Drifting Mallets is a special case; you will immediately understand why the bypass valve on locomotives like 1309 is such an essential component, and recognized to be so very early.
Even drifting them with 'snifting' to atmosphere results in dramatic compression from the very large LP cylinders out there on a two-axis pivot to slop around... and then the hunting from overbalance starts. Very few of them were set up to modulate the intercepting valve for pure drifting (at 15psi or so as on simple engines).
And no Mallet of 1910 had Franklin wedges, roller bearings, modern rings or crossheads, good rod bearing construction, etc. etc. etc.
And the biggest, meanest, spread between indicated and drawbar horsepower of them all is what Wardale reports about the resistance curves of the 3450 in Red Devil.
Really disappointing in that the resistance of the locomotive was multiples of what is reported elsewhere, and his only explanation was that the dynamometer car was out of wack.
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
In my opinion 'indicated horsepower' is about the same as pro formas in a business plan. You use them to estimate the design parameters, but they are BS as far as what happens in reality.
Then you figure out the actual profitability, or actual DBHP, the only thing that matters to actual Davis-formula calculation or predicted performance, and if you want, deduce how to make the DBHP better on actual test under actual significant running or road conditions.
I came to appreciate why PRR calculated their performance curves not in 'horsepower' but in drawbar pull at speed -- it goes directly into Davis-formula calculations for practical train resistance, and then reasonably quickly into acceleration formulae.
Paul Milenkovic And the biggest, meanest, spread between indicated and drawbar horsepower of them all is what Wardale reports about the resistance curves of the 3450 in Red Devil. Really disappointing in that the resistance of the locomotive was multiples of what is reported elsewhere, and his only explanation was that the dynamometer car was out of wack.
Does a DBHP and IHP curve for the Red Devil exist?
sgriggs Paul Milenkovic And the biggest, meanest, spread between indicated and drawbar horsepower of them all is what Wardale reports about the resistance curves of the 3450 in Red Devil. Really disappointing in that the resistance of the locomotive was multiples of what is reported elsewhere, and his only explanation was that the dynamometer car was out of wack. Does a DBHP and IHP curve for the Red Devil exist?
p 266 Rolling resistance curve
p 267 Indicated tractive effort as a function of speed and steam flow
p 269 Drawbar tractive effort as a function of speed and steam flow
p 268 Indicated power as a function of speed and steam flow
p 270 Drawbar power as a function of speed and steam flow
What I want to encourage is reading data from this and other sources and making sense of it.
sgriggs I don't own a copy, but can look for one.
sgriggsPaul, are you referencing Wardale's book, "The Red Devil and Other Tales from the Age of Steam"? I don't own a copy, but can look for one.
Yes, that is the book.
I bought it when they reprinted it a few years ago.
The book chronicles Wardales experience as a British ex patriate first in South Africa, where he was able to modify two locomotives, first, a light-duty 4-8-2 Engine Number 2644 of the South African Railways 19D class and later a heavier-duty 4-8-4 Engine Number 3450 of the 25NC class, considered the most powerful and mechanically reliable of South African steam. His changes to the 2644 were an improved exhaust system along with Porta's Gas Producer Combustion System (GPCS) firebox modification. Changes to the 3450 were that in addition to fitting a larger superheater and extensive changes to the valves, valve timing and inlet steam circuit, including a scary "surgical procedure" of cutting off the "steam chests" and fitting larger ones. The changes were significant enough that the 3450 was designated the prototype (and as it turned out only) member of a new 26-class locomotive.
The Tales from the Age of Steam are also three tales of 3 technology cultures in three different countries. In South Africa, the shop people along with the locomotive operating crews had a can-do, even gung-ho spirit about making these modified locomotives and operating them. Although South Africa had reasons for hanging on to steam, railway management let Wardale actually make these mods but was passive aggressive about doing anything more with them.
The country is the USA, where Wardale worked as a consultant to the ACE-3000 project to build a condensing steam locomotive with sufficient thermal efficiency to compete with diesels during the early 1980s spike in oil prices. This project was characterized by pie-in-the-sky goals (Wardale explains why bringing the ACE-3000 to market would have needed much more time and money than available to the project), a lot of "marketing" and what used to be called Vu-Graph engineering in the days before Power Point presentations.
The 3rd country was China in the latter half of the 1980s, where China had its own reasons to want to power locomotives with domestic coal. This was when China was hitting its stride in engaging with the West after Nixon's diplomatic initiative and Deng's leadership but well before China was building 1000's of miles of high-speed electric rail lines.
Wardale was hired to lead the design of an improved QJ-class 2-10-2 locomotive. Longing for the good times he had in South Africa, he complains bitterly about people at the level of factory personnel and locomotive crews getting all passive aggressive by the way they slow-walked this project until he left, with a full set of design documents but no completed locomotive.
The book is replete with charts giving performance data, especially of the 3450 26-class 4-8-4. There is a section with some stats on Ross Rowlands locomotive number 614, a 4-8-4, but don't call it a Northern, which turned in notably weak performance when it served as a "test article" on the ACE project. Both Wardale and Overmod state that with a firebox leaking into the steam space, this locomotive was not in shape to test much of anything, but I am curious diving deeper into at least the "best case numbers" when the boiler maintenance person "with murder in his eyes" (Wardale's words) "caulked" these leaks (pounded the seams, rivets and staybolt heads into shape from inside the box).
Wardale does a great job explain the "why" of Porta's GPSC and gives a lot of evidence that it is not The Magic Upgrade to Bring Steam Back.
I was hoping the book would be more technical, the the charts are tantalizing in what they leave out, but it is an interesting account of a mechanical engineer (Wardale) and his career focus on keeping mainline steam and what worked and what didn't work out in three different engineering cultures.
Overmod:
Any info on where to get a copy of Fry?
Paul MilenkovicAny info on where to get a copy of Fry?
https://books.google.com/books/download/A_Study_of_the_Locomotive_Boiler.pdf?id=Ez9MAAAAMAAJ&output=pdf&sig=ACfU3U0GfnFdKOOscRef_wT7q2Kc6UQ_4w
If that lunches for some reason, google Lawford Fry, "A Study of the Locomotive Boiler" and the Google Books link will be accessible from the first page of results.
Incidentally, you might appreciate some of the implicit analysis in the data accompanying Dawson's (1975) analysis of Niagara road-testing (including discussion of 5500 that is not included in the 1947 report on motive power). Note the errata listed at the end carefully as you read.
https://nycshs.files.wordpress.com/2014/07/roadtestingniagaras.pdf
Overmod Incidentally, you might appreciate some of the implicit analysis in the data accompanying Dawson's (1975) analysis of Niagara road-testing (including discussion of 5500 that is not included in the 1947 report on motive power). Note the errata listed at the end carefully as you read. https://nycshs.files.wordpress.com/2014/07/roadtestingniagaras.pdf
The Errata do not appear to correct any of the number in Table 4 on p 21 giving indicated and drawbar hp under the states steam flow and firing rage.
The 1500 hp spread between indicated and drawbar values suggests a speed of 70 MPG. The 4000 indicated hp suggests 2/3 of maximum power at that speed. 90 lbs/sq feet of grate firing rate is rather reasonable. How Dawson got 54.7 boiler efficiency out of 82.2 % combustion efficiency (the amount of lost coal, which seems reasonable for the firing rate given that 10% of the coal can end up in the ashpan droppings) and 80.1% absorption efficiency -- should give .822 times .801 = 66 % boiler efficiency.
Where does the los number of 52,500 lbs steam through the blast pipe come from? Is the feedwater heater really drawing off that much from 15.8 times 4000 ihp = 63200 lbs steam/hr entering the cylinders?
The boiler efficiency, to the extent that the numbers could be reconciled seems reasonable. The 15.8 lbs/ihp-hr at 2/3 power seems a tad high in relation to the 16.7 lbs/ihp-hr I quoted from Alfred Bruce's book at full power.
As to you-need-to-figure-on-drawbar-efficiency values, 3 times 2000 HP for E7's to match the peak 6000 HP is about the same weight as Niagara and tender, although maybe you don't need 3 E7s to make schedule on a trains pulled by a Niagara owing to the much higher low-end tractive effort? For comparable HP/weight and frontal area giving much of the 1500 HP spread not accounted by machinery resistance in the steam locomotive, the "loss" involved in pushing the air aside and dragging the locomotive weight is comparable?
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