The most widely used of Junkers' series of six-cylinder inline four-stroke aircraft engines was the L5, first run in 1922. This engine was used in 1927 as the basis of the 665 hp L55, which had two banks of six cylinders aligned at 60°. These banks had the same bore, stroke, camshaft operated twin pairs of valves per cylinder, watercooling etc. as the L5, driving new a common crankshaft in a revised crankcase. A supercharger was added after a year to improve high altitude power.^{[1]: 265–266}

The L55 is only known to have powered two aircraft for certain, the Junkers G 38 early in its career^[1]: 84 and the Junkers A 32.^[1]: 62 The first G 38 originally had two L55s inboard plus two L8 engines. The high altitude research Junkers Ju 49 may have used the L55 at the start of its flight programme.^{[1]: 265–266} The L55 was rapidly replaced by the L88 in both the G 38 and Ju 49.

• Junkers A 32
• Junkers G 38
• Junkers Ju 49, possibly

Data from Kay (2004) pp.265-6

General characteristics

• Type: upright V-12 water-cooled 4-stroke piston engine
• Bore: 160 mm (6.30 in)
• Stroke: 190 mm (7.48 in)
• Displacement: 45.84 L (2,797 cu in)
• Length: 2.287 m (7 ft 6 in)
• Width: 1.273 m (4 ft 2 in)
• Height: 0.84 m (2 ft 9 in)
• Dry weight: 585 kg (1290 lb)

Components

• Valvetrain: two inlet and two exhaust valves per cylinder, one overhead camshaft on each bank
• Supercharger: added to rear of engine in 1928
• Fuel type: petrol
• Oil system: forced
• Cooling system: water-cooled
• Reduction gear: none; direct drive

Performance

• Power output: cruise 665 hp (495 kW) at 1,700 rpm, take-off 690 hp (514 kW)
• Fuel consumption: 150 kg/h (331 lb/hr)

Related lists

• List of aircraft engines

• Gunston, Bill (2006). World Encyclopedia of Aero Engines: From the Pioneers to the Present Day (5th ed.). Stroud, UK: Sutton. ISBN 0-7509-4479-X.
• Kay, Antony (2004). Junkers Aircraft & Engines 1913–1945. London: Putnam Aeronautical Books. ISBN 0-85177-985-9.