Book Review - "How I Built a 5 HP Stirling engine"

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Book Review - "How I Built a 5 HP Stirling engine"

Postby stan.hornbaker » Fri Jan 26, 2007 5:07 pm

"How I Built a 5 HP Stirling Engine"
The Story of The Rice Husk Energy Project in Bangladesh
Dr. L. Merrick Lockwood

This book chronicles the construction development and employment of
the Stirling engine to run a rice hulling mill and dispose of the
hulls by using them to fuel the engine. A rice mill in each of several
villages eliminated trips from the villages to a centralized mill and
back as well as solving the problem of hull disposal. A set of plans
is included for anyone who would like to build a similar engine.

The need for the development of hot air engines including those with a
regenerator or economized was brought about by the explosion hazards
of steam powered pumping engines in the coal mines. Mid-20th century
there was a need for motive power for off grid radios and the first
Phillips engine came into being.

Rice growing, processing, de-husking, and preparation for human
consumption results in an aggregate of four million tons of husk
annually with energy content of 52 giga-joules (gj) in Bangladesh
alone. This is equivalent to more than a billion liters of diesel fuel
per year.

A proposal for the Rice Hull Energy Project grew out of a chance
meeting between Dr. Lockwood and a representative of the Asia
Foundation in 1979.

The project was underway by mid 1981 with the design, construction and
testing of the prototype ST-5 at Sunpower Inc. in Athens, Ohio. A
number of simultaneous activities were undertaken to understand all
aspects of rice from the rice paddy to human consumption, fabrication
techniques and capabilities in the area, as well as any other factors
that might affect the outcome of the project’s goals.

Construction of a locally fabricated engine to duplicate the original
prototype involved redesigning welded components to be replaced by
castings. Auxiliaries necessary to operation were added to the design
requirements. As time passed many problems arose and were solved to
ultimately arrive at the final engine design and its employment to run
a rice hulling mill.

The book is well illustrated with numerous b & w photographs of all
aspects of the project. Thirty-one dimensioned drawings provide
sufficient information to permit finalizing the plans and fabricate
of a replica of the latter redesign of the ST-5.

I can heartily recommend this book as a valuable addition to the
library of anyone having a serious interest in the legacy of the
Stirling engine of the Rev. Robert Stirling

You can preview Chapter 6, which contains the original color photos
associated with the text, by downloading a pdf document from:

Build your own 5 HP Stirling engine similar to the ST-5 formerly made
by Sunpower in Ohio.

A book, "How I Built a 5 HP Stirling Engine" by Dr. L. Merrick
Lockwood is available from

William S. Hornbaker, Knoxville, TN January 26, 2007

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Response to Book Review - "How I Built a 5 HP Stirling engine"

Postby cchagnot » Wed Apr 22, 2009 10:09 pm

I want to point out that the Engine Sunpower
designed for the USAID project in Bangladesh was not the ST-5. True, it was an earlier
prototype but I branched off from Sunpower and the ST-5 is entirely
Stirling Technology's design, quite different in many ways from the Sunpower prototype.
The ST-5 was in production for awhile until the company in India went
belly up.


I've got to set the record straight.
I was the project engineer that led the Sunpower team of engineers that designed
the engine that Merrick Lockwood wrote his book about. These forums drive me to

The ST-5 was NEVER designed by Merrick. He was the Asia Foundation Administrator
of the USAID funded project that had my team at Sunpower design an earlier,
different version that was supposed to be replicated in Bangladesh and then put
into production there. Merrick was supposed to lead the implementation of
building four copies of the first engine designed and built by Sunpower. I led
the engineering team both in the US and Bangladesh. At least I was supposed to
in Bangladesh. I arrived in Bangladesh to find that Dr. Lockwood, (Entomologist)
had completely redesigned the engine to his own version. It never put out more
than 1 or 2 HP. I Advised the project for awhile until it finally became clear
that Merrick simply wanted to play around with his own ideas and wasn't
listening to our engineering advice. I looked at my last report to the Asia
foundation and saw that it said exactly the same as the previous two and quit
advising the project.

I left Sunpower, formed STI and proceeded to actually make successful engines
(The ST-5) in South India.

I don't want to disparage Merrick on the forum. we're still friends and see each
other from time to time. But his book should be titled;

"How I screwed up a perfectly good Stirling Engine Design Project for the Third

The ST-5 is a viable, proven engine as I've said. But it is entirely Stirling
Technology's design.
I tried desperately for a long time to get the engineering back to real
engineering and back on track. But Merrick was determined to play around with
his ideas. After I quit, he had to find someone to replace me in order to keep
the USAID money flowing. He brought in an advisory team consisting of I think
Graham Walker, William Beale (Who always loves the 'clean sheet of paper'
approach) and someone else I can't remember. This group of 'Specialists' then
designed or sketched a new design for him and he charged off, proceeding to do
the same thing he'd done before. I don't really know the details because I
wasn't involved at that point and I knew the Sunpower design engineers weren't
either. (At least as a proper design team, simulating, designing, prototyping,
de-bugging (Ah, that's why an entomologist is needed) and testing that new
engine design. The 'specialists' met for a few days in Dahka then went off,
leaving Merrick to do his backyard tinkering thing. Of course he couldn't have
it ready in time. If he'd had twenty years he'd still be playing around. USAID
finally stopped wasting the taxpayers money.I think the total project budget was
somewhere around $2,000,000

He titles his book, “How I built a 5HP Stirling Engine”. Sunpower built a 5HP engine
For that project but I donÂ’t think that any of his many engines ever produced more than a
few HP.
I donÂ’t know of any instruments being used to truly measure the power.

The original project had very specific requirements that had to be met to get it
to phase two where it would be transfered to Bangladesh, four copies made, then
beta tested and on to a small scale production by the end of phase three. Phase
one was that Sunpower design an engine that could run a small rice mill
(measured by myself as needing 5HP), and could be built in Bangladesh. The
Specialists met in late January (Dr. Walker, William Beale, Someone from USAID,
Merrick and the Sunpower design team to finalize the design approach. Once they
agreed, off they went and I and my team were left to demonstrate a working
engine producing 5HP (3.7 KW) by August 17th. That was a 'drop-dead' date. To
move to phase two that had to happen no later than August 17th of 1982.

We finished the design part in late March, started cutting metal in April then
tested and de-bugged the thing through the summer. Remember, we had to use
methods available in Bangladesh, we couldn't just send stuff out to a specialty
machine shop and have them do it. It was tough but we did it. August 17th came
around ( I don't think I'd slept for a week before that day) and we ran the
engine on rice husks proving the output of 5 HP with a calibrated dynamometer.

USAID signed off. The project went to phase two and was totally under Merrick's
control from that point on.....

Question; How does one make a small fortune in the Stirling Engine business?

Answer; Start with a large one!

Lockwood asserts that most of the mechanical changes were intended to make the
engine more amenable to manufacture using locally available resources and in an
attempt to overcome inherent weaknesses in the drive mechanism. But I understand
your concern when he strayed into modifications to the gas circuit which had
presumably been carefully optimised by whatever simulator was current at
Sunpower, and I guess introducing a brand new design (Ross alpha), no matter how
promising, was way off beam in the context of the project.

Merrick agreed to our method of fabrication in that meeting and to our approach
to design. His claims about easier manufacture in Bangladesh should have been
raised then, at the meeting. Now, he tries to use it as an excuse. But the issue
about the gas spring/ air pump we patented was after the fact and I don't think
it fair that he uses what I did in India with the ST-5 to justify his changes.
Beta testing of the prototype would have proved
the viability of the original design and most certainly we would have had to
make modifications. The ST-5 was after the fact and years after he changed his
design. For him to use it as an excuse is not only insulting, but a very lame
excuse for his wandering off into the DYI environment..

Before we even began to think about the design I spent a month in Bangladesh
examining all materials available, all machining capability and all casting
facilities (Al and Iron). I mean everything! A month in that miserable
place, everyday trudging everywhere to look at rice hullers, how they fixed them.
Diesel engines and how they serviced them. I looked at what bearings were
available (all imported). I came back to the States and Sunpower where we
examined all the info I'd gathered and started to design the 5HP RHEP engine
based on all this info. We made every design decision based on making it in
Bangladesh. The first thing my engineering team said was, ("Holy S%^*!). We then
came up with a design after a lot of work and careful thought to the inability
to control casting quality. A lot of consideration went into the issue of

When the review team met in Athens, to review our preliminary design, we'd run a
few numbers and presented how we'd be able to make it in Bangladesh, every part.
We ran the bearing numbers and came up with a 2000 hour TBO. We considered
service and made sure simple tools only were needed. A couple of screwdrivers,
allen wrenches and something to press the bearings in and out. We explained
every process. And, we told the team that we'd only make the prototype using those
processes in Athens.
We decided to fabricated the original Crankcase from local sheet steel because
of concerns about poor quality casting and the dangers associated with that.
Failure of a welded and fabricated crankcase would be to split a seam and though
damaging to the engine, not destructive to life.

That team, Graham Walker, William Beale, Someone from USAID, Eldon Beagle (Rice
husk combustion expert) and MERRICK LOCKWOOD agreed to the design approach and
signed off on it!

As I've said in a previous post off they went and we completed the design within
all of the agreed upon parameters, made it using fixtures we built as if we were
in Dhaka and then successfully demonstrated it by the required 'drop-dead' date.

We then air freighted the entire engine, burner and system to Dhaka and I
arrived in Dhaka a week after the engine and wondered why Merrick hadn't cleared
it through customs by then. He hadn't even tried and it took me, shoving a
reluctant Merrick another week to get it through customs.

I soon found out why. Remember we were supposed to then build four copies
locally for beta testing? We'd sent Merrick drawings of the fixtures we'd used
so he could start to get a 'jump start' on the project and we could hit the ground

What I found instead, blew my mind. He was more than halfway through a
completely new engine design of his own. Giant, cast iron crankcase. Changes to
the mechanism. Changes to the Heat exchangers. The heater head was now a
'Lockwood prickly pear' design. A bunch of little studs about 6 mm in diameter,
5 mm long spot welded here and there on the outside of a rolled can. I can't
remember what the internal heat exchanger was but at home I have the photos
somewhere. It was a completely different engine, not just in construction, but
thermal design as well.

We at Sunpower had known nothing of this. We were never consulted about whether
or not it could transfer the heat in and out. Nor were we consulted or asked to
simulate (and our programs at the time were usually right on the money) the
performance and expected power output.

But Merrick the Entomologist made it perfectly clear to me that he was in charge
and we could take our engineering opinion and shove it! I did manage to at least
set up our engine finally and run it (ran fine and ran the rice mill fine). But
as for making four copies, Ha! Merrick made what he wanted and basically started
a whole new R&D program of engine design and testing, one at a time, ad
infinitum.... Every couple of months or so I'd come back and along with Asia
Foundation and USAID folks to watch him try and run another DYI prototype. None
of them ever put any usable power.
I remember in one meeting with USAID that was important for him to keep the
money flowing he got angry at me and since he was in charge told me I was to keep my
mouth shut and stop talking about the total lack of engineering. It was after
that that I realized I couldn't win the project back to sense and real
engineering and fairly soon after that I quit the project.

The USAID budget was originally $2,000,000. It's my belief that had we followed
the entire project requirements as written and implemented them as planned we
would have been successful. Sure some changes would have come out of the Beta
testing phase but the original RHEP engine worked and worked well. I have photos
of it back home and I'll try and dig around and find them. Sunpower made two of
the original engines and I still have one of them at STI. It's in pieces at the
moment but all there. I may even have the drawings. When I get home, I'll try
and send or upload the photos and look for the drawings.

Maybe now you might have a better idea of my allergy to DIY Stirling, especially
to Merrick's book. Does he mention that $2,000,000 was spent?

Catherine Chagnot
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Response to Book Review - "How I Built a 5 HP Stirling engine"

Postby justin2929 » Wed Apr 22, 2009 11:36 pm


Thank you for the very informative (and rather entertaining) account. You paint a very clear picture. That whole situation must have been such a farce! IÂ’m still trying to understand, why would anyone with an IQ above room temperature appoint an Entomologist as the on site project manager? (Maybe there where no more qualified Paleontologists available?!) What a shame that potential of this project was so ridiculously wasted. This pathetic waste of 2,000,000 dollars makes the Department of Defense's $640 toilet seat look like a good deal!

“Question; How does one make a small fortune in the Stirling Engine business?
Answer; Start with a large one!”


My apologies if I am unduly harsh to Mr. Lockwood in a way that is in violation of the general friendliness and cooperative spirit that governs conduct on this graciously provided forum. But hearing about such a profound failure that could have so easily been avoided is highly irritating to say the least!
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Response to Book Review - "How I Built a 5 HP Stirling engine"

Postby bptdude___2569 » Wed Apr 22, 2009 11:55 pm

I am staying out of this one, because this is not a technical thing, but could involve various parties in an international legal dispute.

If Dr. L. Merrick Lockwood wrote a book that took some liberties, which it sounds like he did, it really is not important, unless he works for the evil Illuminati and will use such claims to stop Cate's company from releasing the real, 5 HP, working, affordable, actually brought to market, mass production, ST-5.

I will throw my two cents in, which Cate may not like, even though I admire her greatly. I think it will help her.

I have pondered many designs of various Stirlings, and though I could not actually build one, I bet I could win a legal case if it was played out in a fair court and played by the rules of true intent of patents.

The ST-5 is a modern recreation of a well known design, that never had success in the various markets in its various forms. You can not help notice that this is the basic design of the Phillips creation, that went on to become the one the U.S. government funded for a few things, that GM Corporation had their hands on, that is also the basic design of the Dish Stirling project.

Nobody has succeeded where Cate's company is about to, in producing a machine, on that basic design type, that actually balanced all the thermodynamics and practically manufacture hurdles.

Dr. L. Merrick Lockwood may have had a good time playing with the design with somebody's else's money, and I hope he had fun. If he can read this, I hope he would not interfere with the engine coming to market. The very people he wanted to help will actually be able to use this. The intent of Cate's company is to mass produce them at a very reasonable price.

Everybody should cooperate to see this happen for the common good. If the project dies when it should not, because of some stupid legal obstacle, I will write my own book about the conspiracy theory of what is holding back the means to produce small portable power from local renewable heat sources.

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Response to Book Review - "How I Built a 5 HP Stirling engine"

Postby cchagnot » Thu Apr 23, 2009 2:01 am

All I care about is setting the record straight.
What's past is past except his book is being associated with the ST-5 and the ST-5 is
being seen as a failure sometimes due to that.

It's hard to get out there and convince investors and others that we really do have a
viable,tested, working machine that can be produced in reasonable quantities at a
reasonable price.
I only want to make that clear to everyone.

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Response to Book Review - "How I Built a 5 HP Stirling engine"

Postby david_mathews » Thu Jul 09, 2009 4:08 am

HI Cate.....i think u need to go after some of obama's stimulus money.!! At least you would be putting it to good use.......
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Response to Book Review - "How I Built a 5 HP Stirling engine"

Postby adrian.assassi » Tue Dec 08, 2009 1:30 am

Does the author make it clear how much it costs to build the engine according to his design? If so, how much? Also, does he conclusively prove that its output is 5HP?
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Response to Book Review - "How I Built a 5 HP Stirling engine"

Postby stan.hornbaker » Fri Dec 18, 2009 3:18 pm

IF you took the time to read the subsequent posts, the one by # Catherine Chagnot, April 23, 2009 in particular you would have found the answer to your question. i.e. Too Much for the results obtained.

I was not aware of the deviations from original designs until long after the book had been published and my review posted. Ms. Chagnot simply set the recond straight.
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Response to Book Review - "How I Built a 5 HP Stirling engine"

Postby kannan » Sun Jan 10, 2010 2:53 am

I am halfway through reading this book, when I got to read these comments. I dont care too much about the specific characters involved in the book, as long as there is something to learn from the experience # which I think the book provides.

If Catherine has built such a fabulous engine in South India that meets all technical specs, has potentially a very huge market... well, she had everything going for her! Then why did her company go belly up?

Frankly, she is less open about her shortcomings than Lockwood is in the book. If Mr. Stirling, a bishop, could patent the engine, I dont see why an entomologist cant improve upon the idea.
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Response to Book Review - "How I Built a 5 HP Stirling engine"

Postby bptdude___2569 » Sun Jan 10, 2010 7:39 am

I have chatted with Catherine. She is dedicated more than any I know about this project. It certainly does not seem like a big money maker for her.

The new 5 HP engine by her new effort is suppose to be out this year. Many of us are looking forward to it.

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