Stirling and Hot Air Engines by Roy Darlington and Keith Strong
Designing and Building Experimental Model Stirling Engines
ISBN: 186126688X
US $65 SRP, $40 at Amazon.com
240 Pages, all full color
This book's subtitle is Designing and Building Experimental Model Stirling Engines which may set expectations a bit beyond what the book actually delivers. This 240-page book is printed in full color and given the many photographs that is a big plus. 59 of these pages are devoted to CAD drawings of a particular engine. This is the only set of plans in the book and they are for a design that is reasonably complex; far from something most newcomers to the hobby could handle.
Hot air and Stirling engines were pioneered more than 100 years ago by prolific inventor John Ericsson. Rev. Robert Stirling, however, beat Ericsson in patenting the regenerator component and somehow his name has come to be synonymous with hot air engines.
Chapter 1, A Brief History of the Stirling Engine, is a very brief (4 pages) background on Stirling engines. If you are interested in the history of hot air and Stirling technology, this chapter will disappoint - but history is not at all the focus or purpose of this book.
Chapter 2, Principles and Performance Enhancing Techniques, discusses the how such engines work and various optimizations. Lots of design choices are discussed, such as material selection, regeneration and pressurization. While these and other topics are explorer they are examined only at a cursory level; to incorporate any of these strategies more research will be required of the reader. It does help to know what to research, however.
Chapter 3, Design Variations, discusses Gamma, Beta, Alpha and Rider and other design variations. Many topics are quickly covered, from drive mechanisms such as the Scotch Crank, swash plate and the Ross linkage.
In Chapter 4, Gamma Hot Air Engines, the author takes you on a tour of several of his Gamma-style hot air engines.
In Chapter 5, Ringbom Hot Air Engines, is a short 5-page discussion of Ringbom Low Delta Temperature Difference engines.
In Chapter 6, Low Temperature Hot Air Engines, the author shows several Low Delta Temperature and talks a about a 10-inch low delta that he built using a graphite piston. Workmanship on the engines built by the author is outstanding throughout the book.
Chapter 7, Martini Hot Air Engines, examines one of the author's experimental engines. Martini engines have a displacer piston that is not mechanically coupled to the power cylinder which provides a method of throttling the engine. The single model shown in this chapter is very interesting and documented with several photos. It utilizes a small DC motor to operate the displacer cylinder and reportedly achieves 600 RPM and is water cooled.
In Chapter 8, Marble Engines are reviewed. These interesting little engines typically have a test tube-like cylinder that pivots in the middle and have marbles or balls of some sort that move from one end to another when heat is applied to one end. The balls move the air in the cylinder to the other end which causes that end to fall. Various methods of making this simple action operate a piston are shown.
Chapter 9, Unique Twin Cylinder Boat Engine, jumps into an engine design of the author's for powering a model boat.
Chapter 10, Stirling Silver I (Twin-Cylinder Gamma Engine), this chapter continues where the last left off and shows the large model boat and how the twin-cylinder engine fits it.
Chapter 11, Solar Engine (Single Cylinder Beta Engine), shows an engine the author built using a parabolic dish to heat the engine. John Ericsson built a similar type of engine over a 100 years ago and the basic idea behind it holds great promise for greener energy production.
Chapter 12, Stirling Silver II (Single Cylinder Beta Engine), shows a new and improved engine for the boat. This time the author uses a single cylinder Beta type engine and says is was quite a bit more powerful than the first engine with two cylinders in a gamma configuration. I particularly liked the friction disk, an arrangement of a flywheel against a another disk having a rubber contact around the edge operating at 90 degrees with respect to the flywheel to transmit energy to the drive train.
Chapter 13, Buggy (Single Cylinder Gamma Engine), presents a remote control dune buggy style vehicle. Author says it was underpowered, but functional.
In Chapter 14, Lag (Thermo-Acoustic Engines), are discussed. These are similar to the marble engines discussed earlier.
In Chapter 15, Other Interesting Stirling Engines, the author show pictures and discusses several hot air engines that he has seen. Few details are presented on any given engine, but it is interesting to see the variety tinkers from around the world have come up with. In this chapter you feel a bit like you are walking around an engine show or a museum with the author as a guide.
Chapter 16, Workshop Practice and Techniques, is probably the longest single chapter in the book and, for me, is probably the single most educational. The rest of the book is inspirational, this chapter is educational. The author talks about how various cylinders and pistons are machined, including graphite pistons, with lots of tips from the author's experience. Connecting rods, flywheels and several other topics are discussed here.
Chapter 17 are notes about the CAD drawings which cover an engine similar to the Stirling Silver II engine covered in chapter 12.
These chapters get you through 163 pages with the rest being CAD drawings and various appendix and then index.
If you are looking for a book with lots of plans for building hot air engines, this is not it. But if you enjoy reading about projects someone else has done, this book may be the ticket. It is a little pricey, but watch for it to go on-sale and it comes down quite a bit. I'm sure it is more expensive to print with all the color photos. This isn't the only book a serious student of hot air engines will want, but it is a useful book.