20 KVD 25

Translated by Google Translate from German, and somewhat reworked / edited by us.

Original document here

The high-performance diesel engine 20 KVD 25

A contribution to the history of diesel engine construction and the navy of the GDR.

By Günter Stavorinus and Werner Neundorf.

Prefaces

Foreword by Dipl.-Ing. Norbert Krümmling, division manager at WTZ Rosslau

There is now a very extensive literature on the history of technical developments in the former GDR, and the question arises as to what contribution this report can make to it. As the distance to the existence of two German states increases, it is possible to obtain information from formerly secret archives - both from industry and from the armed forces - which shows that technical developments were already being carried out at a very high level in the early 1950s. Of course, this article, with its detailed research into the history of a high-performance diesel engine for propelling fast naval boats, is a treat for enthusiasts in this field.

But he also truthfully reflects the problems of building a post-war economy with all its facets and decisions that are difficult to understand today. All of this was only possible because both authors joined forces at the right time.

This meant that there was a chance to speak to contemporary witnesses of this very secret but still eventful time and thus to find out things that are neither noted in reports nor in any reports. Gratefully, many people who had a large part, directly or indirectly, in the development of this engine were also mentioned, which represents a certain respect for their achievements. May this report be a valuable addition for friends of special diesel engine construction and for those interested in the technical history of their home country.

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Instead of a foreword, comments from a contemporary witness.

From Captain z. See a.D. Dipl.-Ing. Gerhard Vandreier, Head of the Naval Technical Service until 1989 and Deputy Chief of Technology and Weapons in the People's Navy Command until September 1990.

The history of technology always reflects social history. In this study, the authors succeeded in excavating, analyzing and preserving a piece of the GDR's technological history.

It is pleasant to read that the experimental replica of the Daimler-Benz MB 511 marine diesel engine, which was fraught with many problems, was presented without pointing fingers.

The replica of this high-performance engine under the GDR designation 20 KVD 25 was of strategic importance in the 1950s for building the most efficient industry possible. The immediate goal was to cover the need for propulsion engines for fast naval vehicles.

Even from today's perspective, the enthusiasm with which those involved went about solving this complicated task is impressive. There were neither construction documents nor the necessary number of skilled workers. There was also a lack of qualified suppliers.

The test runs that began after assembly revealed a huge number of technical problems, both with the rebuilt machine elements, as well as with other engine parts and even the lubricating oil.

Continuity in development and testing was made additionally difficult by the frequent changes in management bodies or their structural changes. The events of June 17, 1953 had a significant impact. The authors succeeded in making the complicated structures of the GDR economy transparent in this area. They also point out the various difficulties that the development group had to overcome during the reconstruction of the individual parts and the production of the engine.

Thorough research allows us to conclude that at the time the order was canceled, the essential technical problems had been solved on both the engines and the “Forelle 0” boat hull intended for testing.

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Towards the end of 1951, a replica of the 2500 hp Daimler-Benz high-performance diesel engine MB 511 was prepared in the GDR under the type designation 20 KVD 25.

The engine was intended to power fast ships and boats for the newly established naval forces. Their mission was to defend the coast of the GDR and its outskirts. Involved in military planning and as allies of the Soviet Union, they were also tasked with providing a limited offensive potential in the western Baltic Sea. Despite all the changes brought about by advances in military technology, little changed in this concept until the dissolution of the People's Navy in 1990. The formation, disguised as a police formation, was suggested by the occupying power, represented by the naval department of the Soviet Military Administration in Germany (SMAD), and implemented from 1949 onwards.

A development team began working in Berlin-Wilhelmsruh at the end of 1949. The new navy was presented to the public in June 1950 with the establishment of the Maritime Police Headquarters (HVS) in the Ministry of the Interior (Mdl). It received its military status as a People's Police Lake in 1952 before being taken over as a branch of the National People's Army (NVA) in 1956.

The first considerations for building the fleet envisaged high-speed torpedo boats (TS boats) of different tonnage, which were to be powered by, among other things, the Daimler-Benz MB 511 engine, which had proven itself in World War II. Because importing was unthinkable under the conditions of the Cold War, dependencies on the West had to be avoided, and no suitable engine was available from the Soviet sphere of influence, the only alternative was to build a replica. Questions of patent law and license protection played no role under the conditions of the occupation regime. However, the extraordinarily high development and cost effort associated with this was completely underestimated.

Until then, high-performance diesel engines for ship propulsion had only been built in Germany by the renowned companies Maybach Motorenbau and Daimler-Benz, whose production facilities were in the western occupation zones. Most of the supply industry was also located there. With a few exceptions, the territory of the GDR lacked production sites, the basics of metallurgy and manufacturing techniques as well as the experienced personnel for such an ambitious goal. With the help of the socialist planned economy and the enthusiasm of the development generation, people firmly believed in the success of the project.

The reconstruction program began in 1952. After great efforts, it was discontinued at the end of 1958 at a time when the most important technical problems were about to be solved and pre-series production could have started with little more effort. This means that the opportunity to keep up with developments in high-performance diesel engine construction was missed. For the People's Navy, this meant that from now on it would have to rely on imports from the Soviet Union, the purchase, operation and repair of which required a lot of effort and created new dependencies.

The 20 KVD 25 has been described in publications on regional, naval and technological history, but its origins have only been touched upon. The opening of the GDR's archives and the fortunate fact that the technical archive of the Scientific and Technical Center (WTZ) for diesel engines in Roßlau was saved over the fall of communism encouraged the authors to write down the history of the 20 KVD 25. It should not be forgotten that between 1952 and 1959 this engine was at the center of the working lives of many people in Roßlau, Ludwigsfelde and other places in the GDR, whose performance under adverse circumstances deserves respect.

In the first part of the article we will present the most important technical data of the 20 KVD 25 and then in a short description we will introduce the torpedo speedboat “Forelle 0” from the VEB Roßlau shipyard, where the engine was tested in practice. In one The second part examines the 20 KVD 25 as a product of the GDR's armaments industry and describes the connection between political guidelines, plans and their implementation, because many decisions remain incomprehensible to the reader without knowledge of the special structures and management levels of this industry.

The main part reports on the most important design and development offices, mechanical engineering companies and supplier companies involved in the repair of the original engines, the reproduction and the zero-series production. The efforts made in connection with the production of problem components were examined particularly thoroughly. This part concludes with the presentation of the test results on land and at sea.

A summary, the building description and parts of the operating instructions, lists of sources and literature as well as a register of people, together with the acknowledgments, form the conclusion.

Günter Stavorinus wrote the general and armaments economics section, Werner Neundorf the engine technology section of the essay.

It is clear to the authors that many questions remain unanswered in connection with the history of the 20 KVD 25. Therefore, they accept any comments and additions with thanks.

Trappenkamp/Holstein Roßlau/Elbe

Günter Stavorinus Werner Neundorf

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1. The ship diesel engine 20 KVD 25 and the torpedo speedboat "Forelle 0"

The GDR replica of the Daimler-Benz speedboat engine MB 511 under the type designation 20 KVD 25 comes from a series of developments that began with demands for a drive with high performance and operational reliability for airships.

Modified engines with these characteristics were suitable for use on speedboats of the Reich and Kriegsmarine. Their development and production was therefore co-financed by the Navy's design office. At the outbreak of war, the 20-cylinder V-engine MB 501, ready for series production, was available as a naturally aspirated engine with 2000 hp and from 1943 the mechanically supercharged MB 511 with an output of 2500 hp. The latter became the standard engine for the Kriegsmarine's S-boats. The further developed MB 518 with 3000 hp no longer made it to the front.

Technical data of the 20 KVD 25

Engine characteristics:
Model	20 KVD 25
Working principle	4 stroke
Cylinder arangement	Standing V form
Number of cylinders	20
Bore	185
Stroke	250
Displacement per cylinder	6,72 Liter
Compresion	14:1
Weight dry	4550 Kg dry without extra equipment
Type of charging	Centrifugal blower, mechanically driven
Lubrication	Pressure circulation and spray oil lubrication
Cooling	Fresh water with seawater recooling
Regulator	Centrifugal
Direction of rotation	Depending on the version left or right, directly reversible
Reduction gear	1,72:1
Full length without intermediate shaft	4025 mm
Width including exhaust collector	1670 mm
Height including intercooler	2265 mm

	Engine speed	Power
Continous power	1480	1875	180	5 - 6
	1530	2060	185	7 - 8
	1580	2250	190	9 - 10

The 20 KVD 25 was only used in the torpedo speedboat “Forelle 0”. For reasons of In camouflage, this vehicle was also referred to as a "fast cruising yacht, small", "M 5" or "F 5". In the maritime police, a planing boat was preferred over a displacement boat.

VEB Schiffswerft Roßlau received the construction contract in 1952. This company belonged to the Sachsenberg brothers until 1945 and made a name for itself by building fast hydrofoils based on the Schertel system for the Navy. The Soviet occupying power had ordered the continued construction of captured hydrofoils and a special design office had been set up for this purpose, which only ceased its activities in 1948/49 when it was integrated into the Central State Design Office for Shipbuilding in Berlin-Köpenick. After expropriation and partial dismantling, the shipyard became state property in 1949 and was commissioned to make reparations for the Soviet Union.

From the war economy, it had a qualified workforce and a shipyard hierarchy with competent management members. The staff received an innovative boost by taking on skilled workers from Junkers aircraft company.

Under the leadership of the young and imaginative shipbuilding engineer Hans Reinecke, a research and development group for planing and hydrofoil boats was formed in 1952. Because tow channels for fast watercraft were not available in the GDR, model boats were built and tested extensively on Lake Müritz. Soviet experts also occasionally attended these test drives. The boat M 2 a with a stern step showed the most favorable results and provided the template for the construction work on the “Forelle 0”. Under the technical director Postl, there was the chief designer Braun, the engineers Lauterbach (shipbuilding), Wieners (lightweight construction) and Bauer (mechanical engineering) was involved in the design. The shipbuilding planning of the VP-See envisaged a series of 24 boats of this type. Of these, 4 were also intended for the "long coastal voyage" up to 61 degrees north, i.e for the area of the transition from the North Sea to the Norwegian Sea.

For the construction of a first batch originally comprising 6 boats, later reduced to 3, a special hall was set up at the shipyard, with Obermeister Fräsdorf supervising.

According to the information sheet for the "Forelle" object from the Office of Technology, the ship's hull, riveted from AI Mg 4 and 5, was 27.25 m long, had a maximum width of 7.16 m and was a maximum of 3.08 m high. The displacement was included 67.25 t was calculated. With two diesel engines of 2500 hp each, the two-screw boat was supposed to reach a speed of 22 meters per second, i.e. 42.76 knots, in calm and deep water. The cruising range was set at 480 nautical miles.

Use in coastal waters and in the open sea had to be guaranteed up to sea level 6. Two torpedo tubes on the upper deck and light machine cannons were provided as armament.

The crew should consist of an officer and 10 men. The government contract for the speedboat had the number B 5 / 3255 / 084-001 - 006. The construction costs per boat were estimated at four million marks. Construction plans for "Forelle O" have not yet been found. A variant from 1955 , in which the motors should deliver their power to the drive shafts via an angular gear, shown in Fig. 3.

Fig. 3. Sketch project of an unrealized drive variant of the “Forelle” from May 1955 with the only general plan available to date.

(Drawing: Heiner Theuerkauf)

The construction progress was followed with great attention by the clients. An unexpected delay occurred due to the Elbe flooding in 1954. At the end of 1955, Minister Stoph inspected "Forelle 0" in Peenemünde, Vice Admiral Verner, the head of the VP-See, was in Roßlau and was met by the head of the shipbuilding department, Captain of the Sea (Ing.) Wachsmann and the responsible staff, Lieutenant-Captain (Ing .) Blücher and First Lieutenant (Ing.) Pagel, report regularly. Soviet naval officers also showed particular interest in the “Forelle 0”.

As expected, the O-Bdot had defects, the shipbuilding part of which could have been solved. It was only the delays in engine development that contributed to the cancellation of the project, although at the end of 1958 the output of 2275 hp required for construction approval was proven, using original engines largely made up of GDR replica parts.

In late autumn 1958, "Forelle 0", under the command of Lieutenant Commander Paul Bendig and with Fritz Krage as test engineer, reached a speed of more than 43 knots during a mile-long journey in the Tromper Wiek. The usefulness of the technical concept was thus proven.

2. The 20 KVD 25 in the GDR's armaments industry

In July 1952, at the 2nd SED party conference, the establishment of socialism in the GDR and its armed protection were decided. (7) German political considerations did not yet allow the formation of a people's army. Therefore, as a compromise, the Barracked People's Police (KVP) was created in 1956 with a force structure and military ranks. The Ministry of the Interior was given a dual function. It was the police and provisional defense ministry with Willi Stoph at the helm.

This fulfilled Soviet demands that had been raised by Stalin in Moscow in April 1952 and clarified by Marshal Chuikov and Ambassador Semyonov in East Berlin at the beginning of July 1952.8 After the failure of the neutralization policy for Germany and against the background of growing tensions in the East -West conflict, the aim was to establish a strong bond between the GDR and the Soviet bloc and to stabilize it internally.

The armament program imposed on the Central Germans in this context required the GDR economy to use a large proportion of the scarce resources that were available due to war damage, dismantling, reparations and occupation burdens as well as because of the disproportions in the industrial structure of divided Germany. The political and social change, a reorganized economy, which was accompanied by the nationalization of industry, a land reform, and the development of a new basic materials and heavy industry in a socialist planned economy, had not yet reached the old pre-war performance and the standard of living of the population stabilized at a modest level.

1. Fock, Harald, Speedboats - Development and Use in World War II, Volume 2, Herford 1974, pp. 78, 88, 98 and 99.

Möller, Eberhard and Brack, Werner, One hundred years of diesel engines for five German navies with a section on diesel-powered ships with Voith-Schneider propellers, Hamburg-Berlin-Bonn, 1999, pp. 38-44.

2. According to the building description of the KEB Roßlau in the copies from 1954/57 and 1959. The building description is attached as appendix no.l and excerpts from the preliminary operating instructions as appendix no. 2. In this article, the authors use the measurement system that was valid until 1960 . 20 KVD 25 stands for 20 cylinders, K = short stroke, V = four-stroke, D = diesel and 25 = 250 mm piston stroke. In the VP-See documents and in company correspondence the designations KVD 25, D 2500 and 20 KVD 25 M are also used for it .