Throw Shays away -- they weren't and never would be high-speed locomotives. And they only work on one side -- sketch the geometry on curves if you have any question about that.
Heisler is your principle. (I would connect the truck wheels with intermediate gearing rather than with rods, because you'll have some of the rod-fracturing problems that rod-drive electrics did, due to the characteristics of and inertia in the drive train). There is no particular reason why this would have to be a low-speed design -- in fact, there is very little reason why it couldn't be provided with some sort of change-speed transmission and be used at quite high speed indeed.
A Heisler engine at this scale would be essentially a 90-degree angle V4 to V8 cradled under the boiler, with the cylinder heads neatly exposable for maintenance, nice short steam and exhaust passages, and whatever crankcase arrangement you want -- cast ,or open with seal plating. Cardan shaft drive with Nice Big Universals -- they're doubled for constant-velocity, and you can theoretically use big Rzeppa joints although their use in the '40s might not have been cost-justified!
I like the quills as final drive on the higher-speed version of this locomotive. The unsprung mass however doesn't get much worse than it is on an RDC, and of course there is no direct augment in the suspension. So you might get away with little more than the arrangement you see in a typical semi tractor rear, beefed up to take the shock loads, etc. in effective service. Drive is slightly angled in plan to a pinion on one side, with the countershaft arrangement conjugating the truck wheels running on the other side (so the gears work to turn all the wheels in the same direction). There are some pictures on geared-locomotive sites that show this arrangement with open gears -- fine for logging maintenance, but not imho desirable for long life or high speed -- and that will give you an immediate view of how the gearing is arranged. Shafts between trucks are handled with splines and floating U-joints, and center bearings in the shafts where desired.
It might be interesting, as you indicate, to rig up a Heisler engine as a booster on something like a Garratt. There is plenty of room below the boiler, the shafts go direct to the inside engine trucks, and the swing of the articulation to those trucks on a mainline-size locomotive should not be excessive.
The problem with vertical-engine boosters on the tender is that they'll take away too much space for both coal and water. You want to minimize the tender tare weight as much as possible in the first place -- and driving the tender wheels has the same general problem as a conventional Garratt in that the FA goes down as the fuel and/or water is used. This before you start figuring out where the steam and exhaust pipes to the motors have to run...
It might interest you to know that there were at least two advanced Heisler proposals I'm aware of (one in the United States and one in South Africa) and I believe Ted Pritchard in Australia had this layout prioritized for his 'railroad' locomotive plan, as it immediately fit his chosen engine configuration.
RME
Ah, I see, the name is the "Hyper-Heisler"
The question is, would this have been developed or used?
One question- would the cylinders affect the size of the boiler?
Thanks!
Edit- could this be a solution to the starting TE problem?
Yes, the cylinder size is related to the boiler size. Use the formulae in Ralph Johnson's book to get an idea of how. Remember that the boiler can be very large, just as in the V1, to get the system to work; about the only thing you can't do is run the shaft through a firebox.
It's probably not as 'good' a solution to the starting problem as something like a Paget or Besler locomotive, where you have a very large number of little 'power pulses' per driver revolution. There is no doubt that you have better effective TE per ton, and normally lower slip propensity ceteris paribus, with any of the geared locomotive designs; you also have much lower propensity to sustain a slip as the engines overspeed faster for a given throttle and reverser setting...
One place the design would have been extremely valuable is steam switching service. That was the specific way the American locomotive was built, but it was a practical shortline engine too. It was supposed to use submerged-flame combustors to get very high firing efficiency.
As I have said elsewhere, I like this idea for geared drive rather than the multiple-engine-Sentinel approach.
Thanks...
Is there an easy way to eliminate the tread wear issues that dynamic brakes solve?
Putting electric motors on this would be an issue, both cost and maintenance wise. Any ideas?
Also, how to mitigate drive shaft and cylinder intrusion into the firebox, beside going with a Belpaire?
Beyond that, I'm unsure of anything else I can add to the steam discussion!
There are "DB equivalents' on steam locomotives, including various types of counterpressure brake (for example, the LeChatelier 'water brake'. These tend to be limited by the small number of active drive wheels. One railroad that used these on large modern power was D&RGW -- see LeMassena's article in the May 1995 Trains Magazine, and some intelligent discussion here, from 2003 but still useful..
One issue with these kinds of brakes is that you have to get rid of the energy 'liberated' by the brakes in some way. As you probably recognize, this is considerable (think about how much heat has to be dissipated by the grids and fans). Some versions of counterpressure brake involve converting the cylinders into air compressors -- which is great until you start having to dissipate the heat generated there by the compression -- which easily gets you up to the carbonization point of your cylinder lubricant ... in a higher-oxygen environment ... within a short effective time. Hence the use of the 'water' -- which flashes to steam, provides the counterpressure, and is then exhausted carrying away the brake heat which is taken up as latent heat of vaporization. Naturally the source of the 'water' involved can be complicated (I thought) if you're dosing the tender water with treatment chemicals -- one of the great '40s operational enhancements -- but I am assured from a number of sources that the small amounts of hemical do little if any damage.
An issue here is that the braking effort isn't as continuous as with multipoleTMs as generators, and you will get driver tire wear similar to what's produced over time by microslipping and wear. This is not necessarily at the same point as traction-related wear, though.
I have seen proposals to do some 'hybrid' energy storage by saving some of the compressed air in reservoirs, for example in enlarged brake reservoirs. (You don't want to do this with the actual brake air, of course, for a number of reasons I won't tediously go into here.) The catch is that the compression heat is still excessively retained in the cylinder, with the back pressure now developed in the reservoir retarding net airflow out of the cylinders (and hence enhancing the spot heating). That should not stop you from at least looking into the economics of using it. (I don't see it as being cost-justified, or guaranteed safe or reliable enough for long-term use, but don't ever let what I or anyone else say necessarily keep you from working the calculations through for yourself.)
The treadwear contribution of the independent brake can be addressed as I indicated elsewhere, by using lateral caliper brakes that do not act to heat the tire directly. I am unaware of other methods that would work on modern standard-gauge reciprocating locomotives -- although you are welcome to think up and describe something!
I have no hesitation in saying that electric motors on some or evel all the unpowered axles on a reciprocating locomotive will be beneficial -- only that if you do it at full '40s-'50s cost, over a limited installed base, you will not receive positive net return on the investment. The situation changes dramatically when you have large numbers of 'tms available ... but that presumes large numbers of something like diesel-electrics, and perhaps whole generations of diesels that have been depreciated or scrapped leaving their motors for spare parts. That situation does exist for modern steam, and is one of the recognized advantages of an asynchronous compound (in which the exhaust steam from the piston engine is used to run a large turbogenerator/turboalternator with its current used, in part, to run traction motors for boosting. One significant reason to put diesel MU controls on steam locomotives is that an engine crew can control trailing road slugs to produce relatively cheap dynamic, with the slugs having full alternative use with diesels so there is low opportunity cost and low overall risk in developing the approach. I do not know a better way to implement DB than with electric motors operating as generators of some kind, connected to an appropriate load.
I trust you have gone over the advantages and disadvantages of Belpaire vs. other forms of firebox construction. There is extensive discussion of this in the literature, including a couple of specific threads on the Yahoo group steam_tech (which you might want to join). I suggest that the Lima 'double Belpaire' design (in which the combustion chamber is no longer circular, for one thing) be a design you consider if you are retaining stayed firebox and chamber construction.
The shaft is not going through the firebox or throat plate. It would be arranged to go under the ashpan, with appropriate shrouds to prevent ash dumping, corrosion from drips or blowdown, etc. Obviously you would not put any u-joints, splines, or unsealed bearings in that zone if you can help it.
Note that even a deep-firebox boiler with a trailing truck under it has enough 'shaft clearance' to permit the arrangement to work with corresponding permissible wheel size. If you use higher drivers in the trucks, you will want a Challenger-style boiler (where part of the firebox overhangs the drivers) or one of the higher-pitched boiler mountings (as on a modern 4-6-0 or 2-8-8-2).
You might be tempted to run the shaft on one side of the firebox or the other, or to offset the boiler a la shay to make room for the shaft on one side. I do not think I would recommend this, but if you can make the weight balance and not put too much angularity and intermediate gearing in the driveline, it is at least an option. Depth is far more important than width in determining the efficiency of radiant uptake (see David Wardale's discussion of this in the British '5AT' project discussions) so having a deep, narrower firebox is not a Bad Thing.
Be sure if you are using shafts to multiple 'tender' trucks that you remember the culmulative load on the engine and 'first-in-line' gearbox bearings. It's possible that you might want to use a transfer-case-like arrangement (where the engine shaft goes to a transverse gearbox and the output drives symmetrical' shafts forward and backward at roughly equal length to the axle drives). Doing this also would facilitate using 'hybrod' style electric motor/generators somewhere between the engine's crankshaft and this transfer box, with two obvious locationg being on the back of the engine crankcase structure and bolted to or integrated with the transfer box's structure. (That would also give you some of the 'third-rail' capability you were discussing -- look at the arrangements used on some of the '50s lightweight trains with diesel-hydraulic propulsion that had to use third-rail trackage into terminals. (And at the ways those things could produce operational disasters -- 'fifteen more minutes and I would have been a hero' being one phrase you might want to look for... ;-} )
There is plenty more you could add to the steam discussion; it just might not be as 'sexy' as the Big Ideas. For a start, I suggest you look at ways to increase effective radiant uptake in the relevant section(s) of the boiler without causing 'quench' of the effective oxidation (combustion) reactions on the relatively cold inner surfaces in a regular firebox. Or how you shape the combustion space and primary/secondary airflow for best effectiveness. Bet you haven't studied the GPCS system in practice, or how it might be either stabilized or run with nonlinear control the way the F-117 has to be flown...
... and that's just the start of how you might look at things in steam....
Ah yes, the F-117. My brother did some engineering work on that one. He calls it living proof ANYTHING will fly if you put a big enough engine on it!
Firelock76Ah yes, the F-117. My brother did some engineering work on that one. He calls it living proof ANYTHING will fly if you put a big enough engine on it!
Hopeless Diamond airframes fly just fine. They even have pretty good lift.
It's the fact that they're unstable as hell that makes them so much fun -- I bet your brother would be more likely to say ANYTHING will fly if you put a good enough six-axis control system on it... even something with all the glide of a set of car keys...
He couldn't tell me any more than the "big engine" remark. If he did he'd have to kill me.
Wayne
Oh, for heaven's sake, all those aspects of the 117 have been effectively declassified for many years now.
It's also not that difficult to know how the various methods of RAM work, or how the airframe is laid up. It just doesn't do any foreign power any good, because fabricating the microarrays alone is the national defense budget for most wannabees. We just do what Reagan did: outspend 'em and watch them blow up trying to copy us.
Of course, the Australians had an OTH radar (that was essentially in the tin cans and string category as sophisticated EM equipment goes) which could detect the 117 ... well, over the horizon. If you're familiar with weather radar, you will recognize how.
If you are wondering about the 'big engine' -- here ya go (just remember that almost anything else that used this engine had an afterburner section and was muuuuuuch bigger...). If you still have residual curiosity, there are exploded view drawings and parts of the service manual on the Web too.
Well. the F-117 specs are declassified NOW (maybe, maybe not, you REALLY think they've told us everything?) but back THEN he had to keep his mouth shut. We're talking 20 years ago.
However, I told him how I'd detect the aircaft's presense, and he gave me a knowing smile, showing me I'd got something right for once.
Don't ask me how or I'll have to kill YOU!
Ask him about the timing, dispersion, and pulse modulation of the laser ignition in pulse detonation engines, and watch his eyes... ;-}
Just practice the phrase if you don't understand why all the pieces are important. This is one of the things that WOULD be classified if there were any point in using PDEs for high speed in transatmospheric vehicles... or certain other things related to the Northern Lights...
If you're interested in honing your skills, I can send you a review of PDE technology. (Interesting by its absence is any mention of laser ignition, btw, which speaks to the flip side of classification, the delightful hiding-in-plain-sight that has worked in so many places over the years.)
The obligatory extreme-steam reference is that the replacement for the methane-fired PDEs is engines running LH and LOX. And the ejected reaction mass is... ???
!!!
Hi Overmod! Little Brother's not involved in aviation technology anymore, hasn't been for some time, although he still flys helos on occasion. I doubt he'd know about PDE technology, but you never know.
Well now, extreme steam fueled by LH and LOX! Why hasn't THAT been tried yet? Sounds intriguing.
Firelock76 Well now, extreme steam fueled by LH and LOX! Why hasn't THAT been tried yet? Sounds intriguing. Wayne
Only if you want to put a T1 on the moon!
CSSHEGEWISCH Firelock76 Well now, extreme steam fueled by LH and LOX! Why hasn't THAT been tried yet? Sounds intriguing. Wayne Only if you want to put a T1 on the moon!
Why not put a T1 on the moon? Let's see a diesel beat THAT!
Consider that every manned moon flight plus the shuttle flights began their trip with diesel power. The crawler-transporters were powered by Alco 251 engines.
What are your opinions on the DRG class 19.10? http://schneider-mayenfisch.com/drg_lokomotiven_19_1001.htm
.. not too much - it provided an answer to a marginal question , an answer that involved quite an expense on engines if it had been series produced .
The best concept for steam motor type of locomotives has never been found . The V2 engines frame mounted and driving axle directly via mechanical coupling allowing for suspension was a simple and logic concept , a parallel to contemporary electric loco development with E17 and E18 / E19 2-8-2 units . Yet it was not an optimum .
I think the most interesting aspect of the unusual locomotive was that it actually ran in revenue service in as adverse conditions as WW-II and yet did achieve some success with nursing by Prof Roosen of Henschel and others . It could have been further developed , no question , yet it provided no answer to diesels , for instance .
Regards
= J =
As a potentially amusing counterpoint to the Henschel motor locomotive, here is a Carleton Steins (of PRR V1/Triplex fame) patent.
Note the date this patent was filed... and the date it issued. Then compare the Kirchhof patent for what would become Franklin type D , which is a logical system to use on such a locomotive. (In fact, it may be possible that those little circles on the cylinder blocks are stand-ins for cambox covers, although nothing explicit is stated about the form of the motors in the patent itself.)
The type D system ought to eliminate most of the difficulty with physically coordinating cutoff control on separate motors, which required so much 'care' in the Henschel design as built and developed. It also ought to facilitate rapid changes in direction with a simple control, one of the stated objectives in the Steins description.
Not the answer to diesels, either, but I'd surmise that neither Steins nor Kirchhof would have said so as late as the early Fifties. And perhaps in some niches it might have been a reasonable alternative at that time. A light version of this locomotive would be as flexible for various services as, for example, the 44-tonners PRR tried (largest that could be single-manned at that time), and certainly more capable...
Bumping this thread in case new member 'puffy' has an interest in its contents but hasn't seen it yet.
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