Junkers L88

Junkers

Industry	Aerospace, Aircraft engines
Founded	1895
Headquarters	Germany

The Junkers L88 marked Junkers' initial venture into geared V-12 engines, debuting around 1930 and constructed by joining two six-cylinder L8 units. In 1932, a supercharger was integrated to enhance performance. This engine powered the world's second operational pressurized aircraft, the Junkers Ju 49, and was briefly installed in the large G 38 airliner along with its Japanese military derivative.

Design and development

In 1929, Junkers advanced their well-regarded Junkers L5 six-cylinder inline four-stroke aircraft engine by increasing its RPM and adding a reduction gear, resulting in the L8 model. Following a similar approach as with the L55—which combined two L5 engines—the L88 was created by pairing two L8s in a 60° V-12 configuration. It retained identical bore, stroke, water cooling, camshaft-driven twin inlet and exhaust valves per cylinder, and other features from the L5, while sharing a unified crankshaft housed within an updated crankcase. Approximately one year later, an exhaust-driven supercharger was incorporated to sustain power output at higher altitudes; this upgraded variant was designated the L88a.

Operational history

Production of both the L88 and L88a remained limited. The Ju 49 high-altitude experimental aircraft initially flew in 1932 equipped with the L88; by 1934, it was upgraded to use the supercharged L88a. The two G38 aircraft employed multiple engine types during their service lives, including both the L88 and its supercharged counterpart. The heavy bomber version of the G 38, manufactured under license in Japan as the Mitsubishi Ki-20, originally utilized L88a engines but later transitioned to Jumo 204 diesel powerplants, consistent with changes made on the G 38s.

Applications

• Junkers G 38, equipped with both L88 and L88a
• Junkers Ju 49, utilizing both L88 and L88a
• Mitsubishi Ki-20, powered by L88a