Junkers L88

From Wikipedia, the free encyclopedia
Jump to: navigation, search
L88
Type 4-stroke petrol V-12 watercooled aircraft engine
National origin Germany
Manufacturer Junkers Motorenbau GmbH (Jumo)
First run 1930-1
Developed from Junkers L8

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 first pressurised aircraft, the Junkers Ju 49 and, for a while, in the large G 38 airliner and its Japanese built military version.

Design and development[edit]

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]

Operational history[edit]

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.[2] The two G38s used a variety of engines including both the L88 and the L88a.[1] 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 504 diesel engines.[3]

Applications[edit]


Specifications[edit]

Data from Kay (2004) pp.266

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: 45.8 L (2,795 cu in)
  • Dry weight: 510 kg (1,125 lb)

Components

  • 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

Performance

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

See also[edit]

Related lists

References[edit]

  1. ^ a b Kay, Antony (2004). Junkers Aircraft & engines 1913-1945. London: Putnam Aeronautical Books. p. 266. ISBN 0-85177-985-9. 
  2. ^ Kay (2004) Ibid, p. 95
  3. ^ Kay (2004) Ibid, p. 88