Stirling verses Kite

In 1816, inventor and Presbyterian minister, Robert Stirling patented the key element of a heat engine now generally called the Stirling cycle engine. His grandfather, heir to the McGregor clan lairdship, was saved from the kill-on-sight consequences of all McGregor's having been declared outlaw by the English (was it something they said maybe?) through adoption by the Duke of Stirling. Probably they should therefore be called McGregor cycle engines- but nah, this doesn't sound right.
Robert Stirling did another thing well- he chose his parents carefully- with the consequence that he lived to a ripe old age and eventually attained the official title; "Father of the Church of Scotland". One of his sons, James, became a prominent engineer, and another became finance minister of the independent nation of Hawaii- but these things are by the by.


Stirling cycle engines have seduced generations of engineers through their theoretical promise of high efficiency. Billions of dollars have been dissipated on this dream, careers and businesses dedicated to their development have foundered with monotonous regularity in the 200 years that Stirling engines have been around. (Their genesis pre-dated Robert Stirling; Sir George Cayley, better known as an early pioneer of flight, proposed a similar engine in 1804).

In 1961, just 15 years old (my, doesn't time fly), I came across a Philips 102C Stirling engine and fell in love for the first time (or maybe I'm getting this confused with Jennifer Houston). The Philips (of Eindhoven) Stirling engine program started in the 1930's and wasn't finally canned until the obligatory multi-millions had been dissipated, well into the 1980's.

In spite of knowing this dismal history, Don Clucas, the next door neighbour's kid, and I started a Stirling engine development program of our own in 1988.
Don, hadn't been regarded as academically promising, but loved machine tools. Ours being the closest ones, he worked for me part time from when he was 13- and full time for some years from when he left school a bit prematurely.
As it happens, opinions about Don had been dead wrong, and when he began his PhD in engineering, he chose Stirling engine development as the subject, with commercialisation as the goal. He'd caught the Stirling engine disease from me while hanging around here years earlier.
Development started in what is now our kite buggy workshop and in a company created for the purpose: Stirling Research Ltd.
By the early 1990's there was some progress but by then I was being monomaniacal about kite buggy and kite traction development, which frankly seemed more promising to me. So, either through neglect or opportunity, I've never known which, Don shifted the project back to the University of Canterbury at Christchurch (100km north of here) and eventually gained financial support from an electricity retailer who contributed the obligatory many millions through WhisperTech Ltd, a company they established for this development.

Stirling Research Ltd remained in Ashburton and later became our specialist kite research and development arm but has more recently also moved to Christchurch- for Chris, Pete and Fiona's lifestyle preferences and the beach rather than for access to electricity consumer tithes, unfortunately.
By last year, Whisper Tech had completed extensive on-site testing in Europe of their main product; a combined heat and power unit for households that is the size and shape of a dishwasher and uses a Stirling engine (burning reticulated natural gas) to generate a bit less than 1kw of electricity. Rejected heat from the engine is applied to domestic water heating. By my figuring, at this stage the unit was just a very expensive (like $25,000) domestic water heater that could also produce about $3 worth of electricity per day for self-use or re-sale to the grid- and didn't make much economic sense. The engine design was basically unchanged from 1993 but a huge amount of design and development (like 30 staff full time for 10 years) had gone into refinement, accessories, heat exchangers and 'compliance' issues (that is, to persuade grid operators not to discriminate against the electricity it generates on the basis of race).


Two months ago, Whisper Tech secured an order from England for 80,000 units which has allowed them to get the per unit price down to approx. $4000.
For the mutiplicationally challenged, this adds to something over $300mil- 2 to 3 times the world kite industry's total yearly turnover I would guess, and makes this design potentially the most successful Stirling engine the world has ever known.
Perseverance beyond all reason and economies of scale have finally cracked the problem- and now that the per-unit price is low enough to make the system economic for the average European home owner, other major markets will follow in short order.
After 200 years of failure, success at last- and it came out of my 'garage', and, it happened while I was wasting my time flying kites!
Ouch!, It seems those early critics were right all along with their "when's he going to stop playing and do something useful".
I remain unrepentant though!

There, I knew I could tie this into a kite subject newsletter somehow.

Congratulations Don, what a saga.
Can I have one to play with?

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