Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Thanks for the information . But this raises another thought. If the steam is expanding as it cools, then it stands to reason that you would want to cool it as much as possible while in the cylinder. That would mean that thinner walled cylinders might be advantageous.

  This whole question comes to mind because I have on hand several double acting pneumatic cylinders that I thought of using for this build. the walls of the cylinders are about 1/8th of a inch thick. They are rated at 250 psi of air pressure. I have submerged them in a heated oil bath at 300 degrees with no apparent lost of integrity .
  I was thinking that steam pressure of less than 50 psi should make them produce. that would keep the temperature down to approximately 250 degrees or less. The available long stroke of 8 inches and bore of 1-1/4 should allow me to make the rpm output rather slow .
   I might have issues with the flywheel / paddlewheel setup not having enough inertia to carry the crank through its cycle However with the paddles in the water and the boat in motion the water hitting the paddles might help.
 So for now the question still stands.
 Does the walls of the cylinders need to be thick to hold the heat, and aid in limiting condensation inside of the cylinders? or are they that thick just for appearance . or maybe some other reason ?