Re: Diesel aircraft engines

From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
Date:         01 Aug 96 13:34:27 
References:   1 2 3
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[Please followup to *one* of sci.aeronautics.airliners or rec.railroad
unless it really does apply to both groups.  Thanks!]

>What made the Junkers Aircraft Diesels so unusual was the unique
>configuration : an opposed piston two-stroke turbo-supercharged
>diesel. Unlike a Subaru or VW auto engine, there were 2 pistons
>in each cylinder (driven from opposing sides via synchronized

Fascinating.  Fairbanks-Morse (of Beloit, Wisconsin) built Diesel
locomotives with similar engines, derived from their submarine
engines.  I was unaware of any other manufacturer having built an
engine using the opposed-piston design.

On (er, under) the water, Fairbanks-Morse did very, very well,
powering the majority of the U.S. submarines in World War II.  In
the locomotive field they were less successful.  Introduced in the
early 1950s, their Trainmaster (H-24-66) was far more powerful than
anything FM's competitors would offer for years to come, and their
locomotives were generally respected as solid and reliable.

The main problem was that when you *did* have to overhaul them or
do heavy maintenance, it was a difficult and expensive job.  Other
locomotive Diesels can have a power assembly (cylinder, piston, and
connecting rod) replaced individually, and I'd imagine the same is
true of a aircraft radial. The design of the OP engine requires
removal of one crankshaft to get into a cylinder.  Beyond these and
more minor maintenance problems, they were doomed by a small market
share.  Just as most airlines usually get rid of oddball fleets after
mergers to reduce costs, FM's locomotives lost out in the long run.

Karl Swartz	|Home
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