Dear Professor (hon?) Overmod!
I must say, this is an especially boastful sassy effrontery! I must put this straight: there is little if any real arguement in all the many lines you shoved up to burry me under. So I regard this as a personal insult, an attempt to crush each and everything I have written - and have written orderly in full knowledge of the physical laws that play a part in these things I have described.
However I sense you felt obliged to jump to 'rescue' age-old so understood male tech talk superiority over so-misunderstood menace of today's feminist's attempts to intrude each and every remaining male resorts. How wrong you are - me, I'm in no way intending to intrude anywheres, I'm just interested in steam locomotives just as anybody else in this forum may be or may not. Only, due to my being a Diplom Ingenieur still with a classic study of Maschinenbau I can sort out some things that often get entangled in conversations - nobody needs to feel like I stepped on his toes. Cool down Over(sic!)mod! The world will be there tomorrow!
As things are, I can only recommend to all readers to ignore this lengthy, winding and at points illogical and conflicting reply and spare yourself to get confused.
Now, in order no one can say I make it too easy for myself, I will at least reply on some of the 'points' brought up against me within each the shreds of my text:
1. shred:
Quote: "This is not necessarily complete tripe; it is possible that, using the 'reservoir' of supercritical water and excess available superheat at high draft level, there would be 'enough steam' to produce the necessary acceleration. Not particularly cost-effectively, and with no guarantee that the locomotive would hold speed (or continue acceleration) beyond a few seconds or minutes, but the higher cyclic does translate into greater cylinder horsepower up to the point that the valves and gear cannot"
Yes, this *is* complete tripe! And the accusation right with it. What is a 'reservoir of supercritical water' in a conventional steam locomotive? do you know at all what the supercritical stadium of water implies? It is by faaaaaaaaar out of reach of a classic steam loco! Absolute rubbish, just meant to dazzle and deceive an unexpecting person.
'excess available superheat' - where is that and how does it come together? There is non - just baloney!
'there would be 'enough steam' to produce the neccessary acceleration. We learn here physics turned upside-down: in order to produce more ihp you just speed up the acceleration - that no-one has ever come about that! It's so simple! Sports car manufacturers rack their brains about super-powerful engines when all you need is to produce -first- the demanded acceleration - and -second- power output of the engine will follow accordingly! Gee - that's cute, I love it.
(My goodness - this is *not* about the amount of steam but about cylinder performance: *this* cannot produce *higher* t. e. at *higher* speeds even on the same c/o!)
Now, if you suggest to pull out c/o open (lengthen intake) at *increasing* speed you turn upside-down known sound locomotive handling. Of course this would go with a large increase of steam demand and the whole thing in fact means a sluggish (easy) loco working at slower speeds offset by an increasingly harder working as speed increases to the degree of even handling c/o in the *opposite* way of normal, and leaving much non-used t. e. and acceleration in the slower speed range. Now, who would drive a locomotive in this absurd way?
"no guarantee that the locomotive would hold speed (or continue acceleration) beyond a few seconds or minutes, but the higher cyclic does translate into greater cylinder horsepower " A few seconds ... gee! The 'higher cyclic' translates into greater cylinder horsepower: Again, it does not help to have *any* amount of steam - cyclic or not - if valve gear cannot pass it through cylinders. In regular driving the higher the speed the more throttling occurs in the steam passages and therefore less t. e. - excess steam will be blown off by safety valves in the good old way - wether this extra steam comes in cyles or continuously.
"Do I really think that acceleration all the way from "80 to 100" would be faster than "60 to 80"? Not really..." Now, what's that? First you claim it is possible - then you don't believe - yes: - yourself? Then, why should anybody else? This note goes around full circle.
2. shred:
"the old story about the Super Hudson design providing too much 'thrust or kick' and bending rods would be far more applicable to the Niagara. It might be interesting to run comparative numbers for the Niagaras at original vs. stepped-down pressure to assess what the 'right' cylinder dimensions for 265psi would have been."
Completely mislead beause the two classes were two seperate designs. The quoted would only have been correct if both would have been equipped with one unified set of rods! That was not the case, and thus which one was underdimensioned cannot be established by 'running comparative numbers for the Niagaras at original vs stepped down pressure' . How should that show correct cylinder dimensioning??? In regular locomotive construction question would rather be to correct rod dimensioning for 'what the 'right' cylinder dimension for 265 psi would have been' All in all this is completely off the topic. I never dealt with a 265 psi b. p. setting of the Niagara - it was never a question. If Prof Overmod thinks since some J-3a had been reduced, the Niagara should as well have been reduced the same way, this is his personal believe - there is no point against anything *I* said in this. How and why can the propper cylinder dimensioning only be determined at 265 psi? It's very simple mathematics to establish what cylinder volume for 275 or 290 psi or for 265 psi for each a desired t.e.
3. shred:
"But the issues with Niagaras did not involve "greater peak horsepower" -- the water-rate considerations even on a railroad with frequent track pans would have become significant "
There I wrote that the extra power output would have been produced just by a lower specific steam consumption and *no* more steam (btw: i e *less* steam on any lower than maximum ihp!) - and still here are water-rate considerations put up against what I wrote! And where did I write that 'issues with the Niagaras did involve "greater peak horspower"? To criticize a text it is of advantage to read it first - and understand that this was *my own* comment as to Kiefer's choice of cylinder volume for 275 psi (too small for best thermodynamic efficiency in my view)
"if you look at the assumptions behind the detail design of the NYC 5550 (and inherently in the April '45 spec for the C1a) you will see this very clearly. " NYC 5550? chee-chee-chee! Congratulations if you have information about the never-to-be C1 class - but what has that design ever to do with *my* contemplations about the Niagara? What will I see clearly?
"Reading between the lines, I suspect there were the same kinds of failure that N&W was seeing with the extended #4 driver-pair pins " Now it gets ever wilder: now the design of coupling rods interfere with steaming of boiler and with cylinder dimensions - O-M-G!
"#4 driver-pair pins on the original lightweight J rods; the Niagara design was somewhat more susceptible to priming " Now that's the peak: coupling rods design and priming in the boiler - another connection so far ignored by even the most notable steam specialists!?
4. shred
"found a point of failure that came up 'quicker' than valve-gear problems: insufficient valve lubrication (or dimensional clearances) .. and insufficient valve lubrication is not a valve gear problem? What is it then?
"as Ed King memorably put it, that was not a factor in the infamous test failure on PRR either by the noted results or later discussion of the testing by Cover et al. as preserved at the Hagley." Once again: "infamous test failure on PRR either by the noted results or later discussion" Failure by results or by later discussion! Great - I say nothing further! General: now, here you are! If that does't impress the last ignorat bloke! I'm only born in 1976 and by that must bow to the superior mass of historical name dropping here - may I know of physical technology whatever I may. Namedropping used at precisely the right moment has silenced many people - but what is the precisely right moment in a writing? Btw - what is it to tell us? Sorry, I'm always so unimpressed and down to earth.
5. shred
My writing: "Mind that with a 20% over-revving, forces reach 144% of the design maximum". and Overmod: "Especially if Chapelon was correct in his assessment of 'routine' lateral bending in the Timken narrow-section lightweight rods." Plain NO here! The increase I mentioned comes from increase of rpm only - no mechanical bending involved! Full stop!
"over-revved continuously, rather than (as was clear to me) repeatedly high-speed slipped without proper notice -- as in the case of the "130mph and higher" operation"
What is the dfference between the two? revving is revving - no matter if it produces speed over rails or slip over rails - especially when slipppage is "without proper notice" (i e goes on over longer than a moment's time). It's the centrifugal forces that matter here!
"The combination of inertial and shock forces on lightweight rods in high-speed slipping is, if anything, far higher in the deleterious senses than steady-state high speed would be, and probably makes your point even more compelling." Deleterious - hu-hu-hu! No, absolutely not! Again: inertia is *only* dependant of the level of rpm. What shock forces are there in slipping other than in regular high revving? *Far* higher? Seems, if the high speed slippage comes into proper frequency of the drive axle(s) there could be torsion forces and momentary lack of straight 'in line' running of wheels and an increase of over / under speed every 1/4 of revolution. Creepy, somehow, isn't it! That's why designers usually took more notice of that than of other forms of slipping
6. shred
"You're leaving out the enormous amount of maintenance that was used by railroads like the Pennsylvania or NYC to keep a jointed-rail mainline in proper shape. " No, I do not. First, such maintenance as would be needed to keep a jointed and nailed rails track without the typical low spots and bends certainly did not exist - I can say that because the American railroads were economic enterprises and such a sort of maintenance would have simply exploded their maintenance budget, it would have demanded revamping embankment under the joints in comparatively short intervals and straightening / replacing bent rails, really an enormous effort - for sure not in the economic interests of railroads making the bulk of income by freight trains. Further, I saw the real riding over the assumed best of these tracks in the advertising film: bounce-bounce-sway-bounce! Last not least logic (wow this is hard from a woman, I know!) must tell you that with this sloppy sort of track system (nailed rails with always some 15 - 25 % of these nails more or less pulled up) you can *never* compete with modern continuously welded track with sprung double screws on rails into much sturdier sleepers and embankment of defined and clean granite broken stone ballast with alongsides superelevated shoulders to keep the track where it was laid and precision adjusted - the result being a passenger in an ICE or TGV feels smooth like in an airplane in perfectly calm flying weather - no bouncing at all and that not at 120 mph but at 175 mph! Note: you may have a superior knowledge of old times - but don't even try to compete with me in today's technology!
"There are a number of reports -- whether anecdotal or 'doctored' I can't say," Well exactly that is the point - this way 'doctored' i e manipulated reports get involved and when that's the case I quit because then there is no way of sorting out what was true and what was not.
" one of these stories claims the ride on a T1 was considerably better than in 'the business cars behind'"
That would be a unique and really singular turning upside-down of what is normally found everywhere in the world! And oposite of what I saw in that video: the riding of the - fairly new! - T1 was certainly worse than that of the lounge car also filmed at about the same speed; it was rough to say no more: the engineer at one time was even lifted from his chair for a moment in a rebouncing action of the engine and the view along the boiler showed nosing and twisting more than on a run-down 012 Pacific: as much play they had developed in bearings, most all of them always ran dead straight ahead - to a part again result of really good track maintenance on federal DB back then (it is not the same today, off the ultra-high speed lines). In the coach compartment I could stand a 5 DM coin on the table on its edge in direction of travelling and it wouldn't fall for minutes on end before I finally lost patience and took it back again. I had done that when joining my father back then on a trip to Frankfurt - that was the quality of riding in an Intercity train with a 103 class twelve wheel electric at 200 km/h.
7. shred
" In any case my personal, and essentially unjustified, opinion is that PRR made a great more out of high speed running than their actual plant ever really permitted except in a few, fundamentally virtually unimportant, sections. Some of the discussions of doubleheaded K4s up against their practical speed limit (of about 92mph) mention the most alarming loss of compliance or guiding integrity on curves "
Oooops??? Now, there you are - and after a whole chapter of claiming the 'jointed and nailed rails track' to have been as good as .. oh, come on!
Btw - I saw an old super-8 film by a friend travelling the cab of a DR (DDR) two cylinder 03 Pacific (Berlin-) Buechen - Hamburg in 1970 when the driver had - as they then often did 'let her go' and see 'what she could do' on that stretch of well maintained DB track: in fact 145 km/h or 90 mph the guy had stopped them, with 12 coaches, some 500 t metric. Shortly before reaching Hamburg they ran straight line through a small station over high speed switches and then into a wide left superelevated curve. On the switches the engine joggled somewhat then fell back into her unimpaired straight forward running and entered the curve smoothly, maintaining her unimpeded running - no nosing whatsoever. Side remark: what all these engines had was a motion I called 'gallopping' due to the comparatively large mass of reciprocating parts with about just ~ 12% overbalancing, you could see that by the window cut-out vibrating in rpm mode when filming the driver sitting still. (added paragraph Jan 16th)
8. shred
"This is not a major factor for the PRR T1, at any rate, which used an OC gear with lower travel at shorter cutoff, and valves with comparatively low inertia."
My goodness, the other way around! there is much less inertia force in continuously rotating cams than in oscillating cams. This is so self explaining, I will not go into it here! Speed, rpm speed in this case! is a universal physical influence on anything - T1 or not - there are no exceptions in application of physical laws. Ok, I stop here, it makes no sense to pursue this to the very end - there is nothing else but always the same.
To be sure:
Anyone may have their own ideas and preferences or convictions - but the I claim the same right for me and please leave me alone with this sort of stalking really! Ever since the day you claimed the delta truck of my 2-8-8-6 to be "almost" where it should be it was like that: whenever I had posted something - anything! - popp! there was a criticizing comment of your's to it! Look, that six-wheel delta truck was not just 'almost' where it should be - that was an insult to an engineer. I can rightfully say that since I designed the layout of the whole locomotive I put things *exactly* where I want them to be and that is *exactly*where they belong because I know what I'm doing. Back then I really got weary of it and in the end I just quit posting here. Now, again the same! But now I will not quit again - you have to throw me out if you can't stand my words.
I offer you the following agreement:
You don't comment my postings anymore - and vice versa I do not comment yours!
Would that be an acceptable compromise to you, Mr Overmod?
In this sense
All the Best for the New Year 2021
Juniatha
(edited Jan 16th 21)