My latest little Stirling model just arrived from its previous owner today. Excuse the awful photo, I used my phone since I'm at work. This is an interesting addition to my other engines.

The HB9 Deluxe Swingarm is a nice little Stirling engine with lots of monkey motion. Seems to be quite nicely made. I won't try and run it here at work but I'll update this after I get home and give it a whirl. Last time I tried that at work I fired up a steam engine and caused a building evacuation... sigh.

Interestingly it requires use of graphite or ceramic powder to lubricate the rod of the power piston. I've not encountered a need for this sort of lubrication before and makes me wonder what metals they made it out of.

The model is made by Bohm in Germany. They have a huge range of interesting stirling models.

It works in th usual way with the power piston and displacer cranks at 90 degrees to each other. The flame heats the air in the power piston forcing out the piston to the end of its travel. The hot air moves over to the displacer piston and rapidly cools sucking the displacer piston back in this forcing the same air back to the hot side where the process is repeated until the external energy source is removed.