Thanks for the comments, Andrew. But this engine was built before I was even aware of precision model engineering, and internet forums, so there were no build notes or photos and the design was basically 2D Crap-O-Cad. I had sold my business, bought a sailboat, and gone cruising with the intent of getting as far away as possible from computers, (the basis of my business) as possible, but a few months confinement to a marina, with restricted physical activity while recovering from prostate cancer surgery left me with time to think.
This is the result. It was mostly built using a Unimat SL100 and a micro butane torch. There are no existing plans so the best I can do give a quick explanation.
The air pressure enters a tubular shaft at the right end. It is distributed through a rudimentary rotary valve ( a hole in the side of the tube) through a drilled passage in the end plate to the piston at the bottom of the engine and through the piston to the expansion chamber at the apex of the cylinder. The piston in the left end of the cylinder also has an air passage that connects it to exhaust out of the shaft at the left end, but because the exhaust valve, identical to the intake valve but 180? opposite, is closed, the air pressure drives the two pistons apart.
This is just like an elbow engine except that in an elbow engine there are tow expansion chambers, one at each end of the piston, and in this engine there is a single expansion in the middle. The expansion causes the opposed bank of cylinders to rotate.
When the cylinder and pistons have rotated through 180? degrees to the top of the engine, the exhaust valve in the left end opens and remains open as that cylinder rotates through 180? the air is exhausted through the hollow shaft at the left. Uniflow is achieved as air enters at one end of the engine and exhausts through a separate valve at the opposite end. Five pairs of pistons with five bent cylinders means five power strokes per revolution.
I really hope that I have made that crystal clear but if you are interested enough to try to follow it and get bogged down somewhere, just ask and I will try to clarify.
Jerry
