I would be interested to see speed figures for the Seaboard R-2s (including on their 'second wind' as some of the best fast locomotives on B&O). Their 'diesel replacement' had a chassis explicitly designed for higher speed than other builders provided for heavy freight engines.
And the A's were probably faster.
I am still hoping that there is something in the NWHS archives that confirms that the last five As were built to 'compete' with the C&O M-1s in achieving high speed over the mountainous part with their version of a supertrain to Cincinnati -- that great perceived market that never appeared. Six-coupled versions of an engine proven over 110mph with one extra driver pair...
... like I said, the 'science project' restoration next after 5550, with the knowledge we have about how to forge Timken rods, and Voyce Glaze's balancing book and all the drawings for the specific Timken rod-eye forgings in the archives...
BigJim Overmod The only issue is why the "6300hp" number -- with lower boiler pressure, at an early stage of development, and never remotely repeated -- keeps getting repeated. I have no idea where that figure originally came from. The only person that I can think of that would know is Feltonhill. As for being repeated, you know how these things acquire a life of their own! Yet, being that it is just an arbitrary number on paper for someone to use as bragging rights, does it really matter?As I said earlier, what really matters is what happened out on the road between point A and point Z! And that, the N&W Class A had in spades...eastbound and westbound!
Overmod The only issue is why the "6300hp" number -- with lower boiler pressure, at an early stage of development, and never remotely repeated -- keeps getting repeated.
I have no idea where that figure originally came from. The only person that I can think of that would know is Feltonhill. As for being repeated, you know how these things acquire a life of their own! Yet, being that it is just an arbitrary number on paper for someone to use as bragging rights, does it really matter?As I said earlier, what really matters is what happened out on the road between point A and point Z! And that, the N&W Class A had in spades...eastbound and westbound!
Well, imma learn you up!
https://archive.org/details/sim_railway-age_1936-09-26_101_13/page/435/mode/1up
And
https://archive.org/details/sim_railway-locomotives-and-cars_1936-10_110_10/page/421/mode/1up
Are the articles published in 1936 announcing they built the most powerful locomotive in the world. The decade later modification of that curve down for the later, higher boiler pressure locomotives would not get a special announcement in public magazines. In this case that arbitrary number for bragging rights probably had some importance tied to it from a publicity standpoint. In general that number has significance because it is used often when people jabber about who has top trumps and is used as evidence that it is the third (or second) most powerful steam locomotive ever... when it just isn't. And finally, that number has particular importance with regards to the C&O. If the Allegheny is being specifically designed to be more powerful than the A, and the reported power level of the A is something like 900 HP above what it realistically is, that is going to really affect what you are building to. So that number has more impact than you would think.
timz Conductor_Carl ... that are already gaming the drawbar pull bump that increasing the grade provides when no one else that I am aware of does that seems sketchy to me. Nothing sketchy about it, of course. Anyone testing a locomotive should do the same. The point of testing a locomotive is to compare it with other locomotives you've tested. Naturally you want conditions to be the same for all the locomotives, but you're testing them in different places, on different grades. So you adjust the figures for each one: here is what its drawbar horsepower would have been, on level track, at constant speed X. Theory doesn't say a WM 4-6+6-4 could exceed 6000 HP. Ralph Johnson tried to predict its power, but his calculation was all empirical -- a square foot of heating surface will evaporate X pounds per hour of steam, which will produce Y horsepower. All guesses -- based on experience, but still guesses. As he knew.
Conductor_Carl ... that are already gaming the drawbar pull bump that increasing the grade provides when no one else that I am aware of does that seems sketchy to me.
Nothing sketchy about it, of course. Anyone testing a locomotive should do the same.
The point of testing a locomotive is to compare it with other locomotives you've tested. Naturally you want conditions to be the same for all the locomotives, but you're testing them in different places, on different grades. So you adjust the figures for each one: here is what its drawbar horsepower would have been, on level track, at constant speed X.
Theory doesn't say a WM 4-6+6-4 could exceed 6000 HP. Ralph Johnson tried to predict its power, but his calculation was all empirical -- a square foot of heating surface will evaporate X pounds per hour of steam, which will produce Y horsepower. All guesses -- based on experience, but still guesses. As he knew.
My issue with the compensated HP is that the drawbar pull measured is a empirical no kidding value. The compensation that is added to it is calculated using a coefficient for friction. This may not be 100% accurate. Also, if the value is not clearly called out to be based on compensated pull (as Big Boys generally isnt) then comparisons with other locomotives are skewed.
WRT the WM M-2, it is at least a educated guess to its capability. There im just pointing out a ready example of a engine that seems to be fundamentally ill suited to the road it was on, as I think that it is more likely that the length of train allowed and speed limits account for the 1000 HP miss in power during testing than the engineers being so crap that they misjudged what they were building by about 30 percent.
.
Somehow that "80 mph" got stuck to the Big Boy -- it was always in the early publicity. But no "people" with any sense have ever paid any attention to it.
The "80mph" represents the balancing speed of the engine, which you might think of as a kind of Vne for locomotives. You often see it expressed in rpm or rps in this context, with the corresponding 'road speed' (from drivers of known diameter at that rotational speed) understood as less important. For grins, the equivalent balancing speed for Glaze's J 4-8-4 was 540rpm...
At some point it became a Federal requirement that testing be conducted at 10% over the anticipated maximum service speed. I do not know for certain if this was a requirement during the 'golden age of steam'.
BigJim That's fair. I think that the Big Boy is overrated too.
That's fair. I think that the Big Boy is overrated too.
Hey, that brings us back to the topic of this thread!
I'm creeping closer to that conclusion. I understand why the corrected drawbar pull was calculated, but using that on drawbar horsepower readings that are already gaming the drawbar pull bump that increasing the grade provides when noone else that I am aware of does that seems sketchy to me.
That and the fact that people talk about how it was designed to go 80 even though there is no evidence it ever did also reeks of people assigning capabilities that it did not have.
Of course, that could be a question of if the engine was on routes and given loads that would allow it to utilize all of that, or if it is looking more like a WM challenger (which theoretically is able to make over 6000 HP, but on tests was never able to break 5000 in either drags or fast freight work)
BigJimThat's fair. I think that the Big Boy is overrated too.
I have been of the opinion since the early days of the T1 feasibility plan that we need to restore 1218, make a proper set of Timken lightweight rods and valve gear, put Snyder pre heaters and a Cunningham circulator on her, and see exactly how good an engine results. Leaving her display-only is a crime.
BigJim Y'all can argue and toss around your mathmatical equations all you want. As an "operator", not a "statistition", I am more concerned about over the road performance. And, that my friends, in the case of the N&W Class A and in its operating enviroment, has been well established!
Y'all can argue and toss around your mathmatical equations all you want. As an "operator", not a "statistition", I am more concerned about over the road performance. And, that my friends, in the case of the N&W Class A and in its operating enviroment, has been well established!
Thats fair. While I think that the A is overrated (i.e. people attribute to it things that it could not actually do (6300 DBHP)), the N&W built a engine that the overwhelming majority of railroads wouldn't build and then operated it in a way that the overwhelming majority of railroads wouldn't operate, and basically got the maximum over the road performance out of that design that it was possible to.
Overmod OK, initial update. Someone pass me the crow sauce. I turned up a Web copy of the original test-plant report: https://www.coalstonewcastle.com.au/downloads/test-resources/prr_q2_test_report_1945(dist).pdf
OK, initial update.
Someone pass me the crow sauce. I turned up a Web copy of the original test-plant report:
https://www.coalstonewcastle.com.au/downloads/test-resources/prr_q2_test_report_1945(dist).pdf
This is all really neat!
Interesting things to me are that while the indicated HP is what is usually talked about the test report compares everything with drawbar HP, so you can see where the priority lies.
Also the drawbar HP is confusing to me. Whithun quotes 6645 as the maximum drawbar HP. is that a corrected number adding in the calculated tender resistance, because that number never shows up.
The information on the power imbalance between the front and rear engines as well as the surging caused by the harmonics is really interesting. Makes me wonder how many of these issues are less to do with duplexing as a concept and more to do with the front and rear engines being two different sizes. Would a challenger type arrangement have mitigated a lot of this?
Overmod BigJim I'm trying to figure out how my name got drug into this conversation?
BigJim
which clearly notes that the high horsepower figure is indicated (using a Maihak 'improved Bacharach' indicator) at 280rpm (which is where the "57.4mph" came from). Actual peak dbhp noted in the test was about 7013, at 240rpm.
Note page 18 where they discuss that considerably more 'forcing' of the boiler was possible, but give reasons why it would be pointless to 'test' such operation. (They also note that even 7000hp was stressing the capability of the contemporary Test Plant...)
Note the section about phase-antiphase oscillations being severe at lower, rather than higher, rpm. Then consider the possible effect that surge of that magnitude might have if running in 'uncertain rail conditions'...
It must have been N&W I was thinking of.
Lehigh Valley went far enough as to prepare a diagram for their version of a 4-4-6-4 duplex, with a little set of eight wheels probably denoting a 'water bottle' auxiliary tender. That's the only evidence I have of the idea... and I don't think LV used regular dynamometer cars in that era.
Overmod I thought they relied on their plant. But didn't C&O test one at some point around when they tested the T1?
I thought they relied on their plant. But didn't C&O test one at some point around when they tested the T1?
the N&W tested a Q2 against the A but no Dynamometer car was involved.
Don't know about the C&O, but I don't know why they would. for the T1 the C&O was seeing if it was worth buying some of these basically new high speed engines as opposed to getting more J-3's. But seeing how even after all of the controversy and lawsuits the C&O would buy 15 more Alleghenys in 1948, I think they wern't interested in any other solutions for high speed freight.
Conductor_CarlI don't know how else they would have gotten a drawbar pull
disregard, this comment was a duplicate. stinking 504 network timeout!
Eh, a bit less if im totally honest.
Between milemarker 311 and 309 the engine is running more or less at a steady pace of 22 MPH on the .57% grade with the pull gradually increasing untill it peaks at milemarker 309 at 97,000 pounds, for 5690 DBHP. Seeing how it was increasing its HP up to this point it seems sustainable. After that the train begins to slow for the approch into Alleghany summit. This is taken from test run 12 on July 14 of 1943. There is a peak of over 7000 on this test but that is when the train leaves the level grade and starts up the hill going 40 and its clearly unsustainable. As a aside, compensated for grade (no curvature of note at milemarker 309) this is a bit under 6100 HP.
No idea if the Q2 ever hooked up to a dyanmometer car but I don't know how else they would have gotted a drawbar pull otherwise. Unless I am missing information on how the test plant works.
timzPRR never ran a Q2 with a dynamometer car, did they?
Conductor_CarlThe plot I have looked at has the Allegheny sustaining between 5000 and 6000 HP as it hauls coal up the .57 percent grade at Alleghany at between 15 and 20 MPH.
By the way: if we use the usual formula for curve resistance (0.04% per degree) the climb to Alleghany averages about 0.64% compensated for ... ten miles as I recall.
PRR never ran a Q2 with a dynamometer car, did they?
Keep in mind that the 'peak of the horsepower curve' for the Allegheny design is considerably above "15 to 20mph" -- I seem to remember it being corresponding to road speed somewhere in the low 40s. So you would want to see 'smoothed' average of drawbar pull (over a sustained distance either side of a given reference mile location) and derive horsepower from pull and distance. Then correct the figure for the weight of engine and tender as already discussed.
That the Allegheny chassis ought to be able to produce higher horsepower than the Q2 chassis seems almost self-evident -- but it in part would presume that the boiler pressure and the exhaust drafting and back-pressure arrangements were comparable to the Q2's as well. The lack of 300psi pressure only means that the Allegheny would have to trade some mass flow for pressure; I would not expect either of its engines to be valve-limited at 'best speed', the radiant and convective sections of the boiler ought to be able to source this flow, and perhaps most importantly the commodious pipe arrangements that contributed so much toward the 'overweight' problem would not constitute a restriction all the way from the throttle through to the nozzle and front-end arrangement.
Locomotives on the PRR Test Plant did not operate with their tenders attached; this was a probable contributing factor to the perceived surge when the two engines on the Q2 'came into sync' during the testing. If you read the patent discussion for the Westinghouse Langer balancer, although some of it is 'between the lines', you can see the relative importance on the surge component of overbalance that a large, heavy tender helps to damp out.
timz All true -- only problem is, was the 7498 just a momentary blip. We don't know whether it could maintain even 7000 dbhp for five minutes, or ten, or twenty. (That's the usual situation, in the US.)
All true -- only problem is, was the 7498 just a momentary blip. We don't know whether it could maintain even 7000 dbhp for five minutes, or ten, or twenty. (That's the usual situation, in the US.)
So, the 7498 is a momentary reading. Allegedly the Allegheny recorded a maximum sustained drawbar HP of 7375, but I have not seen the plot for this. The plot I have looked at has the Allegheny sustaining between 5000 and 6000 HP as it hauls coal up the .57 percent grade at Alleghany at between 15 and 20 MPH. I believe that this is not compensated for grade or curve, so if it went by the Big Boys way of doing things it would be greater. I am due to get a copy of the test reports soon to clear up some of those questions.
timz Meaning, on the test plant?
Meaning, on the test plant?
Yeah, he doesn't say. Maybe it is over the road, maybe its on the stand (in which case it would have to subtract out the tender because they could not fit it into the building if i remember right)
Conductor_CarlI thought that the Q2 Max HP of 7987 (right?) was IHP on the test stand, and the Alleghenys 7498 (right?) was measured at the drawbar over the road.
Conductor_Carl William Withuhn quotes the Q2 as having 6,645 drawbar HP
BigJimI'm trying to figure out how my name got drug into this conversation?
It wasn't me!
I'm trying to figure out how my name got drug into this conversation?
We had copies of the various PRR records on the Q2 in the files section of the steam_tech Yahoo Group, which were lost when that service imploded so I can't confirm directly. But I recall the horsepower reading being from the plant's data and not derived from indicator data. It is highly possible that the observed horsepower could not have been put effectively 'to the rail' outside of the artificial world of the test plant; E.H. Harley, in his book on the Q2s, mentioned their relative susceptibility to high-speed slipping (usually starting with the forward engine even after sleeving) and the amount of surge reported for the test at high mass flow/high cyclic would have aggravated the causes of such slipping. If we're going to factor in shoulda-woulda-coulda, proper proportional actuation of the antislip system (which was remarkably sensitive and quick-acting in other than valve actuation) might have improved the ability to use the 'available' cylinder horsepower rather than having to 'derate' in the absence of separate trim for the forward engine.
timzNo doubt Ralph Johnson (the Baldwin guy) knew what his simple formulae were worth.
The picture surrounding Baldwin's development of the C&O M-1 turbine between 1945 and 1947 as seen from the PRR motive-power department is almost comedy gold. Carleton Steins had a couple of patents on a design of steam-turbine electric, and Baldwin conducted what was said to be a highly secret development program designing and building those things. In my opinion some of the egregious failures of detail-design vision may be attributable to over-reliance on Baldwin's then design philosophies...
As I recall, both the initial New Haven I-5s and at least the first of the ATSF 3460 class were delivered with defects that did not allow them to be put into service without repairs. The I5s also had the same balancing fiasco as the infamous ACL R1s... and believe me, that was BAD. (I never carefully examined the ensuing finger-pointing and blaming for what to me was manifestly a ridiculous 'formula' recommendation for overbalance allowance, and perhaps that is best for my atrial fib... the question being where was Johnson when the calculations were done for them?)
More shade on Baldwin (and their then-owner Westinghouse) can be had both explicitly and 'between the lines' from Louis Newton in the volume of his memoirs concerned with that later paragon of how not to do a STE, the N&W TE-1.
timz Making the curve is easy -- making it right is the hard part. Impossible, actually. Have you by chance seen Farrington's book The Santa Fe's Big Three? It has DBHP curves for a 4-8-2 and a 4-8-4 that couldn't be calculated "based on the characteristics of the engine". Or based on anything else. Only way to get those curves was with a dynamometer car. (According to the curve, the 4-8-2 had 1200 dbhp at 65 mph.)
Making the curve is easy -- making it right is the hard part. Impossible, actually.
Have you by chance seen Farrington's book The Santa Fe's Big Three? It has DBHP curves for a 4-8-2 and a 4-8-4 that couldn't be calculated "based on the characteristics of the engine". Or based on anything else. Only way to get those curves was with a dynamometer car. (According to the curve, the 4-8-2 had 1200 dbhp at 65 mph.)
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