Stirling Cycle Hot-Air Thermodynamic Engine Model
A challenging, hands-on discovery and STEM project designed for curious young minds aged 10 to 14.
Materials Needed
- • Empty aluminum soda can (2 units)
- • Medium steel wool pad (1 unit)
- • Heavy latex balloon (1 unit)
- • Steel wire coat hanger (1 unit)
- • Hot glue gun and needle-nose pliers (1 set)
- • Mug of steaming hot water or tea-light candle (1 unit)
Pro Tips
- → The displacer cylinder inside is made of steel wool; it moves air back and forth between the hot bottom and cold top without sealing.
- → A flexible balloon diaphragm acts as the power piston, flexing outward when air expands from heat and inward when cooled.
- → Connect the displacer and power piston to a bent wire crankshaft at a 90-degree phase offset to maintain continuous cyclic rotation.
Safety First
Adult supervision required during hot water or small candle operation and wire cutting.
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Step-by-Step Instructions
Step 1
Cut open the top of an aluminum soda can and shape a cylindrical steel wool pad to serve as the loose-fitting internal air displacer.
Step 2
Stretch a flexible latex balloon membrane across the top chamber to act as the pneumatic power piston.
Step 3
Bend a wire coat hanger into a dual-throw crankshaft with a 90-degree angular offset between the displacer and piston links.
Step 4
Rest the base of the engine over a mug of hot water, give the flywheel a gentle starting spin, and watch the thermal expansion cycle run.