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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 wouldn’t give up on building a shorter version but yes I see now the video is probably the more traditional longer displacer chamber. Bumpkin

Story has it that this kind of configuration works best for a stove top stirling. Over 300 cubic feet (8.5m³) per minute, or more with two power cylinders, but it needs more heat to get going.


Similar, but not as good as horizontal cooling fins still catch a lot of the rising heat.
https://youtu.be/A1Lrh10nUzo

Bumpkin wrote: ↑Sun Dec 12, 2021 11:01 pm Similar, but not as good as horizontal cooling fins still catch a lot of the rising heat.
https://youtu.be/A1Lrh10nUzo

This Kontax design looks similar to what I'm building, if I can keep my friction low enough I think there's a good chance of it working.
I have 2 weeks 'till Christmas, hoping to have the whole thing fabricated and tested by the end of this week, I hope I don't have to do a re-design. Still, going to finish this design off strong and apply what I learn to the next model.

Heat Isolation
One of the things that has come up a lot is that my design will likely transfer a lot of heat to the top plate. I have 2 plans to mitigate this.
1. I have additional cooling fins on the top plate, with horizontal airflow this should help keep the top plate cooler.
2. I will be using a regenerating displacer similar to the LTD pancake engines, this will likely be made out of either a ceramic-fiber pack or, if I can't get the materials on time, I think steel wool will hold up to stove top temperatures just fine.

airpower wrote: ↑Mon Dec 13, 2021 6:56 am Over 300 cubic feet (8.5m3) per minute

Perhaps that will be V2 :) I do like the look of those, not entirely certain how they work...

Question for you
It's hard to know what the 'right' way of doing this is there is sooo much information out there, correct me if i'm wrong but it seems that this kind of engine is fairly forgiving in it's design as long as you're not asking a lot of it.. which I'm very much not :)

So yeah it does look like you're right

We have a heated portion, a heat break/regenerator, and a cooled portion.
It definitely is a vertical Gamma engine.
Can anyone tell me what this hole might be for? I thought these engines needed to be air-tight... might it be for some pressure relief on the down stroke maybe? not sure. I've never seen an exhaust hole before.

Biscuit_Ovens wrote: ↑Mon Dec 13, 2021 8:19 am
Can anyone tell me what this hole might be for? I thought these engines needed to be air-tight...

Assuming you aren't referring to the bottom of the power cylinder, I think that whiteish dot is just a reflection on the glass.

Tom Booth wrote: ↑Mon Dec 13, 2021 10:41 am

Biscuit_Ovens wrote: ↑Mon Dec 13, 2021 8:19 am
Can anyone tell me what this hole might be for? I thought these engines needed to be air-tight...

Assuming you aren't referring to the bottom of the power cylinder, I think that whiteish dot is just a reflection on the glass.

Probably but could also be a second fixing to hold top and bottom together if he uses a hollow cylinder.

At second look the black support with the holes next to the fan in the Kontax design is vertical cooling.

A bit over the top engineered twin cylinder liquid cooled stove top Stirling

Spent some time on the power cylinder last night, as well as installed the crankshaft support bearings and squared up a piece for the vertical column, here's what it looks like so far! The piston slides effortlessly in its brass housing, makes a nice vacuum pop when I pull it out against a flat surface.

airpower wrote: ↑Mon Dec 13, 2021 1:32 pm
A bit over the top engineered twin cylinder liquid cooled stove top Stirling

That looks quite overengineered, I love everything about it :)
Your own build?

No, spotted it will cruising the net.
I am separated from my tools for time being because of the crazy world. Nothing I can do but wait.

Very much like yours also
https://youtu.be/fq1iwa_l-CU

OK so i've been off this project a bit, have to keep it going though.
I think I"m going to complete the build as designed and then test it, and then improve it from there. I know I could get caught up in improving the design for years but I really want to see if I can get a finished product first.

I hope to finish this week by adding the displacer and running a test burn
I need something light and sturdy for the displacer so I think I'm going to just use a few 2x4 sections and carve it down as I don't have a lathe

It's been mentioned I should look into a regenerativedisplacer , maybe I can take a stack of brillo pads and turn that into a regen displacer

I'll be testing both.