Diesel engines for submarines of the Imperial Navy
For the selection of the diesel engines for the submarines of the German Imperial Navy , the latter applied the highest technical standards. These requirements, the competition between the leading manufacturers and, last but not least, the well-trained and motivated engineers drove engine development considerably between 1903 and 1918. In around 15 years, the specific fuel consumption has been greatly reduced and the output increased from 200 to 3000 hp per engine.
introduction
The Germania shipyard (since 1902 Friedrich Krupp Germania shipyard) in Kiel was taken over by Krupp in 1896/1902 . It began around 1902 under the influence of Raymondo Lorenzo D'Equevilley Montjustin (* 1873 in Vienna) with the construction of submarines. At first, a battery-powered electric motor was used as a drive . In 1902 the first usable boat with this drive, the trout , was built as a test vehicle . It was sold to Russia in 1904. This test vehicle (project light buoy) was ordered by the Krupp company on July 28, 1902 from the Krupp Germania shipyard. It was laid down on February 19, 1903, and launched after four months. It has been thoroughly tested and a lot of experience has been gained with this drive. On June 20, 1904, it was delivered to Petersburg by rail.
Since the Reichsmarineamt under the direction (1897–1916) of Alfred von Tirpitz showed no interest in the submarines offered by the Germania shipyard, they were also offered abroad. On April 4, 1904, the Reichsmarineamt commissioned Gustav Berling , the chief engineer and head of the submarine department of the Reichsmarineamt's torpedo inspection from 1904 to March 1912, to develop and build a submarine for the navy . In the naval budget of 1905, 1.5 million marks were made available for attempts to build submarines.
In early 1904, the Germania shipyard asked MAN whether they could supply diesel engines to power the submarines. Since MAN did not give the expected promise, the Germania shipyard got into business with Gebr. Körting AG . Körting has been successfully building gas engines since 1886, petroleum engines since 1893 and was able to deliver the desired engines (petroleum engines) with 200 HP per engine. As requested, they were two-stroke engines.
On April 20, 1904, the Imperial Russian Navy ordered three submarines from the Germania shipyard, which were launched in 1905. A characteristic of these submarines was the hybrid drive consisting of a diesel engine, generator, lead-acid battery and electric motor. The early comparable submarines of the French Navy of this time had a hybrid drive consisting of a steam boiler, steam piston engine (primary energy generator), lead accumulator and electric motor. The submarines built by the Germania shipyard in the pioneering phase (three for Russia, six for Germany), on the other hand, were equipped with petroleum engines as primary energy generators. The Imperial Shipyard Danzig built 13 submarines with petroleum engines for the Imperial Navy. Only the submarines from U 19 (1913) got diesel engines, which had meanwhile been developed into lighter and more powerful machines.
As a result of this pioneering work, Krupp, who financed Rudolf Diesel's tests on the first “oil machines” together with MAN , stopped work on diesel engines for merchant shipping. The development department for diesel engines for the navy was relocated from Essen to Kiel to the Germania shipyard.
The first submarine of the Imperial Navy, which was slightly larger than the Russian boats, was launched on August 4, 1906. It was tested very extensively with the help of the Oberelbe lifting ship , was officially designated U 1 in November 1906 and was put into service on December 14, 1906. U 9 propelled by two engines Petroleum (2 × 500 hp) was one of the most successful submarines in the First World War . In seven patrols it sank five warships with 44,173 tons and 13 merchant ships with 8,636 GRT. No other boat sank more warships during the First World War.
Manufacturer competition
Gebr. Körting
Petroleum engines
The Gebr. Körting AG was in Germany, the machine manufacturer with the most experience in the construction of two-stroke engines, because since 1893 Petroleum engines were built according to this principle. For the submarine engines, the shipyard prescribed crank chamber flushing, the underside of the pistons served as flushing pumps. A simple, tried and tested principle, it was later used for a very long time in two-stroke diesel engines and only finally replaced after 90 years by the combination of exhaust gas turbochargers and electrically driven auxiliary fans.
The shipyard attached great importance to a simple construction. The housing was made of bronze, which enabled a thin-walled construction with low weight (17.5 kg / PS). The cross-headed engines had no valves and the inlet and outlet ports were controlled by the piston. Starting valves were omitted because the engine was started by the direct current generator, which was powered by the battery and worked as an electric motor for the starting process. During the start-up process, the petroleum motor was turned over for about five minutes without petroleum supply, the sucked in air was pumped in a circle and heated electrically.
Only then was petroleum added and started. This procedure was only possible with the submarine, other applications started with gasoline. The petroleum was sucked into the ring-shaped mixture space by the piston going upwards via the carburetor. The downward moving piston then pushed this mixture into the cylinder and was ignited by the magnetic tear-off device during upward gear at top dead center. Before the bottom dead center, the control edge of the piston first opened the exhaust gas and then the scavenging slots. The amount of mixture and thus the power was controlled with a throttle valve.
The relatively high consumption of around 0.50 kg / PSh resulted from the insufficient amount of purge air. It should have been 30-50% larger for good combustion conditions.
Soon afterwards, the Imperial Navy also showed interest in these submarines. The first German submarine ( U 1 ) was put into service on December 14, 1906 and, like its predecessor, was powered by two six-cylinder Körting petroleum engines with 200 hp each. All in all, these engines represented an extraordinarily outstanding achievement by the Körting engineers that was hardly ever made public. The engines have proven themselves, although they are prone to failure, U 1 was in use until the end of the war in 1918, at the end as a training boat . By 1911, Körting had built around 100 petroleum engines from this successful type of engine.
The next series from U 5 to U 8 received four petroleum engines with a total of 900 hp per boat and the submarines U 9 to U 18 were each powered by two six-cylinder and two eight-cylinder engines with a total of 1300 hp. With that they ran 15.6 knots over water. The following submarines from U 19 onwards (1913) got diesel engines, which had meanwhile been developed into lighter and more powerful machines. They did not have the disadvantages of petroleum engines - high specific fuel consumption and a white-yellowish smoke plume that was clearly visible due to the insufficient amount of purge air.
Diesel engines
From 1912 Körting also developed diesel engines for submarines, initially based on the two-stroke principle, such as B. two engines for the Russian Navy with six cylinders that had 295 kW (400 HP) at 350 / min (285 mm cylinder diameter, 350 mm stroke). The engines, which were removed in 1914, were installed in a German submarine because of the outbreak of war. At the request of the Navy, four-stroke engines were developed, the test engine developed 44 kW (60 hp) and had four cylinders. Then mainly six-cylinder engines were built for the Navy; the power increased from 150 to 290, 450, 530 hp to 1200 hp (880 kW) (1917) per engine. After that, 1,800 hp (1,325 kW) engines were built that were no longer used. Even the test engine with 700 HP per cylinder did not get beyond the test bench test.
Maschinenfabrik Augsburg-Nürnberg (MAN)
In Germany at this pioneering time , MAN had approached the German and French navies to get an order for a diesel engine. The offered diesel engine, derived from stationary machines, was too heavy for the navies with 75 kg / HP and therefore aroused no interest. MAN therefore decided to use its own resources to design and build a lighter engine. It was given the type designation SM 4 × 280/300 , had four cylinders, a diameter of 280 mm, a stroke of 300 mm and was supposed to produce 140 hp (103 kW) at 400 rpm. This gave a mean specific pressure of 4.25 kg / cm². The specific weight of this engine should be less than 40 kg / HP, stationary engines of this time weighed around 210 kg / HP.
The engine consisted of a box-shaped underframe with the crankshaft bearings, on which four individual round frames were screwed into which the cylinder liners were drawn. The navy was later ready to buy the engine, the order was placed on June 16, 1903 and on October 15, 1904, the engine was delivered to the Kaiserliche Werft Kiel . At 68 kg / PS it was considerably heavier than planned, but on the other hand it was significantly lighter than 75 kg / PS. The motor could not yet be reversed, but reversing the drive with the help of a reversing gear was already designed. Nothing is known about the further whereabouts of the engine.
MAN and Krupp (Friedrich Krupp Germaniawerft ) decided in 1904 to jointly develop a submarine diesel engine based on the four-stroke principle. The head of the diesel engine department of the Germania shipyard (W. Sorsoe) designed a submarine engine with 200 hp in Augsburg in 1904 with Immanuel Lauster and Wilhelm Eberle from Ettlingen. It was not carried out because the Imperial Navy required more powerful engines.
Starting in 1905, MAN (now without Krupp participation) developed an engine that was supposed to produce 147 kW (200 hp) at 400 rpm with four cylinders. The closed box frame gave the engine the necessary rigidity, and cast steel was used for the first time . The pistons were oil-cooled, the cooling oil was supplied via joints. These engines (SM 4 × 360) were installed in the two French Circé class submarines in 1906 , they had a specific power to weight ratio of 33 kg / hp. The first engine delivery (two engines) could not yet be reversed, so a reversing gear was necessary. The following four engines delivered to France could be reversed and later the first two engines were also reversed.
The Imperial Navy showed great interest in this type of engine, but it should be reversible, with six cylinders deliver 850 hp and weigh no more than 26 kg / hp. The dimensions of the piston diameter and stroke were therefore increased by MAN to 400 mm, the speed increased to 45 / min and in 1910 this engine was accepted at the factory. The fuel consumption was 192 g / PSh and was well below the required 200 g / PSh, the specific power-to-weight ratio of 22 kg / PS was considerably below the original requirement of 28 kg / PS. This more than met the high requirements of the Navy. The first success of MAN for the Imperial Navy can also be measured by the fact that seven more engines were ordered that were installed in the U 19 , U 20 and U 21 in 1912/13 .
These diesel engines proved their worth, and since the specific consumption was about half that of the petroleum engines, the range of the submarines increased considerably. The experience feedback from the Navy to MAN resulted in constant improvements and optimizations. The engine power and dimensions were gradually increased during the First World War and the last and largest submarine engine had ten cylinders, developed 3000 hp and was delivered in 1917. By 1918, MAN supplied a total of around 560 submarine engines with over 500,000 hp.
Friedrich Krupp Germania shipyard
Berling developed a two-hull coastal submarine at the Germania shipyard in Kiel; the design is based on the three Karp-class submarines that the Germania shipyard delivered to Russia from 1906 to 1907 . Construction finally began in April 1905 and in December 1906 the submarine developed by Berling was put into service as the U 1 and the first German military submarine by the Imperial Navy. Friedrich Krupp's first submarine diesel engine Germaniawerft, a four-stroke engine with 4 cylinders, was built according to MAN documents. It was put to the test in 1907 with 300 hp, it was already reversible and was built as a test engine in various designs, depending on the source even double-acting.
Like MAN, Germaniawerft built submarine diesel engines with great success, but based on the two-stroke principle. The first was completed in 1911, had six cylinders with a diameter of 350 mm and a stroke of 400 mm, it developed 850 hp at 450 rpm. The specific power to weight ratio was 23.6 kg / hp and eight engines were installed in four German submarines in 1914. In 1912 the Russian Navy ordered six 1150 HP engines, which were installed in German submarines ( U 63 - U 65 ) instead of in Russian because of the outbreak of war . The next generation of these diesel engines had 1650 hp and were the most powerful submarine engines based on the two-stroke principle that the Germania shipyard has ever built.
This engine was also ordered by Russia, but was then installed in the U-cruiser U 139 . The Germania shipyard also developed and built submarine engines based on the four-stroke principle, a total of five sizes from 450–1700 hp.
other producers
Other manufacturers such as Daimler , Benz & Cie. , Linke-Hofmann / Junkers , Deutz , MWM , Görlitzer Maschinenbau-Anstalt and AEG developed and manufactured submarine diesel engines according to their own designs with more or less success.
There was also the group of licensees, who were also often building yards, such as Blohm & Voss , Vulcan, AG Weser and BBC .
Literature and Sources
- Gustav Berling : The development of the submarines and their main machinery. Yearbook of the Shipbuilding Society No. 14
- C. Rainbow: Diesel engine construction at the Germania shipyard. Yearbook of the Shipbuilding Society No. 14
- Bodo Herzog : German U-Boats 1906–1966. M. Pawlik Verlagsgesellschaft, 1990