Hero Reaction Turbine Engine
By Dr. Greg Latta

Main Page and Introduction

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Introduction:
Hero or Heron of Alexandria is credited with the first written record of a steam engine between 10 and 70 A.D. Hero's Aeolipile is actually a reaction steam turbine. In a reaction steam turbine, the steam is ejected from several jets, which operate like little jet or rocket engines. (The other type of turbine, an impulse turbine, operates by blowing the steam against a turbine blade, much as the air blows against a windmill.)

The reaction turbine is a beautiful example of Newton's Third Law of Motion, the Law of Action and Reaction. Models of Hero's engine can be found in a variety of places on the web. Kenyon College has a nice collection of Hero engines, and NASA has the instructions for a Hero engine made from a soda pop can on their web site.

Having built a variety of reciprocating steam engines, I decided it would be nice to design and build my own Hero steam engine. I wanted the engine to be more elegant than some others I had seen, and I wanted it to have interchangeable jets so I could study the effect of jet size on the operation of the engine. I also wanted it to be able to actually build up a head of steam, so that it would continue to operate for a short time after it was removed from its source of heat.

The resulting engine and its construction is detailed in these pages. The engine is made out of brass because brass is denser than aluminum, and the extra heat capacity of the brass allows the engine to continue to run after being removed from the source of heat. (The engine can be made out aluminum if brass is too expensive or too hard to obtain.) Interchangeable brass jets screw into the sides of the engine. The engine is supported by a stainless steel ball bearing fishing spinner, and runs nicely on the heat from an alcohol burner, propane torch, or Bunsen burner. A lathe and milling machine are needed to build the engine, though one could probably use a drill press in place of the milling machine. Below is a picture of the finished engine. I had a lot of fun designing and building the engine. I hope you enjoy reading about it, and I hope you will try building your own.

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Click here for a super detailed view.

©Copyright Statement:
All images, designs, and materials on these web pages are the property of Gregory P. Latta and are ©2008 by Gregory P. Latta. You may use them for personal purposes and for educational purposes, but any commercial or other use is strictly prohibited unless written permission is obtained from the author.

Disclaimer:
Opinions expressed are those of the author or the quoted source. The author is not an employee of or agent for any of the vendors referenced in the text and does not sell or represent any of the products discussed. Vendors may provide products for review purposes and may provide sponsored support through advertising or links. No information provided herein represents professional advice or best practices. All information is provided to help the reader gain a better understanding of the tools and techniques described. Considerable care has been exercised to provide accurate and timely information. However the author cannot be responsible for information which is incorrect or out of date. Power tools and shop practices can be dangerous if used carelessly or improperly - always take proper safety precautions such as wearing protective eyewear and appropriate clothing. All practices, procedures, modifications and product recommendations described herein are to be used at the discretion and risk of the reader.

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If you have any questions or comments, you can send E-Mail to Dr. Greg Latta at glatta@frostburg.edu