The Junkers L 5 was a six-cylinder,

water-cooled Cooling tower and water discharge of a nuclear power plant Water cooling is a method of heat removal from components and industrial equipment. Evaporative cooling using water is often more efficient than air cooling. Water is inexpensive and no ...

, inline engine for aircraft built in Germany during the 1920s. First run in 1925, it was a much enlarged development of the

Junkers L2 The Junkers L2 was Junkers' first water-cooled four-stroke engine and the first to be built on a production line, though only 58 were made. It was a six-cylinder inline engine and powered many Junkers aircraft until replaced by the more powerful ...

Design and development

The Junkers L5 was a development of Junkers' first water-cooled engine, the L2, but at four times the swept volume was a much more powerful engine. It was a water-cooled upright inline 6-cylinder unit, four-stroke and petrol-fuelled, with a capacity of nearly 23 litres. It adopted some of the L2 features, having twin exhaust and inlet valves in each cylinderdriven by an overhead camshaft, twin

spark plugs A spark plug (sometimes, in British English, a sparking plug, and, colloquially, a plug) is a device for delivering electric current from an ignition system to the combustion chamber of a spark-ignition engine to ignite the compressed fuel/air ...

and twin

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s. The

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component of the L2's lubrication was abandoned in favour of a completely forced recirculating system. The twin carburettors of the L2 were replaced with a single float chamber, dual-venturi model. Like the L2, the L5 was a direct drive engine. The compression ratio of the standard version was 5.5:1, but variants had other ratios to cope with fuels with octane ratings between 76 and 95. The G series introduced carburettor heating together with an hydraulically damped mounting system. There were also choices of starting system, from inertial or compressed air systems to the traditional hand swinging.

Operational history

The L5 proved to be reliable and became the engine of choice for most Junkers aircraft in the mid-1920s as well as powering aircraft from other German manufacturers. Many of these powered the

Junkers F.13 The Junkers F 13 was the world's first all-metal transport aircraft, developed in Weimar Republic, Germany at the end of World War I. It was an advanced Cantilever#Aircraft, cantilever-wing monoplane, with enclosed accommodation for four passenge ...

and its derivatives like the W 33, which dominated world air transport in the mid-1920s.Kay (2004), p. 62 The best demonstration of the reliability of the L5 was given by the unit which powered the single-engined W 33 ''Bremen '' in the first fixed wing east to west crossing of the Atlantic in April 1928. For this flight the compression ratio was raised to 7:1 to provide sufficient power for the heavily fuelled aircraft at take off. In July 1925 a W 33 powered by a L5 stayed aloft for 65 h 25 min, with a fuel consumption of 35.6 kg/h.

Variants

*L5 many variants including a variety of compression ratios, power output levels and starting systems. * L55 an upright V-12 built from two L5s on a common crankshaft. *L8 a significant 1929 development with the same swept volume but cruising at 2,100 rpm and delivering 354 hp; take off power was 413 hp. The output was geared down at ratios between 2.47:1 and 1.44:1 to enhance propeller efficiency. Only a few were produced, powering early configurations of the

Junkers G 38 The Junkers G.38 was a large German four-engined transport aircraft which first flew in 1929.EADS Two examples were constructed in Germany. Both aircraft flew as a commercial transport within Europe in the years leading up to World War II. Durin ...

as outer engines, with two L55s inboard. * L88 an upright V-12 built from two L8s on a common crankshaft.

Applications (L5)

Albatros L 73 __NOTOC__ The Albatros L 73 was a German twin-engined biplane airliner of the 1920s. Of conventional configuration, it featured a streamlined, boat-like fuselage and engine nacelles. All four manufactured aircraft of that type were operated by ...

Albatros L 75 __NOTOC__ The Albatros L 75 ''Ass'' (German: "Ace") was a German trainer biplane of the 1920s. Of conventional configuration, it seated the pilot and instructor in separate, open cockpits. The wings were single-bay, equal-span, and had a sligh ...

* Albatros L 83 Adler *

Focke-Wulf A 32 The Focke-Wulf A 32 ''Bussard'' (German: "Buzzard") was a small airliner produced in Germany in the early 1930s. It was developed rapidly at the request of NOBA when Messerschmitt was unable to deliver aircraft on schedule. Based closely on the ...

Heinkel HD 42 The Heinkel HD 42 50, later designated the Heinkel He 42 was a German two-seat biplane seaplane originally designed for the ''Deutsche Verkehrsfliegerschule'', and later built for the German ''Luftwaffe''. The aircraft was used until the end of W ...

Heinkel He 50 The Heinkel He 50 was a German World War II-era dive bomber, originally designed for the Imperial Japanese Navy. Serving in ''Luftwaffe'' prewar dive-bombing units, the He 50 served until almost the end of World War II as a night harassment bomb ...

Junkers F 13 The Junkers F 13 was the world's first all-metal transport aircraft, developed in Germany at the end of World War I. It was an advanced cantilever-wing monoplane, with enclosed accommodation for four passengers. 322 planes of the type were manufa ...

Junkers A 20 Junkers A 35 was a two-seater cantilever monoplane, used for postal, training and military purposes. The aircraft was designed in the 1920s by Junkers in Germany and manufactured at Dessau and by AB Flygindustri in Limhamn, Sweden and conversions ...

Junkers A 35 Junkers A 35 was a two-seater cantilever monoplane, used for postal, training and military purposes. The aircraft was designed in the 1920s by Junkers in Germany and manufactured at Dessau and by AB Flygindustri in Limhamn, Sweden and convers ...

Junkers G 23 The Junkers G 24 was a German three-engine, all-metal low-wing monoplane passenger aircraft manufactured by Junkers from 1925. Junkers F 24 was the designation for single-engine versions of the same aircraft. Design and development The increas ...

* Junkers G 24 *

Junkers K 30 The Junkers G 24 was a German three-engine, all-metal low-wing monoplane passenger aircraft manufactured by Junkers from 1925. Junkers F 24 was the designation for single-engine versions of the same aircraft. Design and development The increas ...

Junkers G 31 The Junkers G 31 was an advanced tri-motor airliner produced in small numbers in Germany in the 1920s. Like other Junkers types, it was an all-metal, low-wing cantilever monoplane. In the mid-1920s, the all-metal construction and an aerodynamical ...

Junkers W 33 The Junkers W 33 was a German 1920s single-engine low-wing monoplane transport aircraft that followed Junkers standard practice making extensive use of corrugated aluminium alloy over an aluminium alloy tube frame, that was developed from the s ...

Messerschmitt M 24 __NOTOC__ The Messerschmitt M 24, otherwise known as the BFW M.24, was an airliner developed in Germany in the late 1920sTaylor 1989, 651 as a further development in the series of designs produced by Messerschmitt, based on the M 18.''The Illust ...

* Rohrbach Ro.VIII

Specifications (Jumo L 5)

Junkers L 5 im Technikmuseum Hugo Junkers Dessau 2010-08-06 02

References

Bibliography

* *

External links

The Hugo Junkers Homepage
* http://www.oldengine.org/members/diesel/Duxford/germaer1.htm {{Junkers Jumo aeroengines 1920s aircraft piston engines L5