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2-6-6-6 H-8 Allegheny

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Posted by WILLIAM ABEL on Tuesday, December 9, 2014 4:31 PM

I heard a similar story many years ago and finally just walked into the B&O Museum and asked them outright about the EM-1 rumored to be stored in some back lot.  They said that it was there for a short time back in the late 50s and then got scrapped.

I saw an EM-1 once as a small child in Ohio.  I was used to seeing the B&O Mikados and the one thing I remember is how big this thing was compared to them - especially the tender.  What a shame that they didn't keep at least one of them.  Just like it is almost a crime that the Pennsylvania Railroad didn't keep just one T-1 (or the S-1 and S-2, or a J-1, or a HC-1, or.......).  Well, getting back to the H-8 issue - hey, if they can rebuild a Big Boy, why not an Allegheny?

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Posted by Overmod on Wednesday, December 10, 2014 11:40 AM

WILLIAM ABEL
Just like it is almost a crime that the Pennsylvania Railroad didn't keep just one T-1 (or the S-1 and S-2, or a J-1, or a HC-1, or.......).

There is correspondence in the surviving PRR files at the Hagley Museum that specifically concerns preserving the S1 "Big Engine" for the Northumberland collection.  I came across this while doing research on the V1 turbine, and didn't make careful notes -- but at the time the S1 was considered second in historical importance only to the 'Lindbergh engine'.  The problem was that the scrap value was something like $37,500 (the rough equivalent of a million in today's money) and management thought it would be unfair to the stockholders (with the railroad doing relatively poorly at the time) not to recover that amount for them...

 

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Posted by thomas81z on Sunday, December 14, 2014 9:20 AM

 http://www.amazon.com/Baltimore-Magnificent-2-8-8-4-Articulated-Locomotive/dp/0939487837

Wow the lowest price is 212.00 wow to steep for me 

Thou i would love a copy someday 

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Posted by Firelock76 on Sunday, December 14, 2014 10:38 AM

thomas81z

 http://www.amazon.com/Baltimore-Magnificent-2-8-8-4-Articulated-Locomotive/dp/0939487837

Wow the lowest price is 212.00 wow to steep for me 

Thou i would love a copy someday 

 

Forget Amazon! Take my advice, prowl the train shows, used book dealers, flea markets and antique shows, and so on, and keep your fingers crossed.  You might get lucky!  I have on numerous occasions.

$212 for a paperback?  Which is probably going to self-destruct in 20 or 30 years time like a lot of paperbacks do? That 's nuts!

By the way, the most I've ever paid for any book was $75 for a book printed and published in 1847 of correspondence between New Jersey patriots during the Revolutionary War.  Yep, ol' General George was in there too.  The condition of the book was like it was printed yesterday, you can still feel the indentations from the printing press in the letters.

I passed on it the first time I saw it, then was in the same book dealer a year later and it was still there.  Well, I know a sign from above when I see it, so it went home with me.  I'm not sorry either.

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Posted by Firelock76 on Sunday, December 14, 2014 10:42 AM

Overmod
 
WILLIAM ABEL
Just like it is almost a crime that the Pennsylvania Railroad didn't keep just one T-1 (or the S-1 and S-2, or a J-1, or a HC-1, or.......).

 

There is correspondence in the surviving PRR files at the Hagley Museum that specifically concerns preserving the S1 "Big Engine" for the Northumberland collection.  I came across this while doing research on the V1 turbine, and didn't make careful notes -- but at the time the S1 was considered second in historical importance only to the 'Lindbergh engine'.  The problem was that the scrap value was something like $37,500 (the rough equivalent of a million in today's money) and management thought it would be unfair to the stockholders (with the railroad doing relatively poorly at the time) not to recover that amount for them...

 

 

A drop in the bucket as assets went even in those days.  They were foolish not to keep it, and a T-1 and maybe the S-2 as well.  C'est la vie.

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Posted by ACY Tom on Sunday, December 14, 2014 10:57 AM

If $212 is not in your budget, I have some words of comfort:  The book has some serious issues.

First, the photos are not well reproduced.  

Second, the binding is not very good.  Pages tend to fall out of my copy.

Third, some very interesting facts about EM-1 detail variations are completely ignored.  For example, the book ignores the fact that the first seven engines, 7600-7606, differed from 7607-7619.  These diferences would be of particular interest to modelers.  The first order should probably be separated into group 1A and 1B because the first seven of the first order had a different sandbox arrangement.  The book ignores the modifications made to 7608's sanders circa 1950.  It also glosses over the different routing of feedwater piping on 7600-7619 before and after modification, vs. 7620-7629.

The book would have served modelers far better if it had mentioned and illustrated the very unusual and interesting whistle linkage, which has very rarely been modeled correctly.

The book is not terrible.  It's a nice collection of photos, with some very interesting locations.  But the reproduction, as I said, is pretty poor, the binding is poor, and the missing information is an irritation to me.  The EM-1 deserved better treatment.

$200 is way too much for this item, so be happy you saved the money. 

Tom  

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Posted by Overmod on Sunday, December 14, 2014 4:03 PM

[quote user="thomas81z] http://www.amazon.com/Baltimore-Magnificent-2-8-8-4-Articulated-Locomotive/dp/0939487837 Wow the lowest price is 212.00 wow to steep for me Though i would love a copy someday [/quote]

Ebay has a slightly lower one - $160 plus $4 shipping:

381087689742
 
I agree with ACY, though; even that lower price is too much to pay for what you get.

 

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Posted by Overmod on Sunday, December 14, 2014 4:32 PM

PM Railfan
... one thing to consider, are you talking boiler hp, or drawbar hp?  I'm talking drawbar hp.

Boiler HP isn't a measure of concern on locomotives; it's based only on heating surface area and really doesn't tell you anything valid.

What you're referring to is 'indicated HP' (also known as 'cylinder HP') which is correctly mentioned in the subsequent posts.  This is a measure of the physical power developed in the 'engine' (or engines, in an articulated).  There's an interim measure taken at the driver wheelrims (net of all the losses and nonlinearities caused by the drive), and then there is drawbar HP which includes the other machine losses of the locomotive.  (Note that DBHP on a grade, or when transiently measured during acceleration/deceleration, also reflects the mass of the locomotive.)

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Posted by sgriggs on Wednesday, December 17, 2014 6:09 AM

Here's a question for you H-8 Allegheny experts.  I'm told the test reports from the 1943 dynamometer testing (the tests during which the well-quoted 7498 DBHP measurement was taken) exist in the C&O Historical Society archives.  I have both Huddleston books (The Allegheny--Lima's Finest, and Worlds Greatest Steam Locomotives), but neither seems to go into detail about coal consumption and steam production during these tests.

If anyone has access to the test reports, can you tell me what the firing rates (lbs/sq ft grate area/hr) were?  If this is not available, an average firing rate can be calculated from the total coal burned (lbs) and the total running time of a given test run.

Thanks in advance!

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Posted by feltonhill on Wednesday, December 17, 2014 6:42 AM

Yes, the H8 tests exist at C&OHS archives.  I also happen to have a copy here.  IIRC, the steam production and coal consumption rates were relatively moderate, indicating that the H8 on test was not being flogged to reach that figure.  Also I believe the train was coming out of a sag, so the 7,498 figure may be just a bit overstated. I'll see what I can dig up later today.  

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Posted by feltonhill on Thursday, December 18, 2014 8:34 AM

Here's what I found regarding the 7,498 DBHP figure.  From the test report:

"Inspection of the final results of all the test trips showed the machine frequently developed a sustained drawbar horse power of 6,700 to 6,900 at speeds of 42 and 46 miles per hour., with a back pressure of 20 pounds or higher.  The highest instantaneous draqwbar horse power occurred on test run No. 106 at mile post 61+1,400 feet, at which time a maximum of 7,498 drawbar horse power was developed at a speed of 46 miles per hour."

I looked at the track charts (C&O page numbers 154 and 155 for those who may have them) and found that there is a sag on either side of MP 60.  So the train was getting some assistance from gravity to achieve 46 mph.  If you look at Huddleston's scatterplots, you'll notice that both the DB pull and DBHP curves have  two outlier points at about 46 mph indicating that something was going on to achieve those readings.  In order to evaluate each point, you have to know the the exact location where the reading was taken.  I haven't found that kind of detail in the papers I have.

Next topic, coal and water consumption.  These quantities are listed over a total run, and no short term readings were included in the test report.  Also, the  peak reading of 7,498 DBHP is atributed to test run No. 104, not 106.  Don't know the answer to that one.  Here's what an average of three runs, WB Russell to Columbus look like.

Distance - 109.85 miles

Totla time - 4'43"

Run time - 3'47"

Working time - 3' 27"

Coal, total - 46,468 lbs

Water - Total tank - 37,166 gal

Total including condensate - 39,856 gal.

Average DBHP - 4,516

Maximum DBHP - 7,150

Maximum sustained DBHP - 7,060

Hope this helps.

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Posted by timz on Thursday, December 18, 2014 12:36 PM

feltonhill
I believe the train was coming out of a sag, so the 7,498 [dbhp] figure may be just a bit overstated.

They did use a dynamometer car, didn't they? The car would measure drawbar pull, and they would calculate dbhp from that. If the engine actually managed 61000 lb drawbar pull at 46 mph then we only need to correct for instantaneous grade/acceleration to calculate a legitimate dbhp. The preceding grade is irrelevant, as long as they know the instantaneous figures.

(So did they know them? Good question. The chart says the engine was on +0.16%, so the grade correction is +1500 lb or so-- corrected drawbar pull is 1500 lb more than the measured pull. If by chance they were decelerating at 0.1 mph/sec at that point then that correction would be minus 4700 lb-- so would be nice to know whether they took that into account.)

In any case, the 7498 figure isn't of much interest. Who cares what the engine can sustain for two seconds? If it can maintain 7000 dbhp for two minutes, say, then that's interesting. If it can maintain 6700 dbhp for 10 minutes, or 6500 dbhp for 30 minutes, then that's interesting. But in the US, at least, road tests never keep such records.

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Posted by sgriggs on Friday, December 19, 2014 12:05 PM

Thank you for the information.  I was surprised by the low average speed (29mph) for the total run, but 14075 tons is a relatively heavy train.  I agree with your statement about the train getting an assist from gravity.  The Davis equations and DB pull plots for the H-8 suggest it couldn't reach 46mph on a level grade hauling 14000 tons.  I think it's unfortunate that the 7498hp number has taken on an aura of legitimacy among people who are not careful to understand the circumstances under which it was measured.

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Posted by timz on Saturday, December 20, 2014 12:07 PM

No need to "understand the circumstances". If we believe the Davis formula, and if we believe the engine reached 46 mph with 162 cars, 14075 tons at MP 61 plus 1400 ft, then it was sustaining 7000+ dbhp.

So maybe we shouldn't believe any of that. Did C&O for sure say the 46 mph was with 14075 tons?

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Posted by Dr D on Saturday, December 20, 2014 2:16 PM

timz,

I am sure that when C&O railroad officials, and those who spent weeks developing the testing of 1600 series locomotives, to say nothing of thousands of employees involved in steam locomotive design finished their work and reported their findings, well!  

I am sure that they were all thinking - that in the year 2014 a guy named "timz" would question all their work and decide it was a capricious overstatement and lacked integrity, fidelity and honisty in reporting.  It is what it is!  Appreciate it, Live with it!

Dr. D

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Posted by GP40-2 on Saturday, December 20, 2014 11:38 PM

Dr D

timz,

I am sure that when C&O railroad officials, and those who spent weeks developing the testing of 1600 series locomotives, to say nothing of thousands of employees involved in steam locomotive design finished their work and reported their findings, well!  

I am sure that they were all thinking - that in the year 2014 a guy named "timz" would question all their work and decide it was a capricious overstatement and lacked integrity, fidelity and honisty in reporting.  It is what it is!  Appreciate it, Live with it!

Dr. D

 

It is not that the C&O, or for that matter the N&W, PRR, UP, etc, didn't report exact data. What the issue is how rail "historians" are incorectly interperting that data and the context it was taken in. The trouble is that many books and articles have been written by individuals who have no clue what they are looking at. They see a number, mix and match other numbers, guess at what it means, then write a book. If that fails, they just make something up to suit their needs.

Probably every book I have ever read in the railfan press about locomotives is littered with inacurate statements and "facts". Nevermind many of those "facts" are scientifically impossible. Timz is rightfully questioning some of the long held facts that many railfans belive just because they read it in some book.

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Posted by GP40-2 on Saturday, December 20, 2014 11:58 PM

ACY

 

The book is not terrible.  It's a nice collection of photos, with some very interesting locations.  But the reproduction, as I said, is pretty poor, the binding is poor, and the missing information is an irritation to me.  The EM-1 deserved better treatment.

Tom  

 

 

That book is the best you are going to get on the EM-1. There isn't any more information. When the B&O started scrapping the EM-1, they threw out all the testing data. Literally, hundereds of pages of test data gone. Back in the 1970's a retired B&O mecahnical engineer that I knew told me when the B&O made the decision to move to diesels, entire file cabinets of steam test data was thrown out. 

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Posted by ACY Tom on Sunday, December 21, 2014 12:49 AM

GP40-2:

According to my understanding of the situation, you are correct.  The information was evidently destroyed.  I do not fault the authors for their inability to find the unfindable.  My complaint had to do with information that can be discovered through careful examination of available dated photos.  It is clear that the first 7 EM-1 engines differed from the next 13, and you don't need those lost records to discover that.

Tom

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Posted by Dr D on Monday, December 22, 2014 11:23 AM

GP40-2,

This is exactly my point on "timz" criticism of the reported horsepower figure of 7498 hp for C&0 H-8 Allegheny. 

The use of the dynometer car in the 1940s was nothing like today with the ability of computorization to digest insurmountable mathmatical problems.  In those days a team of railroad engineers and technicians worked at the math with slide rules and sheets of pen and paper.  Each dynometer car had a full time staff to compute mentally and recieve reports from the locomotive engineer by telephone.  Observers watched out the window or cupola to locate the railroad and mile post.  Data was recorded on rolled paper reel chronograph with 6 ink filled fountain pens!  Accurate record of the distance the train traveled transfered to the rolling paper real - whose accuracy was imperative.  Because all the calculations were based upon the rolling paper trail - was by car wheel with drive shaft to the rolling paper chronograph table.  The travel of the paper was proportionate to the distance of the locomotive, and the work in foot pounds was directly calculated from the "area of the figure described" between the drawbar pull line and the datum line.  Measurement based on the computation of a pen scribble between two lines on a paper! 

This "drawbar horsepower" measurement is primitive to say the least just as was "indicated cylinder hosepower" based upon the mechanical drawing made by the valve action of the locomotive on a "paper card" with a pen.  Run as many cards as you want - lets see if we can get ONE we like!

Lets see if we can get that locomotive pulling real good and see what kind of trace we can get of it on a rolling paper table!  Lets see if we can get ONE we like - do you believe we got ONE trace where she pulled 7,498 hp!

It was the challenge of the test crew just to get the locomotive in a test situation where it would actually operate at its maximum capability.  The professional skill of the engineer and fireman was being tested also.  Many tests would be made but was the engine actually operating in a full power mode?  Given the test parameters and conditions I am not sure they ever got the operational conditions they desired.  Science and engineering being what they were in the 1940s.

J. Parker Lamb in his book Perfecting The American Steam Locomotive explored just this concept - that the age of "Industrial Science" was not yet fully developed, that the steam locomotives were in part a product of the age of "Industrial Arts!" 

Modern scientific re-evaluation of these old tests - with only so much critical review - it is just not possible without going back - without doing it all over again. 

Ralph Johnson steam design engineer for Baldwin notes, "For the calculation of drawbar pull-speed characteristics of a given type of engine, methods have been described...The determination of such curves in the field is quite laborious unless grade and alignment conditions are favorable.  If the actual performance is considerably below the standard the reason may be disclosed by inspection of the locomotive or a study of the methods used by the engine men."

The subjective element is here - favorable conditions!  I am not sure if C&O ever got a true idea how much power the H-8 could develop.  Under certain conditions they did test for and got 7,498 drawbar horsepower - it is there testamony and their witness! 

7,498 hp is what they had to say about their new H-8 locomotive funtioning in their hands supported by their skilled professional staff - that of an entire railroad and of that present technology - the "sitz in leben" - you can review, you can look at it, think about it, but you can't go back and question their fidelity to their work.

Timz, thats my point!  And Lamb notes, "Some Lima engineers wept for joy, that they bested N&W class A!"  And how shall WE ridicule that!

Dr. D

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Posted by timz on Monday, December 22, 2014 12:21 PM

Dr D
you can't go back and question their fidelity to their work. Timz, thats my point!

Ah! I was wondering what it was. Okay, we won't question their fidelity. Might question whether they were right, tho.

Did C&O ever say, in so many words, the 2-6+6-6 was doing 46 mph northbound with 14075 tons at MP 61 plus 1400 ft? If so, we'll question that.

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Posted by Dr D on Monday, December 22, 2014 12:33 PM

timz,

HA!  Seasons greetings to you my friend!

Dr. D

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Posted by feltonhill on Monday, December 22, 2014 12:49 PM

Timz,

What I put in quotes above is directly from the test report summary, hand numbered page 3.  If we believe that Run 106 is accurate, it was westbound from Russell to Robbins with 13,650 tons.  If we believe 7,498 max DBHP to be accurate, this occurred on Run 104 westbound from Russell to Columbus with 14,075 tons.  There's a discrepancy between the test report summary and the individual run data pages.  Oh, the joys of locomotive test reports.....

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Posted by sgriggs on Monday, December 22, 2014 1:06 PM

My point earlier (and I think GP40-2 more clearly stated it) was that the 7498hp reading has been widely reported as a continuous maximum horsepower capability of the H-8, when in fact it was an instantaneous reading that was not corrected for acceleration/deceleration of the train.  It's therefore not a legitimate reading of the continuous horsepower capability of the locomotive.  I came across an interesting 2005 posting on a Yahoo Groups thread that illustrates why uncorrected DBHP readings can be misleading:

" In 1990, 3985 pulled an American Presidents Line stack train up the 0.7% grade at Archer, WY. As the engine reached the top of the grade it was making 35 mph. This train consisted of 143 cars and 7657 tons. Incidentally, this train had been brought east into Cheyenne by three Dash 8-40C diesels. Applying the standard train resistance formulas used by W.L.Withuhn in his article projecting the HP capability of GS-4 4449 in the June '77 Trains, the train's resistance at 35 mph was an amazing 152,753 lbs meaning that an engine would have to exert that much force to achieve a SUSTAINED 35 mph on that grade. A dynamometer car MIGHT have revealed that 3985 was producing 14,256 DBHP. Except, of course, that 3985 was getting an assist. Another engine ahead? No. It was on a momentum grade. Prior to climbing the 3 mile 0.7% grade, 3985 rolled down a similar 0.7% downgrade reaching a speed of 48 mph before encountering the upgrade."

source:  https://groups.yahoo.com/neo/groups/Classic_UP/conversations/topics/938?var=1

This example, along with reporting indicated horsepower, test plant horsepower, or boiler horsepower as directly comparable to corrected drawbar horsepower is what I think needs to be better identified as to the circumstances under which they were collected.  These measures of locomotive capability are not directly comparable to each other.

In my opinion, as a true measure of locomotive power output, the New York Central had a very good process.  They coupled the locomotive under test to a dynamometer car at the head end of a train that was too heavy for the test locomotive to pull.  A second locomotive was coupled into the train to provide just enough assist to keep train speed constant at the desired speed.  That way, train speed could be kept constant and drawbar pull under steady state conditions could be measured. 

I don't want my comments to be taken as a criticism of the railroads whose testing did not follow this practice, as I recognize their objectives may have been different.  Many roads ran tests differently to establish tonnage ratings over specific runs, and not with the explicit purpose of measuring DB pull or horsepower under perfectly-controlled conditions.

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Posted by Wizlish on Monday, December 22, 2014 1:29 PM

Dr D
Under certain conditions they did test for and got 7,498 drawbar horsepower - it is their testimony and their witness! 7,498 hp is what they had to say about their new H-8 locomotive functioning in their hands supported by their skilled professional staff - that of an entire railroad and of that present technology - the "sitz in leben" - you can review, you can look at it, think about it, but you can't go back and question their fidelity to their work.

I have a tentative comment to make.

Whether or not anyone considers 1940s-era dynamometer-car testing to be primitive, it is not a matter of religion, it is a matter of technology.  What is being tested for is a matter of physics and dynamics, not establishing numbers that Lima engineers can weep over, and the results are data, not 'facts' as "dingen an sich" (to continue with the German terminology...)

I think it is abundantly clear that this 7498 dbhp number is no more an 'achievement' than the nominal 126.1 mph "attained" by Mallard during her record run.  And all you have to do to find out, with the available 1940s technology, is to take your little planimeter and integrate even a short distance on either side of the peak measurement, using the C&O data and measurements that were the test department's ACTUAL 'fidelity to their work'.

I have a personal objection to introducing religious metaphors of belief into science in general, and into scientific locomotive testing in particular.  While I don't ask that anyone else share that preference, I do ask that the use of terms like 'fact' be justifiable with actual methodological back-up, not just the logical fallacy of a resort to argumentum ad auctoritatem

(I'd love to find out that an Allegheny would produce 7500 dbhp.  Or that one of the PRR T1s went over 130 mph, or for that matter that PRR 7002 went 127 mph or NYC 999 112 mph.  But you will have to substantiate how it did, not just say in essence that you personally believe it did (or did not, for that matter), so everyone else should accept it as self-evident.  In part, that means that if you want to 'cherry-pick' the raw data, you must tell us the grounds on which you do so, not just present the analysis of the selected or groomed data as 'fact'...

[Now let me play devil's advocate for a moment.  It might be noted first that the original test figure for the N&W A was never even approached again in subsequent testing.  And we had PM Railfan remind us a couple of days ago that the dbhp (or ihp) of an AMC Berkshire was much greater than 'common wisdom' (at least some of that derived from some kind of test reporting) said it was.  Now, if we use PM's figure for the Berkshire ... and consider the Allegheny as if it were "one and a half Berks" in most operational respects ... I don't see a reason to arbitrarily rule out horsepower in the rough 7500 range, necessarily, although I do think that the 7323 or whatever that is commonly quoted as sustained horsepower is a better number to advocate.

It's just that extraordinary claims sometimes require extraordinary evidence...]

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Posted by timz on Monday, December 22, 2014 1:55 PM

sgriggs
the 7498hp reading has been widely reported as a continuous maximum horsepower capability of the H-8

Who has called it that?
sgriggs
it was an instantaneous reading that was not corrected for acceleration/deceleration of the train
We assume it was some sort of instantaneous, but why do you assume it wasn't corrected for the acceleration of the engine? (No need to correct for acceleration of the train.)

sgriggs
[quoting someone else:]

A dynamometer car MIGHT have revealed that 3985 was producing 14,256 DBHP [at 35 mph].

If the dynamometer car read 152000 lb drawbar pull, I guess he means-- no other way to get 14200 dbhp at 35 mph. Think it might have done that?

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Posted by Wizlish on Monday, December 22, 2014 2:22 PM

timz

Who has called it that?

Start by looking at this thread on RyPN..  Then look at some of the 'secondhand' references (like Accurail's) that leave out the 'momentary', or 'peak', or other little disclaimers that usually accompany the "7498" figure when it is mentioned in the literature or on the Web.

It's not too hard to find references that state 7498 as 'the horsepower developed by an Allegheny.'  It proves not difficult to find railfans who state 7498 as the horsepower developed by an Allegheny.  That the test results are more complicated than that is lost in the quick pairing of 7498 with Allegheny.  It's like Jimmy Wales' birthday, or Brazilian aardvarks -- once there is enough repetition of "factitious facts" they take on a life of their own ... and a community of the faithful to bolster them and pass them forward ...

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Posted by timz on Monday, December 22, 2014 5:02 PM

"7498 continuous drawbar horsepower"-- has that phrase appeared in print? Don't see it in your link-- has it appeared elsewhere?

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Posted by sgriggs on Monday, December 22, 2014 7:20 PM

timz

 

 
sgriggs
the 7498hp reading has been widely reported as a continuous maximum horsepower capability of the H-8

 

Who has called it that?

The 7,498hp figure is repeated so frequently in discourse on the Allegheny and without explanation of the test details that it is implied as a continuous capability.  In Huddleston's Allegheny Lima's Finest, he writes, "Dynamometer testing recorded 7,498 horsepower for the 2-6-6-6 and repeatedly proved that it was a legitimate figure".  In World's Greatest Steam Locomotives, the following passage is stated without qualification:  "The figures are too well known to require elaboration:  7,498 maximum drawbar horsepower for the H-8 and 6,300 for the A".  In his Sept 2004 Trains article, Ed King also mentions 7,498 maximum drawbar horsepower.  The steamlocomotive.com website states matter of factly that, "At 40mph [the H-8] could generate 7500hp." 

 

timz

sgriggs

it was an instantaneous reading that was not corrected for acceleration/deceleration of the train

We assume it was some sort of instantaneous, but why do you assume it wasn't corrected for the acceleration of the engine? (No need to correct for acceleration of the train.)

 

 

Several people who have reviewed the 1943 H-8 test report indicated the instantaneous readings were not corrected.  Perhaps someone with access to it can elaborate.  It has been reported that test train was coming out of a dip and was on a rising grade when the 7,498hp reading was taken (consistent with decreasing train speed and an increase in DB pull due to gravity).  At any rate, the degree of scatter in the points on the DB pull and DBHP plots on page 204 of Huddleston suggest great variability in the test results at the higher speeds.

 
timz
 
sgriggs
[quoting someone else:]

A dynamometer car MIGHT have revealed that 3985 was producing 14,256 DBHP [at 35 mph].

 

If the dynamometer car read 152000 lb drawbar pull, I guess he means-- no other way to get 14200 dbhp at 35 mph. Think it might have done that?

 

I think the quoted author was saying that had a dynamometer car been collecting uncorrected DB pull and speed data, it would have shown an instantaneous horsepower reading of over 14,000.  Given the interaction of speed, tonnage, grade, and deceleration, this would clearly be a trivial point in the determination of the horsepower capability of the locomotive.

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Posted by timz on Tuesday, December 23, 2014 12:27 PM

sgriggs
I think the quoted author was saying that had a dynamometer car been collecting uncorrected DB pull and speed data, it would have shown an instantaneous horsepower reading of over 14,000.

If he was saying that, he was wrong. I suspect dynamometer cars didn't show horsepower readings at all-- just drawbar pull and speed-- but in any case the only way it could show 14000 dbhp at 35 mph is with a drawbar pull of 150000 lb.

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Posted by Wizlish on Tuesday, December 23, 2014 1:28 PM

sgriggs
In Huddleston's Allegheny Lima's Finest, he writes, "Dynamometer testing recorded 7,498 horsepower for the 2-6-6-6 and repeatedly proved that it was a legitimate figure".

Proves to me that Gene didn't think before he wrote, or is conflating the results of the analysis of dynamometric testing with the observation data.

You get the horsepower by calculation, not observation; there was no device that "recorded" horsepower directly, and 'instantaneous horsepower' is an effective oxymoron, considering the definition of horsepower.

I would look carefully at the momentum and slack action in the train's consist, relative to the throttle and reverse setting, relative acceleration, and speed of the locomotive and tender.  But I'll bet there's no separate recording of the locomotive motion separate from what the dynamometer car, behind the drawbar, was measuring... 

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