ELECTRIC PROPULSION OF A BATTLESHIP. 



17 



In the torsion meter records for the 24-hour run at 10.01 knots, the figure for horse- 

 power was 2,015. If the Cyclops had to develop 300 more horse-power to get the same 

 speed, this would bring the coal consumption of the Jupiter up to 63.2 tons in place of the 

 50.5 tons stated if the efficiency of the Jupiter's propellers had been reduced to the same level 

 as the Cyclops' propellers. (This point was brought up last year by Mr. E. A. Stevens, Jr.) 

 This is a most important point if true. To accept this statement without reservation would 

 favor the reciprocating engine. Furthermore, the speed and power curves of the Jupiter 

 and Cyclops show that the Jupiter consumes more power for the same speed than the Cyclops. 

 If the statement of Lieutenant Robinson is based upon experiments upon a model of the 

 propeller, then the unreliability of the torsion meter will be further demonstrated. The 

 question of the torsion meter will be taken up later. 



The turbine of the Jupiter consumed 11.68 pounds of steam per shaft horse-power. The 

 auxiliaries consumed about 3.12 pounds additional. Some of this is not properly charge- 

 able to the propelling machinery. The Jupiter has 193 pounds at the boilers and 185 in 

 the engine-room, with 168 at the turbine. This is the best condition, namely, at full speed. 

 The California makes a guarantee of 11.1 pounds of steam for the turbines and engine-room 

 auxiliaries with dry steam at 250 pounds gauge pressure. 



In regard to this steam consumption, the following report upon reciprocating engines 

 built by the firm of Sulzer Bros., Switzerland, is interesting. It shows that reciprocating 

 engines have been built in the past which will compare very favorably with this proposed type 

 of plant. The figures are as follows for these tests : — 



From the foregoing there seems to be a reasonable doubt as to the ability to make any 

 important advance through the turbo-electric combination. An advance in efficiency seems to 

 be contemplated in the California over the Jupiter. A part of this gain must come from 

 improvements in the turbine. Some of this efficiency is due to improvements in the boilers, 

 which improvements would aid a reciprocating engine as well as a turbine. The Jupiter had 

 190 pounds of steam at the boiler and 168 at the turbine. The California is to have 250 

 pounds. This is probably at the boiler. Allowing for a vacuum of 1 pound in both cases 

 and for saturated steam in both cases we can get the maximum possible efficiency from 



Y T' 



T is the absolute temperature or the glass reading plus 460. From 



the formula 



T 



our steam tables we can get the temperatures: — 



T (at 1 lb. pressure absolute) is 102° F. plus 460 equals 562. 

 T (at 190 plus 15 absolute) is 384° F. plus 460 equals 844. 

 T (at 250 plus 15 absolute) is 406° F. plus 460 equals 866. 



