André Chapelon
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André Chapelon (b. 1892-10-26 Saint-Paul-en-Cornillon, Loire, France; d. 1978-07-22) was a noted French mechanical engineer and designer of advanced steam locomotives. He was one of very few locomotive designers who brought a rigorous scientific method to their design, and he sought to apply up-to-date knowledge and theories in subjects such as thermodynamics and gas/fluid flow to the field. He tested his experimental designs thoroughly to understand how they actually behaved, using the most accurate and complete testing and sensing equipment available, such as high-speed stroboscopic photography to watch steam flow.
Before Chapelon, few engineers and designers tried to understand why a certain design worked better than another—they merely worked by trial and error, trying to replicate the attributes of previous locomotives by rule of thumb, by guesswork, and from empirical theories and design rules that had rarely been given adequate testing.
Efficiency was one of Chapelon's primary concerns in design; some of his locomotives exceeded 12% efficiency, which for a steam locomotive was exceptional. With greater efficiency, Chapelon could achieve greater power in a smaller locomotive that burned less coal, rather than simply enlarging a locomotive for more power.
His curse was that despite his abilities and track record, he never got to design a class of brand-new locomotives that actually got built in any number. He was continually stymied by railway management and politicians, and often his superbly performing locomotives were treated as embarrassments by his superiors - because they showed up the poor performance of the officially approved locomotives!
He was a major proponent of the compound locomotive; his other major work included optimising the steam circuit, including improving the steam flow by widening steam passages and paths, improving the flow through valve gear, and improved exhaust systems such as his Kylchap exhaust. Chapelon realised that in order to produce an efficient, powerful locomotive every aspect of it had to be improved and dealt with scientifically. He studied locomotive behaviour at speed and the riding properties of the steel wheel on steel rail; his knowledge was put to use much later on the French TGV high speed trains.
The only locomotives he designed for use outside France were some metre gauge 2-8-4 and 4-8-4 locomotives for GELSA of Brazil. They were highly advanced locomotives with many modern American appliances as well as Chapelon's innovations. André Chapelon was much an admirer of American railroad innovation, even though his work tended to be ignored in the USA.
Chapelon's work lived on in the work of his friend Livio Dante Porta of Argentina, and others, and he was accorded the rare honour for a foreign railwayman of having a British Rail Class 86 (electric!) locomotive named for him.
[edit] Chapelon's locomotives
- The 242 A1 was a locomotive so powerful, that it scared the designers of the early French electric locomotives into increasing the power by another 1000 horsepower. The 242 A1 was a rebuild that first saw light of day in 1946. Developing 5300 HP in the cylinders and with 46,225 lbs of Tractive Effort, nothing in Europe could touch it. Sadly, it was scrapped in 1960.
