This is beginning to get really interesting. You can see the purchased "swivel air fitting" ($10.00 at Princess Auto) at the top of the steel center tube. The pale yellow tube that reaches from the air swivel fitting out towards the Doodlebug is a rigid 5/16" O. D. copper tube. It has a hinged joint where it attaches to the Doodlebug. It also has a short section of 3/16" tube soldered into the outboard end of it, which is connected with a peice of clear neoprene flex tubing to the infeed pipe on the cylinder of the engine. Air supply will come into the bottom of the center pipe thru the bottom, underneath the plywood disk. The rigid pale yellow peice of 5/16" copper tubing will act as a radius arm, and air will flow thru it out to the engine. This way the engine should run around the perimeter of the plywood disc all day without twisting any lines off.
