compressor for Commer knocker fans!

I bought this compressor a year or so ago but recently had to go and collect it as my friend is having trouble with his storage yard. I didnt want any distractions at the moment as I am busy working on my Commer cab but have decided to have a coupkle of days playing with it.
The compressor is a Junkers free piston type. It has a single cylinder opposed piston engine like the Commer but with no crank! Instead ther is a two stage air compressor piston connected directly to each of the engine pistons. It runs (or will do!) at 800 power strokes/min and pdoduces 120 cfm fad at 100psi The engine is rated at 35hp the engine bore is 4.35" and the stoke is 10" at full load and 8.4" at no load. Some of the compressor air is used for scavenging. It uses compressed air for starting at c.400psi. The starting air receiver is at the bottom of the photo.
Rod

Dreamed of a "no rotating part engine" when I was a kid, thought it could power an aircompressor or a diaphragm water pump.
Never gave it another thought until maybe 40 years later, was looking through the WW2 war museum at Hania on Crete.
Bugger me here was my invention, massive great air compressor from a German sub.
Yep a Junkers, big bastard.
Think I was born in the wrong times.
BUT
It's back..........
www.freepistonpower.com/

What a snazzy Little Gadget.
Would love to have this to play with.