I've been having weird ideas again... For a long time, I've wanted to build a solar oven like this one: http://techref.massmind.org/images/member/jmn-efp-786/sun/cookerbo.html The other day, a thought popped into my head: What would that solar oven be doing when I wasn't using it to cook? And the first answer that came to me was that perhaps it could be adapted to work as a low efficiency Stirling engine. One possibility would be to slant the back of the cooker at the opposite angle from the front, making a trapezoid with the bottom larger, but centered under the top. Then I could make a displacer that hangs from the top and swings fore and aft like a pendulum. The rear door could be dogged shut to prevent leaks, and/or replaced with a heat sink to provide cooling. Could a large, sealed wood enclosure act as a displacer cylinder? Will 3/4" plywood 2' by 3' or so on a side be stiff enough to avoid absorbing the pressure change by flexing in and out? Can a displacer be hung from the top and swung like a pendulum without absorbing too much energy to get the motion going? Is there a better way to make a displacer for that shape of enclosure? How can heat exchange abilities be added to such a displacer? Will temperatures in the low hundreds be enough to generate work? Any way of knowing how much power could reasonably be expected from such a system? And finally, incase this post isn't long enough, it looking up information, I came upon this very nice animation of a version I had forgotten: The two cylinder or "alpha" Stirling. http://www.keveney.com/Vstirling.html The neat part is that the only seal between the working fluid and the outside is around the output shaft. Someone save me from getting excited about these stupid, "answer to everything" (not) engines... James Newton: PICList webmaster/Admin mailto:jamesnewton@piclist.com 1-619-652-0593 phone http://www.piclist.com/member/JMN-EFP-786 PIC/PICList FAQ: http://www.piclist.com -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist