Junkers L88
{{Short description|German twelve cylinder engine}}
| {{Infobox Aircraft Begin
| name=L88 | image= | caption= }}{{Infobox Aircraft Engine |type=4-stroke petrol V-12 watercooled aircraft engine |manufacturer=Junkers Motorenbau GmbH (Jumo) |designer= |national origin=Germany |first run=1930-1 |major applications= |produced= |number built= |program cost= |unit cost= |developed from=Junkers L8 |variants with their own articles= }} |
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.
Design and development
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.Kay{{rp|266}}
Operational history
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.{{rp|95}} The two G38s used a variety of engines including both the L88 and the L88a.{{rp|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.{{rp|88}}
Applications
- Junkers G 38, both L 88 and L 88a
- Junkers Ju 49, both L 88 and L 88a
- Mitsubishi Ki-20, L88a
Specifications
{{pistonspecs|
|ref=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)
|length=
|diameter=
|width=
|height=
|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
|turbocharger=
|fuelsystem=
|fueltype=petrol
|oilsystem=forced
|coolingsystem=water-cooled
|power=cruise 675 hp (503 kW) at 1,870 rpm, take-off 788 hp (587 kW)
|specpower=
|compression=
|fuelcon=
|specfuelcon=
|oilcon=
|power/weight=
|designer=
|reduction_gear=choice between 2.47:1 to 1.44:1
|general_other=
|components_other=
|performance_other=
}}
See also
References
{{Reflist}}
Bibliography
- {{cite book |last1=Gunston |first1=Bill |title=World Encyclopedia of Aero Engines: From the Pioneers to the Present Day |date=2006 |publisher=Sutton |location=Stroud, UK |isbn=0-7509-4479-X |edition=5th}}
- {{cite book |title= Junkers Aircraft & Engines 1913–1945|last=Kay|first=Antony| year=2004|publisher=Putnam Aeronautical Books |location=London |isbn=0-85177-985-9}}
{{Junkers Jumo aeroengines}}