Category Archives: Marine

Isotta Fraschini Asso 750 front

Isotta Fraschini W-18 Aircraft and Marine Engines

By William Pearce

In late 1924, the Italian firm Isotta Fraschini responded to a Ministero dell’Aeronautica (Italian Air Ministry) request for a 500 hp (373 kW) aircraft engine by designing the liquid-cooled, V-12 Asso 500. Designed by Giustino Cattaneo, the Asso 500 proved successful and was used by Cattaneo as the basis for a line of Asso (Ace) engines developed in 1927. Ranging from a 250 hp (186 kW) inline-six to a 750 hp (559 kW) W-18, the initial Asso engines shared common designs and common parts wherever possible.

Isotta Fraschini Asso 750 front

The direct drive Isotta Fraschini Asso 750 was the first in a series of 18-cylinder engines that would ultimately be switched to marine use and stay in some form of production for over 90 years.

The Isotta Fraschini Asso 750 W-18 engine consisted of three six-cylinder banks mounted to a two-piece crankcase. The center cylinder bank was in the vertical position, and the two other cylinder banks were spaced at 40 degrees from the center bank. The cylinder bank spacing reduced the 18-cylinder engine’s frontal area to just slightly more than a V-12.

The Asso 750’s crankcase was split horizontally at the crankshaft and was cast from Elektron, a magnesium alloy. A shallow pan covered the bottom of the crankcase. The six-throw crankshaft was supported by eight main bearings. On each crankshaft throw was a master rod that serviced the center cylinder bank. Articulating rods for the other two cylinder banks were mounted on each side of the master rod. A double row ball bearing acted as a thrust bearing on the propeller shaft and enabled the engine to be installed as either a pusher or tractor.

The individual cylinders were forged from carbon steel and had a steel water jacket that was welded on. The cylinders had a closed top with openings for the valves. The monobloc cylinder head was mounted to the top of the cylinders, with one cylinder head serving each bank of cylinders. The cylinder compression ratio was 5.7 to 1. The cylinder head was made from cast aluminum and held the two intake and two exhaust valves for each cylinder. The valves were actuated by dual overhead camshafts, with one camshaft controlling the intake valves and the other camshaft controlling the exhaust valves (except for the center bank). A single lobe on the camshaft acted on a rocker and opened the two corresponding valves for that cylinder. The camshafts for each cylinder bank were driven at the rear of the cylinder head. One camshaft of the cylinder bank was driven via beveled gears by a vertical drive shaft, and the second camshaft was geared to the other driven camshaft. The valve cover casting was made from Elektron.

Isotta Fraschini Asso 750 RC35 crankcase

The cylinder row, upper crankcase, and cylinder head (inverted) of an Asso 750 RC35 with gear reduction. The direct drive Asso 750 was similar except for the shape of the front (right side) of the crankcase. Note the closed top cylinders. The small holes between the studs in the cylinder top were water passageways that communicated with ports on the cylinder head.

Three carburetors were mounted to the outer side of each outer cylinder bank. The intake and exhaust ports of the outer cylinder banks were on the same side. The intake and exhaust ports of the center cylinder bank were rather unusual. When viewed from the rear, the exhaust ports for the rear three cylinders of the center bank were on the right, and the intake ports were on the left. The front three cylinders were the opposite, with their exhaust ports on the left and their intake ports on the right. This configuration gave the cylinders for the center bank crossflow heads, but it also meant that each camshaft controlled half of the intake valves and half of the exhaust valves. A manifold attached to the inner side of the left cylinder bank collected the air/fuel mixture that had flowed through passageways in the left cylinder head and delivered the charge to the rear three cylinders of the center bank. The right cylinder bank had the same provisions but delivered the mixture to the front three cylinders of the center bank. Presumably, the 40-degree cylinder bank angle did not allow enough room to accommodate carburetors for the middle cylinder bank.

The two spark plugs in each cylinder were fired by two magnetos positioned at the rear of the engine and driven by the camshaft drive. From the rear of the engine, the firing order was 1 Left, 6 Center, 1 Right, 5L, 2C, 5R, 3L, 4C, 3R, 6L, 1C, 6R, 2L, 5C, 2R, 4L, 3C, and 4R. A water pump positioned below the magnetos circulated water into a manifold along the base of each cylinder bank. The manifold distributed water into the water jacket for each individual cylinder. The water flowed up through the water jacket and into the cylinder head. Another manifold took the water from each cylinder head to the radiator for cooling. Starting the Asso 750 was achieved with an air starter.

Motore Isotta Fraschini Asso 750

Two views of the direct drive Asso 750 displayed at the Museo nazionale della scienza e della tecnologia Leonardo da Vinci in Milan. Note the three exhaust stacks visible on the center cylinder bank. The front image of the engine illustrates the lack of space between the cylinder banks, which were set at 40 degrees. (Alessandro Nassiri images via Wikimedia Commons)

The Isotta Fraschini Asso 750 had a bore of 5.51 in (140 mm), a stroke of 6.69 in (170 mm), and a total displacement of 2,875 cu in (47.1 L). The original, direct drive Asso 750 produced 750 hp (599 kW) at 1,600 rpm, and weighed 1,279 lb (580 kg). An improved version of the Asso 750 was soon built that produced 830 hp (619 kW) at 1,700 rpm and 900 hp (671 kW) at 1,900 rpm. This engine weighed 1,389 lb (630 kg). The direct drive Asso 750 was 81 in (2.06 m) long, 40 in (1.02 m) wide, and 42 in (1.07 m) tall.

A version of the Asso 750 with a spur gear reduction for the propeller was developed and was sometimes referred to as the Asso 850 R. Available gear reductions were .667 and .581, and the gear reduction resulted in the crankshaft having only seven main bearings. The Asso 850 R produced 850 hp (634 kW) at 1,950 rpm, and weighed 1,455 lb (660 kg). This engine was also further refined and given the more permanent designation of Asso 750 R. The 750 R had a .658 gear reduction. The engine produced 850 hp (634 kW) at 1,800 rpm and 930 hp (694 kW) at 1,900 rpm. The Asso 750 R was 83 in (2.12 m) long and weighed 1,603 lb (727 kg).

Isotta Fraschini Asso 750 rc35 front

Front view of the Asso 750 RC35. The gear reduction required new upper and lower crankcase halves and a new crankshaft, but the other components were interchangeable with the direct drive engine.

Around 1933 the Asso 750 R engine was updated to incorporate a supercharger. The new engine was designated Asso 750 RC35. The “R” in the engine’s designation meant that it had gear reduction (Riduttore de giri); the “C” meant that it was supercharged (Compressore); and the “35” stood for the engine’s critical altitude in hectometers (as in 3,500 meters). The engine’s water pump was moved to a new mount that extended below the oil pan. The supercharger was mounted between the water pump and the magnetos, which were moved to a slightly higher location. The supercharger was meant to maintain sea level power up to a higher altitude, and it provided .29 psi (.02 bar) of boost up to 11,483 ft (3,500 m). The Asso 750 RC35 produced 870 hp (649 kW) at 1,850 rpm at 11,483 ft (3,500 m). The engine was 87 in (2.20 m) long, 41 in (1.03 m) wide, 48 in (1.21 m) tall, and weighed 1,724 lb (782 kg).

In 1928, Isotta Fraschini designed a larger, more powerful engine that had both its bore and stroke increased by .39 in (10 mm) over that of the Asso 750. The larger engine was developed especially for the Macchi M.67 Schneider Trophy racer. The M.67’s engine was initially designated Asso 750 M (for Macchi) but was also commonly referred to as the Asso 2-800. The “2” designation was most likely applied because the engine was a “second generation” and differed greatly from the original Asso 750 design.

Isotta Fraschini Asso 750 rc35 rear

The single-speed supercharger on the Asso 750 RC35 is illustrated in this rear view. Note the relocated and new mounting point for the water pump. The supercharger forced-fed air to the engine’s six carburetors.

The Asso 2-800 had a bore of 5.91 in (150 mm), a stroke of 7.09 in (180 mm), and a total displacement of 3,434 cu in (57.3 L). The engine used new crossflow cylinder heads and a new crankcase. The cylinder heads had intake ports on one side and exhaust ports on the other. Air intakes for the engine were positioned behind the M.67’s spinner, with one intake on the left side for the left cylinder bank and two intakes on the right side for the center and right cylinder banks. Ducts delivered the air to special carburetors positioned between the cylinder banks. The modified engine also had a higher compression ratio and used special fuels. Under perfect conditions, the special Asso 2-800 engine produced up to 1,800 hp (1,342 kW), but it was rarely able to achieve that output. An output of 1,400 hp (1,044 kW) was more typical and still impressive. At speed, the Asso 2-800 in the M.67 reportedly made a roar like no other engine.

Isotta Fraschini made a commercial version of the larger engine, designated Asso 1000. With the same bore, stroke, and displacement as the Asso 2-800, the Asso 1000 is often cited as the engine powering the M.67. However, the Asso 1000 retained the same configuration and architecture as the Asso 750, except the Asso 1000 had a compression ratio of 5.3 to 1. Development of the Asso 1000 trailed slightly behind that of the Asso 750.

The direct drive Isotta Fraschini Asso 1000 produced 1,000 hp (746 kW) at 1,600 rpm and 1,100 hp (820 kW) at 1,800 rpm. The engine was 86 in (2.19 m) long, 42 in (1.06 m) wide, and 44 in (1.12 m) tall. The Asso 1000 weighed 1,764 lb (800 kg). Like with the original Asso 750, a gear reduction version was designed. This engine was sometimes designated as the Asso 1200 R. The gear reduction speeds available were .667 and .581. The Asso 1200 R produced 1,200 hp (895 kW) at 1,950 rpm and weighed 2,116 lb (960 kg).

Isotta Fraschini Asso 1000

The Isotta Fraschini Asso 1000 was very similar to the Asso 750. Note the intake manifolds between the cylinder banks, each taking the air/fuel mixture from one of the outer banks and feeding half of the center bank.

The Asso 750 and Asso 1000 engines were used in a variety of aircraft, but most of the aircraft were either prototypes or had a low production count. For the Asso 750, its most famous applications were the single engine Caproni Ca.111 reconnaissance aircraft (over 150 built) and the twin engine Savoia-Marchetti S.55 double-hulled flying boat. Over 200 S.55s were built, but only the S.55X variant was powered by the Asso 750. Twenty-five S.55X aircraft were built, and in 1933, 24 S.55X aircraft made a historic formation flight from Orbetello, Italy to Chicago, Illinois. The Asso 750 powered many aircraft to numerous payload and distance records. Six direct-drive Asso 1000 engines were used to power the Caproni Ca.90 bomber, which was the world’s largest landplane when it first flew in October 1929. The Ca.90 set six payload records on 22 February 1930.

Although not a complete success in aircraft, the Asso 1000 found its way into marine use as the Isotta Fraschini ASM 180, 181, 183 and 184 engines. ASM was originally written as “As M” and stood for Asso Marini (Ace Marine). The marine engines had water-cooled exhaust pipes and a reversing gearbox coupled to the propeller shaft. The Isotta Fraschini marine engines were used in torpedo boats before, during, and after World War II by Italy, Sweden, and Britain.

Isotta Fraschini ASM 184

The Isotta Fraschini ASM 184 engine with its large, water-cooled exhaust manifolds and drive gearbox. Note that the center bank only has its rear (left) cylinders feeding into the visible exhaust manifold. One of the two centrifugal superchargers can be seen at the rear of the engine. The engine is on display at the Museo Nicolis in Villafranca di Verona. (Stefano Pasini image)

The ASM 180 and 181 were developed around 1933, and produced 900 hp (671 kW) at 1,800 rpm. Refinement of the ASM 181 led to the ASM 183, which produced 1,150 hp (858 kW) at 2,000 rpm. Development of the ASM 184 started around 1940; it was a version of the ASM 183 that featured twin centrifugal superchargers mounted to the rear of the engine. The ASM 184 engine produced 1,500 hp (1,119 kW) at 2,000 rpm. Around 1950, production of the ASM 184 was continued by Costruzione Revisione Motori (CRM) as the CRM 184. In the mid-1950s, the engine was modified with fuel injection into the supercharger compressors and became the CRM 185. The CRM 185 produced 1,800 hp (1,342 kW) at 2,200 rpm.

CRM continued development of the W-18 platform and created a diesel version of the engine. Designated 18 D, the engine retained the same bore, stroke, and basic configuration as the Asso 1000 and earlier ASM engines. However, the 18 D was made of cast iron, had revised cylinder heads, and had a compression ratio of 14 to 1. The revised cylinder head was much taller and incorporated extra space between the valve springs and the valve heads. The valve stems were elongated, and a pre-combustion chamber was positioned between the valve stems and occupied the extra space in the head. Some versions of the engine have a fuel injection pump consisting of three six-cylinder distributors driven from the rear of the engine, while other versions have a common rail fuel system.

CRM 18 D engines

Four CRM 18 D engines, which can trace their heritage back to the Asso 1000. The three engines on the left use mechanical fuel injection with three distribution pumps. The engine on the right has a common fuel rail. Note the three turbochargers at the front of each engine. (CRM Motori image)

The exhaust gases for each bank were collected and fed through a turbocharger at the front of the engine (some models had just two turbochargers). Pressurized air from the turbochargers passed through an aftercooler and was then fed into two induction manifolds. Each of the manifolds had three outlets. The front and rear outlets were connected to the outer cylinder bank, and the middle outlet was connected to the center bank. For the center bank, induction air for the rear three cylinders was provided by the left manifold, and the front three cylinder received their air from the right manifold.

Various versions of the 18 D were designed, the most powerful being the 18 D BR3-B. The BR3-B had a maximum output of 2,367 hp (1,765 kW) at 2,300 rpm and a continuous output of 2,052 hp (1,530 kW) at 2,180 rpm. The engine had a specific fuel consumption of .365 lb/hp/hr (222 g/kW/h). The BR3-B was 96 in (2.45 m) long, 54 in (1.37 m) wide, 57 in (1.44 m) tall, and weighed 4,740 lb (2,150 kg) without the drive gearbox. CRM, now known as CRM Motori Marini, continues to market 18 D engines.

Isotta Fraschini Asso L180

Other than having a W-18 layout, the Isotta Fraschini L.180 did not share much in common with the Asso 750 or 1000. However, the two-outlet supercharger suggests a similar induction system to the earlier engines. Note the gear reduction’s hollow propeller shaft and the mounts for a cannon atop the engine.

In the late 1930s, Isotta Fraschini revived the W-18 layout with an entirely new aircraft engine known as the Asso L.180 (or military designation L.180 IRCC45). The Asso L.180 was an inverted W-18 (sometimes referred to as an M-18) that featured supercharging and a propeller gear reduction. The engine’s layout and construction were similar to that of the earlier W-18 engines. One source states the cylinder banks were spaced at 45 degrees. With nine power pulses for each crankshaft revolution, this is off from the ideal of having cylinders fire at 40-degree intervals (like the earlier W-18 engines) and may be a misprint. The crankshaft was supported by seven main bearings in a one-piece aluminum crankcase. The spur gear reduction turned at .66 crankshaft speed and had a hollow propeller shaft to allow an engine-mounted cannon to fire through the propeller hub. The single-speed supercharger turned at 10 times crankshaft speed.

The Isotta Fraschini L.180 had a 5.75 in (146 mm) bore and a 6.30 in (160 mm) stroke. The engine displaced 2,942 cu in (48.2 L) and had a compression ratio of 6.4 to 1. The L.180 had a takeoff rating of 1,500 hp (1,119 kW) at 2,360 rpm, a maximum output of 1,690 hp (1,260 kW) at 2,475 rpm at 14,764 ft (4,500 m), and a cruising output of 1,000 hp (746 kW) at 1,900 rpm at 14,764 ft (4,500 m). It is doubtful that the L.180 proceeded much beyond the mockup phase.

A number of Isotta Fraschini aircraft and marine engines are preserved in various museums and private collections. Some marine engines are still in operation, and the German tractor pulling group Team Twister uses a modified Isotta Fraschini W-18 engine in its Dabelju tractor.

Dabelju IF W-18 57L

The modified Isotta Fraschini W-18 in Team Twister’s Dabelju. The engine’s heads have been modified to have individual intake and exhaust ports. These crossflow heads are similar in concept to the heads used on the Macchi M.67’s engine. (screenshot of Johannes Meuleners Youtube video)

Sources:
Isotta Fraschini Aviation (undated catalog, circa 1930)
Isotta Fraschini Aviation (1929)
Isotta Fraschini Aviazione (undated catalog, circa 1931)
Istruzioni per l’uso del motore Isotta-Fraschini Tipo Asso 750 (1931)
Istruzioni per l’uso del motore Isotta-Fraschini Tipo Asso 750 R (1934)
Istruzioni per l’uso del motore Isotta-Fraschini Tipo Asso 750 RC 35 (1936)
Istruzioni per l’uso del motore Isotta-Fraschini Tipo Asso 1000 (1929)
Aeronuatica Militare Museo Storico Catalogo Motori by Oscar Marchi (1980)
Aircraft Engines of the World 1941 by Paul H. Wilkinson (1941)
Jane’s All the World’s Aircraft 1931 by C. G. Grey (1931)
https://www.t38.se/marinens-motortyper-i-mtb/
http://www.crmmotori.it/interna.asp?tema=16

timossi-verga laura 3 front

Timossi-Verga Laura 3 Hydroplane

By William Pearce

Mario Verga was a successful silk merchant born in Milan, Italy in 1910. In the late 1940s, he became a well-known Italian speedboat racer, competing in the 450 kg (992 lb) class. He left boat racing in 1950 when he married Liliana Burlazzi, but the pull of the sport was too strong for Verga to stay away.

abbate-verga laura i

The Abbate-built Laura I was a sleek design. Aluminum bodywork covered the Alfa Romeo Typo 159 engine. Note the step between the sponson and the hull.

In 1952, Verga returned to the speedboat world with his 450 kg (992 lb) class Laura I racer. Named after Verga’s young daughter, the boat was built by Guido Abbate at Lake Como and was 17 ft 3 in (5.25 m) long and 7 ft 6 in (2.28 m) wide. The Laura I was powered by an Alfa Romeo Typo (Type) 159 engine, the same type of engine that propelled auto racing legends Nino Farina and Juan Manuel Fangio to respective Formula 1 World Championships in 1950 and 1951. The “a” after the number in the boat’s name designated the Alfa Romeo engine. Verga and the Laura I captured the 450 kg (992 lb) class championship in 1952.

On 7 July 1952, and half the world away on Lake Washington’s East Channel near Mercer Island in the Pacific Northwest, Stanley Sayres and Elmer Leninschmidt set a new world absolute water speed record at 178.497 mph (287.263 km/h) in the three-point hydroplane Slo-mo-shun IV. Sayres, Ted Jones, and Slo-mo-shun IV had set the previous record at 160.323 mph (258.015 km/h) on 26 June 1950, the first post-World War II water speed record. For both records, Slo-mo-shun IV was powered by an Allison V-1710 engine.

timossi-verga laura ii

The Laura II used the same bodywork as the Laura I. However, the sponsons had no step between them and the hull, and the hull had larger fuel tanks. Note the engine’s eight exhaust stacks.

Modifications to Laura I had increased the boat’s weight, and it fell within the 800 kg (1,764 lb) class. On 29 January 1953, Verga set an 800 kg (1,764 lb) class speed record of 125.670 mph (202.247 km/h) in Laura I. He increased the record to 140.737 mph (226.495 km/h) on 15 February 1953. Both records were set on Lake Lugano.

Verga had a new 800 kg (1,764 lb) class boat built by Carlo Timossi at Lake Como. The new boat was named Laura II, and it was 17.5 ft (5.33 m) long and powered by the same Typo 159 engine that powered Laura I. Images indicate that the aluminum bodywork of Laura I was used on Laura II. Verga and the Laura II won the 800 kg (1,764 lb) class championship in Europe on October 1953 and then traveled to the United States. The Laura II won the Orange Bowl International Regatta Grand Prix held at Miami Beach, Florida in December 1953, and also set a speed record for the 151 cu in (2.47 L) hydroplane class, averaging 131.680 mph (211.919 km/h).

Verga’s speed records and the records of other Italian speedboat racers (Achille Castoldi averaged 150.188 mph / 241.704 km/h in the 800 kg class, Ferrari-powered Arno XI on 15 October 1953 at Lake Iseo) inspired the Italian Motornautical Federation to offer a £5,000,000 prize to the sportsman that surpassed Slo-mo-shun’s 178.497 mph (287.263 km/h) record. Stipulations for the prize were that the boat had to be made in Italy, powered by an Italian engine using Italian fuel, and driven by an Italian driver. Verga and a couple of other Italian racers accepted the challenge. However, the other contenders soon dropped out as complications were encountered.

timossi-verga laura 3 engines

The two Typo 159 engines mounted in their frame, as the frame is installed in the Timossi-built Laura 3. The two-stage Roots-type supercharger can be seen on the front engine. Note the propeller shaft extending below the rear engine.

For the water speed record challenge, Vega turned to Timossi for a specially-built boat, named Laura 3. Verga continued with the Typo 159 power plant but decided to use two of the engines. The Typo 159 design stemmed from the Alfa Romeo Typo 158, originally designed in 1937. Commonly called an Alfetta, for Little Alfa, the engine was a straight-eight that used a one-piece aluminum cylinder head and block mounted to a magnesium alloy crankcase. The cylinders had a 2.28 in (58 mm) bore and a 2.76 in (70 mm) stroke, making the engine’s total displacement 90 cu in (1.48 L). The Typo 159 employed a two-stage Roots-type supercharger that enabled the engine to produce an impressive 420 hp (313 kW) at 9,300 rpm.

The two Typo 159 engines were positioned back-to-back, with a 2-into-1 gearbox positioned between the engines. Combined, the engines produced over 800 hp (597 kW). The gearbox increased input speed so that the propeller shaft turned at 1.133 times engine rpm. The engines and gearbox were mounted in a special, tubular-steel frame built by Alfa Romeo. The wooden Laura 3 was a three-point hydroplane built around the steel power train frame, which was installed in the front of the boat. Aluminum body panels covered the engines and cockpit. Extending behind the cockpit was an aluminum tail that had a ground adjustable rudder for stability. The Laura 3 was 23 ft 7.5 in (7.20 m) long and 8 ft .5 in (2.45 m) wide. The boat weighed 2,028 lb (920 kg).

timossi-verga laura 3 hoist

The completed Laura 3 was an elegant hydroplane. Note the tail extending behind the cockpit. The rudder on the tail was ground-adjustable, and its angle could not be changed while the boat was in motion.

In July 1954, Verga and the Laura 3 made a series of test runs up to 100 mph (160 km/h) on Lake Pusiano. The boat was then moved to the larger Lake Iseo. The testing continued in August, and 165 mph (265 km/h) was reached. Verga made a record attempt on 28 August, hitting 170 mph (274 km/h), but a cooling issue was encountered that resulted in damage to one of the engines. Repairs were made, and testing resumed in September. At higher speeds, Verga fought against the boat’s tendency to pull to the left, but was unable to keep the Laura 3 traveling in a straight line. Efforts to correct the issue had been unsuccessful, and it was decided that modifications to the hull were needed before a record attempt could be made safely. Changes to both sponsons were made, and the boat was completed on 8 October.

timossi-verga laura 3 top

Top view of the Laura 3 illustrates the long bodywork needed to enclose the two Typo 159 engines. Note the eight exhaust stack on both sides of the cowling. The writing behind the cockpit reads Bi Motore Alfa Romeo 159 Scarfo Timossi, with “scafo” meaning “hull.”

Although full testing of the modifications had not been conducted, Verga was confident that Laura 3 could break Slo-mo-shun IV’s record. On 9 October 1954, Verga had waited until midday for the Il Trvano wind to die down over Lake Iseo and settle its waters, but the wind persisted. Verga decided to make a run anyway. As Verga and the Laura 3 sped over Lake Iseo at a speed of approximately 190 mph (305 km/h), the boat hit a couple of small waves that raised its bow. At speed, the aerodynamic forces caught the bow and lifted the Laura 3 out of the water. The boat flipped and rolled before smashing back down into Lake Iseo and sinking. Verga was instantly killed in the crash, and the Laura 3 was destroyed. Verga’s run in the Laura 3 was the last time an Italian tried to set an absolute world water speed record.

timossi-verga laura 3 front

The beautiful Laura 3 sits ready for a test run. Note the individual induction scoops for the Typo 159 engines.

In 2015, the Laura I was restored by Tullio Abbate, Guido’s son, with a non-original (2.5 L Alfa Romeo V-6) engine installed. The boat is on display at the Museo della Barca Lariana on Lake Como. The fate of the Laura II is not known. The tail of Laura 3 was salvaged and preserved.

Note: As previously mentioned, the Laura I and Laura II used the same aluminum bodywork. The boats were very similar but had different sponsons. Some sources state that Laura II set the 800 kg record in 1953. However, newsreel footage and the museum housing the preserved Laura I credit the Laura I with the record.

timossi-verga laura 3 front 2

Mario Verga prepares to make a run in Laura 3. Note the “Mario Verga” text on the front of the boat.

Sources:
Risk Takers and Record Breakers by Doug Ford (2012)
Classic Racing Engines by Karl Ludvigsen (2001)
– “The Glorious Obsession of Mario Verga” by David Tremayne, Veloce via www.lesliefield.com
– “Aqua Romeo!” by Doug Nye, Motor Sport (February 2013)
– “Southward Ho!” by Solly Hall, Motor Boating (December 1953)
http://www.vintagehydroplanes.com/boats/laura_3/laura3.html
https://www.threepointhydroplanes.it/abbate-guido-1953-62_c140_en.htm
https://www.threepointhydroplanes.it/timossi-1953-1_c229_en.htm
https://www.threepointhydroplanes.it/timossi-1954-1_c230_en.htm

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

Engelmann VS 5 side

Versuchs Schnellboot 5 (VS 5) Semi-submersible Attack Boat

By William Pearce

In the early 1930s, Rudolf Engelmann of Berlin, Germany began investigating designs to improve the hull shape of seagoing ships. Engelmann felt that a new hull shape could be devised that would significantly improve how efficiently a sea-going ship plowed through the water. At the time, the fastest ocean liners and destroyers were capable of around 35 mph (56 km/h) and 46 mph (74 km/h) respectively. Engelmann’s goals were to increase speed to 46–58 mph (74–93 km/h) with the same amount of power and enable ships to maintain higher speeds through rough seas.

Engelmann patent drawings

Rudolf Engelmann’s original concept of a semi-submersible ship is illustrated in Fig 3 and Fig 4 from his first patent (651,390). Fig 10 shows the updated design from his second patent (651,892), with the exception of line 14. Line 14 indicates the chines that were added in the third patent (651,893).

Engelmann used models to test various hull shapes. On 25 March 1934, Engelmann applied for a German patent (no. 651,390) that outlined his design. Engelmann’s ship had a shape that was very similar to a modern-day submarine—a cigar-shaped (fusiform or spindle-shaped) hull with a propeller at its end and a superstructure in the middle. However, Engelmann’s ship was not fully submersible. The hull traveled beneath the water’s surface, but the superstructure sat above the waterline. The hull’s cross section was pear-shaped, with the narrow part in the middle positioned at the waterline. The submerged hull increased the ship’s efficiency and improved the ship’s stability in rough seas. The superstructure had a streamlined form to cut through the water and slice through waves.

After the first patent, Engelmann continued to develop the semi-submersible design. He applied for two other patents in 1935 that detailed an updated hull shape. The difference between the two later patents was detailed in German patent 651,893, which included a chine added to the superstructure. Tests indicated that in rough seas, the superstructure of the previous designs had a tendency to build up a bow wave. In addition, the design’s minimal reserve buoyancy caused the ship to plow under waves. To correct these issues, the thickness of the leading edge of the superstructure was reduced, and chines were added above the waterline. The chines tapered back and were blended into the sides of the superstructure. They directed water down from the superstructure rather than over it. The additional area created by the chines increased the ship’s displacement and buoyancy with the wave action.

Engelmann VS 5 drawing

A drawing of the Versuchs Schnellboot 5 (VS 5) shows the ship’s profile as very similar to what was depicted in Engelmann’s second and third patents. Note how the ship narrowed at the waterline, which is where the hull and superstructure joined.

Engelmann’s experiments caught the attention of the Kriegsmarine (German Navy), which felt the hull design had military applications. Having the superstructure as the only part of the ship above the water decreased the ship’s detection range and also presented a small target for an enemy to hit. Combined with its high speed, a ship of Engelmann’s design could get very close to an enemy ship undetected, launch torpedoes, and then quickly retreat to a safe distance. Around 1938, the Kriegsmarine ordered a proof-of-concept prototype be built.

The prototype was designated Versuchs Schnellboot 5 (Experimental Fast Boat 5 or VS 5) and was also referred to as the Engelmann-Boot. The ship was a semi-submersible, fast-attack torpedo boat for use in coastal waters. The VS 5 was built along the lines specified in Engelmann’s third patent. Rudders and stern planes at the rear of the ship provided control. The VS 5’s armament consisted of two forward-firing, 21 in (533 mm) torpedo tubes in the bow of the hull and two 20 mm cannons atop the superstructure. However, it is not clear if the weapons were ever installed in the prototype.

Engelmann VS 5 front

The VS 5 in dry-dock, most likely before it was launched in January 1941. The completed ship looked very much like a submarine with an odd sail. Note the chines on the superstructure. Engelmann stated in his patents that the top of the superstructure could be built with an overhang so that its leading edge was angled back to the hull. This configuration would further reduce the tendency of waves to pass over the superstructure.

Power was provided by four MAN (Maschinenfabrik Augsburg-Nürnberg) L11Z 19/30 diesel engines. The L11Z 19/30 was an 11-cylinder, double-acting, two-stroke, inline engine capable of reverse operation. Each of its closed cylinders had a combustion chamber at the top and bottom of the cylinder. A single intake manifold brought air into the cylinders, where the air was directed either above or below the double-sided piston, depending on its stroke. Separate exhaust manifolds collected exhaust gases from the upper and lower combustion chambers. The engine had a 7.48 in (190 mm) bore and a 11.81 in (300 mm) stroke. Since the piston was double-acting and there was an upper and lower combustion chamber, the engine’s displacement was nearly doubled, as if it had 22 cylinders. However, the connecting rod passing through the lower combustion chamber took up around 40 cu in (.66 L) of volume. Total displacement for the upper combustion chambers was 5,710 cu in (93.56 L). Total displacement for the lower combustion chambers was approximately 5,269 cu in (86.35 L). The L11Z 19/30’s total displacement was around 10,979 cu in (179.91 L). The engine 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 four L11Z 19/30 engines were installed in two rows in the middle of the VS 5 and were connected to a common gearbox that drove a single propeller.

MAN LZ 19-30 engine side

The VS 5 was powered by four MAN L11Z 19/30 double-acting, two-stroke, 11-cylinder engines. Note the upper and lower exhaust manifolds separated by the single intake manifold. The gap under the lower exhaust manifold is where the two fuel injectors for the lower combustion chamber were installed. A covered connecting rod passed through the center of each gap. (Hermann Historica image)

The VS 5 was 160 ft 3 in (48.84 m) long and 9 ft 3 in (2.82 m) wide. The keel sat about 11 ft 10 in (3.6 m) under the waterline. The superstructure was around 66 ft (20 m) long and rose about 12 ft 6 in (3.8 m) out of the water. The VS 5 displaced some 292 tons (265 tonnes) and had a forecasted top speed of 58 mph (93 km/h). The ship had a full crew of 17. Some sources state the VS 5 could sink in shallow water to hide from enemy ships. Once submerged, it could not move (other than surfacing), as the ship did not have batteries or the capability to run its engines while underwater. However, the ability to intentionally sink is not mentioned by all sources.

Engelmann VS 5 side

For normal operation, the hull of the VS 5 was completely submerged, and only the superstructure sat above the waterline. The 12 ft 6 in (3.8 m) tall and 66 ft (20 m) long superstructure was a small target for enemy ships to detect and hit.

Construction of the VS 5 started on 1 April 1940, and the ship was built by Deutsche Schiff- und Maschinenbau Aktiengesellschaft (Deschimag) in Bremen, Germany. Deschimag was a conglomerate of eight German shipyards. The VS 5 was launched on 14 January 1941, and trouble was encountered soon after testing began. Despite the changes in Engelmann’s design, the VS 5 still had a tendency to plow under waves in heavy seas. In addition, torque from the single propeller caused the whole ship to list around 14 degrees as full power was applied. The issue was so severe that a speed of 32 mph (52 km/h) could not be exceeded because of the tilt.

The VS 5 project was apparently abandoned in 1942, and what happened to the ship is not known. Plans for a larger 661-ton (600-tonne) ship were cancelled. Twin propellers were planned for the larger ship, and their configuration would have cured the list issues caused by the single-propeller. Engelmann’s design concept was passed over as the Kriegsmarine focused on submarines and fast boats, rather than a combination of the two.

Engelmann VS 5 rear

The chine on the superstructure can easily be seen in this image of the VS 5. The VS 5 had a severe list under full power, an issue that would have been corrected if other ships of the same type had been built. The VS 5 combined elements of both a fast boat and a submarine but did not really offer any advantages over other types of ships.

Sources:
– “Schiff” German patent 651,390 by Rudolf Engelmann (granted 23 September 1937)
– “Schiff” German patent 651,892 by Rudolf Engelmann (granted 30 September 1937)
– “Schiff” German patent 651,893 by Rudolf Engelmann (granted 30 September 1937)
– “Improvements relating to the construction of Ships” GB patent 455,466 by Rudolf Engelmann (granted 21 October 1936)
– “Improvements relating to the Construction of Ships” GB patent 470,907 by Rudolf Engelmann (granted 20 August 1937)
– “High Speed Seagoing Ship” US patent 2,101,613 by Rudolf Engelmann (granted 7 December 1937)
http://ww2f.com/threads/german-submarine-vs-5.20852/
http://s-boot.net/versuchsboote%20km.html
http://strangevehicles.greyfalcon.us/VS%205.htm
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