Hero Engine (Aeolipile) Demonstration Model – KS3+ [1920]

The Hero Engine is a classic and engaging physics demonstration model based on the steam engine invented by Hero of Alexandria around 60 AD. Often referred to as an aeolipile, this apparatus represents one of the earliest known machines capable of converting thermal energy into kinetic energy.

This historical yet highly relevant device provides a powerful visual demonstration of fundamental physics concepts. When heated using a Bunsen burner (not supplied), water inside the sealed glass apparatus turns into steam. The steam exits through angled jets, causing the apparatus to rotate. This motion closely resembles the principle used in modern rocket and jet propulsion.

As steam is expelled, it carries momentum. In accordance with Newton’s Third Law of Motion—that every action has an equal and opposite reaction—the backward force exerted on the steam produces a forward reaction force on the nozzles. This reaction force creates a turning moment about the longitudinal axis, causing the glass engine to rotate smoothly.

Key Features

• Model of the Hero Engine (Aeolipile), invented circa 60 AD
• Demonstrates thermal to kinetic energy transformation
• Illustrates Newton’s Third Law of Motion
• Operates on principles similar to rocket propulsion
• Clear visual rotation driven by steam jets
• Ideal for live classroom demonstrations
• Suitable for KS3 and above

How It Works

Thermal energy supplied by a Bunsen burner heats water inside the glass vessel, producing steam. As the steam escapes through angled outlets, it gains momentum. By Newton’s Third Law, the momentum of the escaping steam results in an equal and opposite reaction force on the nozzles. These forces act tangentially, producing rotation of the entire apparatus about its axis.

This simple mechanism provides a clear and memorable illustration of how energy can be transformed and how forces cause motion, linking ancient engineering with modern physics concepts.

Ideal for School Science Lessons

Perfect for KS3, GCSE, and introductory A‑Level Physics, the Hero Engine brings abstract theory to life through direct observation. It is particularly effective when teaching:

• Energy transformations (thermal → kinetic)
• Newton’s Laws of Motion
• Momentum and reaction forces
• Introduction to steam engines and propulsion systems
• The historical development of scientific ideas

Visually striking and conceptually rich, the Hero Engine is an excellent demonstration tool that connects history, physics, and engineering, inspiring curiosity while reinforcing key curriculum concepts through hands‑on observation.