A local fellow had asked for, I printed and he purchased an HO version of the EMD 567 and now he asked if I could do a Fairbanks Morse Opposed Piston Engine. I'm about 3/4 through the design work and I'll again produce O and HO versions. I'm using the same alternator as I did with the 567. No point in reinventing the wheel. Loco FMs are simpler than stationary or marine versions. Most of the latter have some pretty elaborate turbo-chargers on the end opposite the scavenge blower, that large structure on the near end. Like EMDs, FMs were essentially 2-strokes, but in FMs case there were no valves are all and no cylinder head. The combustion chamber was virtual, being the confined space when the two opposing pistons closed on one another. They didn't touch, but created a small compression space where the dual injectors would spray fuel oil. EMDs were easier to service and were thus more favored by railroads. FMs were very efficient and high power and are still being manufactured for stationary and marine use.
To pull the cylinders in the FM you had to remove all those top covers and then pull the upper crankshaft. This was impossible to do effectively in the field. It was easier to just pull the entire engine and take to a service center. EMDs on the other hand, could have a power pack removed in a half hour. The power pack consisted of the individual head, the cylinder liner, piston and connecting rod. There was provision to mount a hand-operated crane right on the cylinder head so two guys could remove and replace the power pack in the field.
FMs are a uniflow engine. There were two sets of ports cut into the cylinder liner. The upper ports opened a bit later than the lower ones and closed later. Upper was intake air and lower was exhaust. As the bottom piston uncovered the exhaust it would flow to the exhaust box surrounding the cylinder under it's own pressure. Then the upper piston uncovered the top ports allowing incoming air to flood the cylinder. It was under some pressure from the scavenge blower and the pushed the remaining exhaust out. All gas flow was in the same direction from top to bottom, thus the term, "uniflow". It's very simple. The complexity was the bevel gears and shaftings to tie and synchronize the upper crank's motion with the lower one. Power take off came from the lower crank. Because all the cylinders were in line, the engines were rather skinny.
This next image shows how I arranged and scaled the drawings to rough out the shape. In addition to top, front and side views, there is also a good section drawing at the back that gave me accurate shaping of the various bumps and channels. In stationary and marine use, the injectors and associated camshafts were exposed as I showed in an earlier post. In loco use they were covered with removable hatches which I decided to draw. It will be easier on the printing end. I may steal my water pumps from the EMD so I don't have to draw them again. They're pretty generic. The front view in this image is a stationary engine and has all those turbos. There are two exhaust headers, one of each side so there are two sets of turbo chargers too. The loco version just has two big headers leading to two mufflers.
S-38: With the new solder and flux plus a lot more BTUs, I'm in the full soldering mode. I used my fixture and secured the main struts to the main wing. I re-soldered the nacelle that was not very good, and cut and started fitting the engine support struts that were completely missing. I'm using 1/8" square brass for these missing struts and I've also replaced the steel struts with brass. I didn't like how the steel was soldering. It wasn't. The fixture cracked when putting on the second set, but it had done its job and was no longer needed.
With the main struts prepared, and the engine struts soon to be installed, I'll be ready to mate the lower wing and fuselage to the upper wing. I will turning the whole deal over to do that step. I will continue cleaning the solder joints up after I finish this phase.
The missing engine struts were pinned to the nacelles and I'm going to do this too. I opened the existing holes and drilled new holes next to broken pins that had remained in their holes. I soldered the pins (3/64" brass) to the shaped brass and temporarily fixed them in place. I needed to do this so I could get the measurement for the third diagonal brace that goes between these two. There's another V-shaped set of struts that go from the engines' inner side to the fuselage top. Those will have to wait until the main parts are joined.
Things are moving quickly. I'll do work on this tomorrow, but then we're heading back East for a wedding this weekend and will be back at work on this next mid-week.