This might shock you – it did me! – but the French tested a steam-electric locomotive in 1897. No, I haven't transposed the digits – that's 1897!! Try googling "Heilmann locomotive" ...
Craig
Hi Craig
The Heilmann locomotive - yes I had read about it in an early number of the LokMagazin ( ger for loco magazine ) of a collection lot of well over 100 numbers I had bought in an antiquarian bookshop in Berlin in 1992 . I remember having to urge the storekeeper to put them aside for me since as a teenager of sixteen I sure didn't have the money right with me and he was so sceptical if I would ever come back and buy them as I said .
Edited paragraph with extra information :
The loco concept put up by Jacques Heilmann was remarkably advanced with a frame supporting boiler , cross mounted two cylinder compound engine plus generator unit , cab and supplies , resting on two eight wheel power trucks , all axles driven by electric motors . As with later diesel-electrics the locomotive showed a great potential in starting and hill climbing , the article described it as quite successful and two more powerful locomotives were built with an early 'Jules Verne' or 'Nautilus' type of streamlining while on the prototype the engine unit had been mounted pretty much on open deck with the front shaped in quite an earnest looking wooden wedge .
The first test locomotive of 1892 had Lentz boiler of 180 psi , 1000 A / 400 V generator , 44 kW electric motors , all electrical equipment came from BBC ; tests were run on the St.Germain-Ouest to St.Germain Grande Ceinture railway of the Ouest ( Western Railway Co.)
The two locomotives built for the same railway company by Cail & Co , Demain , in 1896 as # 8001 and 8002 intended for passenger service on the Paris - Trouville and Paris - Rouen mainlines were 60.7 feet between bumpers, had a boiler with a Belpaire firebox , nominally steaming 30000 lbs/h at 200 psi , feeding a logitudinally mounted vertically standing six cylinder Willans steam motor with external excentric shaft for driving piston valves and wooden shrouding for insulation ; electric equipment again was provided by BBC , eight traction motors of 92 kW each were suspension mounted in truck frames and developed a total of 736 kW ( 991 hp ) , service speed 75 mph .
In the end the unconventional locomotives were deemed to expensive and operation was considered somewhat complex - probably much of it due to the greatly novel nature of the locomotives - and it appears railway officials didn't really know what to make of it .
In 1910 the North British (NBL ) built a steam turbine-electric experimental , called the Reid-Ramsey for their originators ; the loco was 60 feet between bumpers had an unusual wheel arrangement in two eight wheel trucks in which only the axles to one side of the truck were powered by electric traction motors making it a (2Bo) (2Bo) wheel arrangement - an arrangement that would be hard to define in Whyte classification . The idler axles were however not arranged in guiding bogie to each power truck , all four of them were mounted in common truck frame .
The general concept of the locomotive looked logically sound and included a condensor which was to run in front in order to provide enough air stream for cooling . The experiment was brought to a stop with the outbreak of WW-I . In 1924 the same builder went for another try with the Reid-McLeod steam turbine condensor locomotive , below a frame 66.9 ft between bumper apparently using the trucks left from the earlier experimental , although with electric equipment thrown out and mounting them in symetric positions , thus now resulting in a (2B) (B2) arrangement . This time each bogie was powered by a steam turbine mounted directly to its frame , one having the HP unit and the other the LP unit - the arrangement of steam flow thus resembling that of a compound Mallet locomotive ( if that was a good idea I'd doubt seriously - yet nontheless it was a brave attempt ) external shape was quite harmonious and pleasing , even more car-like than the earlier R-R experimental , with cab mounted pretty much centrally and condensor enlarged and improved . The Reid-McLeod didn't escape the ever-repeated aberrand mounting of forward and reverse turbine on one common shaft and thus suffered from ventilator action losses by the reverse turbine forced to idle inversedly . While power output was up from 590 kW to 734 kW ( 794 to 988 hp ) the R-McL experimental didn't fare decidedly better than the earlier one and to me it looked a bit of a step back in its concept , with bogie mounted turbines by default being a feature of rather dim outlook : being shock exposed and mounted in a quite inacessible position , demanding flexible steam pipes , etcetera .
Only much much later , in the mid 1990s , for afternoons on ends spent in enclosure to the bewilderment of her mother , one American in Berlin privately made another attempt at designing a double truck full adhesion Do-Do steam loco concept ( in quadruple truck BoBo-BoBo flexicoil suspension version , actually ) this time with a full treatment of everything of promising potential to improve thermal efficiency : oil fired water tube boiler , high pressure / high superheat steam , turbine-electric drive plus condensor . Well , I tell you I really dug into it , bugging dad about it until he raised arms admitting he was at his wits end , too , and why wouldn't I just see a movie or go to a concert with friends like any other girl . What I can say from it : a high pressure / high super heat water tube boiler steam turbine-electric condensor locomotive is a formidable excercise in engineering indeed and while it can be done , the sheer complexity and total mass of it will always stand against it . In the end I threw out all steam equipment , replaced it with a gas turbine ( incl beefed up electrical equipment possible with mass saved by getting rid of boiler and condensor ) and - wow ! - there was the power I was looking for !
Regards
Juniatha
I can't say I'm not enjoying this.
Apart from the burner problems with the Triplex, I also have understood that as the tender-***-engine supplied water to the boiler, it tended to get lighter, and that affected adhesion. So, while the burner couldn't really heat the water to provide the steam needed, when it was drawn down by the injectors, the water volume lightened in the tender/engine and made for a lightweight set of drivers.
Okay, so boosters are not ideal, and we have agreed we want unsprung and reciprocating masses minimized? Yes? Then we need a drive mechanism that rotates around an axle that is geared or fluid-coupled to the drive axles. Or a jet engine. Or electric. Cylinders with large reciprocating and valved masses, and connecting rods, are out.
Could we have a burner array that runs along the belly of a boiler, thus doing without the problems of a crownsheet, stays, and so on? We would still need a pretty stiff blower to help the draught up the vertical flues, and we would need a collector system for hot gases to get them to the flue exit, or stack, probably centered on the boiler. The flue pipes would be 'starred' in cross section, with fins running along their outsides parallel to the main axis of the flues for maximum heat transfer. Same for the collector. This system, if it can be built and controlled effectively, would supply heat to the boiler at about twice the rate of a conventional firebox arrangement. To help wick heat away from the bottom of the boiler, to minimize heat gradient stresses, the plating or inner liners of the boiler would need to be designed and built of the correct materials, and probably also have ridging or fins to increase heat transfer.
Some of you probably are thinking to yourselves that it's a good thing some people don't design steam locomotives.
Crandell
Answer me this.
The Garratt seems to be a good design for getting good steaming and a lot of powered wheels. There were even plans (suggestions? pipe dreams?) for "double Garratts" -- essentially a Mallet's double sets of engines and drivers on each of the front and back ends fo the Garratt boiler.
A Garratt may have been able to pull this off -- the big-fat-short boiler with enormous firebox and ashpan suggests that the Garratt's steam-raising ability is without peer.
But . . . even on the "normal" Garratt, how did they get live steam and exhaust steam to and from the two bogies, without a lot of losses from the flexible connections, without thermal and pressure-drop losses in the long pipes involved? Where did those steam pipes even go? Even on a Mallet or simple-expansion articulated you can see those pipe runs to the front engine and driver set, but you don't even see any large-bore steam pipes on the pictures of Garratts I have seen.
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
Hi Crandell
At this point I have to admit , in my 'walk on the wild side' type of private (pre-)engineering me too I had put up a concept of a Triplex , and just because of this very point - supplies vanishing & and tender adhesion mass alleviating - I had carried it just one step further , figuring if you can have two axles coupled in front of the main driver you could as well have the same on the back side of it - makes for a 10 coupled unit .
You'd think I configured it to be a 2-8-8+10-2 ?
Naw-naw-naw , sir - not with my way of thinking ! Ten coupled once introduced , I immediately thought "Why not have it on all the three engine units ?" Mind my previous mentioning preference for identical sets throughout . So I ended up with a 2-10-10+10-2 - all simple expansion . Sure enough there was that vanishing adhesion mass problem again .
Ah , but not with young June : "Let's fit individual throttles , one for each engine unit , three in a bunch to be grabbed together as the throttle levers in a BUFF yet individually adjustable to make the most of adhesion ." The throttles were to have on spot hydraulic power operation so moving the levers didn't take but light effort as you effectively just opened the power valves of hydraulic lines . The idea was , you would start opening the combined levers as one yet just to an extent sure to be supported by adhesion and then as the engine began to move you'd open up further on the second and first engine units , leaving the tender unit as set or just cautiously opening up depending on degree of supplies spent . Since the locomotive was purely intended as a ramp pusher , tender capacity wasn't all that large anyways while no attempt at low empty tender mass was to be made .
Arrangement of live and exhaust steam piping was a point I was particularly content with : it featured a central live steam pipe with short ball type articulated sections with pipes branching out to cylinders ( it was a slightly more complex system than my words describe it here ) Exhaust lines from cylinders would combine in reverse to form a steam jacket around the central live steam pipe thus insulating it against the outside . Each of the short articulated sections also was to contain the throttle to those very cylinders .
You know , at that time I was not all too much concerned about how such an assembly could be put together in actual construction practice and what it would mean to extract one unit for an overhaul in case of wear or breakage . The effects of time did not loom too large in my thoughts back then - yet it was not without charme and I think it wasn't a bad idea in principle - although it clearly would have demanded more in-depth attention to details , mostly about manufacturing , design and shaping of parts and ease of mounting / dismantling .
Maybe I'll put up that old side view picture of back then , if you'd care to see it ?
Juniatha You know , at that time I was not all too much concerned about how such an assembly could be put together in actual construction practice and what it would mean to extract one unit for an overhaul in case of wear or breakage . The effects of time did not loom too large in my thoughts back then - yet it was not without charme and I think it wasn't a bad idea in principle - although it clearly would have demanded more in-depth attention to details , mostly about manufacturing , design and shaping of parts and ease of mounting / dismantling .
You or some others could always build it in "zoo gauge" (12" narrow gauge or whatever is popular for amusement parks and zoos featuring steam railroad lines traversing the ground).
If some airplane hobbyists "from Texas" (folks with gobs of money to spend on eccentric and expensive hobbies seem to hail "from Texas") could perform aerial flyovers of Oshkosh, Wisconsin U.S.A. in a MiG 21 (before the fall of the Wall and before the ouster of Gorbachev, no less), there are people who would have the money, skills, and opportunity to build Juniatha's Triplex Dream Locomotive (Traum Lokomotiv?).
Hi Paul
Model building :
Thanx for the proposition , Paul , yet quite certainly I'll never have time to realize a running steam powered model - nice idea though and I would supply drawings and additional help to someone who would indulge in building one .
Pictures of Garratts with live steam pipes along side of frame
(4-8-2) - (2-8-4) BGB (Beyer Garratt Belpaire) - see pipe emerging from smokebox as usual and going along bridge frame towards rear cylinder
http://www.members.optusnet.com.au/~harburg/locos/DeGarratt-17-aw.jpg
(4-6-2) - (2-6-4) - see live steam pipe monted above bridge frame beam
http://users.powernet.co.uk/hamilton/
(4-8-2) - (2-8-4) - see live steam pipe running along boiler side with exhaust steam pipe returning along outside of bridge frame beam
http://www.flickr.com/photos/sierpinskia/5916460832/
(4-8-2) - (2-8-4) - see live steam pipe running along outside of bridge frame beam ;
http://www.scotlandforvisitors.co.uk/garrett.jpg
(4-6-2) - (2-6-4) - Narrow diameter live steam pipe with at best 'T-shirt' type of insulation running along outside of bridge frame beam . Clearly , the PLM Algerigue 231-132 series passenger Garratt with Cossart poppet valve gear was a locomotive intended for permanently warm Southern Mediterranean / North African climate without severities of Continental European winters .
http://enginemanwook.files.wordpress.com/2010/09/plm-algeria-garratt-231-132bt1-societe-franco-belge-raismes-france-2697-1936-g-hamilton-collection-0909102.jpg
(4-8-2) - (2-8-4) drawings - see live steam pipe specifically running along both sides of bridge frame beams while exhaust pipe is located centrally and returning even below ashpan - arrangement which looks a bit tongue-in-cheek
http://www.johnnyspages.com/rail_dittys_files/garratt_diagram.gif
On most Garratts live steam pipe neither looks of ample diameter nor seems all too well insulated . Live steam pipe placed along outsides of bridge frames doesn't look too elegant as a design nor too thoughtful in the event of flank collision ; since a pipe is not a component normally plagued by wear or failure it should better have been run in protected if hidden space behind frame beams . Because of considerable distance between superheater header and rear cylinders , substantial losses in steam pressure and temperature should be expected , especially since most of these Garratt designs definitely lacked attention to inner streamlining not to mention Chapelon level of scientific care taking for free steam flow . What helped saving temperature losses for sure were hot sunny days in Africa - although I haven't heard of reduction of performance in the dead of a cold stary night ...*g*
It has been suggested the Garratt - possibly developed into a Mallet-Garratt , or as I'd call it : a Mallgarret - could have helped US railroads steam traction with heavy loads on ramps . However , as I had commented in an earlier posting , these suggestions didn't take account for accompanying problems with design of suitable boilers to produce necessary quantities of steam - a problem which already had become virulent in the largest of x-8-8-x simple Mallets and a key reason for their less than dramatic specific power outputs (or higher total mass per ihp or kW ) in relation to large single frame locomotives such as 2-10-4 and 4-8-4 .
Also , each further engine unit added meant no small multiplication of mechanical complexity of a locomotive design , mind the locomotive had to be made flexible enough to pass through superelevation ramps leading into curves , through curves / S-curved switchwork , over humps and sinks in rail alignment without complaint and had to be ready to apply power of all engine units to the fullest in any position and at any point of the line - beyond two engine units related engineering problems tended to really score .
p.s.:
I have edited my previous posting on double truck steam motor and turbine locos and inserted extra information on the experimentals - see page 2 this thread , scroll down 80 % .
On the Garratts, what sort of (flexible?) steam pipe connections did they have at the articulation points?
>> what sort of (flexible?) steam pipe connections <<
Principally same variety as in Mallets ..
| = J = |
Paul Milenkovic You or some others could always build it in "zoo gauge" (12" narrow gauge or whatever is popular for amusement parks and zoos featuring steam railroad lines traversing the ground).
While I realize that the reference to 12" gauge was just an example of a park train size (most are 24" gauge these days), I still had to smile at the thought of Juniatha's 2-10-10+10-2 built as a 12" gauge locomotive... that would be a monster! Aside from the time and money it would take to build it, I can only think of a single 12" gauge railroad in the US where it would be able to run. Most 12" tracks (mine included) are populated by relatively puny 4-4-0's, with tight curves to match. The normal hobby gauges (7+ inches) might be a better choice - there are a lot more of those tracks available - and quite a few articulateds in the 7.5" gauge realm, including at least one Erie Triplex:
http://www.youtube.com/watch?v=7JemEIAnww8
Nonetheless, I would heartily encourage anyone in who is interested in increasing the efficiency of steam locomotives to get involved in live steam. It would certainly be a more economical way to experiment as opposed to full size steam, and it would be very interesting to see the various ideas put forth in this thread actually operating, albeit in a smaller size.
I thoroughly enjoy these types of threads, even if I'm not an active participant. Always fun to read Juniatha's posts! Thanks to all for the interesting reading...
- James
www.nfrailroad.com
WOW! This is SOME thread we got goin' on here! Excuse me while I put my eyeballs back in the sockets and reach for the Seagrams to ballast myself a bit.
Here is an idea which has been kicking around in my head for some years, and maybe someone can expand on it or tell me why it wouldn't work: Why not pressurize the whole firebox and flue system to maybe two or three atmospheres? This would increase the intensity of the combustion, and the higher density of the combustion gases would cause a more efficient transfer of heat through the firebox walls and flues. The pressure at the smokebox would be used drive a turbo to compress the air for combustion, providing a sort of feedback similar to that provided by the exhaust steam in conventional locomotives. Of course, this would be a bit tricky to do on a coal-burner, so it would almost have to be done on an oil-burner.
_____________
"A stranger's just a friend you ain't met yet." --- Dave Gardner
Paul of Covington Here is an idea which has been kicking around in my head for some years, and maybe someone can expand on it or tell me why it wouldn't work: Why not pressurize the whole firebox and flue system to maybe two or three atmospheres? This would increase the intensity of the combustion, and the higher density of the combustion gases would cause a more efficient transfer of heat through the firebox walls and flues. The pressure at the smokebox would be used drive a turbo to compress the air for combustion, providing a sort of feedback similar to that provided by the exhaust steam in conventional locomotives. Of course, this would be a bit tricky to do on a coal-burner, so it would almost have to be done on an oil-burner.
It would seem that to hold back-pressure in the firebox, you would have to severely restrict the exhaust outlet. This would also increase the partial pressure of the exhaust gasses, which I can't imagine would help with efficient combustion.
A blower/turbo in an internal combution engine works because valves open and close which permit the charged or supercharged air from escaping as the piston compresses it further. There is no conceivable mechanism which would allow the same thing to happen in a firebox. You must allow the hot gases to flow readily through the flue pipes in a conventional steam locomotive, but in order to supercharge the firebox, you'd either have to close the flues in the rear flue-sheet or at the far end, at the smoke box. Otherwise, everything just goes faster, and more of it, if you blow into the firebox to raise pressure.
Improved flue design and firing might make a difference, and even the use of improved blowers in the smokebox, although the latter were used routinely right from the start. Except that they drew firebox gases through the flues, and didn't force it through them.
>> Why not pressurize the whole firebox and flue system to maybe two or three atmospheres? <<
Paul ,
there is something in it , for sure , as to intensify heat transfer - and it could also allow for smaller tubes and flues sections in relation to length between tube plates .
It would ask for some thinking about details with oil-firing but present no major problem in that combination .
I had come to a similar idea in order to solve the problem of rapid abrasion of blower blades with coal fired condensing locomotives ( uhm , steam locomotives , that is - *g* ) All those locomotives featured blowers in replace of ejector type of draughting and invariably mounted to the same position . My thought was , ok , if you have an exhaust steam turbine driving a blower why not put the blower to the other side , i e upstream combustion , to blow fresh air through the grate instead of sucking dirty combustion gases out of the smoke box . This would provide some degree of over-pressure above atmosphere , no ways as much as you mentioned , however it would make a difference in gas to wall heat transfer intensity .
With coal firing - that's only where the problem of abrasion of blower blades was severe - that disposition would present one immediate problem : how to tighten ashpan and firebox feeding to prevent escaping of air and - more importantly - flames . Clearly , any detachable feed line , any type of fire doors inside cab were ruled out . While a stoker feed line with archimedes screw filled with coal could probably provide enough resistance for loss of gas flow to become negligible in view of boiler performance , escaping flames and hot gases would still present a very real risk of igniting coal before it had reached firebox . Again , this problem could turn out rather theoretical as long as feed was kept up at pretty progressive working rates - yet it was another thing when stoker should be substantially slowed or stopped while engine still goes on working hard , say to finish an up-grade pull , just going over the top . Some sort of positively closing flaps at the firebox end of feed would have to be provided and they'd have to be working automatically and absolutely reliable , too . Plus , for safety a sprinkler system would have to keep coal wet in continuous spray of water , independant of working rate of stoker feed - much the way as blower has to be 'on' at all times with oil fired boilers to prevent blow back hazards by starting burners or by irregular combustion . The loss of water would not really be prohibitive , not would it present any loss of heat worth mentioning if fed by a small electric pump taking water from tender directly ( my idea for any concept of steam loco tending towards more sophisticated demands of auxiliaries would be to have an enlarged turbo generator provide enough electric energy to power electric motors for diverse smaller auxiliary devices ) On the other hand you'd have to forget about thinking a condensing steam locomotive wouldn't have to take water at all - mind water lossed just by cylinders having to be drained by opening cocks when starting cold engine , boiler blow down valve and other sources . Quantity of water refilling could be down by some 90 % yet never become nil this way - questionable if it needed to with fully effective feed water treatment .
But , hey : my putting power throttles into live steam feed line next to cylinders raised one major problem which only came to me later on - and it provided something to engross thinking about until I got at least some flash that promised a working solution - although still incomplete .
What was it ?
Curious regards
Juniatha, I'm glad you didn't think my idea was crazy. I think I started down this path years ago, after reading about the condensing locomotives in South Africa. (I think.) It seemed to make more sense to put the blowers at the input rather than at the exhaust, then it grew from there. The only way I could think of to make it work with coal would be to seal and pressurize the whole coal bunker and stoker, but that would complicate matters if manual intervention would be required (e.g. breaking up clumps). I wanted to include condensers in my plan for my dream locomotive, but the plans kept getting more complicated with so many heat exchangers and inter-coolers, that I was afraid I was approaching perpetual motion.
Now I'm intrigued about your power throttles next to the cylinders. Are you talking about replacing the conventional valves with valves controlled by a combination of, say, throttle-position, piston position, speed and other parameters, similar to the way modern car engines have computers controlling the mixture and ignition timing? It might provide a more economical use of steam.
Here is another crazy idea (I think I have too much idle time). How about something similar to a diesel cycle: eliminate the whole boiler, have cylinders with massive heads that are heated to a very high temperature and inject water against these heads which would vaporize instantly, providing thrust. Of course these would almost have to be single-acting pistons, as I think providing a seal for the piston rod at such a high temperature would be difficult.
It's fun to think up things like this when you don't have to contend with things like reality.
MidlandMike and selector:
While the exhaust back-pressure would be higher, the pressure of the air entering the firebox would be proportionally higher, so the flow would be essentially the same. The goal is to increase the density of the air, which would cause more intense combustion and greater mass to carry the heat and transfer it more efficiently through the firebox and flue walls. The part I sometimes wonder about is using the exhaust pressure to run the blower, as it seems a little like perpetual motion, but then a jet engine does a similar thing. The exhaust pressure could be used to run other auxillaries, and other means could be used to help provide the pressure.
Pressurized combustion in a boiler? I think that was tried and had a name -- Velox boiler? Did it have success in any applications?
I'll get to the power throttles -- btw having decoded Porta's 'Waggoner' throttle references -- in a bit.
Forced (as opposed to induced) draft has been tried on locomotives, most notably in the Velox boiler. Principal technical issue is fuel feed; secondary issue is the incredible mess that results from any leak in the pressuretight casing (the amount of blankety-blank language from engineers on power-station boilers with pressurized firing can be frightful!)
Biggest thing about use of forced draft is that it's only economically 'optimal' for long, sustained runs at high output. Rail service isn't like that; you're constantly varying steam demand even in general train-handling, and things go quickly out the window if you regularly take siding or experience slow orders. The armchair thermodynamicists never seem to grasp this point adequately.
A better case might be to use a small measure of variable forced draft in conjunction with a GPCS-style firing system (where the gas-tightness of the combustion spaces is required by the system). One thing here is that you would need proportionally larger radiant absorptive surface to take best advantage of this (although I grant you the situation isn't as bad as methods that rely on increasing gas speed) Question is whether the relatively small gains in firing efficiency warrant the capital investment, training requirements, and so forth in general service, as well as the perhaps-severe problems if the added equipment or systems break down or their performance degrades 'ungracefully'. (Hint: not likely in the early '50s, and even unlikely in the relay-logic era of the TE1)
You still need to maintain induced draft at the front end for a fairly wide variety of reasons -- if you do this with a fan or blower, place it where the South Africans did, whether or not using the 'turbine drive' methods in the ACE 3000 patent. This simplifies the forced draft to simple servo following (and not incidentally allows economical 'automatic action' over a wide range of speed and load if the front end is done correctly). I won't go into technical front-end optimization here, but you should note that there are reasons, especially with coal firing, why the convergent-divergent design of the gas passages from the front tubeplate/superheater headers up to the screens is arranged as it is on modern American power.
Part of the issue of stoker fires, etc. would have been handled the same way firing efficiency was traditionally maximized: crew knowledge and experience. Men who 'knew the road' and the characteristics of train handling would understand when to start reducing their firing in anticipation of cresting a grade, or responding to a train order. At least theoretically, a simple slide at the top of the elevator would provide enough of a heat barrier to prevent a stoker fire, particularly if there was a working arrangement to reverse the elevator screw direction. Other approaches, such as nitrogen or CO2 pressurization, would have been applicable in the historic period (diesel design, in particular, had already provided standard CO2 bottling for fire suppression by the late '40s)
On the other hand, it certainly seems to me that chain-grate firing would have been tried to more extent on reciprocating power, and even the arrangement on the TE1 neatly covered the issue of firing control during rapid unpredicted power excursions. (Yes, there's a 'sluicegate' slide at the rear of the firebox that closes down to restrict coal feed...)
With all due respect, you're going in orthogonal wrong directions with the water issue. Yes, you want to restrict the effective water rate. The PRR V1 turbine with Bowes drive was the right answer to almost all the motive-power issues in its era... except that the water rate was so high at its 8000-odd hp that even a large tenderful was only expected to run about 130 train-miles. In the era where all trains had to stop at all division points, and all division points had water, that was not SO bad as it would be today, but imho this was one of the most significant reasons that PRR went with F units rather than turbines...
But on the other hand, there isn't any real reason to throw away water with cylinder cocks and blowdown. I know that you understand boiler-water treatment well enough to know how to keep blowdown minimized on working locomotives -- certainly continuous blowdown was a stupid thing even in the era of relatively well-provided, relatively continuous track maintenance. My own opinion is that better steam separation is a better answer, where it can be done, than Porta-McMahon-style antifoams, when you want to keep a high continuous level of TDS and perhaps emulsified oil in the boiler to preclude scaling and other maintenance horrors. But blowdown of sludge isn't the 'right' answer: keeping sludge from settling out is. Reserve the blowdown for maintenance stations!
Condensing on reciprocating locomotives is, in my unhumble estimation, not warranted in the absence of effective recompression (which is largely intended to benefit the pressure cycle in the engine, and not for 'thermodynamic' reasons alone). Steam-to-air heat transfer at the sheer power level required of a modern reciprocating engine -- even one with steam-motor drive -- just isn't worth the problems it costs to implement. Get the water in liquid phase and the thing becomes more 'do-able'. (I'll keep the ultrasupercritical-motor design for a different thread, as I believe the appropriate alloys and techniques hadn't been commercialized cost-effectively in the '50s...). And therefore we need to fall back on getting better effective heat transfer to the various flavors of 'economizing' to decrease the water rate on the horsepower side, and minimize the required fuel burn on the gas side. I suggest examination of the Snyder combustion-air preheater, the Cunningham circulator, and some flavor of Franco-Crosti-like economizer FWH, at a minimum, before even starting to look at condensing -- any energy you can recover in a Rankine cycle is better than throwing it away -- and when you do start with condensing, start by maximizing effective back-pressure reduction for high mass flow at the cylinders.
Likewise, I'd have expected you, of all people, to have gotten the lesson about heated cylinder blocks from Chapelon. Take the approach a stage further, and use overcritical boiler water in a pumped circuit through comparatively thin lines to keep the cylinder and heads at 'equilibrium' temperature with the boiler water. This is well above the phase-transition temperature for nucleate steam near the end of the stroke (where nucleate condensation produces its evil effects) and hence there will not be any condensate to blow out of cylinder cocks when starting. Now isn't that a more elegant solution?
Now, turning to the individual port throttles -- as it turns out, these are Wagner throttles, and you can save countless hours of trouble by simply reviewing Fritz Wagner's various patents (which basically apply principles of fluidic amplification, to use the more modern term for the principle, to proportional throttle control). There is a certain amount of fun, and a somewhat greater amount of concern about plaintiff's bar, in coordinating four separate Wagner throttles for HP admission, but this is less of a problem than you might at first think because there is little effort required to move the actual linkage, and techniques for coordinating multiple throttle lengths existed perfectly adequately before the '40s.
The short answer, of course, is that the principal steam throttle doesn't have to be via the Wagner throttle. For starting, as an example, you want to restrict steam pressure at the ports (by modulating the throttle) rather than trying to tinker with the cutoff (which will aggravate slipping as well as noncircular driver-tyre wear) -- and this would best be done with a single throttle in the usual place, downstream of the superheater so there's no separately-fired pressure vessel consternation, probably a typical poppet multiport type. (This also allows the kind of sliding-pressure firing that allowed NYC to demonstrate 2-8-0 level fuel consumption on Niagaras when doing 2-8-0-level HP output... but that's another story...)
If you are concerned with bypass or compression issues: (1) use something like a Trofimov valve (and yes, that's the spelling I think you all should use in a modern context at least), and (2) use adequate valve and reservoir capacity to allow Jay-Carter-style modulated compression independent of valve settings and port design. I'd be happy to go into my little 'take' on best approaches for drifting or providing compression 'dynamic' braking on reciprocating locomotives, but that isn't relevant here.
A fun thing to consider (in my somewhat warped estimation) is to coordinate the Wagner throttles directly with Cossart-style drop valves. (Which lets you use salmon rods to improve longitudinal balancing, etc.). For you diehards that want to keep the horizontal piston valves, Trofimov or otherwise... I believe the Berry Accelerator gear that Richard Leonard has found will also allow the salmon rods to work in the correct phase for longitudinal balance... and it's in period!
That's long enough for this post, for now.
RME
Come on, guys -- where is everybody?
Juniatha ...in my 'walk on the wild side' type of private (pre-)engineering me too I had put up a concept of a Triplex , and just because of this very point - supplies vanishing & and tender adhesion mass alleviating - I had carried it just one step further , figuring if you can have two axles coupled in front of the main driver you could as well have the same on the back side of it - makes for a 10 coupled unit ...
...in my 'walk on the wild side' type of private (pre-)engineering me too I had put up a concept of a Triplex , and just because of this very point - supplies vanishing & and tender adhesion mass alleviating - I had carried it just one step further , figuring if you can have two axles coupled in front of the main driver you could as well have the same on the back side of it - makes for a 10 coupled unit ...
This is not all *that* wild. The basic Triplex idea can be 'better' than the original motor-tender-with-2-8-8-0-stability if you attend to some proportioning (and used some care at the joint under the cab): it might be thought of as one-and-a-half Y6s, with only the leading and trailing two-wheel trucks at the ends. Give that locomotive Chapelon-style proportional-IP injection (US jingoists, think of this as a more controllable version of the booster valve Louis Newton described) and there is no particular reason why, compound, it couldn't be worked at normal 45-55mph freight speed. Principal issue for such a thing would be a tendency to pick the 'leading' driver flange of the rearmost engine, but if you were really concerned there are approaches that could be used to address this with minimal loss of potential adhesive weight. (And in case you start fretting about water and fuel mass on drivers, there are ways to address that too...)
You'd think I configured it to be a 2-8-8+10-2 ? Naw-naw-naw , sir - not with my way of thinking !
Actually, if any engine were to remain eight-coupled, it would be the one at the 'wrong' end of the locomotive (no good practical way to use the exhaust even with GPCS steam injection; trouble with the longer rigid wheelbase; relative loss of usable TE, etc.) What you'd do would be put two ten-coupled engines up front, like the infamous Virginian locomotives, but taking advantage as you note of the relatively balanced thrust distribution from five axles with drive on the center one. If you need inspiration on the possibilities of this, look no further than the PRR I1, which would spin happily up to 50mph although admittedly with oxcart ride...
Ten coupled once introduced , I immediately thought "Why not have it on all the three engine units ?" Mind my previous mentioning preference for identical sets throughout . So I ended up with a 2-10-10+10-2 - all simple expansion.
There are a couple of thorns in this particular idea, the most obvious being the lateral-motion implications for the two rear engines. Too much indeterminacy in guiding with lateral-motion devices on adjacent sets of driver axles... and you dare not have too much lateral in those outer rods, too. (There is also some phase-breaking advantage to having more sets with a smaller number of independent drivers, as in the theory of the duplex locomotive, but we can take that point up later).
The real problem is: Where would you find a single train, in that era, which would take advantage of so much over-the-road power? Haul it, and drawbars start popping like corn, or you start to get stringlining fun. Push it, and... you thought Big Liz pushed cars all over the place?
And in any case, six simple-expansion cylinders are going to give you nastily peaky power, and require great care and perhaps great effort in assuring the 'right' amount of steam-generating capability, while the rear-engine exhaust is not terribly useful BUT represents an enormous water-rate loss. You might think you can condense this steam in the tender and canteen water... but you'll be aghast if you actually run the numbers, even with saturated exhaust at atmospheric pressure, and see how quickly the water heats up. The problem with the original Henderson Triplex wasn't that it was compound, just that it wasn't proportioned correctly... make arrangements to keep the LP chests proportionally pressurized, not an impossible exercise even with '40s tech, and you have no need for fancy throttle artistry... even though every engine pulls its full share of the weight.
Sure enough there was that vanishing adhesion mass problem again.
Well if it troubles you so much, use the Concorde solution. Use the 'tender' as adhesion mass, and pipe the actual water (and convey solid fuel, if necessary) to 'reservoirs' on the tender proper (where the injector feeds, stoker worm, etc. are located). You don't even 'need' to do the transfer until you have an actual requirement for full adhesion...
... Ah , but not with young June : "Let's fit individual throttles , one for each engine unit , three in a bunch to be grabbed together as the throttle levers in a BUFF yet individually adjustable to make the most of adhesion ..."
I suspect this isn't exactly the right 'metaphor' for the kind of throttle action you'll actually need. Throttles on a '52 are made as they are because the differential action is clear and fairly easy to comprehend. Just try, though, having to pull back ONE of the fistful, in the middle, to an exact proportion you don't know and can't really sense through the seat of the pants... particularly when the 'right' way to do traction control via the steam is to modulate the valve gear, not the throttle.
This isn't trying to argue you shouldn't have separate throttles for multiple engines -- something like that would have been useful on, say, a four-coupled duplex to allow 'derating' the relatively slip-prone front engine at All Those Times It Wanted To Cut Loose. But making the engineer, who remember is no mecanicien, have to dance with three of 'em all the time isn't going to make you a popular girl ... ;-}
The throttles were to have on spot hydraulic power operation so moving the levers didn't take but light effort as you effectively just opened the power valves of hydraulic lines. The idea was, you would start opening the combined levers as one yet just to an extent sure to be supported by adhesion and then as the engine began to move you'd open up further on the second and first engine units...
Let me interrupt momentarily: there's a reason for long throttle travel completely distinct from effort; it's to give a sense of fine control with fairly coarse physical haptics. What you're doing is far better handled with the analogue of aircraft trim: allow adjustment from 'baseline' for one or more engines, after which moving the single lever automatically gives you the proportions. (Slip being handled several ways I'll take up in a bit...)
You also will have a certain amount of fun with the three reversers, which is where I think I would put the actual proportional power adjustment used for running trim. All three of THOSE would be ganged, but with the ability to tell 'at a glance' if one set were slipping (this can be as simple as a differential with switch running off the relevant valve-pilot sensor, illuminating a slip light over the relevant reverse lever) and then ease back the affected lever in the 'gang' as needed... without compromising what the other engines are doing, or requiring foreground-attention tinkering with settings after the slip has been arrested to keep the engine at full achievable power.
Since the locomotive was purely intended as a [grade] pusher , tender capacity wasn't all that large anyways while no attempt at low empty tender mass was to be made.
This in an age where large pushers weren't particularly useful (see above, but also recognize that there are very few grades where a normal, union-sanctioned crew would have a large enough road engine to pull something requiring so very large a pusher). Three eight-coupled engines is overkill already. On the other hand, there MIGHT be a potential place for something that size as a road engine, on consists that a given railroad could optimize for great size...
...but now we get squarely into the fact that contemporary trains weren't up to that kind of TE. And even before we get into doing DPU with steam locomotives, we have to look at something else: siding and block length. Even before we get into yarding monster trains effectively.
Arrangement of live and exhaust steam piping was a point I was particularly content with: it featured a central live steam pipe with short ball type articulated sections with pipes branching out to cylinders ( it was a slightly more complex system than my words describe it here)
I will tentatively, very tentatively note that late articulated practice was to keep the steam feeds to the cylinders separate, not derived off a common pipe. See how and why there were so many pipes on an Allegheny, for instance...
Exhaust lines from cylinders would combine in reverse to form a steam jacket around the central live steam pipe thus insulating it against the outside... Now this is a nifty idea UNTIL you look at the actual volume that needs to be provided to make the trick work properly. And the heat loss between a fundamentally unshielded steam line (with high superheat required for all the usual reasons) and exhaust that is already starting to think about condensing, certainly enough to provide a nifty amount of evaporative transfer from the hot line. So yes, you need to maintain insulation on your main steam lines inside the 'jacket' pipes, just not as much as you'd need to lag them. But those pipes are going to be VERY fat on the outside, perhaps getting increasingly large the closer to the physical exhaust you go. In the '50s we didn't have simple ways to figure out how to fill available volume with a properly-area-ruled duct... or to fabricate pressure pipes that were noncylindrical in cross-section inexpensively. Not saying this was a 'bad idea' -- just that you have to watch the detail design and decide if it's worthwhile.... Each of the short articulated sections also was to contain the throttle to those very cylinders. But these are hydraulic, aren't they? Especially so if you have Wagner throttles at the ports. It was a reasonable analogy to the way throttle rods were run through boilers, but running the rods through variable exhaust steam isn't going to get you the same inherent compensation for temperature length change... and you now either have the entire linkage to the throttles buried out of sight and in steam flow (not an optimal lubrication situation, and sticking any part of that linkage might be particularly dangerous for control purposes). This to me makes the maintenance of something as elegantly simple as the Q2 butterfly valves look simple by comparison [/sarcasm]. Perhaps best to co-locate the throttle hydraulics with the control for the power reverse, along the underside of the boiler or running boards in a well-protected location, and handle trim and adjustments with servos. (If you haven't researched Meier-Mattern valve gear, you should do so now...) You know , at that time I was not all too much concerned about how such an assembly could be put together in actual construction practice and what it would mean to extract one unit for an overhaul in case of wear or breakage. And, oddly, aside from the considerations above, there is little additional difficulty in 'extracting one unit for overhaul'. Let's look at this: (1) you wouldn't be extracting the center engine for any reason; it's attached to the boiler. (2), the forward engine is just like a Mallet engine, pull the flexible steamline joints and disconnect (and cap) the various control lines... there isn't any need to maintain geometric precision, or require careful measurement of rods or linkages; (3) the trailing unit goes with the tender, and again involves little more than taking pipes and ducts loose and disconnecting lines. You are sooner or later going to have to determine how to handle the bearer-plate issue (it was solved on high-speed simple articulateds only by machining the forward bearer PRECISELY so that the locomotive acted as a long rigid base in the vertical plane -- see Bruce's book if you don't believe me) for all three engines, on a railroad that doubtless contains a plurality of vertical curves... if you don't know where they are, this locomotive will unfailingly find them... Now, in practice, are you going to have large numbers of 'spare' reciprocating engine units ready to be swapped out at a moment's notice? Of course not, for much the same reason as you wouldn't shut a motor tender off when not needed for starting TE -- it's just too much capital to be tied up, when it could instead be assembled into more locomotives and used to produce revenue. Everyone that ever ran those numbers came to a similar conclusion. The effects of time did not loom too large in my thoughts back then - yet it was not without charm and I think it wasn't a bad idea in principle - although it clearly would have demanded more in-depth attention to details , mostly about manufacturing , design and shaping of parts and ease of mounting / dismantling. I presume this is servicing time, and you're trying to limit the duration of any required service -- in many respects a noble and important goal. I am not sure, though, that making ease of engine replacement a high design priority is necessarily the 'best' way to go. Better, I think, to make it less likely for the engines to wear or fail, in the first place, and then do all the rebuilding and PM in parallel when the engine goes in for 30-day (like X-day) servicing, when it can be dismantled and the parts repaired or replaced in parallel. You may have larger service-team personnel requirements, and perhaps a larger shop than you'd need without 'triple quantization' -- but the service time requirements, and hence ability to schedule work better, would be better known. A useful thing to look at in this respect is the difference, the actual important difference, between the Y6 and the Y6b with respect to reliability and maintenance... Maybe I'll put up that old side view picture of back then , if you'd care to see it? Yes, please do -- and while you're at it, put up pictures of all this more current stuff, too. Regrettably, we have all too few of Porta's brainstorming and sketches where they can be seen and enjoyed. Don't you make that same mistake! Now let's see some more discussion on this topic. I haven't seen anyone take up the issue of Besler tubes in a practical boiler, for example. RME
Now this is a nifty idea UNTIL you look at the actual volume that needs to be provided to make the trick work properly. And the heat loss between a fundamentally unshielded steam line (with high superheat required for all the usual reasons) and exhaust that is already starting to think about condensing, certainly enough to provide a nifty amount of evaporative transfer from the hot line. So yes, you need to maintain insulation on your main steam lines inside the 'jacket' pipes, just not as much as you'd need to lag them. But those pipes are going to be VERY fat on the outside, perhaps getting increasingly large the closer to the physical exhaust you go. In the '50s we didn't have simple ways to figure out how to fill available volume with a properly-area-ruled duct... or to fabricate pressure pipes that were noncylindrical in cross-section inexpensively. Not saying this was a 'bad idea' -- just that you have to watch the detail design and decide if it's worthwhile....
Each of the short articulated sections also was to contain the throttle to those very cylinders.
But these are hydraulic, aren't they? Especially so if you have Wagner throttles at the ports. It was a reasonable analogy to the way throttle rods were run through boilers, but running the rods through variable exhaust steam isn't going to get you the same inherent compensation for temperature length change... and you now either have the entire linkage to the throttles buried out of sight and in steam flow (not an optimal lubrication situation, and sticking any part of that linkage might be particularly dangerous for control purposes). This to me makes the maintenance of something as elegantly simple as the Q2 butterfly valves look simple by comparison [/sarcasm]. Perhaps best to co-locate the throttle hydraulics with the control for the power reverse, along the underside of the boiler or running boards in a well-protected location, and handle trim and adjustments with servos. (If you haven't researched Meier-Mattern valve gear, you should do so now...)
You know , at that time I was not all too much concerned about how such an assembly could be put together in actual construction practice and what it would mean to extract one unit for an overhaul in case of wear or breakage.
And, oddly, aside from the considerations above, there is little additional difficulty in 'extracting one unit for overhaul'. Let's look at this: (1) you wouldn't be extracting the center engine for any reason; it's attached to the boiler. (2), the forward engine is just like a Mallet engine, pull the flexible steamline joints and disconnect (and cap) the various control lines... there isn't any need to maintain geometric precision, or require careful measurement of rods or linkages; (3) the trailing unit goes with the tender, and again involves little more than taking pipes and ducts loose and disconnecting lines. You are sooner or later going to have to determine how to handle the bearer-plate issue (it was solved on high-speed simple articulateds only by machining the forward bearer PRECISELY so that the locomotive acted as a long rigid base in the vertical plane -- see Bruce's book if you don't believe me) for all three engines, on a railroad that doubtless contains a plurality of vertical curves... if you don't know where they are, this locomotive will unfailingly find them...
Now, in practice, are you going to have large numbers of 'spare' reciprocating engine units ready to be swapped out at a moment's notice? Of course not, for much the same reason as you wouldn't shut a motor tender off when not needed for starting TE -- it's just too much capital to be tied up, when it could instead be assembled into more locomotives and used to produce revenue. Everyone that ever ran those numbers came to a similar conclusion.
The effects of time did not loom too large in my thoughts back then - yet it was not without charm and I think it wasn't a bad idea in principle - although it clearly would have demanded more in-depth attention to details , mostly about manufacturing , design and shaping of parts and ease of mounting / dismantling
I presume this is servicing time, and you're trying to limit the duration of any required service -- in many respects a noble and important goal. I am not sure, though, that making ease of engine replacement a high design priority is necessarily the 'best' way to go. Better, I think, to make it less likely for the engines to wear or fail, in the first place, and then do all the rebuilding and PM in parallel when the engine goes in for 30-day (like X-day) servicing, when it can be dismantled and the parts repaired or replaced in parallel. You may have larger service-team personnel requirements, and perhaps a larger shop than you'd need without 'triple quantization' -- but the service time requirements, and hence ability to schedule work better, would be better known. A useful thing to look at in this respect is the difference, the actual important difference, between the Y6 and the Y6b with respect to reliability and maintenance...
Maybe I'll put up that old side view picture of back then , if you'd care to see it?
Yes, please do -- and while you're at it, put up pictures of all this more current stuff, too.
Regrettably, we have all too few of Porta's brainstorming and sketches where they can be seen and enjoyed. Don't you make that same mistake!
Now let's see some more discussion on this topic. I haven't seen anyone take up the issue of Besler tubes in a practical boiler, for example.
JuniathaThe Heilmann locomotive - yes I had read about it in an early number of the LokMagazin ( ger for loco magazine ) of a collection lot of well over 100 numbers I had bought in an antiquarian bookshop in Berlin in 1992 .
Is this by any chance "Die Lokomotive"? Because if it is, you should know that nearly ALL the back issues have been scanned and put up as high-resolution .pdfs on the Internet (cf Claude Bersano's site on fini.net). They make very interesting reading...
The loco concept put up by Jacques Heilmann was remarkably advanced with a frame supporting boiler , cross mounted two cylinder compound engine plus generator unit , cab and supplies , resting on two eight wheel power trucks , all axles driven by electric motors
Not to mention the nifty steeple-compound high-speed engine in the later versions. But the real problem was that for all that machinery, and all that length, you really didn't have much more horsepower than a fairly small six-coupled locomotive (not even 1000hp at the railhead even at optimal speed). The follow-on locomotives were underpowered, too.
Even by the time you get to the UP condensing turbines in the late '30s, the power density required to justify all that stuff wasn't there, even with MUCH better boiler pressure, turbine design, and better generators and motors.
As with later diesel-electrics the locomotive showed a great potential in starting and hill climbing, the article described it as quite successful and two more powerful locomotives were built with an early 'Jules Verne' or 'Nautilus' type of streamlining while on the prototype the engine unit had been mounted pretty much on open deck with the front shaped in quite an earnest looking wooden wedge . The first test locomotive of 1892 had Lentz boiler of 180 psi , 1000 A / 400 V generator, 44 kW electric motors, all electrical equipment from BBC; tests were run on the St.Germain-Ouest to St.Germain Grande Ceinture railway of the Ouest (Western Railway Co.) The two locomotives built for the same railway company by Cail & Co , Demain in 1896 as # 8001 and 8002, intended for passenger service on the Paris - Trouville and Paris - Rouen mainlines, were 60.7 feet between bumpers, had a boiler with a Belpaire firebox , nominally steaming 30000 lb/h at 200 psi , feeding a longitudinally mounted vertical six cylinder Willans steam motor with external eccentric shaft for driving piston valves and wooden shrouding for insulation; electric equipment again was provided by BBC, eight traction motors of 92 kW each were suspension mounted in truck frames and developed a total of 736 kW (991 hp), service speed 75 mph.
The first test locomotive of 1892 had Lentz boiler of 180 psi , 1000 A / 400 V generator, 44 kW electric motors, all electrical equipment from BBC; tests were run on the St.Germain-Ouest to St.Germain Grande Ceinture railway of the Ouest (Western Railway Co.)
The two locomotives built for the same railway company by Cail & Co , Demain in 1896 as # 8001 and 8002, intended for passenger service on the Paris - Trouville and Paris - Rouen mainlines, were 60.7 feet between bumpers, had a boiler with a Belpaire firebox , nominally steaming 30000 lb/h at 200 psi , feeding a longitudinally mounted vertical six cylinder Willans steam motor with external eccentric shaft for driving piston valves and wooden shrouding for insulation; electric equipment again was provided by BBC, eight traction motors of 92 kW each were suspension mounted in truck frames and developed a total of 736 kW (991 hp), service speed 75 mph.
But that rated kW per motor isn't at 75mph, is it? Nor is the developed power of the Willans engine though the generator and other components of the drive practically greater than 'constant horsepower' of -- well, call it 750kW. It's possible that forced cooling of the motors might have improved performance somewhat... but: note what the cylinders of a steam locomotive of equivalent weight and length would be developing at that speed... with MUCH less overall cost and complexity.
(I now omit much of the historical details of condensing turbine-electrics, as Juniatha described, and as contained in the delightful pages of the Self site. I would note that the chief problem is that the condenser, even with water spray, can't handle the mass flow and volume from a turbine operated in its efficient range; the 'successful' turbine locomotives all had atmospheric exhaust operating for induced draft.)
Only much much later, in the mid 1990s, for afternoons on end spent cooped up to the bewilderment of her mother, one American in Berlin privately made another attempt at designing a double truck full adhesion Do-Do steam loco concept (in quadruple truck BoBo-BoBo flexicoil suspension version, actually ) this time with a full treatment of everything of promising potential to improve thermal efficiency: oil fired water tube boiler , high pressure / high superheat steam , turbine-electric drive plus condenser . Well , I tell you I really dug into it , bugging dad about it until he raised arms admitting he was at his wits' end, too, and why wouldn't I just see a movie or go to a concert with friends like any other girl...
Where were the girls like that when I was growing up? ;-}
...a high pressure / high superheat water-tube boiler steam turbine-electric condensing locomotive is a formidable exercise in engineering indeed and while it can be done , the sheer complexity and total mass of it will always stand against it.
And that, largely, because you designed it too small. As I've noted, the locomotive can't be like a Sentinel, or one unit of a first-generation diesel-electric -- you need enough capacity both to carry and support all the ancillary systems to use external-combustion steam in an efficient Rankine cycle. That's tough enough without trying full condensing. You were about halfway there with your Bo-Bo+Bo-Bo; the modern 'minimal' configuration would be four Co trucks, but with more traction motors on attached road slugs.
In the end I threw out all steam equipment, replaced it with a gas turbine ( incl beefed up electrical equipment possible with mass saved by getting rid of boiler and condenser) and - wow ! - there was the power I was looking for!
But not the flexibility, and not the easy maintenance, and certainly not the economical fuel consumption, that you could achieve with a positive-displacement engine in a locomotive that size... let alone a free-piston engine with electromagnetic-coil generation on the pistons...
But wouldn't it have been interesting to use GTCC-style steam bottoming on the turbine exhaust, to get your thermodynamics neatly up? Well, yes, you're back up to a large overall unit size, but the practical 'competition' in America is two 4400-hp diesels -- your engine, like Baldwin's original 6000hp Centipede concept, would have been notably shorter and lighter than that combination. (And in Europe, where freight has to run faster and shorter to keep in proper pathing with express passenger service, the much higher hp at speed would have been more useful...)
More fun, still, is to look at the ALPS locomotive, and tell me whether you could spin one generator with a gas turbine, and one with a boosted steam turbine (recovery heat plus some combustion)...
Meanwhile, returning to the original topic: consider the PRR V1 turbine, probably the 'right' answer at the time to how steam power would have evolved. This was NOT originally a steam-electric, and in its 'best' development phase it used what might be considered a fancy self-exciting electric clutch in an otherwise mechanical drive to get higher turbine speed at low wheel rpm. This locomotive would neatly and effectively produce 8000 hp on the steam from a slightly-modified Q2 boiler, with no augment and very little requirement for rigid wheelbase. The catch was that 8000hp worth of mass flow going to atmosphere meant a very, very high water rate. Any other conventional steam locomotive making high hp would also have a high water rate. And this was the one thing that nailed the coffin of powerful-enough steam locomotives shut.
In a modern steam locomotive, you will do as much recompression as possible (to recover the latent heat of vaporization without requiring very large 'condenser' plena and mass-handling capacity). You will have air preheaters, probably in multiple stages, and probably some gas economization a la Franco-Crosti too. Look for high initial pressure (and low exhaust) -- and that means compounding, the continuous compounding of a properly designed and operated turbine. But the key is to get the turbine power to the wheelrims. And for that, electric drive is complex, relatively wasteful, and comparatively fragile... in the period we are considering for near-term evolution.
One interesting thing about the V1 as it was developed is that it was prioritized as a freight locomotive. Just as the T1 was intended as the working counterpart of the GG1, the V1 was the counterpart of the larger electrics being developed by the early '40s with the 428A instead of the 387 -- one of which was a 2-Do+Do-2 like a long GG1 with continuous rating of 7500hp. After the latter half of the '40s came the great falling off of passenger traffic -- if you want a vivid demonstration of the importance of that, consider how quickly the Niagaras were retired and scrapped... when their very high horsepower at high speed was no longer useful for what made the railroad money. Even in a world without diesels, there wouldn't be a place for large heavy steam power.
Meanwhile, consider the C&O M1, a locomotive designed for a particular, and interesting, service. The Chessie trains were intended to run as long and heavy consists, almost like multiple sections of a fast Eastern Pullman train run into one. That's the only possible service for which so large, heavy, and complicated a steam locomotive would have been suited. And when those trains failed to materialize, what was the point, and what was the use, of such large single locomotives? (And, while we're looking at this, why were the M1s unsuited for heavy freight service on C&O...)
There's a fairly direct evolution from the V1 to the early N&W design, through to the TE1, and it's an interesting story to follow. How much of the TE1's design depended on contemporary diesel-electric practice (in ways that wouldn't have happened in the absence of diesel-electric development) is a hypothetical question, of course. Equally hypothetical is what might have happened if the PRR official who was so enthusiastic about diesel and other IC locomotives in the late '20s hadn't died (it's in Clessie Cummins' book) and left the field to lightweight motor trains... and the slipshod electric-derived attempts of the traditional locomotive builders... for a decade. In particular, if you posit WWII and the changes it produced, you get enhanced diesel locomotive development on the 'other side' that might well have occurred quickly even in the absence of Hamilton, Dilworth, Kettering et al. And if a great many historical events hadn't occurred, the shape of steam development might have been very different. (Consider the great hysterical rush to experiment with oil firing when Mr. Lewis pulled the miners out on strike...)
Keep thinking. This is fun.
As far as your Gas Turbine with steam turbine bottoming idea here is a recent Patent for such a locomotive:
http://www.google.com/patents/US20100005775?dq=combined+cycle+locomotive&hl=en&sa=X&ei=AaXQUNa4JemJ0QGOx4GYDQ&sqi=2&pjf=1&ved=0CDgQ6AEwAA
It's essentially a combined cycle powerplant on rails.
My non-technical/engineering backround opinion is that the flaw in the design above is having both turbines drive a common alternator using a complex clutch system to engage/disengage the steam turbine. I would suggest a "Genset" type configuration with the steam turbine coupled to a seperate,smaller alternator might be an improvement, although it is interesting to note that former TRAINS magazine columnist John Kneiling proposed something very similiar to what's described in the patent as one power option for his Integral Train system concept.
There IS a major OEM manufacturer offering a Steam Expander bottoming system for diesel locomotives and railcars; Voith turbo whose product line included diesel hydraulic locomotives:
http://www.voithturbo.com/applications/vt-publications/downloads/1809_e_g_2161_e_steamtrac_2011-02-15_screen.pdf
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
You know, I like the way Overmod and Juniatha think. Bring back the Triplex! It NEVER got a fair chance. Now, say we install a nuclear furnace to take care of the poor drafting problem by eliminating the need for drafting entirely....AND we'd only have to refuel it maybe every ten years or so. Let's see a diesel beat THAT fuel economy!
Wouldn't need a headlight or classification lights either. It'd glow in the dark anyway.
carnej1 As far as your Gas Turbine with steam turbine bottoming idea here is a recent Patent for such a locomotive: http://www.google.com/patents/US20100005775?dq=combined+cycle+locomotive&hl=en&sa=X&ei=AaXQUNa4JemJ0QGOx4GYDQ&sqi=2&pjf=1&ved=0CDgQ6AEwAA It's essentially a combined cycle powerplant on rails.
It IS a combined-cycle powerplant on wheels. (Did I edit GTCC out of my previous post?)
My non-technical/engineering background opinion is that the flaw in the design above is having both turbines drive a common alternator using a complex clutch system to engage/disengage the steam turbine. I would suggest a "Genset" type configuration with the steam turbine coupled to a seperate,smaller alternator might be an improvement, although it is interesting to note that former TRAINS magazine columnist John Kneiling proposed something very similar to what's described in the patent as one power option for his Integral Train system concept.
That's the spirit -- we don't hear nearly enough about Kneiling these days, and we need to resurrect his memory (and, perhaps, some of his iconoclasm) nearly as much as we need the Lippmann idea back...
I actually wouldn't combine the feeds from the GT and ST systems into a common alternator (didn't I say that, either?) as they have to run asynchronously (not in the electrical sense, but the mechanical, as in Russell Brown's asynchronous compound). The thing I'm working on is a conversion of the system designed at UT for ALPS, with the gas turbine on one MegaGen and the steam turbine on another.
You could probably tinker around, as Kneiling was, with mechanical or hydraulic drive from the (distributed) gas turbines -- I tried to talk him out of it then, and would still do so now. (Especially now that so much of the container-train 'action' is ELF, and the distributed turbines would have to 'live' on the end platforms or articulated like that 20' container patent between adjacent units...)
There's a place for direct hydraulics aside from the torque-converter Voith-type transmissions, see the Lewty booster, but a hydraulic road slug begins to raise some potential issues, and its usefulness with other types of locomotive might be limited at best. I think that here, electrical transmission rather than hybrid is the 'best' solution for locomotive use -- at least, for large American locomotives.
One other point: The great insight of the BMW people, when they did combined-cycle with positive-displacement IC engines, was to use the bottoming heat recovery for ancillary power, rather than to try like Volvo et al. to put the power back into the engine shaft a la Wright Turbo Compound. Again, asynchronous operation gives you better operating flexibility over a wider range of 'turndown' -- and there are quite a few systems other than straight traction that need to be powered or otherwise operated on a locomotive...
Left out the point about the genset engines!
The principal difficulty I see with using bottoming on gensets is that the average size of the 'genset' is such that it doesn't provide a sufficient amount of high-grade, recoverable heat to make the economics of the bottoming plant worthwhile. (In the absence, of course, of huge amounts of throwaway-money subsidy for putting it there and then maintaining it, but that's another story!)
If we look at steam directly, Harry Schoell's Cyclone project is both sized and directed toward use in just this type of locomotive -- I think of it as an updated version of the old Baldwin 6000hp 'Centipede' from the late '30s, which were going to use individual genset drive (with not all of them producing traction all the time) for power matching and fuel efficiency. The problem is that I doubt you will see an ultrasupercritical plant running on exhaust heat -- even turbine exhaust heat -- although I certainly would like to see it tried. (There is an approach that would permit high baseload operation of a gas turbine setup, but it is predicated on electrical transmission...) Shy of the Cyclone/enginion AG approach to genset engining, I don't think you can get the water rate down to where a bottoming cycle *of adequate power* will work acceptably with the level of condensation available to it.
Overmod Left out the point about the genset engines! The principal difficulty I see with using bottoming on gensets is that the average size of the 'genset' is such that it doesn't provide a sufficient amount of high-grade, recoverable heat to make the economics of the bottoming plant worthwhile. (In the absence, of course, of huge amounts of throwaway-money subsidy for putting it there and then maintaining it, but that's another story!) If we look at steam directly, Harry Schoell's Cyclone project is both sized and directed toward use in just this type of locomotive -- I think of it as an updated version of the old Baldwin 6000hp 'Centipede' from the late '30s, which were going to use individual genset drive (with not all of them producing traction all the time) for power matching and fuel efficiency. The problem is that I doubt you will see an ultrasupercritical plant running on exhaust heat -- even turbine exhaust heat -- although I certainly would like to see it tried. (There is an approach that would permit high baseload operation of a gas turbine setup, but it is predicated on electrical transmission...) Shy of the Cyclone/enginion AG approach to genset engining, I don't think you can get the water rate down to where a bottoming cycle *of adequate power* will work acceptably with the level of condensation available to it. RME
My thought experiment for a "steam genset" would be 3 or 4 of the Voith "SteamTrac" 4 cylinder steam expanders on a rebuilt GP(or SW) frame with a steam accumulator tank mounted on a drawbar connected flatcar. Good for about 900-1100 HP for switching industries that generate large amounts of process steam (i.e refineries,food processors, ethanol plants, etc.)
After all, there are still some fireless locomotives operating in similiar service in Europe and DLM is trying to market rebuilt (and new, if a customer desires) fireless cookers..
BTW, I use the tem "Genset" in my previous post to describe a multiple power plant setup, I was certainly not suggesting applying the Voith technology to existing diesel-electric Genset designs. I do however, suspect Voith would like to promote the technology to the EMD's(Progess/Cat ect.) and GE's of the world for application to full size road locomotives.
In my extremely humble opinion, you should use something better than just an 'accumulator tank' for this: You'd have a vessel partly full of hot water, and 'bubble' the steam in until you made all the water overcritical at the given admitted-steam pressure (and associated saturation temperature).
1) There are better means of 'storing' enthalpy from various flavors of process heat; see some of Harry Valentine's ideas on 'modern fireless locomotives' for more and better discussion than I could put in here.
2) I hadn't thought the waste process steam in many of these operations was at high temperature and pressure. You could 'tap' the main steamline on a high-pressure boiler (or recovery system) of course, and factor the resulting use of heat into the plant Rankine cycle just as you presently do with powerplant heat-balance calculations for FWH via multistage turbine bleed. But I'd have to wonder about the net ROI if you try using 'spent' process steam unless it is still high (enough)-pressure saturated...
3) Consider the use of some amount of 'onboard' generation that has high enthalpy, or an external heat source, and use this heat (modulated appropriately) for superheating or 'steam drying' (as in the original Indian Point proposal). There are some external 'green' sources that might be used to accomplish this task, but imho they are somewhat 'fiddly'. At the very least you will reduce the 'onboard' combustion requirement to something lower, and potentially gain some of the clean-burn advantages of external combustion or full-stoich internal combustion...
Hi all
At present I just don't have time to spare to answer or write anything . We'll meet again next year .
RME : the way you compose your comments , sometimes it seem slightly difficult to get your point . Just one note in general :
My skipping something I consider self explaining , self-understood , logical or of secondary importance to the point at hand , this way omitting many details for to keep post concise , should not mislead you to believe it was lacking .
On the other hand some points about my early Triplex scheme I touched but briefly may have escaped your attention . So we're square . Don't worry - be happy .
Wishing
Merry Christmas
to all of you and your beloved ones !
Sincerely
Overmod In my extremely humble opinion, you should use something better than just an 'accumulator tank' for this: You'd have a vessel partly full of hot water, and 'bubble' the steam in until you made all the water overcritical at the given admitted-steam pressure (and associated saturation temperature). 1) There are better means of 'storing' enthalpy from various flavors of process heat; see some of Harry Valentine's ideas on 'modern fireless locomotives' for more and better discussion than I could put in here. 2) I hadn't thought the waste process steam in many of these operations was at high temperature and pressure. You could 'tap' the main steamline on a high-pressure boiler (or recovery system) of course, and factor the resulting use of heat into the plant Rankine cycle just as you presently do with powerplant heat-balance calculations for FWH via multistage turbine bleed. But I'd have to wonder about the net ROI if you try using 'spent' process steam unless it is still high (enough)-pressure saturated... 3) Consider the use of some amount of 'onboard' generation that has high enthalpy, or an external heat source, and use this heat (modulated appropriately) for superheating or 'steam drying' (as in the original Indian Point proposal). There are some external 'green' sources that might be used to accomplish this task, but imho they are somewhat 'fiddly'. At the very least you will reduce the 'onboard' combustion requirement to something lower, and potentially gain some of the clean-burn advantages of external combustion or full-stoich internal combustion...
I do think some of those industrial processes produce sufficient steam, after all such industries were major users of Fireless cookers back in the early-to-mid 20th century, and there are still a few active operations in Europe (Germany mainly).
My fantasy locomotive is as "off the shelf" as I could conceive......
I enjoy Harry Valentine's writings though I suspect many of his proposals would require major R&D.
There was an interesting article in the January 2009 issue of "Trains" about the economics of importing new- build fireless engines from Europe (both DLM and Dampflokwerk Meiningen have said they could build them) for industrial use, so that's what I was thinking about. Roy Blanchard(IIRC, he is active in steam preservation/restoration), who wrote the article said the ROI might be favorable given high prices for Diesel fuel.
That might be a more realistic alternative than what I was suggesting but it's fun to speculate...
I am sure very little is lacking in your thinking!
If you prefer shorter posts taking things point-by-point I can make them. I'm happier using the old 'reflector' idea of putting all the responses for one post inline with the text being addressed -- in the old days, that saved bandwidth and made it somewhat clearer to follow when a lot of things were being 'bounced around' at one time.
It is not my intent to be excessively critical, or mocking in any sense; I take steam design seriously even when it's hypothetical.
Just as something to chew on over the holidays: an incomplete list of some of the 'trends' that might have been seen for RECIPROCATING steam in the late '40s and forward. (This is in the American context; there was at least one fascinating 'future history' for European... in fact, I think German in large part... steam on the Web).
Interesting to see whether 'duplex' bugs would be addressable via Deem-style conjugation, perhaps with a Bowes drive acting as the Ferguson clutch between engines. You can put the conjugation on the mains (for faster action) or on the driven axles (less mass on the mains) -- but I don't advise going from the main on the forward engine to the leading undriven axle even if your universals will tolerate it. You conjugate the two units some multiple of 45 degrees apart rather than doing Withuhn conjugated duplexing; this gives you smoother power per revolution and (de facto) cuts down on relative propensity for high-speed slipping (which was the real 'insoluble' problem with T1s, and I firmly believe, the T1a too...)
In any case: MUCH better addressing of dynamic augment and slip propensity. Automated procedures for dynamic balancing of driver wheelsets to within a few lb @ 500rpm, then trim balancing rods-on at the same cyclic rpm. Lathe approaches to keep the driver tires properly profiled (perhaps to some analogue of Porta's HAWP) with compensation for 'egg-shaped wear' due to torque peakiness -- I have not decided whether some flavor of 'Lidgerwooding' with tools or portable grinders on the locomotive frame itself might be a workable alternative to a portable or under-track wheel lathe setup...
Fast traction control, probably via air-over-hydraulic calipers acting on the driver rim faces, or on cheek plates on the drivers (cf. the brakes on an AEM-7 electric). This doubles as the part of the independent brake that acts on the drivers -- no displacement causing slippage or skidding, reduced tendency for tire overheating. Slip control is not a loss, as it is on diesels with wheelset braking, because steam pressure is kept on, proportional to stroke, as the brake holds the drivers, and is still 'elastic' for further expansion.
Better, more reliable automatic cutoff control. This an expanded version of the '20s systems, using some of the Valve Pilot logic, but more featured (I'm positing nothing more sophisticated than fluidic, relay, or vacuum-tube logic)
Two big additions: Snyder preheaters in the air gap between water legs and ashpan; and a good Cunningham circulator setup. (The jet pump from the Cunningham also circulates water through the cylinder jacketing, a point I'll address in a moment.) If using a watertube box, the Cunningham pump can do Lamont-style forced circulation without moving parts...
I don't think the welded 'staybolting' used by Bulleid in the Leader boiler got a reasonable test -- it would be at least interesting to see if flexible hollow-tube stays could be made workable in practice. In the absence of that -- resurgence of interest in watertube fireboxes (NOT WATER TUBE CONVECTION SECTIONS) with proper steam separation at the top, circulation at the bottom). The Cunningham system probably eliminates need for discrete downcomers. I see no particular reason why Bulleid-style syphons wouldn't hold up well -- and staybolting was a primary reason why arch tubes were preferred over syphons in many cases. Note that waterwall firebox construction, even with substantial excursions in firing temperature, can give you much better practical absorption in the radiant section (and of course are amenable to forced circulation)
I'd be expecting to see at least some experimentation with sliding-pressure firing a la NYC, particularly on locomotives with good superheater installations. Fully astounding reductions in fuel and water rate can occur when pressure is modulated to suit demanded hp (cf. Tuplin's report of a Niagara doing the work of a 2-8-0 on a 2-8-0's budget...)
Heat the brake air going into the overfire system -- probably with exhaust steam, with the condensate perhaps going into the FWH system. Steam in the overfire might produce some interesting shift of heat transfer in the convection section, or in the Franco-Crosti range.
Asynchronous compounding, and perhaps Franco-Crosti economizing as part of the feedwater system. All the plates and surfaces in the economizer are either Parkerized (like the inside of the boiler, via some electroless process) or made of material resistant to sulfur corrosion at lower temps in a wet environment. (Be nice to spec low-sulfur fuel, but that's not '40s or '50s priority!) I'd certainly expect to see at least some attempt at Holcroft-Anderson style recompression, even if for no other purpose than reducing the effective water rate. If you run a certain percentage of exhaust mass flow via exhaust-steam injection, and another percentage via recompression (using a proportion of the exhaust steam for the recompressor) you might get within specs for some further ejector-then-exchanger condensation -- and prompt clearing of exhaust back pressure from cylinder-cycle perspective...
Double-piston valves. Note that only one set of these needs active drifting bypass (a la Meiningen-style damped Trofimov valves, or the Wagner setup used on ATSF 4-8-4s) and this gets you around most of the kerfuffle involved with either vacuum or steam-on drifting.
More use of Franklin System (or British Caprotti) style poppet valves and some flavor of cam-timed valve gear. This might NOT involve using the external gearbox-and-shaft drive to physically move the valves; separating the control timing from the actuation gets you around the problem seen on 3752 in testing. Another solution is either to adapt Cossart drop valves or use Berry Accelerator gear to get the drive motion into phase to use salmon rods -- no longitudinal unbalanced moment in the running gear, hence the ability to do very precise dynamic-augment compensation...
Proportional compression control (cf. Jay Carter) rather than just pop reliefs a la Okadee. This is especially needed for very high speed (high cyclic rpm) as you have to match pressure across the valve carefully to avoid gas cutting as the port starts to come open. Poppet seats made of hardened material and made adjustable; valves themselves on ball/spring seating so they close and seal without pounding even when slightly worn.
You'll heat the cylinders. Not with exhaust-steam jacketing: too bulky, too much condensation, not enough enthalpy -- Wardale understands this situation quite well. But pure insulation isn't a full fix. Chapelon's late approach of directing the incoming steam around the cylinder and head before admission to the steam chest is interesting... but not the best approach to keeping the cylinder mass well above the nucleate-condensation point of the expanding steam near the exhaust point. For that I think overcritical water through tubing, with heat-pipe distribution, is a better approach (and as noted above something that 'works' with the Cunningham jet pump) -- this also makes opening cylinder cocks at starting relatively unnecessary, as there won't be condensation there as the cylinders take steam...
Better care with circulation patterns in the convection section -- Cunningham ports, for example, and circulator exits. Very few people seemed to have looked at exactly how the water moves inside those things.
I don't know what the early history of industrial antifoam is -- but some approximation of what has become Porta treatment would surely have become practical if the priming problem could be addressed. There are mechanical ways to improve practical water separation at the dry pipe, but many of the more logical ones involve a higher loading gauge ('a la Rus') rather than just a Woodard-style external dry pipe to forward dome over throttle. That's practical for stack-train era... but not by any means in the '50s or even later. Some of the fancy devices for detecting boiler foaming were interesting, but of limited use in actually preventing problems with carryover in a working environment... I have noted with some amusement how many instantiations of Elesco centrifugal 'dryers' wound up having their separated water dumped over the side instead of being 'drip tray' poured back into the boiler... some question, looking at their literature, as to whether they actually realized what the top of the boiler water acted like...
More use of Centipede tenders, with better control of lateral compliance for reverse/wye moves. This might involve 'softer' Fabreeka springing on the rear wheelsets, a Cartazzi-style curve to the rear pedestals (with radius relative to the yaw center of the tender in motion) or an actual Bissel truck with proper rollers and guiding (it came to me recently that this isn't like a Delta trailer, but more like the lead truck on a Berkshire, in its guiding dynamics and principal purpose...)
Better ash handling. Perhaps some use of an 'ashaveyor' system to allow longer running between ashpan stops... or an automated system for knocking the pan down and running water into it, similar in principle to the way some ore cars were dumped. Not yet in the era where full 'accounting' of ashpan material needs to be made... or where total-loss lubrication becomes prohibited in new construction. But there are approaches for those things with 'contemporary technology' if desired.
Continuation of N&W/NYC style servicing facilities, both in running and shop service. It would be nice to have aircraft-style spares provision for all complex assemblies, including articulated-engine power trucks -- but as I've already noted, I don't think either the money or the justification was there for very much 'overstock' just in case of unplanned failure: the emphasis was increasingly on reliability and ease of service ACCESS going into the '50s, but there's a limit on how much even a fully mechanically reliable steam locomotive 'saves' when so much else about it requires fairly frequent attention (e.g. in lubritoria)
Better lateral compliance and damping, and vertical suspension at the drivers. This involves some care with the trucks as well as good lateral motion in driver wheelsets. Remember that the truck suspension in a reciprocating locomotive is NOT the same as that for a high-speed truck-driven locomotive; you're relying on lateral guiding pressure to steer the chassis, not just accommodate curves with the absence of weird wheel-rail oscillations.
Besler tubes, especially on liquid-fired engines. Better burners... and control theory... for heavy-oil firing. (Would have been interesting to see the practical results of waste-oil recovery from the growing automobile industry, especially if government restrictions on dumping crankcase and lube oil had been used (perhaps passed as wartime legislation in '50-'52?)
Better front-end design. This can't be covered here or you'll all go even deeper to sleep. But practical improvements were just getting under way, and even shy of Lempor/Lemprex mathematics, there was still some flavor of Giesl ejector -- which I think would have been more successful had the combustion-gas path into the smokebox been better understood.
Better (or less expensive) fabrication techniques. The one that jumps out at me is centrifugally-cast, perhaps NNS, driver axles -- these were actually marketed in the late age of steam! Steam-locomotive-grade welded frames probably have to wait for better welding technology (it's only just now coming into practical cost range to do full-pen keyhole welding on heavy plate sections to make a box-section locomotive chassis frame) BUT the welded attachment and NDT testing of driver tires might have been in the realm of possibility.
Enclosed cab, with some form of air filtration, and probably some form of air conditioning or cooling or at least tempering for the crew.
I'd be looking for some method of providing 'remote vision' (perhaps via the TV systems developed during WWII for Aphrodite) that would get round the problems of seeing forward out of a locomotive with full developed boiler diameter -- or, for the V1-style locomotive, full developed volume for the coal bunker. I would staunchly claim this could be 'hardened' enough to be reliable if comparable sorts of ATC circuitry could. There are optical approaches, too, but they're not as 'tolerant' of temperature cycling, dirt and wetness, etc.
For fast locomotives: reduction of both frontal area and Cd, both in longitudinal and 'quartering' sense. This need not be the same thing as 'streamlining' until you get well up into the speed range, as the relative contribution of frontal resistance stays relatively low for longer heavy trains -- BUT rising air resistance rapidly meets falling developed HP at high cyclic rpm, and for even comparatively small speed increases in that region of the curve, anything permitting better incremental acceleration becomes useful...
I'd expect eight-coupled locomotives to be used in favor of six-coupled for new construction -- including Dixie-size locomotives to replace Pacifics and the like. We now run into the intersection of engineering and politics. Richard Leonard says, with some justification, that a 4-8-2 with efficient systems can do any logical work a 4-8-4 does; meanwhile, we have Lima going to vast fireboxes with three axles under them... even for eight-coupled locomotives. A large part of this is going to involve fuel quality -- there was a fairly big push for clean and well-graded coal in magazines like Railway Age in the late '40s, which made great sense to me and might have been of much greater import in the relative absence of road dieselization. I for one would greatly enjoy a discussion of this design aspect based on the merits...
Merry Christmas to you all, and I hope you recover from MEGO in time to eat the cookies and Coke Santa leaves behind on Christmas Eve... ;-}
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