Empty (tare) weight of 611's Auxiliary Tender?

[NW Mailing List]

Dave, 

I have to limit my comments because I was on the research car for two days, and the final numbers have not been run.   However, I can address the conservatism of N&W's testing procedure back in 1945  from  work I did years ago.  The often quoted 5,028 DBHP at 41 mph was actually made in a series of tests that were designed to measure the economy of raising the steam pressure to 300 psi.  As a result, in order to hold constant speed with constant load (1,065 tons), the 300 psi tests were run with a shorter cutoff than the 275 psi tests.  So the word "maximum" doesn't seem to be a very descriptive adjective to apply to the DBHP reading.  I don't believe N&W used it in the test report either.   Also the unit evaporation rate I estimated for the test was about 77 lbs of water per SF of direct heating surface.  Baldwin  recommended 80lbs/SF DHS as a nice achievable figure for daily working.  So, you can draw your own conclusions about whether the sometimes-heard 5,200 DBHP maximum at 45-50 mph is over the top or not.  I don't think it is.  The J's were body-builders in a very stylish outfit!

Dave Stephenson
     From: NW Mailing List via NW-Mailing-List <nw-mailing-list at nwhs.org>
 To: nw-mailing-list at nwhs.org 
Cc: NW Mailing List <nw-mailing-list at nwhs.org> 
 Sent: Wednesday, July 8, 2015 2:07 PM
 Subject: Re: Empty (tare) weight of 611's Auxiliary Tender?
   
Based on the information from Ken, below, and Dave Stephenson in his response, I calculate that the auxiliary tender required about 370 drawbar horsepower to be kept moving at 26 mph on the 1.34% grade.  This includes the following assumptions:- The "Modified Davis" train resistance formula gives a reasonable answer (it's sort of the "industry standard", so that should be safe...)- The Auxiliary Tender was still full- The measurement was on tangent track (this assumption is mandatory since I had no information regarding specific location with respect to a curve) OR the quoted grade was compensated.- Yes, of course I added grade resistance to the rolling resistance. Added to the 4400 DBHP the NS Research Car is quoted as having measured, this compares favorably with the slightly over 4500 DBHP  in the N&W curve reproduced in Col. Jeffries' book, and is just about on (as close as you can read the curve) the curve Classic Trains published (on-line) in conjunction with their special issue on 4-8-4s. Several relevant conclusions, in no particular order:- There have for years been "whispered" thoughts that the N&W's published capabilities for the J were...um...conservative.- Spencer did a super job!- "The Old Girl" hasn't lost a step! Thanks to Ken and Dave for their assistance! Dave Phelps In a message dated 7/8/2015 1:41:37 P.M. Eastern Daylight Time, nw-mailing-list at nwhs.org writes:
Dave 
 The best I can do is off NS' diagram sheet for the 250001 and 250002, last updated was 1-22-1991, which states an average light weight of 143,650 pounds. 
 Ken Miller 


  On Jul 8, 2015, at 10:31 AM, NW Mailing List via NW-Mailing-List wrote:
 
 

 Could some kind soul please provide the empty (tare) weight of 611's current auxiliary tender?   I need the information to complete the input data to calculate, using the modified Davis train resistance formula, how much the addition of the auxiliary tender impacts the drawbar horsepower measurements reported from the NS Research Car during the recent excursions.  Then, a valid comparison can be made with the N&W curve reproduced in Col. Jeffries' book, and the curve Classic Trains published (on-line) in conjunction with their special issue on 4-8-4s.   Thanks in advance,   Dave Phelps________________________________________
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