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. 1892 was a leap year starting on Friday (see link for calendar). ... October 26 is the 299th day of the year (300th in leap years) in the Gregorian Calendar, with 66 days remaining. ... Loire is a département in the east-central part of France occupying the Loire Rivers upper reaches. ... The French Republic or France (French: République française or France) is a country whose metropolitan territory is located in western Europe, and which is further made up of a collection of overseas islands and territories located in other continents. ... Events January January 1 - The Copyright Act of 1976 takes effect, making sweeping changes to United States copyright law. ... July 22 is the 203rd day (204th in leap years) of the year in the Gregorian Calendar, with 162 days remaining. ... Mechanical engineering is the application of physical principles to the creation of useful devices, objects and machines. ... Great Western Railway No. ... The scientific method or process is considered fundamental to the scientific investigation and acquisition of new knowledge based upon physical evidence. ... Thermodynamics (Greek: thermos = heat and dynamic = change) is the physics of energy, heat, work, entropy and the spontaneity of processes. ... A strobe light is a device which produces regular pulses of bright light without the long period of decay in intensity at the end of a pulse, such as happens with ordinary incandescent light bulbs. ...

Prior to 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. Trial and error is a method for obtaining knowledge, both propositional knowledge and know-how. ...

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 embarassments 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 to produce an efficient, powerful locomotive that every aspect of it had to be improved and dealt with scientifically. He did work on locomotive behaviour at speed, on 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. A compound locomotive is a type of steam locomotive where steam is passed that has already passed through one cylinder is then passed through another; i. ... The Kylchap steam locomotive exhaust system was designed and patented by the famous French steam engineer André Chapelon, using a second-stage nozzle designed by the Finnish engineer Kylälä and known as the Kylälä spreader; thus the name KylChap for this design. ... The TGV is Frances train à grande vitesse; literally high-speed train. Developed by Alsthom and SNCF, and operated by SNCF, the French national railway company, it connects cities in France, especially Paris, and in some other neighbouring countries, such as Belgium, Germany and Switzerland. ...

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. Narrow-gauge railways are railroads (railways) with track spaced at less than the standard gauge of 4 ft 8½ in (1. ... In the Whyte notation, a 2-8-4 is a railroad steam locomotive that has one unpowered leading axle followed by four powered driving axles and two unpowered trailing axles. ... The Norfolk & Western Railways Class J locomotive #611, a 1950 product of the railroads own Roanoke, Virginia shops. ... The Federative Republic of Brazil (República Federativa do Brasil in Portuguese) is the largest and most populous country in South America, and fifth largest in the world. ...

Chapelon's work lived on in the work of L.D. Porta of Argentina and others.