MAXIMUM STEAM WITH L.D. PORTA
|2005 marks the 40th
anniversary of the last ordinary service steam trains
being run in Gloucestershire. The steam locomotive era -
which had lasted nearly 130 years previously in the
county - is still recalled by the Dean Forest and
Gloucestershire and Warwickshire Railways as well as
other narrow gauge, miniature and model lines.
A Western Region "Castle" heads "The Bristolian"
Click on picture for more about railways in Gloucestershire
But what if British Railways Western Region steam had not ended in 1965? What indeed if Robert Riddles 3 cylinder 4-6-2 71000 "Duke of Gloucester" had not been the final express passenger steam locomotive built in Britain in 1954? Or the BTC Modernisation Plan of 1955 not precipitated a rush to replace steam with diesel and electric traction?
71000 "Duke of Gloucester"
The scene could have been so different if the decision makers had listened to an Argentine engineer named Livio Dante Porta.
Livio Dante Porta was born on 21 March 1922 and died on 10 June 2003. In between he pioneered a new generation of low-emission, thermally efficient, low-maintenance steam locomotives that is now being developed concurrently in Britain, Japan, Switzerland and the US that will offer a romantic, and surprisingly efficient alternative at the margin of railway operations.
Locomotive 6000 of the New York Central Rail Road - the first of the Niagaras
By the time that Porta had
completed his technical studies in Buenos Aires in 1946,
the classic mainline steam locomotive was in its final
stage of development. On the New York Central, Paul
Kiefer had just produced his mighty Niagara 4-8-4s,
magnificent and brutally functional machines capable of
running at 100mph on level track with 16-car trains on
tight schedules between New York and Chicago, and
clocking up 28,000 miles a month. Exhaustive tests proved
them every bit as economical, and a great deal more
powerful, than the latest diesels.
24 081 One of the first diesel electric locomotives built by British Railways workshops
Click on picture for more about diesel locomotive driving
diesel lobby, backed by the oil industry and politicians
intimately connected with it, was to win the day
worldwide. Electric traction, meanwhile, was attractive,
efficient and clean, with the smooth flow of power from
national grids coursing through its locomotives' motors
at the turn of a driver's handle. If the cheap, simple
and robust reciprocating steam locomotive still made
sense in developing countries such as India and China
well into the 1990s, and even beyond, there appeared to
be no room for advanced technological development in
steam railway traction.
A Train Grand Vitesse in the French countryside.
Click on picture for more about modern high speed railways
much from Chapelon, although his talents were largely
channelled into making existing locomotives types more
efficient than in building new machines. This must have
been a frustration to so creative an engineer, but his
good nature, curiosity and unflappability saw him working
on railways as politically and technically disparate as
those of southern Argentina, South Africa and Cuba.
5778 was one of the diesel electric locomotives supplied to Argentina by English Electric. Not only did their single cabs resemble the British Railways Class 40s but their local nickname "Pampas Crickets" suggests that they sounded like "Whistlers" too! Click on picture for more about railways in Argentina
1940 vintage Peckett six coupled saddle tank engine "Henbury"
5AT : EVERYDAY STEAM AT 113 MPH
Here is some more data on the 5AT 4-6-0 project. Full details can be found at www.5AT.co.uk
The 5AT is a totally new steam locomotive design, incorporating the latest proven steam locomotive technology, for hauling main line steam charter and railcruise trains. With a 100% increase in thermal efficiency over "classic" steam, and 3500 horsepower available from the cylinders (more than an English Electric "Deltic" diesel-electric), its perfomance will amply demonstrate what could have been achieved had steam locomotive development been fully exploited in the 20th Century.
Major features would include a maximum continuous operating speed of 180 kph/113 mph to keep up with modern rail traffic (Maximum design speed would be 200 kph/125 mph) and a high power to weight ratio combined with good adhesion - 1890 kW/2535 hp at the draw bar at 113 kph/70mph. Wide route availability would be achieved with a modest 20 tonne axle load and combined with good footplate conditions, simplicity, reliability, easy maintenance and servicing, low fuel and water consumption, low overall operating and maintenance cost while conforming to the latest safety regulations. Diesel or gas oil fuel (with an option for a coal-fired version) would offer the ability to run 80,000+ km (50,000+ miles) per annum with minimum maintenance.
The 5AT's fuel and water ranges are calculated to be 925 km / 570 miles and 610 km / 380 miles respectively under representative average service conditions. At maximum operating speed and power the figures would be 552 km / 345 miles and 367 km / 230 miles respectively at a (i.e. at 113 kph / 70 mph with 1890 kW/2535 hp at the drawbar)
|Below is a more detailed exploration of Porta's theories. As English was not his first language I have cut out some of his repetition and amplified historical facts as needed.|
Fundamental Principles of Steam Locomotive Modernisation and
Their Application to Museum And Tourist Railway Locomotives
By Livio D. Porta, Consulting Engineer
|Modernisation is defined
as the partial application of technological advances to
existing locomotives without the introduction of
structural changes. And it is a myth that
the steam locomotive reached a pinnacle imposed by its
French locomotive designer Andre Chapelon was the first to realise this from 1926 onwards, and the author, his disciple, continued the work. Whilst a number of mechanical developments, most of them of American inspiration, need to be recorded, thermodynamic advances make up the bulk of the progress rather than replacing spoked by Bulleid Pacific type Boxpok wheels, fitting a superheater throttle or thermic syphons. The author started to put it into practice in 1952, and is still continuing to do so today with serious commercial applications
35030"Elder Dempster Lines" heads of a Waterloo to Bournemouth train in September 1964. This rebuilt Bulleid "Merchant Navy" pacific has retained its Boxpok wheels and thermic syphon.
performance for commercial railways can be justified by a
number of reasons, such as increased line capacity, the
substitution of coal or alternative fuels for oil, the
avoidance of costly investments in diesel locomotives,
and, nowadays, compliance with pollution laws. Increased
power, better fuel economy and environmental
considerations may also lead to modernisation demands for
tourist railways, but museum locomotives are also capable
of justifying modernisation on the grounds that they
should show the furthest development of the technology.
By 1920, the steam locomotive had to withstand the challenge of railway electrification. The fundamental argument for electrification was an increased thermal efficiency leading to a definite reduction in coal consumption. One should not forget that at that time coal was mostly won labour-intensively by hand, which was very expensive (except in Britain). The most demanding services also required premium fuel producing relatively small amounts of ash and clinkers.
Western Region Castle 4-6-0 5077 "Fairey Battle" at Cardiff Canton Depot in 1960.
|One obvious example of
this was Charles B. Colletts "Castle"
Class 4-6-0s introduced by the Great Western Railway in
1923 for its high speed services from London to the West
of England. Like many preceding GWR express locomotives,
4073 "Caerphilly Castle" and its ilk had narrow
fireboxes designed to burn high calorie Welsh steam coal.
In contrast, contemporary express locomotives in the USA
had wider fireboxes to consume much less efficient solid
Experiments up to the outbreak of the Second World War with turbine, uniflow and various other kinds of non-Stephensonian locomotive had not been successful. But Andre Chapelon, working on French railways, realised that the progress of steam lay in eliminating from the Stephensonian scheme a number of absurd imperfections, perhaps the most significant of which was a poor internal streamlining and flagrant violations of thermodynamic fundamentals.
231K 22 was built by the Chemin de Fer Paris - Lyon - Marseilles (PLM) in 1914 and was rebuilt by the Societe National des Chemins de Fer Francais (SNCF) in 1937. The Pacific hauled crack expresses to the French Riviera and also powered the Calais-Paris "Fleche D'Or" ( equivalent of the British Golden Arrow ). During the 1990s it was preserved at Steamtown. Carnforth, Lancashire.
Click on picture for more about lost railways in Lancashire
|He discovered this when,
after sweating to keep a 16 atmospheres boiler pressure
in his Paris Lyon-Marseilles compound locomotives,
the footplate crews destroyed his painful efforts by
strangling the pressure down to 10 atmospheres at the
A steam locomotive can be thought of as a simple machine with cylinders in which the pistons move under steam pressure often with expansive working for fuel economy. Given that the locomotive boiler is large and efficient enough, the size of the cylinders dictates the amount of power available, although enough adhesion weight is to be provided to avoid slipping. For very high speeds, tall wheels are also essential, such as the 2.3 m diameter driving wheels fitted to the streamlined Deutsche Reichsbahn Class 05 Pacifics. And that is all. That has been the very basis of locomotive design in the USA, England, India, South Africa etc. Development was achieved by trial and error, on a merely empirical basis. Exceedingly good performances were sometimes realised. In 1895, British trains competing between East and West Coast Main Lines covered the 869 km between London and Aberdeen in 8 h 29 min with three stops, in the middle of foggy nights!
Caledonian Railway 4-2-2 Number 123
|Similarly, Caledonian Railway 4-2-2 Number 123 - with a pair of 2.15 metre ( 7 feet ) driving wheels was a one-off design built by Neilson - later to become part of the North British Locomotive Company - in 1886 with the works number 3553. The curving design owed much to Caledonian Railway Locomotive Superintendent Dugald Drummond and was the only late Nineteenth Century single driver to appear on a Scottish railway. 123 took part in the 1888 race to Scotland when it hauled a four-carriage West Coast train the 100 3/4 miles from Carlisle to Edinburgh in an average time of 107 3/4 minutes. This included the ascent of Beattock incline which varied between 1 in 74 and 1 in 88 for nine miles.|
|However, a steam
locomotive can also be viewed as a machine for
transforming the fuel's chemical energy into mechanical
work at the drawbar. This thermodynamic
concept of the steam engine became firmly established by
Chapelon in 1926. But since he wrote in French, the world
outside France ignored it. The last of the British steam
locomotive giants, Bulleid, said that
"thermodynamics never sold a single
Thermodynamics makes a different approach. There are two fundamental equations for the steam locomotive:
Power [kiloWatts] =
Steam produced by the boiler [kg/hour] divided by Specific steam consumption [Kg/kiloWatthours]
Power [kiloWatts] =
Heat input [MegaJoules] multiplied by thermal efficiency [ percentage ] multiplied by 10
Thus power is limited by the boiler, while the function of the cylinders is to extract the maximum work from the steam supplied. It is irrelevant to have large cylinders if they are inefficient. The second equation shows that the limit is determined by the ability of the boiler to burn as much fuel per hour as possible, but the resulting power is determined by the thermal efficiency. Both thermodynamic equations, which many steam engineers will now see for the first time in their lives, are of course of academic nature. But Chapelon proved, by means of the performance of his unequalled engines, that they are at the very heart of any steam locomotive, whether it is the best or the most mediocre one. This understanding is essential in order to grasp the nature of the modernization.
The thermodynamic nature of the steam locomotive calls for a minimization of what are called irreversible losses. An example of this are pressure drops that do not produce work, as in the case of Chapelon's driver reducing, by throttling, the steam pressure of 16 atmospheres at the boiler to 10 atmospheres at the cylinder inlet is an irreversible loss. Thus modernization requires an improvement of all steam passages to minimize ineffective pressure losses: this is called improved internal streamlining. On a classical steam locomotive, when it is forced to develop greater power, the specific steam consumption tends to increase sharply. At a certain point, maximum power is obtained because the breathing capacity of the steam circuit (pipes, valves, exhaust nozzle etc.) is exhausted: this is what the Americans call "capacity power". If the same engine is provided with larger steam passages, large valves, improved draught ejector etc., the specific consumption also shows an increase, but the limit is beyond the capacity of the boiler to supply steam: the power of the locomotive is defined by the boiler.
Union Pacific Rail Road Challenger Class Mallet articulated locomotive 3902
Click on picture for more about other kinds of articulated locomotive
|Chapelon was the first to
demonstrate this fact, although it was expressed in a
different form by Anatole Mallet. For different speeds, a
different set of graph curves is obtained. The
English-speaking world did not even suspect this
As the various steam passages are not infinitely large, for a given cut-off the speed-tractive effort graph line drops. For a poorly designed engine, the lines drop so much that the breathing capacity is exhausted: no matter what the ability of the boiler to supply steam may be, there is a maximum power which cannot be surpassed. If good internal streamlining is provided, this breathing capacity is so large that the limit is outside the available operating range, i.e. beyond the evaporative capacity of the boiler.
There are a number of other losses that are now not only identified, but quantified, while at the same time means are provided on the hardware to reduce them to a minimum (piston ring leakage, incomplete combustion, wall effects in the cylinders etc.).
A most important thermodynamic concept is that of the ideal engine: this is the one in which, for given steam conditions, all phenomena occur without irreversible losses (for example, no piston ring leakage, no radiation etc.). The production of draught as demanded for combustion and heat transfer in the boiler requires an energy which, in the form of back pressure on the pistons, reduces the otherwise available power. This obeys the ROSAK-VÉRON dictum (as endorsed by the author):
The design of a combustion and heat transfer apparatus is a compromise between its bulk and the cost of energy required to circulate the fluids.
This principle was (and still is!) unknown to steam engineers but not to the locomotives themselves!
Thus, the boiler cannot be indefinitely forced by sharpening the blast. With ordinary ejectors, this corresponds to a smokebox vacuum of approximately 150 mm H2O. Chapelon, around 1930, developed the KYLCHAP ejector leading to vacuums of 300 mm H2O and more, thus obtaining greater evaporations, say 100 kg/m2h, with acceptable back pressures. Associated with a better internal streamlining, the actual power developed at the drawbar was in some cases doubled in the higher speed range. The author's LEMPOR ejector increased that figure to 140 kg/m2h.
Preserved London and North Eastern Railway Class A4 Pacific 4468 "Mallard" being rebuilt at the National Railway Museum in York. The firetubes are visible at the back of the smokebox while in front of the World's fastest steam locomotive lie its double KYLCHAP blast pipe ( painted white, left ) and its double chimney. The teak built LNER Dynamometer car is visible in the background
Fellow A4 Pacific 4498 "Sir Nigel Gresley" in steam at Weymouth on 4 June 1967
|Chapelon started his work
not by building new locomotives, but by modernising
existing ones. A summary of his main principles, all
showing a multiplicative effect between themselves, is as
The author contributed to the above scheme with:
Even some basic alterations may produce spectacular results. All this depends on the possibilities afforded by the existing design and the particular aims of the owners, and of course on the available money.
Chinese State Railways QJ Class 2-10-2 5751
|What follows may be
considered as a project of maxima, for example, as the
one studied by the author for the Chinese QJ 2-10-2 so as
to reach a power of 5500 hp (compared to the 3300
installed horsepower of an English Electric
"Deltic" diesel electric for example).
The above list should be completed by a number of details and alternatives, totalling perhaps 500, as an answer to minor problems that may become determinant of the performance. Or put another way "No horse will run faster than what is the limit of a poorly fitted horseshoe spike"
Not so much back to the future as on to the past. A working replica of Great Western Broad Gauge express 4-2-2 "Iron Duke" visits the Gloucestershire Warwickshire Railway.
Click on picture for more about advanced technology on the Great Western Railway
|So far, the whole
question has been looked at from the standpoint of
"commercial" railway operation. However, this
point of view may also hold true for tourist traffic as,
for example, on the Grand Canyon Railway, USA. The author
is not conversant with the tourist railway business.
However, a representative opinion poll in Austria
revealed that 79% of the passengers prefer a steam train:
there is some unexplainable difference! So if the
decision has been made in favour of steam, the
requirements may include:
Increased power may be demanded by the ever increasing traffic invariably experienced by tourist steam railways. Improved performance may take the form of a perfect reliability: a hot big end is for sure a tragedy. In terms of reduction of operating costs longer, reliable runs are more economical and driver only operation is an attractive proposal. Sooner or later, smoke will be banned by the environmentalists. The GPCS, as proven in practice, makes a perfectly transparent exhaust possible. CO, HC, and solid emissions are extremely low, NOX emissions are very close to or at the theoretical minimum. Similarly GPCS can control clinkering on higher calorific value coal types.
Similarly, the function of museums may be extended not only to simple preservation, but also to a live presentation of steam locomotives and associated railway vehicles. However, a number of problems may arise, ranging from hot boxes to the most frequent ones: indifferent steaming, boiler scaling and foaming. The appropriate technology to solve these problems is nowadays available.
An historical and philosophical question now comes to the fore. All preserved locomotives have suffered many changes along their lives, of which perhaps the most frequent one was fitting a superheater. What should be the state of preservation selected be? The last one possibly as it requires the least conservation work. But has the process of development truly ended? A steam locomotive is more than the cold hardware. It is a live being. All the alterations introduced along its life are the proof of this. In fact, it is a modernisation process.
One example of this is a Neilson 0-6-0 built in Glasgow in 1888 for service in the authors native Argentina and rebuilt as a 2-6-0 in 1991 by the author in order to improve her performance. This was necessary because of carriages added to the historical train that she pulled. Retrofitting the GPCS is now being considered to avoid the sparks resulting from wood firing. To appease pure preservationists, a sister engine has also been put in service in its original condition as an 0-6-0. The moral is that each museum should offer the general public and locomotive students an example of a full modernisation showing that the steam locomotive is far from being dead: this is more important than putting fossils on exhibition!
The steam locomotive is thus far from being a simple machine. It is very complicated, but its complication is of an intellectual nature. In the past every railway had to have an engineering office; nowadays this painful task has been transferred, in the case of diesels, to the manufacturer. This happens with all technologies, from aeroplanes to shoes. Running tourist railways and museum trains is a matter for professionals, and even in this case, they, unlike their predecessors on state or privately owned railways in the past, lack the institutional support which was developed over more than a century. Much of that institutional support has been lost, and enthusiasm and willingness is not enough to solve the problems.
Riddles and Cox designed Britannia Pacific 70015 "Apollo" , seen at Manchester Victoria with an RCTS Railtour on 19 March 1967. The Britannias were envisaged as simple, rugged locomotives which would last into the 1970s and be replaced by electrification.
|It is false that the steam locomotive reached the pinnacle of its development potential. As a matter of course, steam engineers who are still alive will not accept that: they prefer an honourable defeat by the diesel, although not to the extent that the author once heard: "We have thrown steam into a ditch, and it is better for you to leave it there!" They look upon modernization with horror because it is change that they did not generate themselves. The author believes to have generated much change and advancement. Some of the old important engineers of the steam locomotive, now dead, supported him, like Chapelon, who after a lot of angry discussions accepted, for example, the GPCS; some others - including E. S. Cox who worked on the British Standard steam designs with R.A. Riddles - described it as "abortive". The reader who is faced with the need to increase the power, reduce the fuel bill, abide by pollution laws etc. has to judge for himself whether modernisation proposals are reasonable or merely fanciful. He should, however, remember the fact that he who knows how to paint does the painting, not he who wants to.|
The man and the machine named after him.