Post WW2 RN comments on machinery efficiencies
I have, at last, managed to obtain a copy of “Papers on Engineering Matters”, Number 22, dated December 1946 (from Evil-Bay).
These are relatively rare and are the forerunners of “Journal of Naval Engineering”.
The first article is “Marine Engineering from the Naval Aspect” and is an article based on a lecture given by Engineer-in-Chief of the Fleet at an inter-departmental discussion at the Admiralty on 18th June 1946. The journal was distributed at the “Restricted” level and there is a note to the effect “that several points of special interest have had to be omitted from this reproduction”.
He notes that the lecture is full of generalised information and that individual installations varied.
He covers, briefly, the history of machinery evolution and gives opinions on possible future directions.
Steam Power Plants
He goes on to be equally damning of British inter-war efforts at developing high pressure steam plants and praising of US successes. He notes that fuel consumption gains could be simplistically stated as “about 5% per 100 degrees F at 700-degrees F, falling to about 3% at 900-degrees F.” Steam pressure fuel efficiencies were harder to generalise as there are ideal pressures for different applications, but roughly “the gain is just over 1% per 100 lb. pressure rise in the zone 400 – 600 ib/sq. in.” He stated that “The direct saving in fuel due to the use of the higher steam conditions in American ships as compared with ours is therefore about 8 per cent.”
He criticised the German installation in the Narvik class destroyers with extreme congestion, increased complication with excessive engine-room personnel couple with doubtful reliability and worse fuel consumption than British destroyers.
He included a graph showing the Machinery weight curves for various classes of ship over time. The measures were “Machinery Weights in LBS/S.H.P.” versus years from 1900 to 1945. Roughly the figures are (taken at some arbitrary dates) ;
Battleships
1905 - 190 1920 - 110 1930 - 70 1940 - 55 1945 - 52
Cruisers
1905 - 115 1920 - 55 1930 - 43 1940 - 39 1945 - 38
Destroyers
1905 - 83 1920 - 33 1930 - 30 1940 - 29 1945 - 29
Boilers
He compared British natural circulation boilers favourably against German forced circulation ones. He did, however, like the USN system of controlled superheat which were being introduced in the Weapons Class. He noted various innovations in the French and US navies and said they were being watched with interest. He thought British automatic control of Feed Water was highly advanced and future automation likely.
Propulsion Turbines
Again, he reviewed the progress since WW1.
He provided another graph, this time for Steam Rate Curves for various classes plotting Steam Rate (LBS/S.H.P./HR) versus percentage full power (against a nominal 30 knot maximum speed).
For example in comparing the War Emergency class destroyers with US Destroyers fitted with cruising turbines ;
War Emergency
20% - 9.3 50% - 8.9 80% - 8.6 100% - 8.5
USN
20% - 7 50% - 6.5 80% - 6.5 100% - 6.6
(Both Vanguard and KGVs were slightly more efficient that the War Emergencies)
Staff Requirements
This included a small piece about comparing the KGVs with Washington. He noted that the KGVs were designed for maximum efficiency at full speed, but that Washington was designed for a maximum at 20 knots. He noted that not only was the Washington much more efficient at 20 knots, but it was still more efficient at maximum speed. He split the efficiency as follows “not more than a quarter of this gain was due to higher steam conditions, a third was due to the use of the economisers and controlled superheat and the remainder was sue to the turbines being designed for this [cruising] speed”
Auxiliary Machinery
Again, a brief history. He stated his belief that British Auxiliaries were generally ahead of German and USN ones and he hoped to stay ahead.
Reduction Gearing
A brief history. Not much comment other than to summarise the many lines of research being undertaken.
And a final graph. This time a “Full Power Efficiency Diagram”, plotting Efficiency % (Fuel to Shaft) against programme year. This is the most interesting graph as it gives a good overall summary so all relevant figures will be given ;
Years - Efficiency % - Steam conditions - Comment
1900-1905 - 13.2% - 220/260 psig, 400F - Coal reciprocating 1905-1908 - 11.0% - 220/260 psig, 400F - Direct Drive Turbines 1908-1910 - 10.0% - 220/260 psig, 400F - Oil Fired 1910-1924 - 12.8% - 220/260 psig, 400F - Geared Turbines 1924-1926 - 14.7% - 290 psig, 620F - Superheat 1926-1937 - 18.3% - 300 psig, 650F - Change of Steam conditions 1937-1943 - 17.8% - 300 psig, 650F - Two boilers, High Forcing Rate, Space Reduction 1943-1944 - 21.2% - 400 psig, 700F - Controlled Superheat Economisers 1944-1950 - 25.0% - 650 psig, 825F - Alloy Steel Rotors, Double Reduction Gearing
(It’s a shame there aren’t equivalent figures worked out on the same basis for US ships).
The article finishes with comments on the Internal Combustion Field – almost exclusively diesel (it praises RN submarine diesels, but admires large German engines and the large range of smaller US engines). It continues with Gas Turbine, HTP and a piece on Aircraft Carrier auxiliaries.
The conclusion again reiterates the lack of research and development between the war and lists on-going research.
=====================================
|