Numbers, LOTS of numbers here..

Wed Aug 12 14:53:16 EDT 2015

Andy:

Interesting and valuable summary, thank you - but some issues.   Let's 
start here:
"Note:  Pulling force or tractive effort was one of the only quantities 
that was  determined almost entirely from the locomotive's geometry. It was 
generally the  limiting facter in determining the size of the train the 
locomotive could  pull."  Then, the author/compiler proceeds to give  us a starting 
tractive effort formula -
          c P (d)^2 s

     TE = -----------

               D

TE  = tractive effort in lbs
c  = a constant determined by the mean effective pressure and friction 
(usually  85%)
P  = boiler pressure
d  = piston diameter
s  = piston stroke
D  = driver diameter

This is, of course, the classic "work in = work out" TE  formula.  But, for 
starters, he has "c" which very much was at least as  much an "experience" 
factor as a "geometry" factor.  It takes into account  cutoff % as well as 
pressure losses between the safety valve setting and what  actually presses 
against the pistons.  As it happens, other sources  (Parker, for example) 
also quote 85%, so we won't quibble about the value he  uses.

Now, unless my high school geometry teacher was fibbing, the  area of a 
circle is = pi*d^2/4.  The total work done in a four cylinder  locomotive like 
his Big Boy example requires a factor of 8=the stroke twice  (back and 
forth) times the number of cylinders, four for a Big Boy.  So,  mathematically 
his "2" in his example is correct, but explanation-wise he's left  a big hole. 
 And, where is "pi"?  Well, again, it's hidden in the  mathematics - "work 
out" is TE times driver circumference, the latter being  pi*D.  So the two 
missing "pi" factors cancel out.

IMHO, a more complete explanation would have been much more  helpful to 
those for whom this is new knowledge, and those more versed in the  subject 
would have understood the value of that complete  explanation.

Now, more observations.  The SP GS-4 DBHP number looks  suspicious.  The 
Trains Magazine 4-8-4 DBHP graph for RR-designed 4-8-4s  shows about 4050 DBHP 
for a GS-4, not 5500.  Is there documentation on  this?  The PRR T-1 number 
is also WAY above the Trains graph.  Might  that have been an Altoona 
number, in which case it's almost certainly rail  horsepower at the drivers, not 
DBHP?

Anyway, to end on a well-earned positive, this is a great  summary, and 
thanks for bringing it to our attention.  I've tried to be as  
positive/contributory as possible in my comments; I have no interest in  nit-picking for the 
sake of scoring points.

Dave Phelps

In a message dated 8/12/2015 1:55:51 P.M. Eastern Daylight Time,  
nw-mailing-list at nwhs.org writes:

An interesting read on "big" steam... Lots of  information on this website 
if you dig a bit.  http://www.steamlocomotive.com/misc/largest.php

Andy Jennings

Ft Chiswell

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Sent: Tuesday, August 11, 2015 10:30 PM
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Subject: Re: Numbers

I didn’t miss your point, but there’s another example  of 
non-interchangibility that’s closer to home.

During WWII, the Rio Grande wanted six more of their  Baldwin Challengers, 
among the most powerful of their type.  In its  wisdom, the WPB and WAA 
denied the Rio Grande the Baldwins it wanted, but said  they’d add six 
Challengers to the end of a group they were building for the  UP, to the UP’s 
Jabelmann design like the 3985.

The Rio Grande took them, and as soon as traffic  eased up after the war 
they turned them back to the War Assets Administration  which put them up for 
sale.  The Clinchfield was looking for power,  already had two classes of 
Challengers (the only ones with Baker Valve Gear  and more powerful than the 
UP engines) and got them, supposedly, at a bargain  price.

The “western” Challengers wouldn’t steam on  Clinchfield’s coal.  They 
had steam failure after steam failure, and  finally they put them through the 
shops at Erwin and redesigned the front  ends, throwing away the double 
smokestacks and double exhaust nozzles,  replacing them with a single nozzle and 
stack.  It was also necessary to  replace the grates.  After this, they 
evidently steamed well on  Clinchfield’s fuel.

But the Centipede tenders were never  satisfactory.  At several points, it 
was necessary to turn the engines on  wye tracks, and it was found necessary 
to put new crossties and gauge rods in  the far leg of all the wyes (that’s 
the leg you always have to back  around).  Those tenders wanted to 
straighten out all the wyes.   

When the 3985 was brought down to the Clinchfield, it  evidently had 
already converted to oil so steaming wasn’t a problem, but I’m  wondering how 
they got the thing turned around . . .

EdKing

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Subject: Re: Numbers

Ed,

I guess you missed my basic point  that all the engines discussed were good 
at what they did but were not  interchangeable. Statistics aside, you 
couldn't take an A, Y-6 or J and use  them on any other railroad and get the same 
results. Same going the other way.  That was my point. They were not GP-9s 
or RS-11s that performed almost  identically on any railroad in similar 
service. Steam was built for specific  purposes on specific railroads and 
generally not interchangeable.

Definitely no argument that the  Roanoke designers and engineers were more 
than equal to the task of turning  out supreme steam.

Roger Huber
Deer Creek Locomotive Works

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Sent: Tuesday, August 11, 2015 7:13  AM
Subject: Re:  Numbers

Jerome -  Roger -

Comparison of N&W's locomotives with anyone else's is  interesting but not 
valid.  N&W's locomotives were designed to  fit N&W's specific operating 
requirements with no outside engineers or  builders interposing their ideas 
upon them.  From a mechanical  engineering standpoint, Roanoke's designers 
were the equal of anyone  else's.

The J was not "over-designed" and it's difficult for me to  understand how 
that conclusion was reached.  The J was designed  specifically to fulfill 
N&W's passenger operating requirements, which  it did.  The operating 
difficulties the J's faced every trip were too  many to list here.  The 600 
rolled out of the shop in 1941 and went  right to work doing what it was 
designed to do.

The Challenger was  designed front to back; Alco was worried about 
front-end 
stability so it  convinced UP and others that the four-wheel lead truck was 

necessary.  In order to keep the engine within length parameters, the  
boiler 
was moved forward on the mechanism which required the firebox to be  raised 
above the drivers, resulting in a constricted throat area  necessitating a 
larger-than-normal grate area to compensate.  The A  was designed back to 
front; the firebox was behind the drivers allowing a  nice throat and 
combustion chamber plus adequate flue length.   N&W's engineers were 
capable 
of designing a two-wheel truck which  would be adequate for the 70 + MPH 
speeds desired.  It was entirely  satisfactory.

The Y-6 and Big Boy are comparable only when  contemplating the operating 
requirements of the two locomotives.  The  N&W refined the Mallet Compound 
to 
an extent not seen elsewhere; IMHO  the commercial builders would rather 
construct huge simple articulateds  for which they could get higher prices 
in 
preference to finding out the  factors which made the Mallet too slow (in 
their opinions).  The  N&W liked the compound concept.  The DBHP of the Y-6 
at 30 MPH  was comparable to that of the Big Boy and the H-8.
Both those engines  developed greater DBHP at higher speeds, but the Y-6 
horsepower curve  suited the N&W's requirements just fine.  And it weighed  
considerably less than all these competitors and used a boiler the size of  
that of a big 4-8-4.  Could a Y-6 designed with 63" driving wheels  have 
satisfied the UP's speed requirements?  Probably, but nobody but  N&W was 
interested in compounds.

So lets not compare apples and  oranges.  The N&W could not have been any 
more profitable with  any of those locomotives you mention, and probably 
considerably  less.  No Challenger could have taken a 16,000 ton train from 

Williamson to Portsmouth in four hours like the A did, routinely.  No  Big 
Boy could have brought 10,000 tons up New River at 31 MPH like the Y-6  
did, 
and then with a like sister, lift the train over Allegheny Mountain  (it 
would have taken three AGs to lift that train over the  Mountain).  No 80" 
4-8-4 could have lifted a 16-car Pelican out of  Marion on a rainy night 
and 
have it up to 60 MPH passing Atkins.

My  two cents, for what they are worth.

EdKing
-----Original  Message----- 
From: NW Mailing List via NW-Mailing-List
Sent: Monday,  August 10, 2015 7:41 PM
To: _nw-mailing-list at nwhs.org_ (mailto:nw-mailing-list at nwhs.org) 
Cc:  NW Mailing List
Subject: Re: Numbers

Roger:  My 2 cents  regarding the A vs. the UP Challengers.  The A is plus 
14,000  pounds
on starting T.E.; has drivers 1 inch greater diameter; and weighs  50,000 
pounds less.
The Y and the Big Boy are not directly comparable;  although the Y's 
starting 
T.E. is 30,000
pounds greater.  The J  seems to have been overdesigned; approached its 
limit 
more in
excursion  service than in its pre 1960 'career'.

Jerome Crosson;  NWHS; st.  Louis Museum of Transportation; residing in St. 
Peters  MO.

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Sent:  Mon, Aug 10, 2015 5:39 pm
Subject: Re: Numbers

"None of the UP’s big three (800, Challenger, Big Boy) could have come  
down to the N&W and done what the N&W”s big three  did."

EdKing

And  likewise, the N&W Magnificent Three wouldn't have been very productive 

on the Onion Pathetic doing the jobs their ugly Big Three could  do!

First they had lousy coal for the Pig Boy that  worked for it but would 
have 
gagged the N&W  beasties.

The Y-6b couldn't have hauled at the speed  the Challengers did.

The J would have beat itself to death  running the speeds the FEF's were 
operated even though it was proven to  run pretty fast.

The A could have probably done the same  job as the Challengers if they had 
good coal.

I'm NOT a  UP fan but steam engines were railroad and service specific and 
a  
magnificent engine for one road wouldn't necessarily have been worth a  
flip 
on another railroad for various reasons.

I  think the Challengers and FEFs were very good engines. I think the Pig 
Boy  
was a huge publicity event and the subject of way too much hype but then  
again I'm rather prejudiced towards the A, AG, H-8, EM-1 and Missabe  
M-3/4s. 
I don't care for the UP steamer look either compared to how the  N&W 
cosmetically treated their power. Apples vs oranges! I think the  engineers 
& 
designers in Roanoke were able to create much better  esthetically pleasing 
locomotives than Alco.

In reply  to another post about the 3 engines side by side in Roanoke I 
think 
seeing  them in 2015 all together is just as impressive an event as having 
the 611  out running again. Who would have ever dreamed we'd see that 
again?  
WOW!!!

Anyway, just my 2¢!

Roger  Huber

Deer Creek Locomotive  Works

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(mailto:nw-mailing-list at nwhs.org) >
Sent:  Monday, August 10, 2015 6:33 AM
Subject: Re:  Numbers

I confess – the sum of the N&W big three adding up to the UP 
4-6-6-4  was sent me by Vello Nickolaou, an old friend who just got back 
home 
after  viewing all three at the VMT.  Vello was the producer of some of the 

railroad programs done by the Histrophy Channel a few years  back.

And Mike is correct –  3985=676!

And, Mike, Clinchfield 677 is coming out of my backshop soon.  I  
always wanted a Bowser Wowser, and I’m finally getting mine done, thanks  
to 
the Rev. Jim Nichols who supplied some needed parts.  I numbered  it after 
a 
Southern Ks 2-8-0 that was at Bristol for a spell.  Fits  right after the 
renumbered UP  job.

And  no, Frank; the N&W big three do not in any other respects add 
up to a  UP Challenger.  None of the UP’s big three (800, Challenger, Big 
Boy)  could have come down to the N&W and done what the N&W”s big three  
did.

EdKing

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Sent: Sunday, August 09, 2015 9:35  PM

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Cc:               NW Mailing  List

Subject: Re:  Numbers

I drove  past VMT yesterday (8/8/15) and all three were lined up under the 
pavilion  (1218, 611, 2156, left to right, viewed from Shenandoah Ave north 
side of  the tracks), not a tarp in sight.  They looked pretty good to  me!!

Dave

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Sent:  Sunday, August 9, 2015 11:15 AM
Subject: RE:  Numbers

3985…. And are all three under tarps at VMT? What is 
the reason to visit  Roanoke and VMT if they  are.

Mason  Cooper

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Sent: Saturday, August 8, 2015 9:52 AM
To:  NW Mailing List
Subject:  Numbers

What is the sum of 611, 1218 and  2156?

EdKing

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