I see lots of explanations and reasons why a larger stirling is not
efficient, would be too large, too expensive, etc...
But I see no "failed" projects. No one horse stirlings the size of a
But I do see interesting things, like the 5hp stirling built in
Bangalore or something. I called sunpower by the way, they will
design and build and 5 hp or so stirling for 12,000 to 14,000 dollars
After finally realizing success on my tin can sized stirling, and
finding pretty much no information or large projects on the internet,
I decided to build one for myself. I might fail. It might not work.
Then at least everyone can have a picture of what will not work.
I already started. Scrounged up a very large acetylene tank out of
the barn behind the shop. Its about 14" in diameter, and stands about
5' high. Looks about right. Did I mention I am not and engineer?
Drained the rest of the gas out. Must have had a lot left in it, the
tank turned icy on the outside. I hope I didnt have a deposit on this.
Unscrewed the valve, it was easier than I thought it would be.
Filled the tank with water, hoping this would be the best way to purge
the rest of the gas. Turns out, when I cut the top of the tank with a
torch, it didnt blow up, so I guess it was. I cut the tank right
below the weld joint for the top of the tank, so now I have a long
cylinder with a nice bottom in it.
I want a wood fired deal, even though somebody said that would suck,
because...well, why not? So, after a great deal of thought, careful
planning, and engineering (about 5 minutes of sitting on my stool and
staring at it), I decided to cut a access door in the lowest part of
the side. Why? To get the ashes out of course! The hole is about 6"
by 6" and extends about to the middle of the tank bottom. Later I
will box it in with 1/4" plate and make a door. Lucky for me, the
bottom is welding in, and the joint leaves about a 1/4" or 3/16 lip on
the inside where the bottom slug is slid into the tank. Looks great
for holding a fire grate. So, I dug out a piece of walkway grating
left over from another project, and using the top I cut off for a
pattern, cut out a circle and trimmed it until it slid down the tank,
and sat on the lip. Oops, need a fire door.....cant get wood in
otherwise. No problem. Fire up the torch, careful measuring and
plotting.....nice square opening. Great, even if I stop now, I still
have made a really heavy duty fire barrel.
After some precision measuring with my craftsman tape measure, I
decided to make the displacer section 14" by 20" long, so that means I
need to cut a circle out of some plate and weld it in 20" from the
top. I should have some drop left, when I make the top plates, so
that can come later. After some careful deliberation, I decided top
make the displacer piston 13.5" long, and use 6" for stroke. Being
that I am really impatient, I wanted to get started on the displacer
cylinder. So, I cut out some 20 gauge steel with the plasma arc into
a strip 13.5" by 44". The length was figured 14" x pi, plus a little
extra. I thought the shop down the road had a roller, to form my
tube, but they couldnt do one that small. So, being that I am
impatient, I marked out 40 or so lines, one inch apart, and bent it
the the brake, each line about 10 degrees or so, to form a tube. It
doesnt look too bad, At first I wanted it too be smooth on the sides,
but now I think that the "bent" sides will add some strength to the
displacer piston. For the jig to weld the seam up, I think I will
take some plywood, and cut some 13 1/2" holes in it, and slide a few
over the tube, to keep it straight while I weld the side up. I
stopped fooling with it while I worked on another project in the shop
today, but I did decide to do a Scotch yoke drive (sort of), that I
think will be super easy to build. I did manage to bum some 12mm
chrome plated shaft material today, look like it will work great for
the displacer rod, and being ground rod that is triple plated (like
hydraulic cylinder rod), it should run smooth in a bushing and seal.
It came from some work that was done at a local papermill, some part
they replace every year. Something about coating on paper, I dont
know, I just know I have 10 foot of the stuff for free.
A few things I have decided, but may yet change.
I want a atmospheric pressure engine or one that can pressurize itself
with a onboard pump. (like the 5 hp deal)
I think I will make 2 power pistons/cylinders, pretty much just
because I have 2 short pieces of 3 1/2 DOM tubing that will work
great, and I dont have anything else handy that will work for a
cylinder. Well, I do have some leftover sleeves out of of the race
motors, they are a 4.125" bore, but the wall thickness is only about
.090 or so. But, I do have some pistons already that out fit them...
so who knows.
Water cooling? Very probably. I am just not going to bother with
making a water jacket until (if) I get it to run.
I decided on a variation on the scotch yoke, just because it fits into
my idea. After realizing a walking beam would be huge, I had thought
about a chain driven rhombic.....but the scotch yoke came to me in a
brainstorm this evening, so hey....sounds good to me.
Dont care how much it weighs
Dont care how big it is
Dont care if all it does is make enough power to run itself (it will
make a cool looking heater)
If you respond, please only helpful input. Lemme say this. I am
doing this for fun. Sitting in the same shop is a 2800 hp twin turbo
2005 mustang pro mod I built from scratch, I have a decent machine
shop. I am a competent fabricator. Part of my job is to piddle with
stuff like this. Wheeeeeeeeeeeeeee.........lets have some fun! I
will post some pics when I figure out how.