Junkers L5

L5
Junkers L5
Type Inline aircraft engine
Manufacturer Junkers Motorenbau GmbH (Jumo)
First run 1922[1]
Major applications Junkers F.13
Number built >1,000[2]
Variants Junkers L55
Developed into Junkers L8

The Junkers L 5 was a six-cylinder, water-cooled, inline engine for aircraft built in Germany during the 1920s. First run in 1925, it was a much enlarged development of the Junkers L2, in turn a licensed development of the BMW IV.

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 cylinder[2]driven by an overhead camshaft, twin spark plugs and twin magnetos. The splash 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.[2]

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.[2]

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.[2] Many of these powered the Junkers F.13 and its derivatives like the W 33, which dominated world air transport in the mid-1920s.[3]

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.[2]

Variants

Applications (L5)

Specifications (Jumo L 5)

Preserved Junkers L 5 engine on display at the Junkers Museum

Data from [2]

General characteristics

Components

Performance

Cruise - 208.8 kW (280 hp)

See also


Related lists

References

  1. ↑ Gunston, Bill (1989). World Encyclopaedia of Aero Engines (2 ed.). Wellingborough: Patrick Stephens Ltd. p. 85. ISBN 1-85260-163-9.
  2. 1 2 3 4 5 6 7 8 9 Kay, Antony (2004). Junkers Aircraft & engines 1913-1945. London: Putnam Aeronautical Books. pp. 264–5. ISBN 0-85177-985-9.
  3. ↑ Kay (2004) Ibid, p. 62
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