André Chapelon, always under heavy ,
updated march 13, 2021
André Chapelon. October 26th, 1892 - july (22nd?), 1978.
He was nicknamed "Le petit" - "Shorty" - by colleagues and friends.
"The work accomplished by Chapelon, by transforming locomotives which were far from new and bringing incredible improvements to their performances, justify an opinion making him the greatest engineer in locomotives since Robert Stephenson. If it's true, that's because him alone seemed to be able to embrace the full significance of these biological interactions between the various organs of the machine and to deal with them in a scientifical manner, in such a way that he was even able to predict the extroardinary results they will gave. His locomotives reached a power to weight ratio and a thermic efficiency never sawn before with steam locomotives, and they gave no more incident in service than those who were in charge of them had wanted to."
J.T. Van Riemsdijk & K. Brown, "The
history of steam power", "Steam on the railways" chapter,
London 1980 and Gallery Press, 1984. Retranslated
from a french edition.
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 R.R., 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:Etat
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.