Robert Stirling, a Methven man invented two centuries ahead of its time, a simple and elegant engine that gave to the world the most efficient solar energy capture device, created the means to “effectively” sink the pride of the US Navy, the $6.2 billion dollar, nuclear-powered, Nimitz-class aircraft carrier, the USS Ronald Reagan and is helping to save millions of lives through its use in ultra-low temperature vaccine storing freezers. He is immortalised as one of the most brilliant engineers of all time, but that was not his main occupation, his daily occupation was as a minister in the Church of Scotland.
The Reverend Dr. Robert Stirling D.D. (25 October 1790 – 6 June 1878) was born at Cloag Farm in Methven (top of School Brae/College Road, cottages and farm are on the left). For many years, the place of his birth was often just listed as Scotland, but these days his remarkable invention is now finding breath-taking new uses. Not only was Robert Stirling a world-renowned engineer, but his brother James was also just as remarkable. Even their father Michael was a renowned manufacturer and inventor of the first rotary threshing machine (1756/1758) and their descendant’s family legacy in the railway industry is legendary.
Many visitors from around the world come to visit and stay at the birthplace of Robert and James Stirling in Methven, at Cloag Farm (www.cloagfarm.co.uk). Throughout the world, people are fascinated by the simple and elegant dynamics of Robert Stirling’s engine. In every ‘gadget shop’ you can buy a model of a Stirling Engine, the first engine that he invented in 1816. Prices range from about £20 to well over £200.
The initial reception given to the eponymous 1816 Robert Stirling Engine was underwhelming and it was subsequently only sporadically developed. Where low to medium power was required they were used for driving small ventilators, to pump water on farms, to generate electricity and even to pump air for church organs. Its usefulness and demise came when it was superseded by a safer and much more powerful forms of the steam engine.
The steam engine was pioneered by another Scot, James Watt (1736–1819) from Greenock. Watt improved the efficiency of the existing Newcomen steam engine by adding a separate condenser in 1776. (Watt also developed the concept of horsepower, and the SI unit of power is named after him, the Watt.)
Even later, the internal combustion engine took over and Stirling’s engine was almost forgotten about, that is until the later part of the 20th Century when its unique operational properties are making its usage particularly advantageous in many ways.
Robert Stirling was in 1816 a Church of Scotland Minister of the Second Charge of Laigh Kirk, Kilmarnock and then in 1824, Minister at Galston. In this area there were hundreds of coal mines and Robert was witness to many instances of the carnage caused by these early steam engines spectacularly exploding.
Steam engines used to pump out water from mines were extremely dangerous, many exploded killing many of the coal miners. Robert Stirling decided to use his engineering skills to invent a different type of engine, one that was much safer. He came up with the concept of heating the air in a cylinder, rather than the water in a boiler. It has been described as a type of external-combustion engine. The first practical 2hp Stirling engine was used to pump water from a quarry in Ayrshire in 1818.
Stirling remembered seeing his mother making jam and came up with the idea of making this engine that was much safer. When hot jam is placed in a jar, Robert noticed that the cloth cover rose as the heated air at the top expanded. This gave him the inspiration to develop the concept of heating the air in a sealed cylinder from an external source. His hope was that he would eliminate the need to have any combustible source or pressure boiler down in the coal mines.
The Stirling Engine works by converting energy made by the expansion of fixed amount of air or other gas within a closed (sealed) system. A difference in temperature of the air at both ends is all it requires to work. When the air is expanded by heat applied at one end, it pushes up a displacer piston in a cylinder, changing the internal volume of the air. The air is moved between a hot and cold side of the engine, expanding on the hot side pushing the piston inside the cylinder and contracting on the cold side making the piston return.
The top of the piston is connected via a linkage to transfer the power and drive a flywheel, a pump or other workshop machinery. Amazingly the source of power can be either hot or cold. By applying cold to one end of the cylinder, say ice cubes, you can make the engine run in the opposite direction. More sophisticated modern cold power examples use Liquid Nitrogen. The closed loop of heating and cooling makes the Stirling Engine more power efficient than steam or even modern petrol and diesel engines. Stirling engines are unique heat engines, their theoretical efficiency is nearly equal to their theoretical maximum efficiency.
There are also many other types of the Stirling engine, the biggest asset that this type of engine has, is that it has no combustion chamber, power can come from an external source, no internal heat is generated, it has no exhaust output, it can be driven by a clean external power source, cylinders do not need to be cooled as in gasoline engines, and it makes little noise.
Subsequent development by Robert and his brother, James Stirling successfully increased power output of the Stirling Engine, enough for example to drive all the machinery at the Dundee Iron Foundry where James worked as an engineer and manager.
James Stirling (1800 – 1876) was also born at Cloag Farm, 20 July 1800. The Dundee Iron Foundry and James Stirling built the 146,000-gallon cast-iron cistern dome water tank, engine, ball & socket pipes, and pump for Perth’s (1832) Waterworks in Tay Street. The building was designed, and the work superintended by the Rector of Perth Academy at the time, Dr. Adam Anderson.
The Dundee Foundry and James Stirling built the cast iron cistern for the Perth Waterworks in Tay Street. This building is now known as the Ferguson Gallery. The rotunda domed; Neo-Classical waterworks is one of Scotland’s most significant industrial buildings. This is the earliest example of a cast iron building in Scotland.
Water was pumped by a steam engine from filter beds near Moncrieffe Island (north end) and the cistern could hold 146,000 gallons of water. The original urn atop the engine-house chimney was destroyed by lightning in 1871.
James Stirling (3 March 1799 – 10 January 1876, initially followed his brother’s career by studying divinity. Maybe, he was inspired by his brother’s engineering ability and the spirit of invention so he decided to become an engineer himself. James was apprenticed for six years to a company in Glasgow, Claud Girdwood and Co, the makers of Cotton Manufacturing Machinery. He then became manager of the Dundee Foundry.
The Dundee Foundry built three locomotives for the Dundee to Newtyle Railway. This was a fascinating railway enterprise, it comprised of three rope worked incline planes to get the wagons over the hills and a tunnel through the Law Hill in Dundee. James Stirling also made several more locomotive engines, for the Coupar Angus and the Arbroath and Forfar Railways.
The village of Newtyle was built shortly after the railway opened to take advantage of the communications link to Dundee. (Dundee is about 24 miles east of Perth and Newtyle about 20 miles Northeast just over the county border in Angus.)
This was the time when steam engines were proving to be, not more efficient, but more practical. The ‘Stirling’ engines had to be kept in a static position, they were very heavy and probably could not be developed much further.
Competition came from James Watt, he had by this time developed his own advanced steam engine, with the separate condenser (in 1766). This is what really produced the power necessary to start the Industrial Revolution.
Indecently, Robert Stevenson and Co. (Newcastle and son of George) also built an engine for the Dundee to Newtyle Railway. (The famous Rainhill trials with George Stevenson’s steam locomotive, The Rocket was in 1829.)
Extensive operations were carried out at the Dundee Foundry during James Stirling’s time: castings for engines, steam boilers, textile and spinning mill machinery, railway equipment and even a steam engine for a steamship that was built by Garland & Horsburgh. This was the 100-ton steam tug, Industrien, built for William Brodie, a Scottish merchant based in Göteborg, Sweden. The Dundee Foundry built the third steam engine for the Dundee to Newtyle Railway’ Trotter, excluding the tender at a cost of £700. It was put into service on 2 March 1834. James managed to run the Trotter up the Balbeuchly Incline (between Baldragon and Auchterhouse), 1690 yards on a rising of 1 in 25.
James Stirling further developed the second patented Stirling Hot Air Engine (1841) at the Dundee Foundry, the merit of the original idea belonging to his brother Robert. The new concept was to use compressed air in order to get more power out of the engine. The engine also used an economiser (regenerator or respirator) which reused hot air from the exhaust to increase the efficiency of his air engine – an idea which was also the invention of Robert Stirling. the economiser is still used to this day in many industrial processes to save heat and make engines more efficient. This development may be Robert’s most important contribution to engineering.
Steam locomotives built by the Dundee Foundry/James Stirling & Co included:
Trotter, built 1834 for the Dundee and Newtyle Railway
Princess, Victoria and Britannia, (all 2-2-2s) built 1838/9 for the Arbroath and Forfar Railway – 1,676 mm (5 ft 6 in)
Two further locomotives for the Arbroath and Forfar Railway
At least one locomotive for the Newtyle and Coupar Angus Railway
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On 3 October 2014, the Reverend Robert Stirling DD was posthumously inducted into the Scottish Engineering Hall of Fame. Robert Stirling’s air engine of 1827 is in the Hunterian Museum, University of Glasgow. Stirling also invented several optical and scientific instruments and was awarded an honorary degree by the University of St Andrews in 1840 in recognition of his scholarly and scientific attainments.
Robert Stirling had seven children and a long ministerial career of 63 years. He was known as the Father of the Church of Scotland when he died in Galston on 6 June 1876.
A gifted speaker, Robert Stirling was truly beloved by his flock. He is buried in Galston Cemetery where a new gravestone was erected in December 2014 by public subscription and was rededicated in May 2015.
James Stirling in 1837 married Susan Hunter, afterwards known as Susan Stirling who published successful novels such as “Fanny Hervey or the Mother’s Choice” (1849). James Stirling lived at 11 Hill Street, in Edinburgh’s New Town. He died on 10 January 1876 and is buried in the south-west spur of Dean Cemetery in western Edinburgh.
Robert and James were remarkable engineers The brothers learned their skills from their father, Michael, who was born on 18 February 1708, at Glassingall, Dunblane. He was a renowned manufacturer and inventor of a rotary threshing machine (1756-8).
In addition, their descendants, Patrick, James and Matthew Stirling became legends in the railway industry throughout the world during the 1800s. The railway engine GNR 4-2-2 No. 1 (Stirling Single) by Patrick Stirling is now part of the National Collection at The National Railway Museum, York.
Family descendants.
Patrick Stirling (1820-1895), born in Kilmarnock, was the son of the Reverend Robert Stirling. Patrick was Chief Mechanical Engineer of the Great Northern Railway and was well-liked by the railwaymen of the GNR. For his 70th birthday, they erected a fountain in his honour in Doncaster and 3,000 GNR railwaymen braved pouring rain to accompany his funeral procession when he died.
Patrick’s brother, James Stirling was also a locomotive engineer, and Patrick’s son, Matthew Stirling was the Locomotive Superintendent (and CME) for the Hull & Barnsley Railway. Another son of Patrick played for Doncaster Rovers and was Mayor of Doncaster.
Other sons of Robert Stirling, William, born 1822 and Robert, born 1824 were engineers with the Lima to Calao railway in Peru (the oldest in South America).
James, the youngest son, born in 1835, was the Locomotive Superintendent with the Glasgow and South-Western Railway Company and later, the South-Eastern Railway, he introduced many improvements to locomotive power. An attempt to shoot James was made on 29 June 1885. George Hopkins had been a footplateman and following an accident was put in charge of a stationery boiler for the forge at Ashford Works. Due to this accident and a subsequent loss of earnings, he blamed the railway company and tried to murder James Stirling.
Modern developments
Modern developments and inventions allowed for new uses of the Stirling Engine.
In the 1950s, the Ford Motor Company looked at the possibility of Stirling Engines being used in vehicles.
Since 2004, a Stirling engine has been used to generate energy from concentrated solar power. The Eurodish parabolic array in Seville, Spain, focusses the Sun’s solar energy by curved mirrors to a Stirling Engine that in turn drives an electric generator. At one time, it was the most efficient means of converting the maximum of solar energy into electricity. Stirling Engine solar-electricity systems can also be found in Arizona USA and the Kalahari Desert.
In 2005, the originally diesel-electric powered, Swedish submarine HSwMS Gotland, succeeded in getting past a large US Navy battle group of ships totally undetected on multiple occasions. In a war game exercise with the $4.5 billion aircraft carrier USS Ronald Reagan and its escort fleet, the HSwMS Gotland just popped up from out of nowhere in the middle of the fleet and took multiple pictures of the carrier to prove that they had “effectively” sank it. Despite all the elaborate anti-submarine technology employed by the US fleet, the $100 million, HSwMS Gotland totally bamboozled and utterly demoralised those aboard the US ships.
Stirling Engines are used to ‘silently’ power diesel-electric submarines in use by the military navies of Sweden, India, Singapore, Japan, China, and many other countries. The Swedish (Saab) Kockums-built Stirling Engine Air Independent Propulsion (AIP) system is used to power an electrical generator for up to 20 knots propulsion and/or charging batteries. Stirling Engine powered submarines can run silent underwater for up to two weeks without the need to surface or snorkel. Quietly as well at perhaps only a slow 5-10 knots, but long enough however, to sneak right up to an enemy’s coastline without being detected. These submarines are regarded as a cheap alternative to expensive nuclear fission powered submarines.
Stirling Engine powered submarines can use the surrounding sea water as a heat sink to increase efficiency. Modern Swedish stealth submarines use GHOST (Genuine HOlistic STealth) technology. They are designed shape-wise to minimise their radar and passive sonar signature. Gotland class submarines are fitted with 27 electromagnets designed to counteract its magnetic signature to Magnetic Anomaly Detectors (MAD). Its hull has sonar-resistant coatings, and the tower is made of radar-absorbent materials. Interior machinery is coated with rubber acoustic-deadening buffers to reduce sonar detectability.
Stirling Engines have been retrofitted to many existing submarines throughout the world. China operates two types of diesel submarines powered by Stirling engines. The latest Stirling Engine powered Chinese submarine prototype has been claimed to generate 320 kilowatts power output to its electrical generators and the Type 032 Qing-class submarine is capable of submerging for 30 days. It is reported to be the world’s largest operational diesel submarine, with seven Vertical Launch System cells capable of launching cruise and ballistic missiles. Three Stirling Engines are being used as a main power source in the latest Swedish Blekinge-class (A26) submarines.
The ‘Stirling’ engine on submarines can use liquid oxygen or hydrogen as a power source. Depending on how much of that fuel can be stored, the submarines run totally silent under water, and long enough to sneak right up to an enemy’s coast without being detected.
Additionally, with the acoustic signature produced on these stealth submarines designed to be exceptionally low, they can also mask their infrared signature, their magnetic signature, their active sonar response, and their radar signature. The Stirling Engine used on these submarines can also drive a slow turning propeller which reduces cavitation effect normally caused. This all makes these boats exceedingly difficult to detect.
Since October 2015, the Kilopower Reactor using Stirling Technology (KRUSTY) system has been considered by NASA as a power source for interstellar travel and long-duration stays on planets. Some private enthusiasts have built Stirling Engine powered cars, boats and a miniature Stirling Engine was prototyped as a computer chip cooler, using the heat from the chips to drive a cooling fan.
Stirling Engines are used in portable refrigerators and in cryogenics. They are helping to save lives during the current pandemic. They are a component that makes the new class of ultra-low temperature freezer s (ULT freezers) reliable, stable and efficient. ULT freezers are used to store vaccines and medical samples. The Stirling Engine that has been engineered for this use is hermetically sealed, it requires no oil or lubricants and is nearly maintenance free.
A company in Gloucestershire is currently developing a new type of Stirling Engine based heat pump and refrigeration system. It is claimed to improve the efficiency of heat pumps by at least 50 percent and eliminate the need to use gasses which have a high global warming potential. The remarkable Near Isothermal Stirling heat pump uses Fluid Mechanics patented near isothermal compression and expansion technology.
Notes:
The Dundee Foundry also built 3 locomotives (1838 – 1840) for the Arbroath and Forfar railway, the Victoria, Britannia and the Caledonia. At the time, no less than three establishments in Dundee (the only place in Scotland) were making railway locomotives. The engines built in Dundee by James and George Carmichael, the Earl of Airlie and the Lord Whamcliffe may have been run the first regular scheduled passenger service in Scotland, in September 1833. (Robert Stephenson’s locomotive, the 29 mph Rocket at the Rainhill Trials was a few years earlier, in 1829 and three years after James Stirling died was the Tay Rail bridge disaster, 28 December 1879 at 19.16pm)
The Hunterian Museum, Glasgow (Science Balcony) (part of the University of Glasgow). The Museums, Art Gallery and The Mackintosh House are located on the Gilmorehill campus, 3km west of Glasgow city centre. Admission Free, Hillhead Subway is probably the closest on the Glasgow Subway system.
Research by Ken Bruce
Reverend Dr Robert Stirling DD
Eurodish system schematic
Simple gadget type – low temperature – Stirling Engine
Dundee Foundry Victoria Locomotive 2-2-2 – Arbroath and Forfar Railway- source Wiki Commons – Whishaw, F, (1840) The Railways of Great Britain and Ireland: Practically described and illustrated London: Simpkin, Marshall and Co.
GNR 4-2-2 No. 1 (Stirling Single) by Patrick Stirling. It is now part of the National Collection at The National Railway Museum in York (Image Credit)
Public Domain Illustration of Robert Stirling’s 1816 Patent Application
Robert Stirling’s air engine, 1827, Hunterian Museum, Glasgow
A conceptual drawing of four Kilopower reactors on Mars’ surface. Image NASA
