Anyone have any insight into the high cylinder power achieved with a small grate with Chapelon's 242 A1 locomotive?
The French National Railroad (Societe Nationale de Chemin de Fer) counted axles instead of wheels, so a class 242 was a 4-8-4 Northern type. Brian Hollingsworth in "Steam Passenger Locomotives" describes it as achieving "5500 hp in the cylinders", which I guess means "indicated horsepower", a higher amount than "wheel rim horsepower" after deduction for mechanical friction and "drawbar horsepower", which I always thought it a nebulous measure. Especially with a high speed passenger locomotive, a lot of the power of the locomotive is overcoming air resistance where the locomotive at the lead end has much higher air resistance than the trailing cars in its draft.
Anyway, this locomotive with 2720 sq ft "heating surface", 1249 sq ft in superheater tubes, and a 54 sq ft grate equals roughly the hp (quoted at 6000 hp "in the cylinders") with 5271 sq ft heating surface, 2177 sq ft superheater, and 107.5 sq ft grate of a Norfolk and Western J class?
I first thought the 242A1 was designed to achieve roughly double the thermal efficiency of an American Northern to pull this off. But I also read that "the French compound (expansion steam locomotives)" were "maybe 10% more efficient than the best simples." Wardale in "The Red Devil" suggests that Chapelon may have been "playing tricks" to get this much power from such a small locomotive, intimating the use of "the best Welsh steam coal with just the right caking tendency" so the firebed would not be blown off the grate at the combustion rates involved?
Any thoughts on this question?
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
Juniatha would probably know, but I got a message from her earlier today she's been "bounced" from the Forum, I don't know why, my investigation hasn't started yet. So there's one fantastic source of knowledge concerning European steam lost to us.
More anon. You don't want to know what Lady Firestorm has to say about this. It would have made General Patton blush! God rest his mighty soul!
I don't know of anyone being banned by our fine hosts here at Trains.com. A Moderator may lock a thread that has reached a dead end or a stalemate of bickering t'is, t'ain't. A Moderator may send a diplomatically worded e-mail to "cool one's jets." Or a Moderator may simply delete posts that unnecessarily get folks all fired up.
I have seen Juniatha "suggest parameters" on a thread, and I just read a post offering "push back" to such boundaries, and it was also unfortunate that this push back offered advice to a "non-native speaker of English." I tried to smooth things over, in the way we do in 'Sconsin, by changing the conversation topic to "How bout dem Packers?"
Here's to hoping that folks' feelings all settle down and life goes on as before.
Howdy, Paul.
Back when Bergie was forum king he exiled several people to Siberia. Do the names Al Mayo and Mark Newton strike a chord? Not the only ones, just the ones I know about.
Chuck
Some people have skin that is thinner than a Form 19 train order.
Never too old to have a happy childhood!
BaltACD Some people have skin that is thinner than a Form 19 train order.
Yes indeed, but the question is WHO? Full disclosure here, I'm very fond of that young lady.
tomikawaTT Howdy, Paul. Back when Bergie was forum king he exiled several people to Siberia. Do the names Al Mayo and Mark Newton strike a chord? Not the only ones, just the ones I know about. Chuck
...Futuremodal, Michael Sol, and one or two others who have crept back and mostly behaved.
Paul Milenkovic Anyone have any insight into the high cylinder power achieved with a small grate with Chapelon's 242 A1 locomotive? The French National Railroad (Societe Nationale de Chemin de Fer) counted axles instead of wheels, so a class 242 was a 4-8-4 Northern type. Brian Hollingsworth in "Steam Passenger Locomotives" describes it as achieving "5500 hp in the cylinders", which I guess means "indicated horsepower", a higher amount than "wheel rim horsepower" after deduction for mechanical friction and "drawbar horsepower", which I always thought it a nebulous measure.
The French National Railroad (Societe Nationale de Chemin de Fer) counted axles instead of wheels, so a class 242 was a 4-8-4 Northern type. Brian Hollingsworth in "Steam Passenger Locomotives" describes it as achieving "5500 hp in the cylinders", which I guess means "indicated horsepower", a higher amount than "wheel rim horsepower" after deduction for mechanical friction and "drawbar horsepower", which I always thought it a nebulous measure.
On page 48 of the June 1974 Trains it states the A.1 developed 4500 drawbar horsepower at 60 mph. Not sure if that helps or not.
Hi everyone
First of all , I'm back / never was off - whatever . It seems to have been a misunderstanding .
So far , to quote ELP :
“ Welcome back my friends
to the show that never ends “
( http://www.youtube.com/watch?v=AhYBq6Iz2nQ )
Second , they told me they have re-organized moderating in-house and clearly I'm 'out-of-house' by a decent distance I shall not moderate now – be that to the relief or regret of some or other .
So , in PRR symbolism : no more 'Sally-One' in stand-by , if diesels run late they'll have to see how to make up all by themselves - *gee* .
Ok as concerns the Chapelon 242.A.1 :
Correct , 5500 ihp [metric] was maximum output calculated from both measuring drawbar hp and reading indicator diagrams . This was in fact a formidable output for the size of engine , both cylinder-wise and boiler-wise . It was this engine , too , that on one of her last test runs crushed the fastest electric traction train schedule between Paris and LeMans and that with a specially superincreased train consist and even including a stop for water Chartres due to the given small tender .
For proper evaluation one has to keep in mind the one-and-only express 4-8-4 type in France came about as a rebuilt from the unhappy ETAT 241.101 of the C’ie de Fives Lille equipped with Renaud poppet valve three cylinder simple expansion unit . ETAT standing for 'state railway' as in contrast to the private railways in France before coming of the national SNCF - Societé Nationale des Cemins de Fer – but shortly before outbreak of WW-II .
In France during the 1930s some efforts sprang up by individual engineers to replace compounding with simple expansion ; besides said 241.101 , for example another such effort was by deCaso of the NORD who experimented with two prototype Pacifics rebuilt from their second series 3.12xx ‘Super Pacific’ four cylinder de Glehn into two cylinder simple engines with Cossart ‘poppet valve’ gear ( uhm , I will not enter *that* issue about poppet / piston valves again , I call them poppet valves since they pop open and close – full stop ) . This had successfully been applied in his powerful ( over 2000 ihp ) fast accelerating 2-8-2 tank engines for suburban commuter passenger traffic . The point of course was to simplify mechanism and do away with drives between frames .
In a nutshell : non of these efforts were successful because unlike railroads in the US or national railways in Germany or Austria , French railways never were prepared to pay the price in terms of increased coal consumption and compromised power output with comparatively light engines . In this case , the rebuilt twin tin Pacifics compared less than favorable where the 3.1200 Super Pacifics really sparkled as they topped long inclines at 70 mph heading first rank international express trains between Paris and the Atlantic coast or to the North . For the lightly laid NORD performance came first and that’s why they ordered Chapelon type Pacifics as an intermediate next step above the narrow grate (!) Super Pacific herself stemming from duBousquet Pacifics of pre-WW-I years .
DeCaso , not yet defeated , was meanwhile looking at his own plans for a vastly enlarged two cylinder poppet valve Pacific , eventually evolving plans into a 4-6-4 of 2200 mm drivers ( ~ 86 in ) , 8 of which were later on built as scaled down series 232.R ( three cylinder simple ) /.S ( four cylinder compound ) plus one having been reserved to receive a turbine engine unit , never realized , finally completed as 232.U.1 , again with Chapelon-influenced cylinders and steam flow . These deCaso 4-6-4 engines were already pointing towards the direction Chapelon had envisioned for his SNCF family of high performance types : combining thermodynamically advanced compound cylinder unit layout and valve gear with highly advanced American type mechanical sturdiness, complete with roller bearings on axles , Franklin automatic wedges in solid frames , and many detailed features .
Seeking to overcome adverse voices within SNCF headquarters , Chapelon took the chance when decision had come due what to do about the former ETAT 241.101 lying derelict with damaged Renaud poppet valve gear . Brought to the Ateliers de la Marine et d’Homécourt at Saint-Chamond , the engine then underwent extensive rebuilding from 4-8-2 into 4-8-4 , as a compromise due to the times of war , unfortunately having to retain the Mountain type’s boiler as it was , i.e. never taking full advantage of the twin axle Delta truck , small firebox clearly to be seen in right angle side view photos ( although with ~ 80 in combustion chamber ) .
The lone ETAT engine was especially well suited to form a prototype to Chapelon’s proposed high performance 4-8-4 since it already featured a three cylinder drive when the future family of steam loco types was proposed have three cylinder compound units . The reasoning behind choosing this rarely applied rather unusual type should be made a topic of its own , I will skip it for now . The 242.A.1 featured two Trick piston valves on her inclined inside HP cylinder , positioned down below , which unlike one might be inclined to think turns out pretty logical when looking at cross sectional drawing of the cylinder block with steam envelope applied to it . The large outside LP cylinders – larger in volume than would have been those of a two cylinder simple expansion engine unit had it been applied to this locomotive – were controlled by Willoteaux piston valves with double admission / double exhaust , actuated by a newly designed Walschaerts .
To cut a long story short , when finally turned out in 1946 the 242.A.1 began an exhaustive series of test runs over the principal lines of each the former railways , starting with the PLM where the she dwarfed all standards of performance established by the big yet undwieldy PLM Mountain types including their much improved one-off prototype 241.C.1 tested with high hopes and the intention of once and for all beating the Chapelon Pacifics – if by one more drive axle and big boiler with wide firebox and 5 m² grate – and chosen in 1948 as specimen for the SNCF ‘standard type’ 241.P Mountain type ( side remark : it was not to be , in the comparison tests arranged by the NORD railway looking for the best way their locomotive development was to take , the formidable C.1 succumbed to the infatigable 231.700 series P.O.-Midi Pacific participating )
When the 242.A.1 was tested on the ex PLM Ligne Imperiale , she stormed up the long and winding climb to Blaisy Bas tunnel upkeeping speed at formerly impossible better than 100 km/h ( 63 mph ) with 20 coaches behind the tender . Apart from a cracked HP cylinder cast – probably to be attributed to inferior material of casting available in those times of austerity , the replacement cast steel cylinder never showed any signs of weakness – the engine on her further series runs went from test passed with flying flags to passed with flying flags continuously and in grand style wherever tried . In fact , at least by my looking at it , for some at the SNCF head quarters this locomotive might have proved just too successful – after all , didn’t she even question reason and need for electrification ? From a technical viewpoint , with every run she seemed to spread the parole Chapelon’s outlook on a modern steam traction really had enough going for it to afford a new look at decisions concerning immediate future of train traction on the SNCF !
Interestingly , the engine was never pooled with series 241.P locos in neither of the depots the latter had been stationed , in contrast she remained stationed at LeMans – reknown city as it was for motor sport – running in turns with the valiant yet much smaller 141.P dual purpose Mikados until taken out of service but shortly after Chapelon had left office for retirement . Almost a decade later some survivors of the thinned ranks of 241.P Mountains by then sent wayfaring about the SNCF took refuge at LeMans for last stand express services towards Nantes and the Atlantic coast , never seeing Paris anymore , until here too , the last of steam was laid aside in 1969 while some beaten yet refusing to abdicate 141.R American Mikados remained until around 1970 to write the very last page of steam in France , doing obscure secondary services off the renown main lines .
The reason 5500 ihp could be achieved with a comparatively small grate was twofold : first , an excellent draughting by triple Kylchap exhaust brought grate limit to a maximum , second , steam was made best use of in a cylinder unit of excellent efficiency . This and further supporting features such as proportionally fitting degree of superheating , high boiler efficiency in fact enabled overall locomotive efficiency to attain approximately twice the typically best values found in US 4-8-4 types , namely it went into the vicinity of 15 % overall indicated efficiency from coal specific heat content by mass fed into firebox to mechanical output of cylinders . As for the locomotives planned by Chapelon in 1950 they were to attain maxima of 17 – 18 % overall indicated efficiency and by further optimization , using higher live steam enthalpy values this could be tuned to just reach 20 % in a classic reciprocating steam locomotive – without using some of the more far-out features Porta’s engines sported .
Much later , when steam was all gone , Chapelon’s achievements have repeatedly been questioned in various minor aspects mostly by – sorry – non-professional , miserly heads . In each and every case I have read about , taking a more or less scrutinizing look at things soon nullifies the reproaches ; in their own reasoning those accusations are all crooked in some way or other , in very contrast to Chapelon’s scientific method of establishing and collecting test run data . Quite certainly , by simply taking a look at photos of Chapelon locomotives on test runs , one can see they did *not* carry especially selected better-than-daily-quality loads of coal – in contrast again , in his 1938 book Chapleon himself specified he could have quoted even superior performance values had he picked out carefully selected measuring points with locomotive and combustion at optimum working conditions – yet , he wrote , this would be misleading since daily life for a locomotive just afforded to go through low cylinder temperature working at the start of a journey and include firing under all conditions caused by demands to be met during a trip . So , at least in my regard , such attempts at compromising what Chapelon had achieved are but expressions of envy or lack of capacity to appreciate a brilliant engineers honestly attained life work , left incomplete already by disfavoring influence of times ( early electrification starting on P.O.-Midi the railway he worked for , dictating his having to be content with but rebuilt engines , then WW-II , then nearing end of steam ) , by jealousy and diverting aims ( modernizing steam / electrification now quickly gaining momentum ) within the engineering corpus of the SNCF .
Finally , if you may pardon me , not just as an engineer but as a man André Chapelon even in the winter of his life , from all I have seen in photos showing him in those years around the end of steam in Paris in 1968 , which he had commented upon , he had retained an upright dignity and urbane gentleman’s conduct until finally receiving his call very nearly 10 years after . And this impression of mine – built just from glimpses some photos provide , from his way of writing on technical topics and in answering letters published in a book on his life , some texts and labels to drawings hand-written by him – got confirmed by a friend who has had the privilege of corresponding with him during those final years still discussing matters steam .
As for the relative advantage of compounding , it can be proven by theory and by calculating actual examples , whatever perfection should be built into simple expansion engines – using the same technology in a compound will result in some 10 to 12 % thermodynamic superiority , by using high end live steam properties and steam envelopes / warming / cooling of cylinders / steam chest the thermodynamic advantage of compound will even be augmented .
Although seemingly there are historic examples abounding of comparisons between compound and simple expansion , the results turn out to be inconclusive and contradicting if comparing tests on one railway with those of another railway , most of these at the same time intermixing comparison of simple twin outside cylinder drive with outside / inside four cylinder drive – which all by itself tends to blurr the picture for inevitably it had to cover vast differences in design and consequent differences in quality and longevity of the locomotives concerned – none of them can be considered to provide a final answer , rather , it seemed in the majority of cases engines got designed – consciously or unconsciously – to yield the anticipated results to suit preferences while in other cases , results simply got ignored if not fitting the parole of the day . So , it seems after having dealt with more or less intensive testing back then , everyone rejoined the band wagon and on they went forging on same as ever until the hammer wore out on the anvil and it was left to modern traction to provide the answers the steam league had denied .
Regards
Juniatha
I have heard sources (Wardale?) claim that the best efficiency (indicated? wheel rim? drawbar?) in England of the Britannia class and one-of Duke of Gloucester reached 9 percent whereas "the French compounds" achieved 10 percent thermal efficiency.
So maybe the 242 A1 was not simply "one of the French compounds" but rather the best of the French compounds, and probably by some margin?
A good indication of thermodynamic cycle efficiency apart from the limits of combustion and heat transfer efficiency at the "front end" and mechanical friction from cylinders to wheel rim is that of the water rate. What was the evaporation rate of the 242 A1 at peak hp? If it was evaporating much less water than a U.S. Northern, that could explain how this hp was achieved with about half the grate area and half the heating surfaces?
Does "La Locomotive a Vapeur" have these data? I guess the next task is to acquire a copy of that book, and the next task after that is to exercise my limited skills in the French language?
I told you lads Juniatha was our "fount of knowledge" concerning M'sieu Chapelon and his locomotives. Wow and more wow.
Glad you're here young lady, don't know what we'd do without you.
Emerson, Lake and Palmer. JMJ, I haven't thought about them in years!
No need to brush up on the French language... there is an excellant English translation of "La Locomotive a Vapeur" available. (I do believe there is a 2nd edition already). A web search will find a couple of dealers selling them (as well as e-bay).
Semper Vaporo
Pkgs.
That's G.W.Carpenter's translation, published by Camden Miniature Steam Services (ISBN 978-0953652303). For the ISBN-10, and a resource 'back' to other books on modern steam, see this page from the 5AT people. I don't know about a 'second edition'; are you sure you're not confusing this with the recent re-reprint of Wardale's Red Devil book?
As with all too many of these things (see Vernon Smith's One Man's Locomotives, the 'rare-book' vultures have run the price of this book up to where normal people can't afford a copy. Even so, it's well worth having -- and using.
a most enlightening discussion. thanks all
Juniathato find one example of the 1938 book will ask for good lookout to put it mildly ..
And be prepared to bring more than one checkbook!
I do have scanned images of a copy of the '38 edition (that are being used to prepare a colloquial translation of it into English at some very indefinite future date, for the use of the steam_tech Yahoo group) but they aren't clear enough for comfortable reading -- people joining the group are welcome to request access to them there. We also plan to redraw the figures as we translate the words in them, so there won't be any copyright-violation questions when the work is done. As Juniatha says, this edition IS 'that important' -- too important to be held to ransom by rare-book people.
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