| L5 | |
|---|---|
 | |
| Junkers L5 on display at the Junkers Museum | |
| 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 |
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.
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]
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]
Data from [2]
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