SA Supplements 65, 1681supp, 203 (March 1908)