The purpose of this book is
to “fast track” newcomers to Stirling engine
people are likely to be innovators.
Being strong willed and
independent it is likely that ”taking
advice” in an anathema.
put your pride and strong
This book is reporting the experience
of 15 years of a group of Stirling devotees and their
in matching the Stirling engine to the task of small boat
As one (very highly skilled) newcomer to
first four engines wouldn’t even run – let alone pull
the skin off a rice pudding.”
take the ideas that are presented here. Reproduce them. Learn.
improve, evolve and develop.
quote Tom Lehrer – “Don’t shade your eyes -
There are three basic types of
Stirling engine and many variants within those types.
have I presented the beta engine, rather than the alpha or the
Because we have built alphas, gammas – and
Each engine can take many months to build.
And we have had the best success with the pumped
We don’t claim to be “great men”
– but please stand on our shoulders.
Some “why nots”.
alpha engine needs two pistons (or more).
The gas seal of
the piston is crucial. It is also a good source of friction.
the private workshop builder, one piston/cylinder is quite
The gamma design brings with it dead space.
Looking carefully at commercial engine designs, these
issues of friction and dead space are overcome by raising the
power. Gas pressures are usually many tens of bar. This just
raises the fabrication challenge to new heights.
tubes? Even more dead space.
Meanwhile, the beta –
as Dennis put it – “It has negative dead space.”
And one piston.
So, we have spent,
literally years, building and learning from various variants of
the Stirling engine. We would like to save you a lot of
The other engine types all work.
of the boats that we have and use, the betas work well.
Going back to the beta, one of the
fundamentals is how big is the pressure
the engine. In an atmospheric 90 mm hot cap diameter beta,
peak was measured at 22 psi absolute. The trough at 8 psi. A ratio
This ratio, pmax/pmin
is a fundamental ratio for the
engine. It is an indicator
of the power of each engine cycle.
Looking at the reference books of major engines,
they are all lower (weaker) near 2.0 - because of the higher dead space.