![Launch boiler, firebox removed (Brockhaus)](https://upload.wikimedia.org/wikipedia/commons/0/03/Launch_boiler%2C_firebox_removed_%28Brockhaus%29.jpg)
A launch-type, gunboat or horizontal multitubular boiler
is a form of small
steam boiler
Steam is a substance containing water in the gas phase, and sometimes also an aerosol of liquid water droplets, or air. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization. ...
. It consists of a cylindrical horizontal shell with a cylindrical furnace and
fire-tubes within this.
Their name derives from the boiler's popular use at one time for small
steam yacht
A steam yacht is a class of luxury or commercial yacht with primary or secondary steam propulsion in addition to the sails usually carried by yachts.
Origin of the name
The English steamboat entrepreneur George Dodd (1783–1827) used the term ...
s and
launches. They have also been used in some early Naval
torpedo boat destroyer
In naval terminology, a destroyer is a fast, manoeuvrable, long-endurance warship intended to escort
larger vessels in a fleet, convoy or battle group and defend them against powerful short range attackers. They were originally developed in ...
s.
Description
![Skansen w Chabówce -maszyna 08](https://upload.wikimedia.org/wikipedia/commons/6/68/Skansen_w_Chab%C3%B3wce_-maszyna_08.JPG)
The cylindrical furnace or firebox fits entirely within the boiler's outer shell. Unlike the
locomotive boiler
A fire-tube boiler is a type of boiler in which hot gases pass from a fire through one or more tubes running through a sealed container of water. The heat of the gases is transferred through the walls of the tubes by thermal conduction, heating t ...
, there is no firebox grate emerging beneath the main boiler. The boiler has similarities with both the locomotive boiler (the multiple small fire-tubes), and the
Scotch marine boiler
A "Scotch" marine boiler (or simply Scotch boiler) is a design of steam boiler best known for its use on ships.
The general layout is that of a squat horizontal cylinder. One or more large cylindrical furnaces are in the lower part of the boiler ...
(the short cylindrical furnace). As a fire-tube boiler it has generous heating area and so is an effective steamer. Firebox construction is also simpler, thus cheaper, than for the locomotive firebox. As the circular furnace is largely self-supporting against boiler pressure, it did not require the extensive and costly
stay
Stay may refer to:
Places
* Stay, Kentucky, an unincorporated community in the US
Law
* Stay of execution, a ruling to temporarily suspend the enforcement of a court judgment
* Stay of proceedings, a ruling halting further legal process in a tri ...
s of the locomotive boiler. This also allowed the boiler to be made with a bolted joint in the outer shell and so the whole furnace and tube nest could be withdrawn for inspection and maintenance.
The firebox is of limited size though, and unlike the locomotive boiler cannot expand beyond the size of the boiler shell. This limits the sustained output that is possible.
The grate and ashpan are also limited in size, the grate being a set of bars part-way across the furnace tube and the ashpan the restricted space beneath this. These features limit the boiler's ability to burn hard
bituminous coal
Bituminous coal, or black coal, is a type of coal containing a tar-like substance called bitumen or asphalt. Its coloration can be black or sometimes dark brown; often there are well-defined bands of bright and dull material within the seams. It ...
and they require a supply of Welsh
steam coal
Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen.
Coal is formed when dea ...
, or similar, instead. Firing with wood or
biomass
Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bi ...
fuels was difficult. Firebox capacity is further restricted by the space used for the ashpan and also by the dry-back furnace.
The small ashpan also restricts their ability to steam for long periods.
One drawback of the boiler was the large diameter of the furnace relative to the boiler shell, and thus the small steam space above the crown of the furnace. This made the boilers prone to
priming
Priming may refer to:
* Priming (agriculture), a form of seed planting preparation, in which seeds are soaked before planting
* Priming (immunology), a process occurring when a specific antigen is presented to naive lymphocytes causing them to d ...
, particularly on a rough sea, where water could be carried over into the steam pipe.
A more serious danger was the limited reserve of the water level, where the water level had only to drop by a small amount owing to inattention before the furnace crown would be exposed, with likely overheating and risk of boiler explosion. The boiler was safe when correctly fired, but could not be left unattended. These water level restrictions became even more troublesome when the boiler was tilted, even by as little as a steep railway line. An unusual rate of wear and number of replacement furnaces supplied for the Heywood locomotives has been put down to this cause.
The boiler did see some popularity in mainland Europe, as a boiler for small
portable engine
A portable engine is an engine, either a steam engine or an internal combustion engine, that sits in one place while operating (providing power to machinery), but (unlike a stationary engine) is wikt:portable#Adjective, portable and thus can be ...
s. A similar boiler, but arranged with return fire-tubes, was built in America as the
Huber boiler.
Bagnall boiler
![DMM 2562 Dampflokomobile](https://upload.wikimedia.org/wikipedia/commons/c/cf/DMM_2562_Dampflokomobile.jpg)
To reduce the limitations of the small furnace, an enlarged form was developed. The area of the boiler shell alongside the furnace was enlarged in diameter, but remained circular. This permitted a larger diameter of furnace to be fitted. The firebox section of the shell was offset downwards, so that the tube nest from the upper part of the furnace was in the lowest, water-filled, portion of the shell. As the plates were still cylindrical they did not require stays, but there may have been a few small rod stays to support the flat part of the throatplate between the two sections of the shell.
This boiler design was used for semi-portable engines from the 1860s. As the wider grate allowed the burning of poor fuels, such as straw or sugarcane waste, it was favoured for agricultural use and was widely known as the 'colonial' type.
Marshalls
Marshalls is an American chain of off-price department stores owned by TJX Companies. Marshalls has over 1,000 American stores, including larger stores named Marshalls Mega Store, covering 42 states and Puerto Rico, and 61 stores in Canada. Mar ...
built many of these and patented the design as their 'Britannia' firebox. This was also offered in a lengthened form as a log-burning furnace, particularly for use in Australia and Africa where forest land was being clear-felled for agriculture.
All-circular launch boilers (rather than locomotive boilers) were not widely used in coal-rich Britain, apart from these enlarged types. They were sometimes known as 'marine' boilers, although this enlarged form was not favoured for marine use, owing to its raised centre of gravity.
Bagnall railway locomotives
![Appleby industrial narrow gauge 0-4-0 saddle tank locomotive](https://upload.wikimedia.org/wikipedia/commons/e/e4/Appleby_industrial_narrow_gauge_0-4-0_saddle_tank_locomotive.png)
The enlarged circular firebox was also used by
W.G. Bagnall for narrow-gauge locomotives, from 1890.
One of the last of these to be built, the last industrial narrow-gauge steam locomotive to be built for use in the UK, was ''
Monarch
A monarch is a head of stateWebster's II New College DictionarMonarch Houghton Mifflin. Boston. 2001. p. 707. Life tenure, for life or until abdication, and therefore the head of state of a monarchy. A monarch may exercise the highest authority ...
'', an articulated locomotive built for
an industrial railway in Kent in 1953. This was one of a batch built for sugar plantation railways in South Africa, although it is slightly larger at itself. These were articulated to
Bagnall's modified Meyer design. The original
Meyer locomotive
A Meyer locomotive is a type of articulated locomotive. The design was never as popular as the Garratt or Mallet locomotives. It can be best regarded as 19th Century competition for the early compound Mallet and also the Fairlie articulated design ...
used two articulated bogies beneath a tank locomotive frame carrying the boiler and water tanks. This limited the space available for the firebox, a disadvantage which could be avoided, for small locos, by the use of Bagnall's boiler with a circular firebox entirely above the frames.
Railway locomotives
![Dot at Narrow Gauge Railway Museum - 2010-03-07](https://upload.wikimedia.org/wikipedia/commons/8/82/Dot_at_Narrow_Gauge_Railway_Museum_-_2010-03-07.jpg)
Launch-type boilers were only rarely used for railway
locomotive
A locomotive or engine is a rail transport vehicle that provides the Power (physics), motive power for a train. If a locomotive is capable of carrying a payload, it is usually rather referred to as a multiple unit, Motor coach (rail), motor ...
s, although they were notably used by
Sir Arthur Heywood
Sir Arthur Percival Heywood, 3rd Baronet (25 December 1849 – 19 April 1916) is best known today as the innovator of the fifteen inch minimum gauge railway, for estate use.
Early life
He was the eldest son of Sir Thomas Percival Heywood ...
from 1874 for his
minimum gauge railway
Minimum-gauge railways have a gauge of most commonly , , , , , or . The notion of minimum-gauge railways was originally developed by estate railways and the French company of Decauville for light railways, trench railways, mining, and farming ...
s at
Duffield Bank and
Eaton Hall.
Other minimum gauge railways, notable the gauge works railways at
Crewe
Crewe () is a railway town and civil parish in the unitary authority of Cheshire East in Cheshire, England. The Crewe built-up area had a total population of 75,556 in 2011, which also covers parts of the adjacent civil parishes of Willaston ...
,
Horwich
Horwich ( ) is a town and civil parish in the Metropolitan Borough of Bolton, Greater Manchester, England. Prior to 1974 in the historic county of Lancashire. It is southeast of Chorley, northwest of Bolton and northwest of Manchester. It l ...
and the
Guinness brewery
St. James's Gate Brewery is a brewery founded in 1759 in Dublin, Ireland, by Arthur Guinness. The company is now a part of Diageo, a company formed from the merger of Guinness and Grand Metropolitan in 1997. The main product of the brewery is ...
in Dublin, also used launch-type boilers, owing to the limited space between the frames for a conventional firebox.
![Boiler backhead, Ursula, Perrygrove Railway](https://upload.wikimedia.org/wikipedia/commons/3/32/Boiler_backhead%2C_Ursula%2C_Perrygrove_Railway.jpg)
A limitation of this design for steam locomotives was the need to fit fire, grate and ashpan all within the confined circular furnace tube. This limited the radiative heating surface of the furnace, and thus the immediate steam-raising power of the boiler. They were noted as being slower to light from cold than conventional. As the ashpan space beneath the grate was small, locomotives could only operate for a short time before needing to rake out this ashpan. On a main line railway this would have required a return to the engine shed.
On small narrow gauge contractor lines, the ash would simply be dumped wherever convenient and so this was much less of a drawback.
Conical boilers
![Hohenzollern_Locomotive_Works_447_heeresfeldbahn_locomotive](https://upload.wikimedia.org/wikipedia/commons/8/8a/Hohenzollern_Locomotive_Works_447_heeresfeldbahn_locomotive.jpg)
In 1888 the
Hohenzollern Locomotive Works
The Hohenzollern Locomotive Works (Aktiengesellschaft für Lokomotivbau Hohenzollern) was a German locomotive-building company which operated from 1872 to 1929. The Hohenzollern works was a manufacturer of standard gauge engines and about 400 fi ...
delivered the first two narrow gauge
Feldbahn
A , or , is the German term for a narrow-gauge field railway, usually not open to the public, which in its simplest form provides for the transportation of agricultural, forestry () and industrial raw materials such as wood, peat, stone, earth an ...
locomotives for the
Prussian Army
The Royal Prussian Army (1701–1919, german: Königlich Preußische Armee) served as the army of the Kingdom of Prussia. It became vital to the development of Brandenburg-Prussia as a European power.
The Prussian Army had its roots in the co ...
. These used a conical development of the launch boiler. A backplate of enlarged diameter and a greatly reduced smokebox tubeplate were fitted into a steeply conical shell. This was installed with the upper edge of the cone horizontal. The purpose of the conical shape was to increase water depth over the furnace, the hottest part of the evaporative surface. The furnace and tubes were moved to the lower part of the shell, with the tubes running upwards parallel to the lower edge of the cone. A difficulty was the boiler's lack of steam space, requiring an enlarged dome, of almost as much capacity as the main shell.
As a major virtue of the launch boiler is the simplicity of its construction, rolling a conical shell and fitting a large dome represented a considerable increase in their complexity and cost.
These locomotives, and their boilers, were a complete failure. They were undersized and underpowered for the task, with tiny wheels prone to derailment on uneven track and (for the first 2-2-2 locomotive) limited adhesion from its single driver. Despite being some years after Heywood and the publication of his ''Minimum Gauge Railways'', they ignored almost all of Heywood's principles. The boilers lacked evaporative capacity and could not support sustained running.
Lentz boiler
A large launch-type boiler with a
corrugated furnace, described as the ''Lentz boiler'', was fitted to the first
Heilmann steam-electric locomotive ''La Fusée Electrique'' of 1890. The boiler design was German in origin. A similar boiler, the 'Vanderbilt' was used in the USA.
Lancashire & Yorkshire Railway
![LYR 0-8-0 Class 30 1903](https://upload.wikimedia.org/wikipedia/commons/c/cc/LYR_0-8-0_Class_30_1903.jpg)
The
Lancashire & Yorkshire Railway
The Lancashire and Yorkshire Railway (L&YR) was a major British railway company before the 1923 Grouping. It was incorporated in 1847 from an amalgamation of several existing railways. It was the third-largest railway system based in northern ...
suffered problems with
firebox stays, leading to a
boiler explosion
A boiler explosion is a catastrophic failure of a boiler. There are two types of boiler explosions. One type is a failure of the pressure parts of the steam and water sides. There can be many different causes, such as failure of the safety valve ...
with an
0-8-0
Under the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of no leading wheels, eight powered and coupled driving wheels on four axles and no trailing wheels. Locomotives of this type are also referre ...
'Class 30' near
Knottingley
Knottingley is a market town in the City of Wakefield in West Yorkshire, England on the River Aire and the old A1 road (Great Britain), A1 road before it was bypassed as the A1(M). Historic counties of England, Historically part of the West Ridi ...
in 1901
Their Chief Mechanical Engineer
Henry Hoy
Henry Albert Hoy (1855–1910) was a locomotive engineer with the Lancashire and Yorkshire Railway (L&YR). Hoy was born on 13 January 1855 in London, and educated at King Edward VI's Grammar School in St Albans, and at St John's College, Li ...
, sought to avoid the problems of the stayed firebox altogether and so developed an alternative boiler and firebox. This used a corrugated tubular furnace and cylindrical outer firebox, as for the Lentz.
Such corrugated furnaces were already in widespread use locally, with the
Lancashire
Lancashire ( , ; abbreviated Lancs) is the name of a historic county, ceremonial county, and non-metropolitan county in North West England. The boundaries of these three areas differ significantly.
The non-metropolitan county of Lancashi ...
and
Galloway
Galloway ( ; sco, Gallowa; la, Gallovidia) is a region in southwestern Scotland comprising the historic counties of Wigtownshire and Kirkcudbrightshire. It is administered as part of the council area of Dumfries and Galloway.
A native or i ...
stationary boilers of the Lancashire cotton mills and local makers already had several designs available. The furnace was also of steel, rather than the
copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
used for fireboxes at this time.
Hoy's involvement was ironic, as a major cause of the original accident had been Hoy's invention of a new brass alloy for firebox stays, an inelastic alloy that turned out to have serious drawbacks.
One Class 30, ''396'', was rebuilt in 1903 and 20 more were built new with this boiler.
In service the boilers showed a number of drawbacks. They were slow to warm up after lighting and the limited ashpan space limited their working time away from the shed. Both of these were as a result of the furnace heating area largely being shielded by the grate across it. It has been suggested that they would have been more successful with oil firing, as this would have allowed the whole furnace diameter to have been used and would have avoided ash build up.
The new boiler design did not last long in service and the locomotives were rebuilt with conventional boilers after ten years.
Hoy's successor,
George Hughes, described these boilers unfavourably in papers read to the
I. Mech E.
NZR E class
![Locomotive boiler in the Petone Railway Workshops ATLIB 274420](https://upload.wikimedia.org/wikipedia/commons/9/9e/Locomotive_boiler_in_the_Petone_Railway_Workshops_ATLIB_274420.png)
The single
NZR E class of 1906 was an experimental
Vauclain compound
The Vauclain compound was a type of compound steam locomotive that was briefly popular circa 1900. Developed at the Baldwin Locomotive Works, it featured two pistons moving in parallel, driving a common crosshead and controlled by a common valve ...
articulated 2-6-6-0T
Mallet
A mallet is a tool used for imparting force on another object, often made of rubber or sometimes wood, that is smaller than a maul or beetle, and usually has a relatively large head. The term is descriptive of the overall size and proport ...
, intended for working the
Rimutaka Incline
The Rimutaka Incline was a , gauge railway line on an average grade of 1-in-15 using the Fell system between Summit and Cross Creek stations on the Wairarapa side of the original Wairarapa Line in the Wairarapa district of New Zealand. The t ...
. Compounding encouraged the choice of the then remarkably high boiler pressure of , which required a strong firebox construction. The NZR chief draughtsman G. A. Pearson chose a corrugated furnace design in a tapered boiler, similar to the Vanderbilt.
References
{{steam engine configurations, state=collapsed
Steam boiler types
Marine boilers