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

Gil, fine machine!

What's the phasing on the engine?

I'd be very interested in seeing the difference between air vs steam.

 
What I noticed when running my make shift Märklin compound: When 180 phase I don't think running on air  impact performance badly* even though under steam the subsequent expansion wouldn't be there. But at 90 degrees,  noticeable impact. My setup has a timing chain but your fine engine is more suitably engineered.

*My air compressor regulator isn't very accurate so it wasn't exactly the same pressure.

I believe all triples are constructed with crank arms 120 degrees apart. Compounds are 90 degrees apart. I am ready to be corrected if wrong. Receiver size (volume) is also important in delivering the correct charge to the next cylinder in line. All scale model triple expansions I have seen have the same 120 degrees offset of crank arms whether built for air or steam. Remember they also should get some power from the final expansion from a vacuum created by the condenser. You can replicate this by putting a vacuum on the exhaust of your compound.