I Made an Engine

[SteevyT]

So I saw Sterling Engines made out of some cool stuff, including a couple made out of Pringles cans. I decided I wanted to try one out of Pringles cans. I found some instructions, modified them to work with what I had, cussed out the pile of stuff I had some, and finally came up with this.

The final thing is made from two Pringles cans (the instructions originally called for four), part of a box my printer came in, part of a box my textbooks came in, some nylon thread, a balloon, a Styrofoam McDonald\'s cup, a straw, a wire coat hanger, four pennies, and a lot of hot glue.

[Ydoow]

What is this powered by?

Is it one of those engines that only needs a temperature differential to run? How does it work exactly?

[Kryten]

Here\'s a nice animation of this kind of thing;

air in one side of the piston is heated, making it expand, pushing the cylinder. As the cylinder moves, the air is forced to expand, and cools. This cooling makes the air contract again, pulling the cylinder inwards.

[SteevyT]

What is this powered by?

Is it one of those engines that only needs a temperature differential to run? How does it work exactly?

It just needs a high enough temperature differential to run. The teacandle heats the bottom of it. The bottom Pringles can has a section of another Pringles can inside it with both ends closed off as a displacement cylinder. When the cylinder is at the top, the air expands, forcing the diaphragm (balloon) to move up which pushes the straw upward. As it moves upward, the displacement cylinder moves down, forcing the air to the top of the Pringles can which is cold. The air contracts which causes the diaphragm to move down, pulling the displacement cylinder up, and this just repeats.

[Phoxtane]

Try putting some ice at the top, to increase the temperature differential.

[SteevyT]

Try putting some ice at the top, to increase the temperature differential.

I would, but I would need some way to keep the water from going down the tiny hole the thread runs through.

I have some spare thermal paste and spare cooling block lying around, I\'ve been thinking about seeing if I can somehow cram that in there.

[socket7]

Why not put the ice in a plastic bag? then it won\'t leak or ruin the cardboard.

[SteevyT]

That\'s an idea. Although it runs pretty well on two teacandles. If I throw the lighter under there too it really starts to pick up speed, almost to the point where I\'m afraid the connection for the displacement cylinder will slip out of place. It does if there isn\'t enough pressure on it.

[Radsoc]

Wow cool. Good work!

[Guest]

I wanna make my own SRB. Send some kerbs up for fun IRL.

[Ydoow]

Question:

Would it work if you put a really low temperature at the bottom instead of a candle?

You said it only needs a temperature differential, so I\'m wondering if it could go either way at the bottom, or if the bottom always has to be hotter than the top.

[SteevyT]

Hmmm.....might have to see if I can get some dry ice from the physics department (doubt it would happen though). I think it would run the other way if I cooled the bottom instead of heating it.

[Ydoow]

For dry ice, you can fire off a bunch of CO₂ fire extinguishers directly onto a plate or something.

I\'ve done this at work (except on the ground). Tiny flecks of Dry Ice accumulate. If you fire enough of them in rapid succession you can get a decent pile built up.

Make sure you have them setting on the ground when you fire them off. Fire Extinguishers will build up a massive static charge when firing them if not properly grounded.

I watched one of my co-workers legs involuntarily kick up into the air because he forgot about it

Lethal, no.

Painful, very.

P.S. You\'d have to buy your own CO₂ extinguishers since, ya know, tampering with building/company extinguishers is a felony