Sombart Slide Valve Gas Engine

[Peter]

I purchased this great model at Dublin NH show this weekend. Ive watched this model - offered locally over the last couple years. This year my budget and sellers bottom line converged. The engine came with instructions and paperwork indicating this was built by our own wayne grenning (sponsor). The fuel is specified as acetelyene. Its about 18 inch tall with a 10 inch flywheel and very nicely machined and finished. I scanned a photo that came with it. Mine is identical and appears never run. I may try and run this and wonder if anyone has experience to share on that. And, I would like to find an alternative fuel, available in small cylinders, like MAPP, or somehting easy to tote around. Or is there a method to xfer acetelyene from my big shop tank to a small table top size tank?

Alos included is pic (taken form privious harry post) of the only american made (?) surviving sombart. Engine location coolspring. I assume the inspiration for this model.

[M&WJOE]

Nice engine. You are lucky to get it. Thanks for sharing Joe

[Andy Rafferty]

Danger Peter!
Never consider transfering acetylene to another container. It took years for union carbide to figure out how to contain this. The inside of the cyl. is actually a honeycomb structure containing alcohol the acetylene is disolved into. This is how they acheived pressures above 15psi with out shock detonation. (read big boom upon slightest impact) By the way yes the red neck in me did try this and I'm glad I still have all my body parts. I bet camp fuel or mapp will work and be cleaner burning. as acetylene is very dirty with poor oxygen mixing. Great looking engine let us know how it goes. Andy

[Tanner Remillard]

I would'nt think Acetylene would be a very safe fuel method either. It goes BOOM way to easily. But besides that, neat engine. I've seen the original run before, its quite impressive.

[Wayne Grenning]

Andy, You are absolutely right. Never transfer Acetylene from one tank to another. I work for Praxair (ex - Linde Division of Union Carbide that makes welding and atmospheric gasses) You should see the piping that is used to do this at a filling station. The walls of the transfer pipes are thick enough to handle spontaneous decomposition at pressures reaching 20,000 PSI +. Enough said here. You can go to a welding supply company and get a small Acetylene bottle. They make them about 5" in diameter and 18" Tall.

Now to answer the question concerning the Sombart engine model fuel choice. The fuel needs to be very explosive as combustion takes place in the middle of the intake stroke at less than atmospheric pressure. Traditional fuels like propane, map gas or methane may work but the operation will be very poor at best. Hydrogen is hands down the best choice, however due to availability and dangerously low ignition energy it is not the wisest choice for the average model engine hobby enthusiast. Acetylene is the second choice. As it was mentioned previous in this post it is a sooty fuel when burned in air, However, probably the most practical. As I am sure you already figured out liquid fuels will not function in this engine. The original fuel early noncompression engines ran off of was Illuminating gas which was high in H2 and had some Methane. The H2 was great for ignition at subatmospheric pressures and the methane gave it the extra energy that allowed the engine to produce useful power.

For reasons I can not explain, this model does not run well with acetylene supplying the ignition flame. There are also problems with it melting the ignition port check valve. As a result. I experimented with propane, this allowed for more stable operation

Hope this helps - Wayne