Stirlingengineforum.com

I intend to eventually build an inline alpha engine based on the old 2 cylinder rider pumping engines. It will strongly resemble an engine built by Devin and seen here on http://www.youtube.com/watch?v=0priQGnkHcs The main difference will be the presence of a "cold cap" much like a hot cap except instead of being heated it will be cooled by a forced flow water jacket. Other changes will be a phase angle substantially smaller than 90 degrees in order to increase compression and displacement. I expect a Vmax/Vmin exceeding 4/1. size is yet to be decided but both pistons will have the same bore and stroke, considering about 2.5 to 3 inch bore and 2 to 2.25 inch stroke, will probably build a smaller prototype. Will heat with Dasifier type gasifier. I hope to power a small boat with this engine

Will post pics when building commences, which will likely be early this summer (my lathe will not likely be in my garage until after spring semester is already started)

P.S. this is my first post on this forum

onecycleDan 1990, welcome aboard, sounds interesting. I would suggest that you make one crank adjustable (you may end up with 2 crankshafts, one trial, and the pemanant one). Set up initially at 90 deg, and mark the crank. Test the motor for torque and revs., to find the power out put,
watts=RPM X torque(in inch oz)divided by1352, or watts=RPM X torque
(in gram X cm)X .oooo1026. Next move the crank not more than 5deg and retest, and keep doing that until the performance dropsquite a bit, or the motor wont go. Go back to 90 deg, then do the tests in the opposite direction. you will proberbly find the spot some were between 85deg and 105deg, but start with 90 deg because that works, and is a good place to start.
Today we have the advantage of modern stainless steels for the hot end of the displacer cylinder, and for the displacer, or the hot cap on the hot piston. Also stainless shim stock/ foil, or stainless steel wool for use in a regenerator. Ian S C

good idea about the two crankshafts, one adjustable. as for regeneration, at this stage in planning a formal mesh/foil/wool/etc regenerator will be absent. The hot and cold caps will be more than 3 diameters long and made of (if I can afford the molds) spun 18/10 stainless. Instead of paying for 2 molds (one for the cylinder extension/hot or cold cap, one for the smaller piston crown) I think I will commission a single mold; the length of the cylinder and the diameter of the piston crown. The procedure to form the cylinder will be to fill the blank with water, and place the water filled blank into a plugged thicker walled tube of the desired outer diameter. Said assembly is then placed into a freezer; when the water freezes it expands, pressing with enormous force on the inside of the blank, causing it to stretch until it is stopped by the far stronger pipe it is inside. The annular gap will be very small, IE. less than one fiftieth of an inch. This will hopefully cause intense convective heat transfer and a crude regenerative effect.
Have you seen the greenpowerscience youtube videos depicting a air cooled version of the Ross V 15. Its hot end is close in form to my idea for both hot and cold end exchangers http://www.youtube.com/watch?v=3y5X11MXsRc is a look inside, andhttp://www.youtube.com/watch?v=5pdqDQwehlk is a longish video of it running 1:27 and 4:38 on the second video give a crude idea of what a high compression, high delta T, unpressurized engine can do even without a large regenerator. They claim 100 to 150 watts from a 15 cc engine, personal guess is between 25 and 50 watts, even that is quite unusual and highly impressive when most engines put out less than one watt per cc per atmosphere.

thank you for your response and ideas,
Daniel.

I'm also a bit sceptical about the 100-150watts, your figure's a bit nearer, Andy's 35cc Ross Yoke engine, according to the artical in Model Engineering mag back in 1981 had a maximum power of44.1 watts at 2750 rpm., and a free speed of over 4000 rpm.
The method of forming stainless sounds interesting, I'v heard of explosive forming, the engineering dept at the local university does it in their lab, it's also used for swageing the ends of steel cables, and making dental plates ie., upper dentures.
The idea of the two crankshafts is that you can make the first one adjustable, and when you find the ideal angle, you then make a non- adjustable one which will be stronger, not essential to make the second one. Ian S C