1930s: German navy switchs to diesel power?

davebender said:

When I was on U.S.S. America boilers were never completely cold when at sea. Only a couple minutes were required to bring an idle boiler into service. This sort of thing happened when an aircraft had a flap / slot problem that required a higher landing speed or more wind over the flight deck.

If the USN could find a solution I suspect other nations could also.

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There's a difference between 'cold' and 'not up to working pressure' with steam boilers dave.
I had a job on the MV Antonio de Satresqui, which was totally steam driven, winches you name it...fantastic relic to be on.
Cheers
John

Readie said:

Points taken SR but, the A4 was the last word in steam locomotive power and although steam lasted longer here than in the USA, no steam locomotive bettered Gresley's designs.

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Spoken like a true Englishman.

Comparing British and American steam locomotives gets difficult because the Americans had larger loading gauges (height and width) and usually heavier rail which allowed for higher axle loading's.

American coaches were also usually much heavier. 70-90 tons? Mallards record setting run with 7 coaches would have been the equivalent of 3 American coaches.

Nothing can take away from the Mallard's record run but the title of "last word in steam locomotive power" has to at least consider the NYC Niagara class. Granted they were almost 10 years newer and twice the weight of a Mallard but their record stands almost alone (See Norfolk Western J class).

NYC Niagara - Wikipedia, the free encyclopedia

to get back on topic railway practice and "high powered" ship practice began to separate back in the 1880s. Ships shifted to water tube boilers and not only compound expansion (used by a number of locomotives) but triple expansion (rarely, if ever, used successfully on a locomotive) and in some cases quadruple expansion. The Coming of turbines at about the turn of the century further separated the designs. Low powered ships continued to use reciprocating engines because they were cheap and relatively easy to build.

Pre WW I it was common to separate destroyer engines/boilers from cruiser and battleship/dreadnought engines and boilers. Pre WW I destroyers were expected to be lightly built and their engines to suffer from breakdowns that would not be tolerated in a WW II destroyer. Their engines/boilers did offer a much better power to weight ratio than the larger ships. Reliability and durability was paid for in weight and volume.
I believe there is even a design sketch for a Diesel installation for a dreadnought in the 1913 Brassey's annual. Theory was always ahead of practice
Same volume mentions shaft turbines too.

Shortround6 said:

Spoken like a true Englishman.

Comparing British and American steam locomotives gets difficult because the Americans had larger loading gauges (height and width) and usually heavier rail which allowed for higher axle loading's.

American coaches were also usually much heavier. 70-90 tons? Mallards record setting run with 7 coaches would have been the equivalent of 3 American coaches.

Nothing can take away from the Mallard's record run but the title of "last word in steam locomotive power" has to at least consider the NYC Niagara class. Granted they were almost 10 years newer and twice the weight of a Mallard but their record stands almost alone (See Norfolk Western J class).

NYC Niagara - Wikipedia, the free encyclopedia

to get back on topic railway practice and "high powered" ship practice began to separate back in the 1880s. Ships shifted to water tube boilers and not only compound expansion (used by a number of locomotives) but triple expansion (rarely, if ever, used successfully on a locomotive) and in some cases quadruple expansion. The Coming of turbines at about the turn of the century further separated the designs. Low powered ships continued to use reciprocating engines because they were cheap and relatively easy to build.

Pre WW I it was common to separate destroyer engines/boilers from cruiser and battleship/dreadnought engines and boilers. Pre WW I destroyers were expected to be lightly built and their engines to suffer from breakdowns that would not be tolerated in a WW II destroyer. Their engines/boilers did offer a much better power to weight ratio than the larger ships. Reliability and durability was paid for in weight and volume.
I believe there is even a design sketch for a Diesel installation for a dreadnought in the 1913 Brassey's annual. Theory was always ahead of practice
Same volume mentions shaft turbines too.

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Not the Pennsylvania's K-4 Pacific SR?
With US British steam locomotives its horses for courses rather like with cars and motorbikes.

We had to keep steam going longer than planned as we were broke after WW2 and the money to invest in a new infrastructure locomotives etc simply wasn't there. I remember the steam hauled express from London to Plymouth and the smell of coal etc...but, when the new generation of diesels arrived and times were quicker that was more important than nostalgia.

Thanks for the information in the rest of your post, fascinating stuff. I'll do some reading up.
Cheers
John

I disagree in general!

The Diesel propulsion system was groundbreaking.

After the decision to go with the high pressure steam turbines from Bremen Class (Bremen (1929)) at 1934, the research funds to MAN were massivly shortened (1934).

After the massive problems with the high pressure steam turbines in servive the research funds to MAN were massivly boosted (1938), with result of the VZ 12 32/44 (1940), 24 Zylinder V engine with 60ts and 12500 PSe normal poweroutput, without help engines, for exampple compare to the MZ9 42/58 of the the Panzerschiffe with 7.100 PSe and 90ts, plus 43ts MZ5 42/58 for the help engine for two MZ9 42/58 .
Three were built with turbo charging till 15000 PSe for normal poweroutput an example is at the Museum of Sinsheim.

The VZ 12 32/44, 24 Zylinder V engine was revolutionaire for the propulsion system of Warships, Cruisers and Destroyers, and I think it could be ready 1938/39 without the switch of to the high presuure steam turbines.

A BB with a 4 shaft propulsion system could manage to get 16 x 12500 PSe = 200000 PSe normal poweroutput to the water with Diesel engines and the massive pros of the consumption and without any disadvantages at the weight, because this engine weight only 60ts without any help engine.

The Diesel propulsion systems were hardly "ground breaking". First ocean going ship to use a diesel was in 1910 and first to use a diesel as the sole means of propulsion was in 1912. A diagram of a "diesel" engine room layout for a dreadnought can be found in the 1913 Brassey's annual (never actually built).

If the information in Wiki is accurate the Bremmen didn't use high pressure steam by the standards of WW II. A bit above "normal" perhaps. Bremen used 23 Atm pressure. Hipper class used 85 Atm? British battleships of the 1890s use 14-15Atm.


The weights given for those WW II engines seem a bit optimistic, A current MAN brochure shows a modern 4 stroke turbo charged V-16 diesel of 12,182hp max continuous (a 32/44?) weighing 87 tons.

http://www.mandiesel.com.cn/files/news/filesof15981/32_44 CR.pdf



Granted the older engines may have been two stroke double acting but MAN uses the first number as an indicator of the bore in centimeters and the second as the length of the stroke. There is also a bit of confusion as to what maximum continuous may be. Ships run 1 hour, 4 hour and 8 hour trials, not 5 minutes like airplanes. But some engine makers rate engines for different duties. A electrical generator engine ( 24 hours a day for weeks on end) will be rated lower than the same engine for even work boat duty let alone more intermittent use.

I will note that a modern Diesel can operate at about 4 times the BMEP of a 1920s diesel however.


"In 1914 there were fewer than 300 diesel powered vessels in service with an aggregate tonnage of 235 000 grt; by 1924 there were the fleet had grown to some 2000 ships of almost two million grt and by 1940 the total tonnage had risen to 18 million grt embracing 8000 motor ships."

From "Pounder's Marine Diesel Engines and Gas Turbines"

available here: http://www.albadr.org/www/pdf/library/487.pdf

The Germans suffered from trying to push the envelope a bit to far both with the Diesels and the high pressure steam. What works in test installations ashore doesn't always work so well in a sea going ship ( and what works in a ship often doesn't work in a railway locomotive).
A lot of early installations of light weight machinery had to be de-rated in order to get the desired reliability.

The degree of reliability (or unreliability) that can be tolerated in small high speed ships/craft built by the dozen (if a full destroyer flotilla has to leave one or two ship/s behind with bad engines it is not a disaster) is not what is wanted for big ships built in small numbers where a bad engine can seriously affect the battle fleets strength..

After the decision to go with the high pressure steam turbines from Bremen Class (Bremen (1929)) at 1934, the research funds to MAN were massivly shortened (1934).
After the massive problems with the high pressure steam turbines in servive the research funds to MAN were massivly boosted

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The KM and German merchant marine had a wealth of experience with diesel propulsion from 1910 onward. I don't understand why Admiral Raeder was so determined to use an unproven high pressure steam system.

Because, as we have been saying, the available diesels of the time could not provide the needed (wanted) power at a low enough weight or volume. Neither could normal pressure steam power plants.

Because, as we have been saying, the available diesels of the time could not provide the needed (wanted) power at a low enough weight or volume. Neither could normal pressure steam power plants.

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That´s incorrect. See above post of 4th of dec. Diesel was well capable to provide the power required to propel a fast battleship or a cruiser within the confines of the not-so-confined-german-machinery-spaces.
Correct is that HP plants -when new in 1933 to 1938- typically claimed more efficiency than it was cabale to deliver. The selling companies made it up. A higher fuel efficiency negated one of the principles of Diesel propulsion hence the Diesel was dropped after preliminary successes with the PBB´s. That´s not because the PBB´s were considered to be a failure. The Panzerschiff D ERSATZ ELSASS was to be buildt initially by MAN DIESEL engines, too. The change to HP turbine was a recognized failure in NÜRNBERG, HIPPER´s, SCHARNHORST´s, BISMARCK´s and GRAF ZEPPELIN´s (all laid down 1934 to 1938). It took time until lessons could be learnt from the newly laid down vessels. The H-class and ALL SUBSEQUENT classes of KM cruiser and BB´s were designed with Diesel propulsion instead.

Granted the older engines may have been two stroke double acting but MAN uses the first number as an indicator of the bore in centimeters and the second as the length of the stroke. There is also a bit of confusion as to what maximum continuous may be. Ships run 1 hour, 4 hour and 8 hour trials, not 5 minutes like airplanes. But some engine makers rate engines for different duties. A electrical generator engine ( 24 hours a day for weeks on end) will be rated lower than the same engine for even work boat duty let alone more intermittent use.

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The specifications of the marine Diesel engines in question are well understood. Max. continuous rating can be found as "Höchstzulässige Dauerleistung" in the MAN specification for each marine engine. Rated power was typically only lightly higher and aviable for 10 hours and MAN Diesels were expected to have a 10% safety margin with short term power (1 hour for marine Diesel).

Technology can swing back and forth. A diesel that hits it's performance numbers in 1940 is just a big a gamble to a ship that started construction in 1939 as the high pressure steam plants were. If it fails there is an awful lot of rework to do.

It is also difficult to get good numbers for some of these installations or to try to compare them from ship to ship, especially between classes. One book gives "entire" (whatever that means, including auxiliary power plant/generators but not fuel? propeller shafts and propellers?) "propulsion system" weights of Deutschland as 21.96kg per HP. and the Hipper at 18.5kg per HP. Same book says 20.3 KG per HP for the "entire drive installation" for the Bismarck and the "entire power installation" for the "H" class as 31.4 KG per HP. Notice the different wording?

Germans had been "burned" several times during WW I by Diesel makers failing to deliver promised engines for German Dreadnoughts.

Some of the later planned German ships were to use mixed propulsion systems. The O,P,Q battle cruisers were to use cruising diesels of 60,000shp with a steam turbine of 116,000shp. The M class light cruisers of 1938 were to use diesels on the center shaft and steam turbines on the wing shafts as did the SP 1-3 scout cruisers. The Germans schemed an all diesel destroyer in 1938 but actual construction of Diesel destroyer wasn't started until 1943, it was never completed due to bomb damage while building.

My comments about what is meant by "maximum continuous power" is while we may know what MAN means in a 2007-2013 brochure it may not be what was meant in in 1940-41. The Modern MAN diesels at the modern "maximum continuous power" rating do NOT match for a power to weight ratio what is claimed for the 1940 engines. Perhaps a different definition of MAX CON power is the explanation or perhaps the 1940 engines did not have the power to weight claimed?

Apropos of nothing but just to show steam tech still has plenty to show for itself. A few years back I worked as a contractor for a firm installing a steam generating plant in an edible oil refinery. The obsolete 1960s steam plant we removed was the size of a 40 ft shipping container with a feedwater condenser of about half the size. They were connected by a snakes honeymoon of pipework and all this was controlled by a switch panel worthy of a 1950s computer all flashing lights, dials and valve levers, all contained in a seperate boiler house. This was cut up by yours truly with a gas axe and taken away by a scrap merchant in quite a number of lorries.

The replacement steam generator came on the back of a medium sized lorry and was put onto its concrete base by a fork lift. It was roughly the size shape and look of a large double door catering refrigerator with a discrete control panel. When we hooked it up to the fuel and water supply and all the pipework which fed the steam to the refinery we pressed a button stood back and within 10 minutes steam was blowing out of all the relief valves in the refinery. The refinery man who had run the old plant for about 30 years said it took the old boiler the best part of a shift to build pressure up.

Readie said:

Shortround, We'll have to agree to differ about Mallard's tech spec being 'low tech', she was the first A4 to be fitted with a Kylchap double blast pipe and her WSR, which is held to this day, speaks for itself.
The steam gunboats were turbines not compound pistons. Great performers in heavy seas but, having to be kept 'in steam' was a disadvantage.
The British Gun Boats etc with 4 × Packard 4M 2500 petrol engines, total 5,000 hp went well but, the thought of sitting on all the petrol is eye watering....
A pretty explosive choice really....superheated steam or petrol.
Cheers
John

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The Steam Gunboats had armour added to the boilers to at least make them bullet/splinter proof which slowed them down a bit. Still an explosive choice I agree