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I have a LTD with a 10 cm displacer chamber sitting on top of the PC
monitor. Out of curiosity I timed the rpm several times sometime after
shutting down the PC. The rpm dropped from 40 rpm to 22 rpm and the
last timing was at approx. 20.7 rpm and the engine stalled shortly
after completing the last turn. The next test will to be making a
controlled heat source to see what the lowest speed can be attained
and sustained.

I don't think that there is any theoretical minimum, although they tend to run at non uniform speeds as they get extremely slow. Try reducing the friction and increasing the moment of intertia of the flywheel. [build a larger flywheel with more of the weight around the perimenter]. Our MM-6's will quite consistently run at about 30 rpm.


I suggest that you make a free Stirling engine web page on this server and show us what you have done.

I came accross a web site (lost the link) that had a water wheel Stirling that did something like one RPM. It was made up of bulk freon tanks out on spokes and a plumbing system that would transfer the freon to the tanks on one side of the wheel making gravity do the work. This is a crude discription but it worked something like that. It produced considerable torque but no real RPM's. The bottom of the wheel dipped into a pond to cool and condense the freon back to liquid.

Answers:"This is a crude discription but it worked something like that. It produced considerable torque but no real RPM's. The bottom of the wheel dipped into a pond to cool and condense the freon back to liquid."

The wheel you refer to is known as a "Minto Wheel." Much discussed but what can best be described as 'interesting but of doubtful value. Too big, too slow, too expensive for the resultant output.