THE AFRICAN QUEEN

   The movie "The AFRICAN QUEEN" in 1952 made a big impression on me, but only
the boat. Not the mushy stuff.  Then I saw the movie again recently, plus NBC
ran a clip about the restored QUEEN on Key Largo.  So we headed south for the
two hour drive and saw her up close.  Really impressive, but also very
complicated.  We wondered how a smaller, simpler woodburning steamboat could
be made using parts commonly found today and using only modest shop equipment.
The AFRICAN QUEEN from the movie.
The fully-restored AFRICAN QUEEN.
The AFRICAN QUEEN steam engine.
The functions of the engine parts.
   A pump to put mineral oil on the cylinders at the end of a working day
   B the steam inlet valve from the boiler (throttle)
   C part of the pump that forces condensed steam back into the boiler
   D the other part of the condensate pump
   E chain from the prop shaft to the condensate pumps
   F one of two cylinder drains
   G Stephenson valve linkage (changes prop rotation for forward or reverse)
NBC TV clip of the restored AFRICAN QUEEN (19MB).
   A piston air compressor can be converted into a steam engine.  A 1963 issue
of "Steamboats and Modern Steam Launches" Sept-Oct explains how to do that.
The result is a true chug-chug-chug steam engine. But our modest 9 x 20 lathe
and mini-mill could not handle that job.  So other options were tried.
   We first tried using steam in a Husky 3/8" air drill.  It has a very robust
planetary gear reduction and so drills 3/8" holes in 3/8" steel easily.  It
also works just as well on CO2. But using our CO2-cylinder test boiler proved
that 90 PSI steam does not work in air tools that have a sliding-vane rotary
motor when the steam condenses back into (incompressible) water.
   Then a pneumatic paint shaker with a large, robust piston was adapted for
steam. But it turned out to have a leaky piston-ring/cylinder-wall seal.  So
we moved on to door closers, the Goldilocks discovery!  See the next page.