New to the forum - here's my ideas so far

[spandit]

Planning on making a displacer (gamma?) type engine to power a fan on top of my woodstove, so it needs to be able to operate at high temperatures.

Planning on making a displacer out of aluminium drinks cans, possibly filled with expanding foam, with a stainless steel cylinder. The power piston will be made from a steel bearing cap (from a Land Rover propshaft UJ) in a brass tube (because that's what I've got lying around the workshop). The fan is a metal one from an old electric fan heater, about 6" diameter.

Only thing I'm unsure about is stroke length - any formulas available to calculate this? Hoping to make the con-rods from stainless rod but might just be using a bent wire crank

Hoping for a result something like this: http://www.myersengines.com/engines/sto ... engine.htm

[Longboy]

........Your stroke length is determined by the displacer and cylinder length. Example: if your cyl. is 4 in. long and the displacer is 2 1/2 in. long, the difference of 1 1/2 inches sets your parameters for the stroke. Here a 1 in. stroke will give a 1/4 gap at each end of the stroke so it doesn't bottom out at the push rod side of cyl. or slam into the end of the hot tube.