André Chapelon, toujours , Mis à jour
André Chapelon. 26 octobre 1892 - 22 juillet 1978
Surnommé "Le petit" par ses amis et collègues
"Le travail accompli par Chapelon en transformant des locomotives qui étaient loin d'être neuves et en apportant d'incroyables améliorations à leurs performances justifie une opinion qui fait de lui le plus grand ingénieur en matière de locomotives depuis Robert Stephenson. Si cela est vrai, c'est que lui seul a semblé être capable d'embrasser l'entière signification des interactions biologiques entre les divers organes de la machine et de les traiter d'une manière scientifique, d'une façon telle qu'il était même en mesure de prédire les résultats extraordinaires qu'elles donneraient. Ses locomotives atteignirent un rapport poids / puissance et un rendement thermique jamais vu auparavant avec des locomotives à vapeur, et elles ne donnèrent pas lieu à plus d'incidents en service que ceux qui en étaient en charge ne l'avait voulu."
J.T. Van Riemsdijk & K. Brown, "The
pictorial history of steam power", chapitre "Steam on the
railways", Octopus Books, London 1980 and Gallery Press,
PLEASE NOTE: Every paragraph will become a link to a specific page in a (more or less) close future... These are only short introductions. More hours per day, please! Come back from time to time, I sometimes add a few details here.
His first creation: The KYLCHAP exhaust system, one of the
first examples of high efficiency "fluid engine"
What was exactly his contribution and theories to
compound locomotives design: Mainly the to relegate of
rule-of-thumb and voodoo-inspired theories and design rules to the
"cul de basse-fosse", deep holes were thrown and forgotten
alive persons in ultimo punishment some centuries ago, in favour
of the real scientific knowledge of his time and by a systematic
checking of theories by the use of extensive tests of engines in
real conditions and with the help of correctly used modern
metering equipment such as, for example, high speed stroboscopic
cameras he used to study steam flowing. Details and more by
clicking HERE someday may be
His compound locomotives:
Three series of PACIFICS resulting of the 3566 prototype (1929-35).
The 4 6 2 P.O.'s 4521 turned into the 4 8 0 P.O.'s 4701, most powerful locomotive of any kind (electric, diesel, ...) in europe at that time (1931) with 4 200 H.P..
Two series of 4 8 0 resulting from the prototype, first in 1932, second in 1940, the latest being quite modernized with an improved power output of 4 700 H.P..
2 12 0 prototype, 6 cylinders compound (2 H.P., 4 L.P.) with re-superheating between H.P. and L.P. cylinders, steam envelopes (around cylinders, forgive this precision if you know a bit about physics, mechanic of fluids or 100 000 H.P. boats' steam engines) and other features unusual in the world of locomotives. The most innovative steam locomotive based on the classical Stephenson's concept (no turbine, no super high boiler pressure or other gimmick inapplicable to a locomotive).Once completed, extensive test started in the beginning of 1946. Those tests were acknowledged by railroad's international community as the most extensive and complete ever done on a locomotive, and allowed the discovery of absolutely virgins fields of experiments. Lessons gained here opened a really new and refreshing track that nobody has used yet. Measured normal tractive effort: 83700 lbs. Chapelon had computed that if applied to the 4 4 6 4 Q 2 of the Pennsylvania RailRoad, efficiency figures obtained with the solutions used on 160 A 1 would raise the power output of the P.R.R. engine up to 18.000 H.P.and give an equivalent (in percent) increase of tractive effort.
His last normal gauge locomotive: The 4 8 4 A 1, 3 cylinders prototype, pre-WWII project also completed in 1946, again the most powerful european locomotive at that time (50's), 5,300 H.P., mean tractive effort of 46,255 lbs..
Very innovative work on single expansion engines too:
An invention curiously unrecognized made by an assistant of
Chapelon: The Willoteaux's
piston valve, used on the 242 A 1, 141 E 113, and a on a great
number of machines designed by other french engineers. Its major
advantages if it is
compared to a Trick piston valve are that it twices
flow sections for bot inlet and exhaust, another being its
lightness. If you know application of those in other countries,
please send me some infos.
Il y en a d'autres!
Applications of Chapelon's theories and creations to other french railroad companies' locomotives:
International opinions about the work of André
Chapelon, some texts also containing interrogations and RIGHT
answers about the evident negation of this work made by
nationalized railroads management against
unanimous technical staff opinion leading to premature withdraw
of most then to the total destruction of Chapelon's highly
subversive engines. Straight
I think only some engineers and scientists around the world can
figure out to how much non scientific or technical but
administrative, hierarchical and thus human difficulties Chapelon
was faced to all along his career. It's not only my opinion, it's
shared here and elsewhere by everyone knowing the topic and seems
thus reach the status of Historical truth. Unfortunately, it seems
to be a constant of the life of engineers and researchers in
France still today (3000 engineers left France for foreign
countries in 1996, an official figure in constant and regular
MANY MORE bibliography to come! I.S.B.N. codes available (when it exists!) on request.
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