440
makes sense to me, dual service too.
# 441
If you have ‘extremely poor coal’ - then an x-x-6 type of w/a might have made sense - there was a discussion about the Lima 4-8-6 offered as an ‘answer’ ( or not ) to the diesel invasion and I had posted my view it had presented an answer to a question no one had really asked . However , for really poor coal … problem with poor coal was it was actually unsuited for locomotives in many ways and presented all kinds of troubles , including lots of cinders and clinkers even increased corrosion in boilers for high sulphur contents , dependiong on its actual consitence .
Duplex or single drive set - that depends if you want a purely ( not poorly ) express engine or dual purpose . Since most US RR in the end never allowed any motive power to escape the dual torture service , a 4-8-6 would probably apply . If you want a flatland racer it’s the Duplex you might prefer …
Regards
Juniatha
#442
The SP&S went to oil-their late steam burned it, including their Challengers, which were copies of NP designs that burned coal. The Washington coal was just so poor. Since the SP&S’ passenger trains were mostly just forwarded NP and GN trains, I think the 4-8-6 is more likely, even if the duplex is more fun! But it would have been fun to see blasting along the Columbia.
#443
How about a firebox design similar to what Mr. LaPorta used on those 750mm 2-10-2s in Argentina? They had a diet of poor grade coal which clinkered easily. His solution of a gas producer firebox setup with steam fed up through the grates resulted in practically eliminating clinkers and with 70% of the primary air for combustion coming in above the firebed, there was very little solid abrasive material carried through the flues and out the stack. Really neat, efficient, little hogs! So maybe SP&S could burn some of that local real estate without wearing out the boiler and burning up the countryside in one of those handsome 4-8-6s.
# 4-4-4 (g)
on # 442 and 443 :
Gas Producer Combustion System , he called it , GPCS . I’d think this would have made sense if it would have been available back then - I believe Porta only developed it in steps through the 1950s or even the sixties . It is not without its challenges - if you read Wardale’s “Red Devil and other tales …” you get an impression although at points I feel you have to read somewhat between the lines to get the real McCoy . One thing , it seems to work best when a locomotive can settle down on a pretty constant pace for an extended time – which would have made it look good for freight train service on many of the long mainlines across the United States . The logics in his theory of reducing temperature of the fire bed to obtain fine , non-clogging ashes look good . I’m less happy with having air holes in firebox walls and obstructing thermal expansion of the sheets . Some of what Porta allegedly has reported of upkeep of his fireboxes tends towards the ‘story-like’ – without having seen hard evidence of maintenance and ton-miles service sheets I’m not fully convinced .
One point is GPCS would ask for a larger firebox volume and grate surface – a case for that six-wheel Delta truck .
However – with all that upheaval why not go for ten coupled , making it a 4-10-6 ? There you have tolerably all the guts you want to ask of an American Super Power steam locomotive !
Chooooo-wah !
Juniatha
#445
I mentioned a SP&S 2-10-6 much earlier in this thread, but a 4-10-6 makes more sense, especially for dual service. Maybe also a Dominator 4-6-6-6?
GPSC sounds interesting, I’ll have to do some research!
# 4-4-6 - g
445 : >>Maybe also a Dominator 4-6-6-6?<<
Oh , that would be another story … how to get a 2 x 6 coupled Duplex through curves .
It could be done yet it would take some scrutinizing design effort to go into a well balanced arrangement of
lateral displacement , centering forces and springing characteristics .
Regards
Juniatha
#447
The 4-6-6-6 would be an articulated, an expansion of SP&S’ Challengers. Looking at satellite photos, a 2X6 Duplex wouldn’t like the curves on this line…
#448
Juniatha,
A kind of late reply to #4-4-4 (Baltic?).
I dug up some figures on Porta’s 2-10-2s from an online article;
Superheater elements, no replacements after 310686 miles of service.
10% of the tubes were replaced during the first 248548 miles of service, all failures were attributed to longitudinal cracks caused by overexpansion during initial assembly.
No boiler shell or firebox sheet repairs during the first 12 years of service.
These engines averaged 7456 miles per month, average train was in the 1500-1700 ton range. And, yes I believe you are right in saying the GPSC was developed gradually through the 1950’s.
So, maybe if we invent a steam powered time machine…
# 449
A steam-powered time machine? The “steampunks” are working on it. Let’s give 'em some time and see how it works out.
#450
And if I had a steam powered time machine, I would go back to post #448 and replace “Baltic” with “Jubilee” or “Reading”!
451
Some out of box thoughts on steam. I will start this by saying I am not an engineering student or any kind of expert. But that having been said I can maybe think of things out of the box. 1st thought. If a way could be found to increase the available torque from the format of a shay or climax type locomotive. With a rod geared locomotive I would think that a lot of problems associated with trying to balance the main drivers. The other advantage they had was like diesels they had all the weight on the drive wheels and did not need pilot trucks. 2nd thought. A steam turbine with the ability to adjust the jets against the blades. Combined with a blade that had different pitch from root to tip. Instead of adjusting the pitch of the blade have different points at which the steam nozzle was aimed at the blades. This way you could get more leverage at one point but as you increased speed move the nozzle to apply force at a different point on the blades. Essentially providing a way to change gears. This is kind of hard to describe and maybe someone has thought of this already. But as I said I am no expert. Last thought on this is think of how a variable pitch propeller works on a n airplane. The difference being is the propeller does not change pitch but where the steam is applied to the is changed. Thx IGN
452
Injecting steem into a turbine is not all that different from injecting steam into a reciprocating steam engine’s cylinders. The steam pushes the whole face of the piston, not just a specific area close to the valve inlet. The same applies to turbine blades.
But there is different approach that night work. On a large and wide turbine, don’t just have one inlet port and one outlet port around the circumference . Have four pairs. Control the steam so you have only say the intlet port at 3 dgrees and the outlet port at 357 degrees for low power, the inlet ports at 3 and 183 degres and outlet ports at 177 and 175 degrers for half power, and inlet ports at 3, 93, 183, and 273, and outlet ports at 87, 177, 267, and 357 degrees for full power. Has anyone built such a turbine?
Dave, look at the control-nozzle arrangement on the Met-Vickers turbine in the “Turbomotive”. This does the important half of what you propose.
For engineering reasons, there is little if any point in arranging multiple outlet ports on a turbine this size. The exhaust involves very large plena with progressively increasing volume, and the orientation of multiple plena is going to involve some iteresting packaging to get it in line with the draft-producing apparatus in the front end. (While I am a fan of Holcroft-Anderson ‘recompression’ to utilize the latent heat of vaporization in the Rankine cycle, I am not particularly hopeful that a 6000+ hp turbine can be meaningfully condensed with meaningful overall cost-effectiveness…) I invite you to calculate just how many degrees the exhaust plenum represents, and why a single plenum served by multiple throttle nozzles was chosen.
Note that at least one proposed approach to this kind of turbine involves a pair of turbines, sharing a mainshaft and central drive pinion. Inlet is inside, close to the pinion; the large exhaust plena are outboard, where there is ample room for them. and the reversing is handled internally. In all probability these turbines would combine impulse and reaction – the original design I saw had an initial impulse stage, and then multiple reaction stages; the
# 454 - classic long standing Chevy BigBlock
on 451
What you aim at is a full adhesion geared steam motor concept - something that could have been done and would in fact have made steam competitive to diesels on a 1 : 1 basis of serviceable locomotive mass as far as starting tractive effort and limit by adhesion factor on rail is concerned - however , not likely so in view of power output per unit of serviceable locomotive mass . Or on the other hand , first generation diesels were so low in motor power they had to use a considerable part of it only to propel themselves at speed , so maybe an excellent design of the above mentioned might have stood a chance ; however , then again exactly that was the problem of steam locomotives of this unconventional concept : there was no excellent design realized and hardly could be expected in that preciously short a development time as at best available for steam at the onslaught of dieselization .
Your ideas on steam turbines I’d rather not comment - we may all have dreams , why not .
on Daveklepper # 452
Injecting steem into a turbine is not all that different from injecting steam into a reciprocating steam engine’s cylinders <<
Oooh - it’s a totally different story !
on Overmod # 453 ( please put in yo
# 455
Juniatha, could you explain to me (and other readers) the basic difference between injecting steam via piston valves into a reciprocating steam locomotive’s cylender, and via the intake port of a steam turbine? Other than the fact that the intake port is continuous in operation while the piston valve opens only a fraction of the time, the fraction depending on cutoff setting. What I don’t understand is the idea the the steam from the intake port could exert force on only a portion of the blades and not the entire blade area.
# 456
Essentailly, in a Turbine, each blade has the function of both the piston and the valve in a cylinder, since it receives steam (or gas or water for that matter in water-wheel) only at the time when it has just past the injection port and the time that the next blade passes. I imagine there must be a difference in the way the steam forces the blade forward and the way the steam forces a piston forward, or otherwise the differnces in blade ;profiles would not amount to much, and yet choosing the right blade profile is an important part of turbine design. I don’t know of any locomotive cylinder pistons that were not flat-faced. Were there any?
One other idea. Are not entrance ports on turbines always on the circumference? Suppose there were five entrance ports, two on each side within the area swept by the blades and one on the circumference. Then would not choice and number of entrance ports used have the same degree of control as changing blade profile?
# 457
Dave
these questions enter thermodynamics and conversion of thermic into mechanic energy and should receive a more complete answer . I would answer it , however I first must see when I will have time to spend . As things usually are , I’d expect before I even open up trains forum next time , Overmod will have posted a 100 lines reply …
[:S]
Uhm , Dave I have just sent you an e-mail with a quick reply for now .
Regards
J__uniatha
… and I would really really appreciate if each participant could put up that counting # on top of his post again - thank you all .
4__5__8
Following up on Juniatha’s email, I investigated a website, and I will leave it to Juniatha to post the reference. I found that I had forgotton whatever I had learned about turbines at MIT. I was thinking of a turbine as something like a waterwheel, that powered much New England machinary, pipe organs dating back to possibly the “Hydraulis” that some say was an organ in the 2nd Temple in Jerusalem, but a turbine is very different. The individual blades receive fresh steam (or gas) around the entire circumference, with alternate fixed and rotating blades shaped to create the torque and the rotary motion.
Power is controlled by something analogous to a throttle, and generally the turbine operates at maximum efficiency and minimum noise at its rated rpm and at or near maximum load.
But this is like running a conventional steam locomotive with only the throttle to control power and no “Johnson bar” (reverse lever). A locomotive engineer that completes a run with the bar “in the corner” all the time might well be fired for using far too much fuel, and possibly creating other problems in the locomotive as well.
There should be a way to provide “cutoff” in a turbine. Imagine each rotor has 16 or 24 or 36 or 48 blades. Full power has all openings open, reduced power one out of four around the circumference closed (entrance and exit, staggered appropriately) further reduction, half closed, and minimum power only one out of four remaining open. The result should be a turbine that can operate efficiently at different power levels. Constant speed or not is another question, since power is torque times revelutions per minute (times a constant), and answering that question takes more turbine designing skill than I claim to have.
If there is any monetary reward for this idea, Juniatha should certainly share! It is simply applying a