Linc, you might want to read Dr Koopmans' work before assuming he's simply promoting another theoretical faith-based drafting concept - nobody in recent history has done more real world science based under controlled measured conditions testing of theories regarding front ends than he, and he's been very generous about sharing his methods and results with the rest of us.

I am not disparaging Dr. Koopman. What I am saying is that in TODAY'S real world, it simply doesn't matter and the changes would end up costing far more than any savings that might result.

Understand here, I am not talking about steam operations that operate virtually daily. I am talking about the large, mainline-type locomotives that are fortunate to run 10 or 20 days a year. Think the 4-6-2's, 4-8-4's, articulateds of both kinds, etc. Some would be happy to get to run 20 or 25 days a year because it would be way more than they do now.

In the practical world of no extant locomotive test plants, we can do simulations until the cows come home. Those simulations cannot reliably take into account the many variables such as fuel quality, boiler condition, operator skills (or lack thereof), water quality, ambient temps, wind, etc. The only way to actually test these things is on the road, under variable conditions. That is not going to reveal anything meaningful in just a few days, much less allow for changes, tweaking, etc. And it's unlikely that a busy Class 1 or Class 2 railroad would sit still for such things, anyway. The 614T days are behind us.

For the sake of discussion though, what if such new devices did deliver measureable improvements in performance and reductions in fuel or water use? How important is that in terms of running 10 or 20 days a year? What are the development costs, compared to the accumulated savings? IOW, in a dollar and cents manner, what is the ROI, if any?

How long does it take to pay back those developmental and modification costs when the results are saving a few cupfuls of oil or a scoopful of coal per trip when you are only going to run 10 or 20 days annually?

I have test data on various types of feedwater heaters vs. injectors under real world conditions, pulling real trains on real railroads with highly skilled crews. Some of the tested systems produced only 1%-2% savings in coal and water, which was not nearly enough to justify purchasing, installing, and maintaining the tested heaters fleet-wide.
Others produced 10%-15% savings. NOW we're talking! But not for a 2017 operation.

IMO, when the subject is modifications to existing big steam, operating under current conditions, this is akin to tasking NASA with designing a more efficient buggy whip.

I understand your points. However, since the original front-end had 2x4 smooth orifices I raised the question whether adding triangular Goodfellow projections to decrease the orifice area was a wise thing. Imho some homework should have been made before fabricating the present layout.
In cases were I have been consulted the starting problem was the size of the orifice(s) made smaller to cope with insufficient steaming, mostly it was a one-way to a load of other problems, insufficient combustion, soot, poor superheat, huge consumption, you name it. People do not understand a front-end is just a textbook fluid dynamics theory application, however, most engineers never looked over the walls of their sphere of comfort, alas!
Kind regards
Jos Koopmans

Looking at the drawing in the film, I am getting very uneasy! It appears that the original orifices were in the order of 3 in. Since Big Boy is rumored to exhaust some 37 tons of steam I am able to calculate the backpressure.
Now there is a problem once that passes a certain value where the exhausted steam reaches its sonic velocity value. Unless special orifices are used (de Laval) the steam will not go into transsonic velocities. This means that any attempt to decrease the orifice area is fruitless. So please folks, if you understand the problem, verify!
Kind regards
Jos Koopmans

Dr. Koopmans,

To start, you're technical data is quite compelling and I appreciate you sharing this. What you have not yet answered is the quantifiable benefits of implementing such alterations as you have meticulously detailed? The majority of us would like to know more from a operating cost perspective. Something a bookkeeper can hang their hat on and financially support. What, based on your calculations could be netted as an estimated savings in dollars per mile traveled using relevant fuel/water/treatment costs? It would be nice to see, side by side a comparisons of the front end arrangement as is, versus the alterations your suggesting.

Best,
DC

Hi, I am not really in this for quantifiable reasons, it is just for saving water, coal, diminish pollution and educating the next generation. Most people find it interesting and leave it that. However the locomotives that still exist are of a ripe old age and the boiler is its most expensive item. The boiler life expectancy is not really helped by an unnecessary heat flow through it because of a lousy front-end. I am sure you are not thrashing your grandma, so why is that suddenly normal for heritage equipment of the same age! Should we not hand over such equipment in the same condition as we would enjoy?
Ok, costs, our situation is different, coal is imported in Europe all over and even in the UK local coal supplies are becoming scarce meaning that locomotives should have minimal coal consumption which they start to appreciate. My last front-end adaption was a case were the locomotive did not steam anymore after some changes after say a million dollars and 25 years of restauration. A 400 dollar 4-orifice blastcap saved the project, took care of sufficient vacuum and lowered drastically coal consumption as they stated. So it is really about the application of proper theory and forgetting the abundant fairy tales!
I hope I gave some sort of an answer,
kind regards
Jos Koopmans

Some of you may be interested to read of Jos’ successful work for the Monticello Railway Museum in Illinois a few years ago:

http://www.trainweb.org/tusp/last30/monticello401.html

Note that UP decreased the nozzle diameter from 3-1/2" to 3-3/8" on the Big Boys in the winter months and allowed for an increase in back pressure from 14 psi to 15 psi to account for combustion of denser ambient air. A seasonal adjustment of 125 thousandths of an inch in a 7000 HP machine for optimal efficiency is not voodoo, trial and error pseudo-science. People that proclaim "it's not PhD rocket science" can't do PhD rocket math.

Study of the UP drawings reveals many things. As for the 3985 Lempor, "A violin does not constitute a symphony." - LDP

Thanks for the orifice data. Since the critical back backpressure is around 11 psi, afaik, it is clear that the UP locomotives could operate above the sonic barrier. My understanding is that velocity cannot increase but since the pistons keep on pushing, the mass flow remains the same and the density increases. As momentum that has to be transferred to the combustion products has velocity squared in it and density only linear the combined effect is not what one would want.
Now for the extra orifices, if you Google "diffuser performance" a chapter of the fluid dynamics handbook by Blevins is made available, look at Fig.7-12b
It shows performance data of diffusers, in our speak tapered chimneys or stacks. The chimney of the BB is 49.5 in high and has a throat diameter of 24.5 in., that would give a length ratio of around 4. However since 4 orifices use this chimney, for each of the four flows the length/radius is 4 times larger and is around 16. The diffuser angle is about 7 degrees, it increases 6 inches over its length and the performance indicator of the diffuser is around .72. This is the ratio between the recovered pressure and the velocity pressure at the mouth of the diffuser. Now adding an extra orifice would raise the length ratio to 20 with a Cp of around .77, so
all things being equal the vacuum goes up by 77/72-1 or 7%.
From the present data I could calculate that below a steam consumption of 37 tons no problems with the sound barrier would exist, reducing the orifice area would lower that amount. I do not know how much extra air is requested because of oil firing but in the coal case the orifices could have been made larger if the extra vacuum was not needed. The maximum possible would be a seven orifice system, Cp goes up to close to .80, clearly diminishing returns.
Kind regards,
Jos Koopmans

My remark about Porta theory being flawed apparently needs some extra explanation. There are a number of momentum theories for steam locomotive front-ends developed over the years. The first one was Zeuner who wrote down the momentum expression still found in fluid dynamics textbooks. Since he was discussing long cylindrical chimneys, he was right. Once he started adding theory for tapered chimneys, he went haywire! After him Strahl, Chapelon, Giesl-Gieslingen and Porta developed theories which have all in common that they included the movement of the combustion products and a very elaborated mathematical formulation. However, and there is the crux, none of them showed a calculation compared to test data as proof of their being correct. I cannot really blame them, in the days of hand calculations and sliderules such a calculation was a lot of work and probably they gave up because the results did not match.
Since I have received some 550 test results of the elaborate testing scheme of British Railways of different locomotives I could try different calculation methods made possible by Excel.
I did take account of the pressure on the wall of the chimney but also on the imperfect exit velocity distribution. This last one by using the above mentioned diffuser data. I did not include the momentum of the secondary flow (combustion products). The results were fine, 1-5% difference between calculations and 550 test results of standard and one Giesl chimney. No data are available for Kylchaps and Lempors so I cannot compare. However since all were calculated without secondary momentum my conclusion is that including that is erroneous. If this is valid for 2 types of calculations, the induction principle says that will also be valid in other cases and Porta's formulation will not give proper results.
The full article can be found here:
https://www.researchgate.net/publicatio ... erformance
Kind regards
Jos Koopmans

.

Kelly makes a good point that I ( and many others I suspect ? ) have been thinking for a long while as this thread has gone on and on about an issue that is relatively academic to this project.

As Kelly rightly states this machine, pulling relatively light passenger consists, will never come remotely close to its designed maximum outputs and thus the whole discussion of making marginal improvements to its sub systems is a waste of bandwidth.

IMHO-Ross Rowland

Mr. Rowland is right - no one will possibly care about anything technical once it pulls trains; no one is alive to judge its performance (to what other locomotive running anyway) and certainly no data will be collected or shared for those with an interest. However, it is sometimes valuable to contemplate outdated things and ideas and this is an appropriate place to do so. There is a thread on livery somewhere else.

I will speak specifically of the UP 4-6-6-4’s because that is what I have complete drawings for, though I do have the UP “All Drawing” index as well as generic drawings. Many carry over to the 4-8-8-4. The main nozzles have an angled entry throat. A fifth central blower nozzle was experimented with. Plain nozzles were applied, later replaced by Goodfellow-type on some classes. The blower nozzles are DeLaval. Single stacks and triple stacks were experimented with, as well as individual petticoats for each nozzle within each stack on a double stack application. The present arrangement reflects development into 1953 which includes alterations of the stack dimensions (narrowing the throats), quite some time after the 4-8-8-4 oil burning arrangement drawing dates. UP methodically tested and developed front-ends that worked for their locomotives, and were undoubtedly aware of front end development outside their organization. That said, there are better arrangements for locomotives which are built with or can be modified to have their steam and exhaust circuits flow better. This is an enlightenment which is apparent with the later N&W locomotives as well as Chapelon and Porta’s work. The 3985’s Lempor arrangement did away with a lot of the flat area of the nozzle plates and I believe improved the local flow to the extent it starved for steam during the exhaust events because the upstream piping is so restrictive. This would be only more pronounced on a 4000 Class. To relate to something more relevant than a steam locomotive, a Cummins 12 valve 6BT diesel can flow 40% better with a “street” Hamilton performance cylinder head or more with their aggressive ones. From this foundation, you can achieve efficiency or performance levels the original 6BT designers never conceived of in the 1970’s. Without starting at the fundamental level, you are more or less bolting on parts for at most a marginal improvement - sometimes negative if you alter some unknown equilibrium. To get back to the less relevant topic, the 3985’s Lempors were also asked to move a much larger volume of air in the firepan. Mr. Austin enlarged the area during his tenure at the UP shop with good results and this was again enlarged with the Lempor installation. A confounding variable being all the while 3985 had filled in for 844 and was very tired. You can hear its exhaust getting softer and softer and more of a dull roar from the stack train video onward. The Lempor installation was a failure for all of these reasons and more, which I may or may not explore in a section of a book which would be written for an audience of less than six people in the world.

The academic question in my mind is are the existing drawings for an oil burning 4-8-8-4 being followed, or are inferences being drawn of later developments from other classes? Why new nozzle plates? The nozzles press into the plates and mechanical condition of the plates alone could be enough to explain their replacement for new nozzles or perhaps there is an alteration of their placement (base circle)? It is a lot of work to make nozzle plates because the blower passages are integral - the effort was not carried-out for vanity alone.

Whatever the oil burning details are, I believe we will see a performance improvement over the 4-6-6-4 and 4-8-8-4 oil conversions simply because the mechanical standard is going to be above 100% as-built and/or in-service. Improving any single component or subsystem would not yield more improvement than the higher general condition/quality this locomotive will have. This locomotive is going to be so steam-tight that it will suck the plating off the sand scoop the first time it goes over Sherman Hill with a load.

The real implication of the project to me is that this project will negate the significance of any past rebuilding/restoration project. What we are seeing is the manufacturing of a new Series 1 4000 Class from a core (4014.) Unless there is some hidden/irreversible flaw, it will bear no personality of its donor and little historical significance. Every aspect which could be experienced by the public will be new and perfect. I believe the roots of this aesthetic-forward style started with the 4449 and later developed more mechanical significance in the 2860 program. Restoring everything to print is a current corporate as well as established military mechanical strategy. It allows the stake holders to be assured a high level of reliability over a determined period of availability with minimized risk. The 2816 was probably the first ground-up application of this style in North America, though such meticulous work can be found in the UK in particular. The scale of this project is unprecedented - the size of the locomotive, but also the scope. Even the facility has been restored to be “proper” for the project - and is truly dedicated to it. If there are coffee table books on steam locomotives in 5 years, the restoration of this locomotive will be the only one anyone has.

What is a shame is that there are a lot of technically more interesting aspects of locomotive restoration which will be eclipsed. Such as: engineering what you have to determine if it will work or can be reclaimed for the intended service; designing and manufacturing new injectors and new safety valves; remanufacturing journal bearing axle boxes; rebuilding cannon roller-bearing axle boxes; rebuilding roller side rod components; CAD/CAM design, manufacturing and installing a truly all-welded firebox; manufacturing thermic syphons and specialty firebox shapes using traditional methods. Even something so humble yet so vital as designing and manufacturing the right oils. Many of these competencies, because of their lack of exterior aesthetic importance, are undervalued, under documented, and likely to be lost in the near future. One skill we may see attempted in this project is manufacturing large locomotive leaf springs- a recent loss.

Unless the 3985 is restored by the current UP steam Shop manager, I see this project as final chapter in steam locomotive restoration. From the modest beginnings in the 1960’s of hydroing a park engine and/or pulling a tube to determine if it can be run to this- something that sets the bar so far above the established Codes & Standards of fixing things and beyond the means of all others that the complete value of that past body of work is void.

Unless it is used for something far more demanding than what is proposed for it, the 4014 will not work hard enough to take advantage of whatever tinkering is going on with it now.

This restoration is beyond a doubt the costliest ever attempted, being in the 8-digit cost range. That alone is a giant spike in 3985's coffin.