ENGINEERING PROGRESS IN THE U. S. NAVY. 



79 



It is rather curious that the auxiliary steam consumption of the Delaware and 

 the scout cruisers at full power are about alike, although the Delaware requires fifty 

 per cent more indicated horse-power under this condition. I fully believe that the 

 only way to arrive at a true comparison between the Delaware and the Parsons 

 turbine-driven ships is to send them out together for runs at cruising speeds, on 

 conditions similar to scout tests, or preferably burning oil fuel only. 



As regards Curve D, this is hypothetical. 



The total coal consumption figures actually recorded on the builders' accept- 

 ance trials are of interest. 



COAI, CONSUMPTION TRIALS. 



I have plotted a curve (see Plate 45) of speed and total coal consumption in 

 pounds per hour for the Delaware and Utah. At 2 1 .0 knots speed for the Delaware 

 and the corresponding speed of 20.82 knots for the Utah, the Delaware burned 1.14 

 times as much fuel as the Utah, but at 12 knots speed for the Delaware, corre- 

 sponding to 12.17 knots speed for the Utah, the latter burned 1.12 times as much 

 fuel as the former. 



Dealing with the question of breakdowns, I have been under the impression 

 that reciprocating-engine ships do go regularly to navy yards for repairs. News- 

 papers have reported within the last year that the Idaho, Mississippi, Nebraska, 

 and Connecticut have required the services of a navy yard to make repairs to the 

 propelling machinery. 



As regards breakdowns of the machinery in turbine-driven ships, only two of 

 these causes are applicable to the turbines of Parsons reaction type. 



Blade Stripping. — Practically all troubles of this nature have occurred in cruis- 

 ing turbines, and my opinion is that they are largely due to making the blade tip 

 clearances too fine. We have aimed for getting maximum economy, when it is 



