Take away Stirling's regenerator and you have a hot air engine. How a hot air engine works is simple. Air becomes what is termed the "working fluid." A heat source, in the case of most soda can Stirling engines, this is a tea light candle, heats the air causing it to expand. The air is then cooled, causing it to contract. The expansion and contraction of the air, or working fluid, is a thermodynamic cycle. Now, use this thermodynamic cycle to move a piston and you have effectively allowed the thermodynamic cycle to produce useful mechanical work. When you attach a crankshaft to the piston, and add on a flywheel, you have the basics of an engine.
Get through building one Stirling engine and you'll learn more than a few lessons on home-brew engineering. Most of all, building one is a lot of fun, and gives you a chance to get creative with what most people consider junk. And seeing it work takes it to a whole new level.
Sound simple? It is, but there is still a while to go before the engine is built. You'll need more components, a few materials and an understanding of how they all fit together before your engine is chuffing away.
Here's what you'll need:
- Three (3) soda cans
- One (1) balloon
- Two (2) spoke nipples
- Four (4) 5A electrical terminal blocks
- Steel wire wool
- A bottle cap from a plastic bottle
- Steel wire
- Copper wire
- Dowel rod
- Electrical wire
- Fishing wire
- Three (3) compact discs
- Can opener
- Utility knife
- Super glue [source: ScrapToPower.com]
Let's take a tour of the components you'll be constructing, see how they work, what they do, and how it all fits together.