Steam speed records including City of Truro and Mallard

Let me be clear then: you are wrong. And you need to go back and re read this thread to see why.

 

Oh I agree, we cannot in any way be sure nothing has changed. Reballasting, subsidence, everything else. But how much can rail height have changed. A metre? Half a metre? And how much of that is relative - if the whole track is 400 mm higher than it was then then its neither here nor there. Of course it will be much more complicated than that. But a measurement of the modern gradients will definitely give us more than simply taking the gradient posts. It's got to be interesting, but of course one must bear in mind the caveats.

 

Inaccurate is, well, an accurate word, but maybe too emotive. Maybe limitations is a better one. Was the machinery designed for ultimate accuracy of instantaneous speeds. Of course not. Accuracy costs. One might hazard a guess that Pareto comes into it and the last 20% of accuracy costs you 80% of the build cost. Would a practical engineer like Gresley have gone chasing decimal points that were of no value to him? Of course he wouldn't, he was far too smart for that.

 

Point of info Jim - I have used the word “limitations” throughout!

 

I have long had a curiosity to understand just how how the various components worked together in the Kylchap: it is evident that the Kyllala exhaust came first and Chapelon improved it but I am not exactly sure how wether this was by carefully adjusting the proportions systematically or by some more basic change.

The appuratus seem to have four places where the the interactions changed round the exhaust steam increasingly mixed with the gases from the fire box:

1 in the blast pipe orifice there was a metal cross that split the steam into four streams.

2 then, after a gap, there was the "splitter" which at the bottom was like the entrance to a petticoat pipe but firmly divided into four inside and emerging as four separate jets at the top formed so what was coming up to be entrained could get all around the exits.

3 above the splitter you were getting the effect of a multi jet - though higher volume less speed out of the splitter.

4 finally there was a simple petticoat with a gap between it and the bottom of the chimney.

i.e. there were four different levels where the Kylchap could suck in. To get to grips with the exhaust the effects cannot have been identical at every stage all the way out.
The extra in the Kylchap is the splitter, now one would naturally use something simpler and longer with multi jets as in a Lempor.

It was undoubtedly an effective exhaust with low back pressure and had the virtue that it gave a good draught if the locomotive was being lightly worked. (The last was elegantly complemented by the concentric Houlet superheater elements which gave a good steam temperature in the same circumstances.)

 

I did not say/suggest he was infallible.

I answered a question from another post asking if Mr.Andrews worked on the original document.
I also added ( as per the I.Mech Eng article ) that he had been an archaeologist ( I assume, but
do not know that he might have experience of handling irreplaceable documents. )

It is because of such responses by you that I will not be commenting further.

Michael Rowe

 

This thread, and I might add, your contributions to it, are so inchoate that one can draw any number of conclusions from them.

 

I stand corrected. However the only other records of distance or time are the manually added quarter mile marks, which are likely to be less accurate. Anyway the point of my post was my second sentence.

 

I have to be honest Michael when I say that I’m perfectly fine with that.

It was more than a bit presumptuous on your part to dictate what someone in academia should be spending their time on.

I would never deign to dissuade someone from doing something that has been done before; fresh minds can sometimes produce different results.

If they don’t produce different results? Great! We have corroboration between independent investigations and that is excellent for all involved.

Yes, that’s the point: I am at the start of the study, I have some preliminary findings, I shared some thoughts on it, I explained why I didn’t agree with someone else’s thoughts, I’ve provided evidence to those who’ve asked for it.

This is generally how academia starts up.

 

Understandable but can `t You just ignore?
I have appreciated Your inputs and we are maybe very close to an explanation.


The red end plug 0n commanding roll has as I see four radial webs, ribs etc and if they somehow are connected to drum we have our quarter mile disturbance.
The paper speed is only determined in the contact zone between the two shiny rolls.
The blue curve is an analysis made 1964 by NRM







It has not much relation to speed of train as it will need more than 3000 ihp extra from a stressed engine to give the acceleration implied.
It can be removed to look somewhat like the red LNER 1938 curve by meaning over 7 second(time to drive a quarter mile at 124 mph) but the maxima will be around 0.5mph lower and we cant have that,can we?.
If LNER 1938 had done this the red curve would have a one mile wave amplitude(still having nothing with trainspeed to do) of ca half a mph.
Rekord then 124.5 and probably still bogus.
If centre of drum is eccentric ca 0.4mm ( slide rule) we are home.
It can also be the drum driving gear (24 teeth) not quite ok.

 

They’re not manually added. They are marked automatically. What has not happened is any calculations on them. The LNER team only did half and full mile calcs, and five second intervals over the area of the speed record.

My approach, which is new, is to see if going to the quarter mile produces anything new, which my preliminary work is saying “yes, there’s something new to analyse here”.

 

Discontinuous rails: in 1938 there were still 40 ft rails in the up fast down Stoke, not 60 ft, Great Northern Railway ones, one third more rail joints.

The story is that after Mallards record Gresley received a note from the Civil Engineer responsible for the track: congratulating him but asking him to please not to repeat it until the short rails had been replaced with longer.

 

I stand corrected again. Can someone please remind me (and all of us) which page of this thread shows an image of a section of the actual roll, as I have forgotten what the various kinds of information recorded on it are, besides the regular marks recording (with possible errors) the time elapsed and the distance travelled.

I have said that I find Andrews' argument persuasive. I have not said that he is right and Simon is wrong, but I would dearly like to know what data, extracted from the roll, persuades Simon that Andrews was wrong, and where Andrews' analysis is at fault.

 

I’ll drop you a PM later on and I’ll happily share what I can. I feel I have explained to an nth degree my position, and I can’t do much more on this thread without tearing my own hair out.

 

This I believe is not apocryphal and is in fact true. There is also several reports on track condition around the 1930s for the LNER that have survived and are of interest in relation to the high speed railway question.

 

A real ugly explanation could be that the one and quarter mile marking mechanism is dragging the drum drive?

 

If the speeds are all calculated from the distance and time marks, any fluctuations in the paper speed should not matter much.

 

Only if the automatic 1/4 mile marks are independent of the paper roll mechanism. The one mile marks are from milepost observations entered manually. Andrews (below) also states that the paper speed had little variation.

"There are distance marks on the paper, automatic ones made every quarter mile and ones made when the train passed lineside features such as mileposts. Observers on either side of the dynamometer car held push buttons which generated a mark on the paper. The distance between these mileposts was checked over a long stretch (12 miles or 24 feet of paper) and this showed the paper was moving at an average rate of 24 inches per mile with an error of less than five parts per ten thousand (Impressive as some of that must be due to errors in the author’s own measurements and to errors in the positioning of the lineside mileposts – nothing is perfect).".

 

See the post following from @MellishR and my reply to him.

 

Is it a possibility that the quartermile disturbance can be from the automatic quartermile mechanism(however that works) dragging paper and drum?

The one mile marks are made manually and cannot retard paper at all?
Not the pen or whatever either?