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I’m a fan of diaphragms, particularly the truck air brake canister type, but to be fair to pistons; no they don’t take energy to reverse direction/reciprocate from a crankshaft — obviously the bearings will have higher friction with higher loads, but the mass gives back to the flywheel on decelerati...

I think there will always be issues with heat flow in and out of a Stirling, and the minimal dead space of a well designed regenerator would almost always be worth it, for just the reasons you mentioned.
Bumpkin

Actually I just worked backwards from inch pounds and RPM to the standard 33,000 ft lb per minute =1 hp. I’m sure there are better/simpler formulas and I’m not even sure I did it right. Yes the snifter does just what you say. It needs to have a very light actuating pressure to get full advantage. Bu...

Hi Brian, dunno no physics but here’s some basic thoughts. It sounds like rounding your numbers down to about 7 CID and at a 2/1 temp difference — (thank-you for understanding absolute temperature, though by the way, 300k is assuming some pretty good cooling,) and rounding up to 15 PSI atmospheric, ...

About hot caps, I mistakenly said cylinder when I meant piston. Anyway it can be domed or flat as long as it matches the cylinder for least dead space, but if it is flat it would need to be heavier to handle the same pressure differences. It should be longer than the stroke and slightly less diamete...

Hey BTYork: For the overheating rings issue: (and you’ve probably already been there but if not,) look into heylandt ? (spelling) crowns - “hot caps” with which you add a thermally isolated extension to the hot cylinder to keep the heat away from the bearing parts.
Bumpkin

airpower said: “But the reality is the company that made the SunPulse SP-500 no longer exists and as far as I know the claimed power was never independently verified. The engine has a diameter of 1300mm (51 inches) and models a tenth of the size don’t manage a tenth of the power.” A tenth of the siz...

Yes we’re still here, just slow. Your math is fine but doesn’t account for a displacer to chamber side clearance/air gap or some other form of passage/regenerator. That would lower the swept volume a bit. Some of the compromises are flow, heat exchange, regeneration, isolation, and dead space. Then ...

Hey Tom good catch. I was thinking that was just a fancy base but when you get a still pic it sure looks more likely it’s the bottom of the displacer chamber, likely with a thermal break to the upper portion. Apologies to all - it takes forever for me to watch a video on my connection. I still would...

Hey airpower; I’m pretty sure the temperature chart you posted is in Fahrenheit not Celsius. Anyway, I’m happy to see a conversation on home-made diaphragms. I believe diaphragms properly applied can take Stirlings into some useful areas. An issue as Tom mentions; is the material being too flexible ...

Half a cubic inch power cylinder seems small to get much power from an atmospheric pressure engine. If you could increase that to get the expansion ratio to fit the thermal ratio might be better. But either way should work to some degree if friction is low enough. Your displacer chamber dimensions s...

Welcome to the forum. Woodstove Stirlings are always of interest to me. If the 4” pipe is very thick it will carry too much heat to the “cool” end and you won’t get the needed temp difference. It needs to be as thin and non-conductive as possible.Same for the displacer itself. Length helps but every...

There actually are thermo-acoustic engines. Forum member Tibsim has done some interesting work there. It’s not the thermal lag principal and yes, using correct terminology would aid understanding for those trying to inventioneer original designs or modify existing designs to fit different materials ...

Goneroaming - A temp difference of 25c to 280c is a bit less than a 2/1 absolute temperature ratio. The transfer inside a running engine would be less. So your compression ratio needs to be well under 2/1 to get heat to flow in the right direction - otherwise you’ve built a heat pump. If your engine...

Hello Gary. Actually Stirlings are naturally double acting anyway, but yes the pressurized variant using two displacers for one power cylinder has some advantages if you don’t want to seal and pressurize the crankcase. If you type “starspin” in the search bar above you’ll get some of the forum’s pas...