Category Archives: Diesel Engines

MAN 6-cyl WWI

MAN Double-Acting Diesel Marine Engines

By William Pearce

Maschinenfabrik Augsburg-Nürnberg (MAN) was involved with diesel engines since their inception. From 1893 to 1897, MAN* worked with Rudolf Diesel to develop his combustion cycle and build the first diesel engines. When Diesel’s engine first ran in 1894, it produced around 3 hp (2 kW) at 88 rpm. Just 15 years later, MAN was contracted to develop a diesel engine capable of 12,000 hp (8,948 kW) at 120 rpm.

MAN 6-cyl WWI

The MAN six-cylinder, double-acting, two-stroke, 12,000 hp, diesel marine engine under construction. The three workers provide a good reference as to the engine’s size.

The remarkable rise of diesel power caught the eye of many militaries. Anton von Rieppel, general manager of MAN at Nürnberg (Nuremberg), felt that diesels had matured enough to power the latest battleships. In August 1909, Rieppel proposed a new engine to the Reichsmarine (Germany Navy). By late 1909, a development contract was issued to MAN for the construction of a 12,000 hp (8,948 kW), six-cylinder diesel engine. Six of the engines would be needed to produce the 70,000 hp (52,199 kW) required for the latest German battleships. Given the uncharted territory MAN was traversing, a three-cylinder engine would be built first to prove that a six-cylinder engine could meet the desired specifications. Other companies were also contracted to build competing engines.

MAN’s design was an inline, two-stroke engine that used double-acting cylinders. Each of the closed cylinders had a combustion chamber at its top and bottom. Originally, each combustion chamber had four intake valves, four fuel valves, and two safety valves that were also used for air-starting the engine. The safety valves were located at the center of the combustion chamber. The locations of the remaining valves were split between passageways that branched off from either side of the upper combustion chamber. With the exception of the safety valves, the valves for each side of each combustion chamber were actuated by a single underhead camshaft. This configuration had a total of 20 valves for each cylinder and four camshafts for the engine. The final (seventh) combustion chamber design retained the four intake valves but had only two fuel valves and one safety valve (located in the upper combustion chamber). The changes lowered the number of valves per cylinder to 15. Exhaust ports were located in the middle of the cylinder and were covered and uncovered by the piston.

MAN 6-cyl section

A drawing of the final cylinder design of the World War I engine. Fuel valves are on the left of the drawing, and intake valves are on the right. The exhaust manifold is positioned at the center of the cylinder. Note how the two piston halves are bolted together.

The double-headed piston was constructed of two parts. The lower part was connected to a non-articulating piston rod, and the upper part of the piston was bolted to the lower part. The piston rod was connected to the connecting rod via a cross head. The cross head slid in vertical channels on both sides of the inner crankcase. Oil was circulated through the piston to cool it. The oil flowed up through passageways in the piston rod and into the lower part of the piston. The oil then flowed to the upper part of the piston and down the center of the piston rod. The upper and lower combustion chamber sections were bolted to the center section of the cylinder, and the assembly was attached to the crankcase. A water jacket surrounded the cylinder. The center section of the cylinder and of the upper combustion chamber were made of cast iron. The crankcase, piston, lower combustion chamber, and many other components were made of cast steel. Each complete cylinder assembly was around 12 ft (3.5 m) tall, and the engine was over 24 ft 3 in (7.4 m) tall.

Each cylinder had a 33.4 in (850 mm) bore and a 41.3 in (1,050 mm) stroke. Since the piston was double-acting and there was a lower combustion chamber, each cylinder’s displacement was nearly doubled, as if it were two conventional cylinders. The upper combustion chamber displaced 36,359 cu in (595.8 L). However, the connecting rod passing through the lower combustion chamber took up around 3,021 cu in (49.5 L) of volume. Displacement for the lower combustion chamber was approximately 33,337 cu in (546.3 L). The cylinder’s total displacement was around 69,697 cu in (1,142 L). The three-cylinder test engine displaced 209,094 cu in (3,426 L), and the six-cylinder engine displaced 418,187 cu in (6,853 L). The engine drove three double-acting air pumps to scavenge the engine. Each air pump had a 52.0 in (1,320 mm) bore and a 31.5 in (800 mm) stroke.

The three-cylinder engine was first run on 12 March 1911. Severe delays occurred as technological issues were encountered. In January 1912, a failure caused the intake manifolds to explode, killing ten workers. By June 1913, the three-cylinder engine had met its requirement by producing 5,400 hp (4,027 kW) at 90% power. Construction of a six-cylinder engine followed.

The six-cylinder engine was first run on 23 February 1914. By September 1914, the engine was producing 10,000 hp (7,457 kW) at 130 rpm. By this time, World War I was underway; priorities shifted, and shortages were encountered. A single cylinder made a five-day run at over 2,000 hp (1,491 kW) in April 1915. On 24 March 1917, the six-cylinder engine produced 12,200 hp (9,098 kW) at 135 rpm for 12 hours. In April 1917, the engine passed its five-day acceptance test, running at 90% power and producing 10,800 hp (8,054 kW) at 130 rpm.

MAN M9Z 42-58

One of the MAN M9Z 42/58 engines built for installation in a Deutschland-class cruiser. At least 24 of the engines were made. The fuel injection pumps for each cylinder can be seen above and below the housing along the engine’s side.

By mid-1917, it was obvious that due to delays and the war, the engine would never be used, and the other five engines would never be built. MAN decided to test the engine to its limits. The engine test stand at MAN could not absorb the maximum anticipated power of the complete six-cylinder engine, so just one cylinder was run. On 16 October 1917, a single cylinder produced 3,570 hp (2,662 kW) at 145 rpm. If all six cylinders could match that performance, the complete engine would produce 21,420 hp (15,973 kW). The engine was later scrapped as a result of the Treaty of Versailles.

After World War I, Germany entered a period of economic ruin. It was not until 1926 that MAN designed the first engine in a new series of double-acting, two-stroke diesels. Overseen by engineer Gustav Pielstick, the new engines were similar in concept to the double-acting engine built during World War I, but they incorporated many new features. Pielstick had developed MAN submarine engines during World War I but did not work on the large double-acting engine.

MAN MZ42-58

Sectional drawings of a MAN M9Z 42/58 engine. The rotary exhaust valves are positioned in a runner between the cylinder and the exhaust manifold. Note the long through bolts that pass through the entire engine.

The main structure of the new engines was made of steel plates welded together. This construction kept the engine rigid, but made it lighter than using cast components. Pairs of very long through bolts were positioned between the cylinders. They held the center part of the cylinder, crankcase, and crankshaft together and allowed for the disassembly of individual cylinders without compromising the integrity of the overall engine. The double-headed pistons were again made in two parts. From the top, the piston rod passed through the lower part of the piston, which was threaded to a shoulder on the rod. The upper part of the piston was threaded to the top of the piston rod. The skirt of the upper part of the piston slid into the skirt of the lower part. A sealed gap between the skirts allowed for the differential expansion of the individual piston halves. The piston was oil-cooled, like the World War I engine. The lower part of the piston rod was threaded into the cross head. Unlike the World War I engine, the cross head of the new series slid in a mount attached only to one side of the crankcase.

The new engine had no valves in the cylinder. In the middle of the cylinder were two rows of intake ports. The top row serviced the upper combustion chamber, and the bottom row serviced the lower combustion chamber. Air was forced into the cylinder by an auxiliary “pumping” engine. Fuel entered the cylinder via a single injector in the upper combustion chamber and two injectors on each side of the piston rod in the lower combustion chamber. The injectors were water-cooled and provided fuel to each cylinder at 3,625–4,350 psi (250–300 bar). Mounted to the side of the engine was a camshaft that drove the fuel injection pumps. Each cylinder had an upper and lower injection pump that respectively provided fuel to the upper and lower combustion chambers. Both pumps for each cylinder were controlled by a single lobe on the camshaft.

MAN LZ 19-30 section

Sectional view of the MAN L11Z 19/30 shows that the rotary exhaust valves have been placed inside of the exhaust manifold to conserve space. Otherwise, the engine and cylinder are very similar to the larger engines.

Each combustion chamber had its own exhaust ports which led to separate manifolds for the upper and lower combustion chambers. The intake and exhaust ports were on the same side of each cylinder, and their relative positions allowed the cylinder to be loop scavenged. Rotary valves inside of the exhaust manifolds closed off the exhaust port before the piston and allowed the cylinder to be charged with incoming air. The valve itself was supported by a hollow tube through which water was circulated to keep the valve cool. Otherwise, the intake and exhaust ports were covered and uncovered by the piston. All the engines of the new series used the same basic cylinder design, but the engines differed in their bore, stroke, and number of cylinders.

After cylinder testing, the first complete engine built of this type was the D4Z 23/34. In MAN nomenclature, “4” represents the number of cylinders per bank and “23/34” the bore/stroke in cm. With its 9.1 in (230 mm) bore and 13.4 in (340 mm) stroke in a double-acting cylinder, the engine displaced around 6,591 cu in (108 L). The D4Z 23/34 produced 1,000 hp (746 kW) at 800 rpm. The D4Z 23/34 was run in 1927, and tests went well.

On 27 March 1928, the Reichsmarine contracted MAN to develop a larger engine for what would become the cruiser Leipzig. Four M7Z 30/34 engines powered the middle shaft in the Leipzig, while two other shafts were powered by steam turbines. The seven-cylinder M7Z 30/34 engine had a 11.8 in (300 mm) bore and a 13.4 in (340 mm) stroke. Each engine displaced around 19,624 cu in (321.6 L) and produced 3,100 hp (2,312 kW) at 800 rpm, giving a total of 12,400 hp (9,247 kW) for the four engines.

Compared to a steam turbine, the diesel engine took up less space, was simpler to operate, had nearly instant power, and could suffer damage without disastrous consequences. Shrapnel passing through a diesel engine would shut down the engine, most likely one of several. Shrapnel passing through a steam boiler would cause the boiler to explode, most likely killing some of the crew in the room.

MAN LZ 19-30

Front view of the MAN L11Z 19/30. The camshaft ran to the side of the cylinders and controlled the fuel injection pumps. The handle on the front of the camshaft was used to adjust the camshaft when the engine was run in reverse. (Hermann Historica image)

The Reichsmarine decided to use only diesel-power for the Deutschland-class Panzerschiffe (armored ships) cruisers: Deutschland (later renamed Lützow), Admiral Scheer, and Admiral Graf Spee. In these ships, four nine-cylinder engines powered each of two propeller shafts. Engines were ordered in October 1928 for the Deutschland, on 9 January 1930 for the Admiral Scheer, and on 14 March 1931 for the Admiral Graf Spee. The engine type for these ships was the M9Z 42/58. With a 16.5 in (420 mm) bore and a 22.8 in (580 mm) stroke, the nine-cylinder, double-acting engine displaced 84,359 cu in (1,382 L). Each engine produced 7,100 hp (2,494 kW) at 450 rpm and weighed around 110 tons (100 tonnes). Combined, the eight engines provided a total of 56,800 hp (42,356 kW).

The artillery training ship (Artillerieschulschiff) Bremse was ordered in 1931. Powering the ship were eight M8Z 30/44 engines—four engines on each of the two propeller shafts. The M8Z 30/44 was the same engine used in the Leipzig but with an additional cylinder. The eight-cylinder M8Z 30/44 engine had a 11.8 in (300 mm) bore and a 13.4 in (340 mm) stroke. It displaced 22,427 cu in (367.5 L) and produced 3,350 hp (2,498 kW) at 600 rpm, giving a total of 26,800 hp (19,985 kW) for the eight engines.

The light cruiser Nürnberg was ordered in 1933 and used a combination of diesel engines and steam turbines, like its sister ship, the Leipzig. Four M7Z 32/44 engines powered the ship’s center shaft. The engines were larger than the ones used on the Leipzig but appear to have the same rated output. The M7Z 32/44 engine had a 12.6 in (320 mm) bore and a 17.3 in (440 mm) stroke. The seven-cylinder engine displaced 28,894 cu in (473 L) and produced around 3,100 hp (2,312 kW) at 600 rpm, giving a total of 12,400 hp (9,247 kW) for the four engines.

MAN piston rods

The piston, piston rod, connecting rod, and crankshaft section for a M9Z 65/95. The piston halves were threaded onto the piston rod, which was threaded to the cross head. An oil line can be seen attached to the cross head. The assembly is displayed in the Deutsches Museum in Munich. (enwo image)

Around 1933, the Reichsmarine looked to steam turbines to fulfill their power needs, so the funding for MAN’s large diesel marine engines was severely cut. At the same time, a new engine was needed to power the latest German airships, the LZ 129 Hindenburg and LZ 130 Graf Zeppelin II. Pielstick adapted the basic design of the double-acting diesel to create a lighter, smaller engine, the L7Z 19/30. After the Daimler-Benz DB 602 engine was selected to power the airships, MAN added four cylinders to the L7Z engine to create the 11-cylinder L11Z 19/30 for marine use. The L11Z 19/30 used an engine-driven blower to provide intake air and cylinder scavenging. The engine had a 7.48 in (190 mm) bore, a 11.81 in (300 mm) stroke, and a total displacement of around 10,979 cu in (179.9 L). The L11Z 19/30 had a maximum output of 2,000 hp (1,491 kW) at 1,050 rpm and a continuous output of 1,400 hp (1,044 kW) at 900 rpm. The engine was approximately 157 in (4.0 m) long, 39 in (1.0 m) wide, and 98 in (2.5 m) tall. It weighed around 8,378 lb (3,800 kg) and was reversible. L11Z 19/30 engines were used in torpedo boats, with three engines installed in each Schnellboot S 14 to S 17 (S 14 was launched in January 1936) and four engines installed in the Versuchs Schnellboot VS 5 (launched in January 1941). The three L11Z 19/30 engines from S 15 survived. One engine is in the MAN Museum in Augsburg; one is in the Deutsches Museum in Munich, and one is in a private collection.

In 1935 and under Nazi leadership, the Reichsmarine was renamed Kriegsmarine. That same year, the Kriegsmarine initiated the design of new H-class battleships. The first of the ships would be powered by diesel engines. In 1938, the Kriegsmarine showed a renewed interest in large diesel marine engines, and MAN’s developmental funding was substantially increased. MAN developed the M9Z 65/95 engine for the H-class battleships in 1938. Four of these engines would power each of three shafts. The nine-cylinder engine had a 25.6 in (650 mm) bore, a 37.4 in (950 mm) stroke, and a total displacement of approximately 330,945 cu in (5,423 L). The M9Z 65/95 weighed around 248 tons (225 tonnes) and had a continuous output of 12,500 hp (9,321 kW) at 256 rpm and an emergency output of 13,750 hp (10,253 kW) at 265 rpm. The 12 engines gave a total of 150,000 hp (111,855 kW) for continuous operation and 165,000 hp (123,040 kW) for emergencies. In early 1939, 24 M9Z 65/95 engines were ordered by the Kriegsmarine, followed later in the year by another order for 24 engines. However, the orders were cancelled in late 1939, and only one test engine was built. This engine was tested in 1940 but was destroyed during an Allied air raid. A piston and rod assembly survived and is displayed in the Deutsches Museum in Munich. No H-class battleships were completed.

MAN V12Z 32-44 section

Sectional view of the MAN V12Z 32/44 engine illustrates a cylinder design similar to that used on the inline engines but with a completely different manifold arrangement. The large upper manifold was the intake, and the three other manifolds were for exhaust. Note the camshaft and fuel injection pumps on the outside of the cylinder banks.

By 1939, Pielstick used the basic cylinder design of previous engines to create larger and more powerful engines in a V configuration with 24 cylinders. The V-24 engines had a 45 degree bank angle and a new manifold arrangement, but the cylinder design and other components were similar to the previous inline engines. Positioned in the Vee of the engine was a lower exhaust manifold that collected the exhaust gases from the lower combustion chambers. Above this manifold was the intake manifold that serviced all the cylinders. Each cylinder bank had an upper exhaust manifold that collected the exhaust gases from the upper combustion chambers. These manifolds were positioned between the intake manifold and the respective cylinder bank. The fuel injection camshaft and pumps were located on the outer side of the cylinder banks. An engine-driven blower was positioned at the rear of the engine and fed air into the intake manifold.

The first V-24 was designated V12Z 42/58, and the engine was designed for the German O-class battlecruisers, with four engines powering each of two shafts. A third shaft was powered by a steam turbine. The V12Z 42/58 had a 16.5 in (420 mm) bore, a 22.8 in (580 mm) stroke, and displaced around 224,957 cu in (3,686 L). The 150.5-ton (136.5-tonne) engine produced 15,600 hp (11,633) at 450 rpm. The eight engines planned for use in the O-class would have produced a total of 124,800 hp (93,063 kW), but the O-class was cancelled, and no ships were built. One V12Z 42/58 engine was built and completed a 200-hour test run, generating a continuous 10,000 hp (7,457 kW) at 243 rpm.

A second, smaller V-24 engine was the V12Z 32/44 (sometimes called the V24Z 32/44). This engine was designed in 1940 for the Zerstörer 1942, of which one was built, the Z 51. Most sources state that the Z 51 was powered by six engines, with two engines powering each of three shafts. Other sources claim the center shaft had four engines and that the outer shafts had one engine each. The V12Z 32/44 had a 12.6 in (320 mm) bore and a 17.3 in (440 mm) stroke. The engine displaced around 99,066 cu in (1,623 L) and produced 10,000 hp (7,457 kW) at 600 rpm. A turbocharged version was planned that would increase output to 16,000 hp (11,931 kW). The V12Z 32/44 weighed 56.0 tons (50.8 tonnes), and the turbocharged version weighed 66 tons (60 tonnes). The Z 51 destroyer was nearly complete when it was sunk during an allied attack on 21 March 1945. Sources state that either four or six V12Z 32/44 engines were built. One engine was preserved and is on display in the Auto & Technik Museum in Sinsheim.

MAN V12Z 32-44 construction

The MAN V12Z 32/44 engine under construction. The blower was mounted to the rear of the engine. Note the many access panels incorporated into the engine’s crankcase.

In the early 1950s, MAN again offered their double-acting, two-stroke diesel engines. The largest of these post-war engines was the D8Z 70/120. With a 27.6 in (700 mm) bore and a 47.2 in (1,200 mm) stroke, the eight-cylinder engine displaced 430,953 cu in (7,062 L) and produced 8,000 hp (5,966 kW) at 120 rpm. More efficient engines that required less maintenance overtook the double-acting, two-stroke power plants. Today, MAN continues to build diesels for automotive, industrial, and marine use.

*Maschinenfabrik Augsburg AG worked with Rudolf Diesel. The company merged with Maschinenbau-AG Nürnberg in 1898 to become Vereinigten Maschinenfabrik Augsburg und Maschinenbaugesellschaft Nürnberg (United Machine Factory Augsburg and Machinery Construction Company Nuremberg). In 1908, the company was renamed Maschinenfabrik Augsburg-Nürnberg (MAN).

MAN V12Z 32-44

The 24-cylinder MAN V12Z 32/44 engine as displayed in the Auto & Technik Museum in Sinsheim. The cars behind the engine give an indication of the engine’s size. Note the large blower housing attached to the engine. Six of these engines were to power the Z 51 destroyer. (Technik Museum Sinsheim und Speyer image)

Sources:
“Multicylinder Combustion Engine” US patent 1,836,498 by Gustav Pielstick (granted 15 December 1931)
“Internal Combustion Engine” US patent 1,887,661 by Gustav Pielstick (granted 15 November 1932)
“Fuel Valve” US patent 1,919,904 by Gustav Pielstick (granted 25 July 1933)
“Piston for Double Acting Internal Combustion Engines” US patent 1,922,393 by Gustav Pielstick (granted 15 August 1933)
“Internal Combustion Engine” US patent 1,962,523 by Gustav Pielstick (granted 12 June 1934)
“Housing for a Vertical Combustion Power Engine” US patent 1,969,031 by Gustav Pielstick (granted 7 August 1934)
Diesel’s Engine by Lyle Cummins (1993)
Ungewöhnliche Motoren by Stefan Zima and Reinhold Ficht (2010)
Pocket Battleships of the Deutschland Class by Gerhard Koop and Klaus-Peter Schmolke (2014)
http://www.deutsches-museum.de/en/collections/machines/power-engines/combustion-engines/diesel-engines/large-diesel-engines/marine-diesel-engine-1938/
http://www.deutsches-museum.de/en/collections/machines/power-engines/combustion-engines/diesel-engines/large-diesel-engines/marine-engine-l11z-1930-1939/
http://www.hermann-historica-archiv.de/auktion/hhm61.pl?f=NR_LOT&c=6902&t=temartic_M_GB&db=kat61_m.txt

mercedes-benz-mb-518-v-20-rear

Mercedes-Benz 500 Series Diesel Marine Engines

By William Pearce

Daimler-Benz was formed in 1926 with the merger of Daimler Motoren Gesellschaft and Benz & Cie. Prior to their merger, both companies produced aircraft engines under the respective names Mercedes and Benz. After the merger, the Daimler-Benz name was used mostly for aircraft engines, and the Mercedes-Benz name was used mostly for automobile production. However, both names were regularly applied to marine engines. For clarity in this article, the name Daimler-Benz will refer to aircraft engines, and the name Mercedes-Benz will refer to marine engines.

mercedes-benz-mb-501-v-20-rear

The MB 501 shows the close family resemblance to the DB 602, but the engines had Vees of different angles and completely different valve trains. The tubes for the pushrods can be seen on the outer side of the cylinders. Note the two water pumps on the rear sides of the engine.

As Germany began its rearmament campaign in the 1930s, high-performance marine diesel engines were needed to power various motorboats. The Kriegsmarine (German Navy) turned to Mercedes-Benz to supply a series of high-speed diesel engines. These engines were part of the MB 500 series of engines that were based on the Daimler-Benz DB 602 (LOF-2) engine developed to power the LZ 129 Hindenburg and LZ 130 Graf Zeppelin II airships. The 500 series diesel engines were four-stroke, water-cooled, and utilized a “V” cylinder arrangement.

The first engine in the 500 series was the MB 500 V-12. The engine’s two cylinder banks were separated by 60 degrees. The MB 500 used individual steel cylinders that were attached to an aluminum alloy crankcase. About a third of the cylinder was above the crankcase, and the remaining two-thirds protruded into the crankcase. This arrangement helped eliminate lateral movement of the cylinders and decreased vibrations. The crankcase was made of two pieces and split horizontally through the crankshaft plane. The lower part of the crankcase was finned to increase its rigidity and help cool the engine oil.

mercedes-benz-mb-501-v-20-crackington

The crankcases of the wrecked MB 501 engines on Crackington Haven Beach have completely dissolved over the years from constant exposure to salt water. Only the engine’s steel components remain. Note the fork-and-blade connecting rods. The engine’s gear reduction can be seen on the left side of the image. (gsexr image via 350z-uk.com)

Each cylinder had two intake and two exhaust valves. The camshaft had two sets of intake and exhaust lobes per cylinder. One set was for normal operation, and the other set was for running the engine in reverse. The fore and aft movement of the camshaft to engage and disengage reverse operation was pneumatically controlled. Bosch fuel injection pumps were located at the rear of the engine and were geared to the camshaft. Each injection pump provided fuel to the cylinders at 1,600 psi (110.3 bar). Fuel was injected into the center of the pre-combustion chamber, which was in the center of the cylinder head and between the four valves. For low-speed operation, fuel was cut from one bank of cylinders.

The MB 500 had a compression ratio of 16.0 to 1. The engine used fork-and-blade connecting rods that rode on roller bearings fitted to the crankshaft. The camshaft also used roller bearings, but the crankshaft was supported by plain bearings. Speed reduction of the engine’s output shaft was achieved through the use of bevel planetary gears. Two water pumps mounted to the rear sides of the engine circulated water through the cylinder banks. Each pump provided cooling water to one cylinder bank. The pumps were driven by a cross shaft at the rear of the engine. The engine was started with compressed air.

mercedes-benz-mb-502-v-16

With the exception of the different intake manifolds, the MB 502 was nearly identical to the DB 602. Note the Mercedes-Benz emblem on the rear of the V-16 engine.

The MB 500 had a 6.89 in (175 mm) bore and a 9.06 in (230 mm) stroke. This cylinder size directly corresponded to the cylinder size used on the DB 602. The MB 500’s displacement was 4,051 cu in (66.39 L). The engine had a continuous output of 700 hp (522 kW) at 1,460 rpm and a maximum output of 950 hp (708 kW) at 1,630 rpm. Fuel consumption was .397 lb/hp/hr (241 g/kW/hr). The MB 500 was 9.6 ft (2.93 m) long, 3.2 ft (.98 m) wide, and 5.7 ft (1.73 m) tall. The engine weighed around 4,784 lb (2,170 kg). MB 500 engines were installed in Schnellboote that Germany built for Bulgaria. A Schnellboot, or S-boot, was a fast attack boat and was referred to as an E-boat (Enemy boat) by the Allies.

For more power, the MB 501 was built with two rows of ten cylinders, creating a V-20 engine. The MB 501 was similar to the MB 500, but it also had a number of differences. A 40 degree angle separated the cylinder banks, and the engine used two camshafts positioned in the upper crankcase, one on each side of the engine. Rollers on the lower end of the pushrods rode on the camshaft. Two pushrods for each cylinder extended up along the outer side of the cylinder bank to operate a set of duplex rocker arms for the two intake and two exhaust valves. The fork-and-blade connecting rods were attached to the crankshaft with plain bearings.

mercedes-benz-mb-507-v-12

The MB 507 was based on the DB 603 inverted V-12 aircraft engine. Although the engine’s architecture was similar, the MB 507 had a completely different crankcase and reduction gear than the DB 603, and it was not supercharged.

The MB 501’s bore and stroke were increased over the MB 500’s to 7.28 in (185 mm) and 9.84 in (250 mm) respectively. The engine displaced 8,202 cu in (134.40 L). The MB 501 had a continuous output of 1,500 hp (1,119 kW) at 1,480 rpm and a maximum output of 2,000 hp (1,491 kW) at 1,630 rpm. Fuel consumption was .397 lb/hp/hr (241 g/kW/hr). The engine was 12.7 ft (3.88 m) long, 5.2 ft (1.58 m) wide, 5.6 ft (1.71 m) tall, and had a weight of 9,303 lb (4,220 kg). Three MB 501 engines were installed in each 1937 class Schnellboot. Six engines were installed in each of the U-180 and U-190 submarines. However, the MB 501 engines proved unsuitable in the submarines, and they were soon replaced by MAN diesels. The remains of three MB 501 engines can be found on Crackington Haven Beach in southeast Britain. The engines belonged to Schnellboot S-89, which was surrendered to the British after World War II. S-89 slipped its tow on 5 October 1946 and was wrecked upon the shore.

The MB 502 was essentially a Daimler-Benz DB 602, except it had water jacketed intake manifolds that protruded above the engine’s Vee. The rest of the MB 502’s specifics mirrored those of the DB 602. The MB 502 was a 50 degree V-16 with a single camshaft located in the Vee of the engine. The engine had a 6.89 in (175 mm) bore and a 9.06 in (230 mm) stroke. The MB 502 displaced 5,401 cu in (88.51 L) and had a continuous output of 900 hp (671 kW) at 1,500 rpm and a maximum output of 1,320 hp (984 kW) at 1,650 rpm. The engine was 9.9 ft (3.02 m) long, 4.0 ft (1.22 m) wide, and 6.2 ft (1.90 m) tall. The MB 502 weighed 5,952 lb (2,700 kg) and had a fuel consumption at cruising power of 0.37 lb/hp/hr (225 g/kW/hr). Three MB 502 engines were installed in each 1939 class Schnellboot.

mercedes-benz-mb-511-v-20-aeronauticum

The MB 511 engine on display in the Aeronauticum museum in Germany. Note the finning on the lower half of the crankcase. On the front of the engine (left side of image) is the gear reduction with the supercharger above. The square connection above the engine is for the induction pipe. (Teta pk image via Wikimedia Commons)

The MB 507 was based on the Daimler-Benz DB 603 inverted V-12 aircraft engine, but some features from the DB 602 were incorporated. The normally aspirated MB 507 was an upright V-12 diesel engine that used monobloc cylinders and had a compression ratio of 17 to 1. A new finned crankcase was fitted that was similar to those used on other MB 500 series diesel engines. For the initial MB 507 engines, the bore was decreased from the 6.38 in (162 mm) used on the DB 603 to 6.22 in (158 mm). The stroke was unchanged at 7.09 in (180 mm). This gave the MB 507 a displacement of 2,584 cu in (42.35 L). The DB507 weighed 1,834 lb (850 kg). The engine had a continuous output of 700 hp (522 kW) and a maximum output of 850 hp (634 kW) at 2,300 rpm. An updated version of the engine, the MB 507 C, reverted back to the 6.38 in (162 mm) bore, which increased its displacement to 2,717 cu in (44.52 L). The MB 507 C produced 750 hp at 1,950 rpm and 1,000 hp at 2,400 rpm. The engine was 6.0 ft (1.83 m) long, 2.6 ft (.79 m) wide, 3.5 ft (1.06 m) tall, and had a weight of 1,742 lb (790 kg). Two MB 507 engines were used in a few LS boats (Leicht Schnellboot or Light Fast boat), and the engine was also installed in some land vehicles, such as the Karl-Gerät self-propelled mortar.

The MB 511 was a supercharged version of the MB 501 V-20 engine. The bore, stroke, and displacement were unchanged, but the compression ratio was decreased to 14 to 1. The supercharger was positioned at the front of the engine, above the gear reduction. With the supercharger, output increased to 1,875 hp (1,398 kW) at 1,480 rpm for continuous power and 2,500 hp (1,864 kW) at 1,630 rpm for maximum power. The MB 511 was 13.1 ft (4.00 m) long, 5.2 ft (1.58 m) wide, and 7.6 ft (2.33 m) tall. The engine weighed 10,406 lb (4,720 kg). Three MB 511 engines were installed in each 1939/1940 class Schnellboot. An MB 511 engine is on display in the Aeronauticum maritime aircraft museum in Nordholz (Wurster Nordseeküste), Germany. Also, the MB 511 engine was built by VEB Motorenwerk Ludwigsfelde as the 20 KVD 25 in East Germany in the 1950s. Two 20 KVD 25 engines were installed in an experimental torpedo boat.

mercedes-benz-mb-518-v-20-drawings

The sectional and cylinder drawing are for the MB 518 but were basically the same for the MB 501 and MB 511—all were 40 degree V-20 engines with individual cylinders. Note the pre-combustion chamber, valve train, and two camshafts.

The MB 512 was a supercharged version of the MB 502. Its compression was decreased to 14 to 1, but its output increased to 900 hp (1,398 kW) at 1,500 rpm for continuous power and 1,600 hp (1,864 kW) at 1,650 rpm for maximum power. The MB 512 was 10.0 ft (3.05 m) long, 4.2 ft (1.28 m) wide, and 6.3 ft (1.92 m) tall. The engine weighed 6,834 lb (3,100 kg). MB 512 engines replaced MB 502s in some Schnellboot installations.

The MB 517 diesel engine was a supercharged version of the MB 507. Returning to its DB 603 roots, the engine was inverted, but it retained the 6.22 in (158 mm) bore and 7.09 in (180 mm) stroke of the early MB 507. The supercharger boosted power from the 2,584 cu in (42.35 L) engine to 1,200 hp (895 kW) at 2,400 rpm. The MB 517 was installed in the Panzer VIII Maus V2 tank prototype.

mercedes-benz-mb-518-v-20-rear

The MB 518 was the last development of the V-20 engines. This image shows the large intercooler installed on the engine’s induction system.

The MB 518 was a continuation of the MB 511 and featured an intercooler. The large intercooler was positioned in the intake duct, above the engine and between the supercharger at the front of the engine and the intake manifolds in the engine’s Vee. The first MB 518s had a continuous output of 2,000 hp (1,696 kW) at 1,500 rpm and a maximum output of 3,000 hp (2,237 kW) at 1,720 rpm. After World War II, updated versions of the engine went into production starting in 1951. The MB 518 B had a continuous output of 2,275 hp (1,696 kW) and a maximum output of 3,000 hp (2,237 kW). The MB 518 C had a continuous output of 2,500 hp (1,864 kW) and a maximum output of 3,000 hp (2,237 kW). A turbocharger was added to create the MB 518 D. It had a continuous output of 2,900 hp (2,163 kW) and a maximum output of 3,500 hp (2,610 kW). The MB 518 engine was 14.8 ft (4.52 m) long, 5.2 ft (1.58 m) wide, and 8.0 ft (2.44 m) tall. The engine weighed around 11,332 lb (5,140 kg). MB 518 engines were used to power several different vessels for the German Navy and were also exported to 35 countries. Some of the engines are still in use today.

Schnellboot S-130, the only remaining German S-boot from World War II, was originally powered by three MB 511 engines. After the war, S-130 was reengined with two MB 518s, and one MB 511 was retained. S-130 is currently part of the Wheatcroft Collection and undergoing restoration. Four MB 518 C engines for the restoration were obtained from the Arthur of San Lorenzo, formerly known as the S39 Puma and originally built as a German Zobel Class fast patrol boat in the early 1960s.

mercedes-benz-mb-518-v-20-assembly

A number of MB 518 engines under construction show many different details. The lower crankcase half is on the floor, while the upper half is in the engine cradle; note the two camshaft tunnels. The crankshaft and its fork-and-blade connecting rods can be seen. Farther down the line is an engine with cylinder studs installed, and farther still is an engine with studs and pushrod tubes installed.

Sources:
http://alternathistory.com/dvigateli-nemetskikh-torpednykh-katerov-razrabatyvavshiesya-i-seriino-stroivshiesya-v-1920-1940-gody
https://de.wikipedia.org/wiki/Mercedes-Benz_MB_518
http://ftr.wot-news.com/2014/11/25/maus-engine-by-captiannemo/
https://ww2aircraft.net/forum/threads/opportunity-lost-db-16-cyl.21836/
http://www.german-navy.de/kriegsmarine/ships/fastattack/schnellboot1937/tech.html
http://www.german-navy.de/kriegsmarine/ships/fastattack/schnellboot1939/tech.html
http://www.german-navy.de/kriegsmarine/ships/fastattack/schnellboot1940/tech.html
http://www.wrecksite.eu/wreck.aspx?163703
http://www.shipspotting.com/gallery/photo.php?lid=1885985
http://s-boot.net/sboats-vm-forelle.html

daimler-benz-db602-zeppelin-museum

Daimler-Benz DB 602 (LOF-6) V-16 Diesel Airship Engine

By William Pearce

Around 1930, Daimler-Benz* developed the F-2 engine, initially intended for aviation use. The F-2 was a 60 degree, supercharged, V-12 engine with individual cylinders and overhead camshafts. The engine had a 6.50 in (165 mm) bore and an 8.27 in (210 mm) stroke. The F-2’s total displacement was 3,288 cu in (53.88 L), and it had a compression ratio of 6.0 to 1. The engine produced 800 hp (597 kW) at 1,500 rpm and 1,000 hp (746 kW) at 1,700 rpm. The engine was available with either direct drive or a .51 gear reduction, and weighed around 1,725 lb (782 kg). It is unlikely that the Daimler-Benz F-2 powered any aircraft, but it was used in a few speed boats.

The Daimler-Benz OF-2 diesel engine was very similar to the spark ignition F-2. Note the dual overhead camshafts in the Elektron housing above the individual cylinders. This was one of the OF-2’s features that was not incorporated into the LOF-6.

The Daimler-Benz OF-2 diesel engine was very similar to the spark ignition F-2. Note the dual overhead camshafts in the Elektron housing above the individual cylinders. This was one of the OF-2’s features that was not incorporated into the LOF-6.

In the early 1930s, Daimler-Benz used the F-2 to develop a diesel engine for airships. This diesel engine was designated OF-2 (O standing for Ölmotor, or oil engine), and it maintained the same basic V-12 configuration as the F-2. The individual cylinders were mounted on an Elektron (magnesium alloy) crankcase. Each cylinder had four valves that were actuated by dual overhead camshafts. The OF-2 had the same bore, stroke, and displacement as the F-2, but the OF-2’s compression ratio was increased to 15 to 1.

Fuel was injected into the cylinders at 1,330 psi (91.7 bar) via two, six-plunger injection pumps built by Bosch. The fuel was injected into a pre-combustion chamber located between the four valves in the cylinder head. This design had been used in automotive diesels built by Mercedes-Benz. Sources disagree on the gear reduction ratio, and it is possible that more than one ratio was offered. Listed ratios include .83, .67, and .58.

The Daimler-Benz OF-2 engine had a normal output of 700 hp (522 kW) at 1,675 rpm, a maximum output of 750 hp (559 kW) at 1,720 rpm, and it was capable of 800 hp (597 kW) at 1,790 rpm for very short periods of time. Fuel consumption at normal power was .392 lb/hp/hr (238 g/kW/hr). The engine was 74.0 in (1.88 m) long, 38.6 in (.98 m) wide, and 42.5 in (1.08 m) tall. The OF-2 weighed 2,061 lb (935 kg).

daimler-benz-lof-6-db602-diesel-rear

This view of a display-quality DB 602 engine shows the four Bosch fuel injection pumps at the rear of the engine. The individual valve covers for each cylinder can also be seen.

The OF-2 passed its type test in 1932. At the time, Germany was developing its latest line of airships, the LZ 129 Hindenburg and LZ 130 Graf Zeppelin II. These airships were larger than any previously built, and four OF-2 engines would not be able to provide sufficient power for either airship. As a result, Daimler-Benz began developing a new engine to power the airships in 1933. Daimler-Benz designated the new diesel engine LOF-6, but it was soon given the RLM (Reichsluftfahrtministerium or Germany Air Ministry) designation DB 602.

Designed by Arthur Berger, the Daimler-Benz DB 602 was built upon lessons learned from the OF-2, but it was a completely new engine. The simplest way to build a more powerful engine based on the OF-2 design was by adding two additional cylinders to each cylinder bank, which made the DB 602 a V-16 engine. The two banks of eight cylinders were positioned at 50 degrees. The 50 degree angle was selected over the 45 degree angle typically used for a V-16 engine. This gave the DB 602 an uneven firing order which helped avoid periodic vibrations.

The individual steel cylinders were mounted to the aluminum alloy crankcase. About a third of the cylinder was above the crankcase, and the remaining two-thirds protruded into the crankcase. This arrangement helped eliminate lateral movement of the cylinders and decreased vibrations. The crankcase was made of two pieces and split horizontally through the crankshaft plane. The lower part of the crankcase was finned to increase its rigidity and help cool the engine oil.

Daimler-Benz LOF-6 DB602 V-16 diesel engine

Originally called the LOF-6, the Daimler-Benz DB 602 was a large 16-cylinder diesel engine built to power the largest German airships. Note the three-pointed star emblems on the front valve covers. Propeller gear reduction was achieved through bevel planetary gears.

A single camshaft was located in the Vee of the engine. The camshaft had two sets of intake and exhaust lobes per cylinder. One set was for normal operation, and the other set was for running the engine in reverse. The fore and aft movement of the camshaft to engage and disengage reverse operation was pneumatically controlled. Separate pushrods for the intake and exhaust valves rode on the camshaft and acted on duplex rocker arms that actuated the valves. Each cylinder had two intake and two exhaust valves. Four Bosch fuel injection pumps were located at the rear of the engine and were geared to the camshaft. Each injection pump provided fuel at 1,600 psi (110.3 bar) to four cylinders. Fuel was injected into the center of the pre-combustion chamber, which was situated between the four valves. For slow idle (as low as 300 rpm), fuel was cut from one cylinder bank.

The DB 602 engine was not supercharged and had a .50 propeller gear reduction that used bevel planetary gears. The engine used fork-and-blade connecting rods that rode on roller bearings fitted to the crankshaft. The camshaft also used roller bearings, but the crankshaft was supported by plain bearings. Two water pumps were driven by a cross shaft at the rear of the engine. Each pump provided cooling water to one cylinder bank. The engine’s compression ratio was 16.0 to 1, and it was started with compressed air.

The DB 602 had a 6.89 in (175 mm) bore and a 9.06 in (230 mm) stroke, both larger than those of the OF-2. The engine displaced 5,401 cu in (88.51 L). Its maximum continuous output was 900 hp (671 kW) at 1,480 rpm, and it could produce 1,320 hp (984 kW) at 1,650 rpm for 5 minutes. The DB 602 was 105.9 in (2.69 m) long, 40.0 in (1.02 m) wide, and 53.0 in (1.35 m) tall. The engine weighed 4,409 lb (2,000 kg). Fuel consumption at cruising power was 0.37 lb/hp/hr (225 g/kW/hr).

lz-129-hindenburg

The ill-fated LZ 129 Hindenburg on a flight in 1936. The airship used four DB 602 engines housed in separate cars in a pusher configuration. Note the Olympic rings painted on the airship to celebrate the summer games that were held in Berlin.

Development of the DB 602 progressed well, and it completed two non-stop 150-hour endurance test runs. The runs proved the engine could operate for long periods at 900 hp (671 kW). Four engines were installed in both the LZ 129 Hindenburg and the LZ 130 Graf Zeppelin II. Each engine powered a two-stage compressor. Each compressor filled a 3,051 cu in (50 L) air tank to 850 psi (59 bar) that was used to start the engine and to manipulate the camshaft for engine reversing.

Plans for a water vapor recovery system that used the engines’ exhaust were never implemented, because the airships used hydrogen instead of the more expensive helium. The recovery system would have condensed vapor into water, and the collected water would have been used as ballast to help maintain the airship’s weight and enable the retention of helium. Without the system in place, expensive helium would have been vented to compensate for the airship steadily getting lighter as diesel fuel was consumed. With the United States unwilling to provide helium because of Germany’s aggression, the airships used inexpensive and volatile hydrogen, as it was readily available. The Hindenburg was launched on 4 March 1936, and the Graf Zeppelin II was launched on 14 September 1938.

Engines for the Hindenburg were mounted in a pusher configuration. In April 1936, the Hindenburg’s DB 602 engines experienced some mechanical issues on its first commercial passenger flight, which was to Rio de Janeiro, Brazil. The engines were rebuilt following the airship’s return to Germany, and no further issues were encountered. The Hindenburg tragically and famously burst into flames on 6 May 1937 while landing at Lakehurst, New Jersey.

daimler-benz-db602-musee-de-l-air-et-de-l-espace

Front view of the DB 602 engine in the Musée de l’Air et de l’Espace, in Le Bourget, France. Above the engine are the cooling water outlet pipes. In the Vee of the engine is the induction manifold, and the pushrod tubes for the front cylinders can be seen. Note the finning on the bottom half of the crankcase. (Stephen Shakland image via flickr.com)

The Graf Zeppelin II was still being built when the Hindenburg disaster occurred. Design changes were made to the Graf Zeppelin II that included mounting the DB 602 engines in a tractor configuration. The inability of Germany to obtain helium, the start of World War II, and the end of the airship era meant the Graf Zeppelin II would not be used for commercial travel. The airship was broken up in April 1940.

The DB 602 engine proved to be an outstanding and reliable power plant. However, its capabilities will forever be overshadowed by the Hindenburg disaster. Two DB 602 engines still exist and are on display; one is in the Zeppelin Museum in Friedrichshafen, Germany, and the other is in the Musée de l’Air et de l’Espace, in Le Bourget, France. Although the DB 602 was not used on a wide scale, it did serve as the basis for the Mercedes-Benz 500 series marine engines that powered a variety of fast attack boats (Schnellboot) during World War II.

*Daimler-Benz was formed in 1926 with the merger of Daimler Motoren Gesellschaft and Benz & Cie. Prior to their merger, both companies produced aircraft engines under the respective names Mercedes and Benz. After the merger, the Daimler-Benz name was used mostly for aircraft engines, and the Mercedes-Benz name was used mostly for automobiles. However, both names were occasionally applied to aircraft engines in the 1930s.

daimler-benz-db602-zeppelin-museum

Rear view of the DB 602 engine on display in the Zeppelin Museum in Friedrichshafen, Germany. A water pump on each side of the engine provided cooling water to a bank of cylinders. (Stahlkocher image via Wikimedia Commons)

Sources:
Aircraft Diesels by Paul H Wilkinson (1940)
Aerosphere 1939 by Glenn D. Angle (1940)
Diesel Engines by B. J. von Bongart (1938)
High Speed Diesel Engines by Arthur W. Judge (1941)
Diesel Aviation Engines by Paul H Wilkinson (1942)
“The Hindenburg’s New Diesels” Flight (26 March 1936)
“The L.Z.129’s Power Units” Flight (2 January 1936)
https://en.wikipedia.org/wiki/LZ_129_Hindenburg
https://en.wikipedia.org/wiki/LZ_130_Graf_Zeppelin_II

Zvezda M503 Rear

Yakovlev M-501 and Zvezda M503 and M504 Diesel Engines

By William Pearce

Just after World War II, OKB-500 (Opytno-Konstruktorskoye Byuro-500 or Experimental Design Bureau-500) in Tushino (now part of Moscow), Russia was tasked with building the M-224 engine. The M-224 was the Soviet version of the Junkers Jumo 224 diesel aircraft engine. Many German engineers had been extradited to work on the engine, but the head of OKB-500, Vladimir M. Yakovlev, favored another engine project, designated M-501.

Zvezda M503 front

Front view of a 42-cylinder Zvezda M503 on display at the Technik Museum in Speyer, Germany. Unfortunately, no photos of the Yakovlev M-501 have been found, but the M503 was very similar. Note the large, water-jacketed exhaust manifolds. The intake manifold is visible in the engine Vee closest to the camera. (Stahlkocher image via Wikimedia Commons)

Yakovlev and his team had started the M-501 design in 1946. Yakovlev felt the M-224 took resources away from his engine, and he was able to convince Soviet officials that the M-501 had greater potential. All development on the M-224 was stopped in mid-1948, and the resources were reallocated to the M-501 engine.

The Yakovlev M-501 was a large, water-cooled, diesel, four-stroke, aircraft engine. The 42-cylinder engine was an inline radial configuration consisting of seven cylinder banks positioned around an aluminum crankcase. The crankcase was made up of seven sections bolted together: a front section, five intermediate sections, and a rear accessory section. The crankshaft had six throws and was supported in the crankcase by seven main bearings of the roller type.

Each cylinder bank was made up of six cylinders and was attached to the crankcase by studs. The steel cylinder liners were pressed into the aluminum cylinder block. Each cylinder had two intake and two exhaust valves actuated via roller rockers by a single overhead camshaft. The camshaft for each cylinder bank was driven through bevel gears by a vertical shaft at the rear of the bank. All of the vertical shafts were driven by the crankshaft. The pistons for each row of cylinders were connected to the crankshaft by one master rod and six articulating rods.

Zvezda M503 Rear

Rear view of a M503 on display at Flugausstellung L.+P. Junior in Hermeskeil, Germany. The upper cylinder gives a good view of the exhaust (upper) and intake (lower) manifolds, and the engine’s intake screen can just be seen between the manifolds as they join the compounded turbosupercharger. The exhaust gases exited the top of the turbine housing. (Alf van Beem image via Wikimedia Commons)

Exhaust was taken from the left side of each cylinder bank and fed through a manifold positioned in the upper part of the Vee formed between the cylinder banks. The exhaust flowed through a turbosupercharger positioned at the extreme rear of the engine. Exhaust gases expelled from the turbosupercharger were used to provide 551 lbf (2.45 kN / 250 kg) of jet thrust.

The pressurized intake air from the turbosupercharger was fed into a supercharger positioned between the turbosupercharger and the engine. The single-speed supercharger was geared to the crankshaft via the engine’s accessory section. Air from the supercharger flowed into a separate intake manifold for each cylinder bank. The intake manifold was positioned in the lower part of the Vee, under the exhaust manifold, and connected to the right side of the cylinder bank.

The M-501 had a 6.30 in (160 mm) bore and a 6.69 in (170 mm) stroke. The engine displaced 8,760 cu in (143.6 L) and produced 4,750 hp (3,542 kW) without the turbosupercharger. With the turbosupercharger and the thrust it provided, the engine produced 6,205 hp (4,627 kW). The engine weighed 6,504 lb (2,950 kg) without the turbocharger and 7,496 lb (3,400 kg) with the turbocharger.

Zvezda M503 Bulgaria

This partially disassembled M503 at the Naval Museum in Varna, Bulgaria gives some insight to the inner workings of the engine. The turbine wheel can be seen on the far left. Immediately to the right is the air intake leading to the compressor wheel, which is just barely visible in its housing. From the compressor, the air was sent through the seven outlets to the cylinder banks. The exhaust pipe can just be seen inside the water-jacketed manifold on the upper cylinder bank. Note the studs used to hold the missing cylinder bank. (Михал Орела image via Wikimedia Commons)

By 1952, the M-501 had been completed and had achieved over 6,000 hp (4,474 kW) during tests. The program was cancelled in 1953, as jet and turbine engines were a better solution for large aircraft, and huge piston aircraft engines proved impractical. The M-501 was intended for the four-engine Tupolev 487 and Ilyushin IL-26 and was proposed for the six-engine Tupolev 489. None of these long-range strategic bombers progressed beyond the design phase.

The lack of aeronautical applications did not stop the M-501 engine. A marine version was developed and designated M-501M. The marine engine possessed the same basic characteristics as the aircraft engine, but the crankcase casting were made from steel rather than aluminum. The M-501M was also fitted with a power take off, reversing clutch, and water-jacketed exhaust manifolds.

The exact details of the M-501M’s history have not been found. It appears that Yakovlev was moved to Factory No. 174 (K.E. Voroshilov) to further develop the marine engine design. Factory No. 174 was founded in 1932 and was formerly part of Bolshevik Plant No. 232 (now the GOZ Obukhov Plant) in Leningrad (now St. Petersburg). Factory No. 174 had been involved with diesel marine engines since 1945, and Yakovlev’s move occurred around 1958. Early versions of the marine engine had numerous issues that resulted in frequent breakage. In the 1960s, the engine issues were resolved, and Factory No. 174 was renamed “Zvezda” after the engine’s layout. Many languages refer to radial engines as having a “star” configuration, and “zvezda” is “star” in Russian. Zvezda produced the refined and further developed 42-cylinder marine engine as the M503.

Zvezda M503 cross section

Sectional rear view of a 42-cylinder Zvezda M503. The cylinder banks were numbered clockwise starting with the lower left; bank three had the master connecting rod. Note the angle of the fuel injector in the cylinder and that the injector pumps were driven by the camshaft (as seen on the upper left bank).

The Zvezda M503 retained the M-501’s basic configuration. The engine had a compounded turbosupercharger system with the compressor wheel connected to the crankshaft via three fluid couplings. The compressor wheel shared the same shaft as the exhaust turbine wheel. At low rpm, the exhaust gases did not have the energy needed to power the turbine, so the compressor was powered by the crankshaft. At high rpm, the turbine would power the compressor and create 15.8 psi (1.09 bar) of boost. Excess power was fed back into the engine via the couplings connecting the compressor to the crankshaft. Air was drawn into the turbosupercharger via an inlet positioned between the compressor and turbine.

The M503’s bore, stroke, and displacement were the same as those of the M-501. Its compression ratio was 13 to 1. The M503’s maximum output was 3,943 hp (2,940 kW) at 2,200 rpm, and its maximum continuous output was 3,252 hp (2,425 kW) at the same rpm. The engine was 12.14 ft (3.70 m) long, 5.12 ft (1.56 m) in diameter, and had a dry weight of 12,015 lb (5,450 kg). The M503 had a fuel consumption of .372 lb/hp/h (226 g/kW/h) and a time between overhauls of 1,500 to 3,000 hours.

Zvezda M503 Dragon Fire

Dragon Fire’s heavily modified M503 engine under construction. Each cylinder bank is missing its fuel rail and three six-cylinder magnetos. The turbine wheel has been discarded. The large throttle body on the left has a single butterfly valve and leads to the supercharger compressor. Note that the cylinder barrels and head mounting studs are exposed and that each valve has its own port. (Sascha Mecking image via Building Dragon Fire Google Album Archive)

M503 engines were installed in Soviet Osa-class (Project 205) fast attack missile boats used by a number of countries. Each of these boats had three M503 engines installed. Engines were also installed in other ships. A heavily modified M503 engine is currently used in the German Tractor Pulling Team Dragon Fire. This engine has been converted to spark ignition and uses methanol fuel. Each cylinder has three spark plugs in custom-built cylinder heads. The engine also uses custom-built, exposed, cylinder barrels and a modified supercharger without the turbine. Dragon Fire’s engine produces around 10,000 hp (7,466 kW) at 2,500 rpm and weighs 7,055 lb (3,200 kg).

For more power, Zvezda built the M504 engine, which had seven banks of eight cylinders. Essentially, two additional cylinders were added to each bank of the M503 to create the 56-cylinder M504. The M504 did have a revised compounded turbosupercharging system; air was drawn in through ducts positioned between the engine and compressor. The intake and exhaust manifolds were also modified, and each intake manifold incorporated a built-in aftercooler. At full power, the turbosupercharger generated 20.1 psi (1.39 bar) of boost. The M504 engine displaced 11,681 cu in (191.4 L), produced a maximum output of 5,163 hp (3,850 kW) at 2,000 rpm, and produced a maximum continuous output of 4,928 hp (3,675 kW) at 2,000 rpm. The engine had a length of 14.44 ft (4.40 m), a diameter of 5.48 ft (1.67 m), and a weight of 15,983 lb (7,250 kg). The M504 had a fuel consumption of .368 lb/hp/h (224 g/kW/h) and a time between overhauls of 4,000 hours. The engine was also used in Osa-class missile boats and other ships.

Zvezda M504 56-cyl

The 56-cylinder Zvezda M504 engine’s architecture was very similar to that of the M503, but note the revised turbocharger arrangement. Wood covers have been inserted into the air intakes. Just to the right of the visible intakes are the aftercoolers incorporated into the intake manifolds.

In the 1970s, Zvezda developed a number of different 42- and 56-cylinder engines with the same 6.30 in (160 mm) bore, 6.69 in (170 mm) stroke, and basic configuration as the original Yakovlev M-501. Zvezda’s most powerful single engine was the 56-cylinder M517, which produced 6,370 hp (4,750 kW) at 2,000 rpm. The rest of the M517’s specifications are the same as those of the M504, except for fuel consumption and time between overhauls, which were .378 lb/hp/h (230 g/kW/h) and 2,500 hours.

Zvezda also coupled two 56-cylinder engines together front-to-front with a common gearbox in between to create the M507 (and others) engine. The engine sections could run independently of each other. The 112-cylinder M507 displaced 23,361 cu in (383 L), produced a maximum output of 10,453 hp (7,795 kW) at 2,000 rpm, and produced a maximum continuous output of 9,863 hp (7,355 kW) at the same rpm. The engine was 22.97 ft (7.00 m) long and weighed 37,699 lb (17,100 kg). The M507 had a fuel consumption of .378 lb/hp/h (230 g/kW/h) and a time between overhauls of 3,500 hours for the engines and 6,000 hours for the gearbox.

Zvezda engineer Boris Petrovich felt the 56-cylinder M504 engine could be developed to 7,000 hp (5,220 kW), and the M507 (two coupled M504s) could be developed to over 13,500 hp (10,067 kW). However, gas turbines were overtaking much of the diesel marine engine’s market share. Today, JSC (Joint Stock Company) Zvezda continues to produce, repair, and develop its line of M500 (or ChNSP 16/17) series inline radial engines as well as other engines for marine and industrial use.

Zvezda M507 engine

The M507 was comprised of two M504 engines joined by a common gearbox. The engine sections had separate systems and were independent of each other.

Sources:
Russian Piston Aero Engines by Vladimir Kotelnikov (2005)
Unflown Wings by Yefim Gordon and Sergey Komissarov (2013)
Ungewöhnliche Motoren by Stefan Zima and Reinhold Ficht (2010)
http://www.propulsionplant.ru/dvigateli/dizelnye-dvigateli/proizvodstvennoe-obedinenie-zvezda/dizeli-tipa-chn1617.html
https://de.wikipedia.org/wiki/Swesda_M503
http://www.zvezda.spb.ru
http://www.shipyard.lv/en/services/engineering/
http://lunohoda.net/forum/viewtopic.php?t=6067
http://www.competitiondiesel.com/forums/showthread.php?t=128242
https://en.wikipedia.org/wiki/Osa-class_missile_boat

Junkers Jumo 224

Junkers Jumo 224 Aircraft Engine

By William Pearce

Under Junkers engineer Manfred Gerlach, development of the Junkers Motorenbau (Jumo) 224 two-stroke, opposed-piston, diesel aircraft engine began when the development of the Jumo 223 stopped in mid-1942. The Jumo 223 had encountered vibration issues as a result of its construction, and its maximum output of 2,500 hp (1,860 kW) fell short of what was then desired. More power was needed for the large, long-range aircraft on the drawing board.

Junkers Jumo 224

Front and side sectional views of the Junkers Jumo 224 engine. Note in the side view how the turbochargers feed the supercharger/blower mounted in the “square” of the engine. The front of the crankshafts engage gears for the propellers, supercharger, and fuel injection camshafts.

The Jumo 224 retained the same basic configuration as the Jumo 223, with four six-cylinder banks positioned 90 degrees to each other so that they formed a rhombus—a square balanced on one corner (◇). The pistons for two adjacent cylinder banks were attached to a crankshaft located at each corner of the rhombus. The complete engine had four crankshafts, 24 cylinders, and 48 pistons.

Like the Jumo 223, the Jumo 224 engine was constructed from two large and complex castings—one for the front of the engine and one for the rear. Each casting had four banks of three-cylinders. To enable the use of contra-rotating propellers, two gears were connected to the front of each crankshaft. The first gear was the bigger of the two and engaged a large central gear at the front and center of the engine. The outer propeller shaft was connected to the front of the central gear. Through an idler gear, the small gears on all the crankshafts drove a smaller central gear that was connected to the inner propeller shaft. However, the engine could be configured for use with a single propeller rotating in either direction. The central gears provided an engine speed reduction of .35.

Junkers Jumo 223 with prop

Although never completed, the  Jumo 224 would have closely resembled a larger version of the Jumo 223 shown above.

The upper and lower crankshafts also drove separate camshafts for the left and right rows of fuel injection pumps. These camshafts as well as the injection pumps were located near the upper and lower crankshafts. Through a series of step-up gears, the left and right crankshafts powered a drive shaft for the engine’s supercharger/blower, which was located in the rear “square” of the engine.

Exhaust gases from each cylinder bank were collected by a manifold that led to a turbocharger at the rear of the engine. Each of the four cylinder banks had its own turbocharger. After passing through the turbocharger, the air flowed into the supercharger where it was further pressurized, and then into the cylinders via a series of holes around the cylinder’s circumference. As the pistons moved toward each other, the intake holes were covered and the air was compressed. Diesel fuel was injected and ignited by the heat of compression. The expanding gases forced the pistons away from each other, uncovering the intake holes (for scavenging) and then the exhaust ports, which were located near the left and right crankshafts.

At its core, the Jumo 224 was four Jumo 207C inline, six-cylinder, opposed-piston engines combined in a compact package. Using the proven Jumo 207C as a starting point cut down the development time of the Jumo 224 engine. The Jumo 224 used the same bore and stroke as the Jumo 207C. While the Jumo 224 was being designed, a Jumo 207C was tested to its limits to better understand exactly what output could be expected from the Jumo 224. Tests conducted in late 1944 found that with a 200 rpm overspeed (3,200 rpm), intercooling, modified fuel injectors, and 80% methanol-water injection, the Jumo 207C was capable of a 10 minute output at 2,210 hp (1,645 kW)—twice its standard rating of 1,100 hp (820 kW).

Junkers Jumo 207C

The Junkers Jumo 207C had an integral blower and turbocharger. The engine served as the foundation for the Jumo 224; its cylinder dimensions and various components were used.

The Jumo 224 had a bore of 4.13 in (105 mm) and a stroke of 6.30 in (160 mm) x 2 (for the two pistons per cylinder). Total displacement was 4,058 cu in (66.50 L). Without turbochargers, the engine was 111.4 in (2.83 m) long, 66.9 in (1.70 m) wide, 73.6 in (1.87 m) tall, and weighed 5,732 lb (2,600 kg). The opposed pistons created a compression ratio of 17 to 1. The planned output of the Jumo 224 was initially 4,400 hp (3,280 kW) at 3,000 rpm. However, many different combinations of intercooling, multiple-stage turbocharging, turbocompounding, and using exhaust thrust for up to 400 hp (300 kW) of extra power were proposed that gave the engine a variety of different outputs at critical altitudes up to 49,210 ft (15,000 m). Specific fuel consumption was estimated as .380 lb/hp/hr (231 g/kW/hr), and the engine’s average piston speed was 3,150 fpm (16.0 m/s) at 3,000 rpm.

From mid-1942 on, design work on the complex Jumo 224 moved ahead but often at a very slow pace. Developmental work on the 24-cylinder Jumo 222 and turbojet Jumo 004 engines took up all of the engineers’ time and Junkers Company resources, leaving little of either for the Jumo 224. The RLM (Reichsluftfahrtministerium or German Ministry of Aviation) was interested in the Jumo 224 engine for the six-engine Blohm & Voss BV 238 long-range flying boat, the eight-engine Dornier Do 214 long-range flying boat, and other post-war commercial and military aircraft projects. Even so, the RLM was more interested in the other Jumo engines, and they were given priority over the Jumo 224.

junkers-jumo-224-gears

Gearing schematic of the Jumo 224 showing left and right propeller rotation. The drawing indicates the number of teeth (z) and their height (m) on each gear.

By October 1944, the Jumo 207D engine had proven itself reliable. This engine had a bore of 4.33 in (110mm)—.20 in (5 mm) more than the Jumo 207C. Thought was given to using Jumo 207D cylinders for the Jumo 224. This change would have increased the engine’s displacement by 396 cu in (6.5 L), resulting in a total displacement of 4,454 cu in (73.0 L). However, it is not clear if the larger bore was ever incorporated into the Jumo 224.

In November 1944 the RLM ordered the material for five Jumo 224 engines. At this stage in the war, with streams of Allied bombers overhead, it was nearly impossible for Junkers to find contractors able to produce the specialized components needed for the Jumo 224 engine. Even under ideal conditions, it would be years before the Jumo 224 engine would be ready for production. By the end of the war, the first Jumo 224 engine was around 70% complete. As Allied troops neared the Junkers factory in Dessau, Germany in late April 1945, almost all of the Jumo 224 plans, blueprints, and documents were destroyed to prevent the information from falling into the hands of the Allies.

After the Junkers plant was captured, the Jumo 207C that produced 2,210 hp was sent to the United States for study. The plant, Dessau, and all of eastern Germany was handed over to the Soviet Union. In March 1946, the Soviets expressed interest in the Jumo 224 (and 223) engine, and development continued in May 1946. Gerlach was still at the Junkers plant and continued to oversee the Jumo 224. However, building the engine in post-war, Soviet-occupied Germany proved to be more of a challenge than building the engine during the war. Jumo 224 development continued but at a very slow pace. In October 1946, Gerlach and a number of others were relocated to Tushino (now part of Moscow), Russia to continue work on the Jumo 224.

Junkers Jumo 224 installation

Installation drawing for the Jumo 224. Clearly seen are the four turbochargers and contra-rotating propellers. The inside cowling diameter is listed as 72.8 in (1.85 m).

Operating out of State Factory No. 500, the group was to continue development of the Jumo 224 engine, now designated M-224. The M-224 was turbocharged, 123.1 in (3.13 m) long, 66.9 in (1.70 m) wide, 74.7 in (1.90 m) tall, and weighed 6,063 lb (2,750 kg). Gerlach believed in the M-224 and did what he could to continue its development, but the Germans did not find themselves very welcome at the factory, and nearly everything they requested was slow in coming. To make matters worse, Jumo 224 parts and equipment that the Soviets had captured and sent from Dessau never arrived in Tushino.

Junkers Jumo 224 advert

Junkers post-World War II advertisement for the Jumo 224 stating the high performance diesel aircraft engine was for large, long-distance aircraft.

Factory No. 500 was headed by Vladimir M. Yakovlev (no relation to the aircraft designer), who was hard at work on his own large diesel aircraft engine—the 6,200 hp (4,620 kW), 8,760 cu in (143.6 L), 42-cylinder M-501. Yakovlev was critical of the work done on the M-224; he felt that the engine took resources away from the M-501. With little progress on the M-224, Yakovlev was able to convince Soviet officials that his engine had the greater potential, and all development on the M-224 was stopped in mid-1948.

No parts or mockups of the Jumo 224 / M-224 are known to exist. The Yakovlev M-501 engine was run in 1952. The engine was not produced for aircraft, but it was built in the 1970s as the Zvezda M503 marine engine and is still used today for tractor pulling.

Sources:
Junkers Flugtriebwerke by Reinhard Müller (2006)
Flugmotoren und Strahltriebwerke by Kyrill von Gersdorff, et. al. (2007)
Russian Piston Aero Engines by Vladimir Kotelnikov (2005)
Opposed Piston Engines by Jean-Pierre Pirault and Martin Flint (2010)
https://ru.wikipedia.org/wiki/%D0%9C-224