Junkers L88

The Junkers L88 was Junkers' first geared V-12 engine, appearing c.1930 and based on a pair of 6-cylinder L8s. In 1932 a supercharger was added. It was used in the world's second working pressurised aircraft, the Junkers Ju 49 and, for a while, in the large G 38 airliner and its Japanese built military version.

In 1929 Junkers developed their successful Junkers L5 6-cylinder inline 4-stroke aircraft engine into the L8 by increasing its rotational speed and gearing down the output shaft. Just as the L55 V-12 was made by combining two L5s, the L88 combined two L8s into a 60° V-12. This had the same bore, stroke, camshaft operated twin pairs of valves per cylinder, watercooling etc. as the L5, like the L55 driving a common crankshaft in a revised crankcase. An exhaust driven supercharger was added after a year to maintain power at high altitude and this version was named the L88a.^[1]: 266

Only a few L88 and L88a engines were built. The Ju 49 high altitude research aircraft initially (1932) flew with the L88 and later (1934) with the supercharged L88a.^[1]: 95 The two G38s used a variety of engines including both the L88 and the L88a.^[1]: 266 The heavy bomber variant of the G 38, built in Japan as the Mitsubishi Ki-20 was initially powered by L88as. These were replaced, as on the G 38s, by Jumo 204 diesel engines.^[1]: 88

• Junkers G 38, both L 88 and L 88a
• Junkers Ju 49, both L 88 and L 88a
• Mitsubishi Ki-20, L88a

Data from Kay (2004) pp.266

• Type: upright V-12 water-cooled 4-stroke piston engine
• Bore: 160 mm (6.30 in)
• Stroke: 190 mm (7.48 in)
• Displacement: 45.8 L (2,795 cu in)
• Dry weight: 510 kg (1,125 lb)

• Valvetrain: two inlet and two exhaust valves per cylinder, one overhead camshaft on each bank
• Supercharger: exhaust gas driven
• Fuel type: petrol
• Oil system: forced
• Cooling system: water-cooled
• Reduction gear: choice between 2.47:1 to 1.44:1

• Power output: cruise 675 hp (503 kW) at 1,870 rpm, take-off 788 hp (587 kW)

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.