Letters: More on the Junkers Opposed Piston Diesel Engine

The Junkers opposed-piston diesel engine, explained by C.H. Wendel.

| October 2008

In reference to August 2008's "The Man Behind the Books": I am confused on the line, "a single-cylinder opposed-piston engine diesel." Opposed to what? Another piston? No, "single piston." I hope you can explain more on the Junkers diesel. How about construction plans? Sounds like a good project to build. 

Bob Comer

Regarding the Junkers opposed-piston diesel engine design: It was proposed by Hugo Junkers, of Germany, prior to 1911. The Fairbanks-Morse OP engine was introduced in 1933. Some engineers claimed Fairbanks pirated the Junkers design.

The schematic above shows the basic design, two pistons coming together, with ignition between the piston heads. The top piston was connected through rods to the crank, the latter having three throws.

Junkers was the first to apply a modified opposed-piston engine to aircraft, building some diesel-powered aircraft during World War I. The partial cross-section photo shows a Junkers aircraft diesel of World War II. The Ju205 was a formidable heavy bomber.

During World War II, the Junkers factory at Dessau was completely destroyed.