Discussion in 'Steam Traction' started by TonyMay, Apr 3, 2010.
I took NIH to mean Not Invented Here.
Which is why I said "I presume" as I wasn't quite sure of the ownership of the Giesl rights. I saw NIH as some maybe sort of Austrian Mega corporation hanging on to outdated technology for a Kings ransom. Anyway, I think that it's high time that we sorted out the acronym list, SWMBO would order me to comply!!
Thanks Jos. The bit I'm struggling with is that the 3A and 3B boilers have the same boiler dimensions (near enough) although the 3A firebox is about nine inches longer. I appreciate that this would modify the tube/grate area ratio, but not those o0f the flues' and tubes' A/S ratios. The Black Fives were always, under normal conditions, good steamers but the 5X very variable, hence my confusion. I'm inclined to agree that the problem lies ultimately in the chimney and blastpipe arrangements rather than the tubes, flues and elements.
If I understand Powells reporting correctly, the improved single chimney outperformed the original one while the double
outperformed the improved single again. Quite logically btw, the length diameter ratio of these chimneys was improved in this process. However, if the A/S ratio of the flues is not superior over that of the tubes, any draughting improvement will cost you
superheat temperature, that is the catch-22 here. Right now my best guess is that this is the cause of the small amount of
Jubilees that got another front-end.
NIH, not-invented-here, Giesl used a plate valve in the smokebox that could cover part of the tubes. When applied the
ratio of free space through the flues compared to the total rose significantly and more combustion gases through the flues
gave higher superheat, he reported 470 degrees, that is Celsius , not Fahrenheit!
Since I do not know anything about the actual dimensions applied to Galatea during restoration, I have absolutely no idea whether this is applicable in this case.
As for the 3A and 3B boilers, they were used in 3-cylinder and 2-cylinder locomotives resp., a 3B on a Jubilee would give
Jubilee problems, not boiler ones. Although the average mass flow is comparable, the peak flows are not, hence the smaller
orifice of a 3-cylinder.
Further to this, I happen to be in the possession of a compilation of the original testdata of 5722. If I use the trendlines of the measured data, it appears that the original chimney allowed 20760 lbs of feedwater evaporated by about 3350 lbs of Blidw. coal giving steam of 605 F. with a backpressure of 6.9 psi and 3.8 in water as vacuum. For the same water and coal rate the improved chimney steam temp. remained the same, backpressure was 5.6 psi and vacuum 4.3 in water. The double chimney gave 602 F steam with only 4 psi backpressure and 5 in water vacuum. Imho the drop in backpressure more than compensates the few degrees drop in steam temperature.
I happen to know that worldwide locomotive owners and heritage directors are too busy to have time for internet fora, however, if Galatea is restored in say 1955 condition a second look at the frontend might be very usefull.
I don't understand how different levels of smokebox vacuum can give the same water and coal rates. I would expect more vacuum to mean more draught and therefore burning more coal.
Nothing can be done about the tube and flue proportions in the short term, but might it be possible to fit wider flues when they are due for renewal, by enlarging the holes that they fit into?
By enlarging the flues you would leave precious little space between the holes in the tubeplate, which would surely compromise its strength.
I dont know how true it is but ive heard cases where in steam days crews who were on a known poor single chimney steamer made a slight improvement on shed by putting a thin block of wood over the centre of the blastpipe and then try and keep it there with steel wire!! Although this was forbidden in the case it worked loose, it effectively made it into a double chimney loco and thus improved steaming.
Don't really know if a thin block of wood would last very long but there were certainly similar devices used.
I think thats whats called a 'Jimmy' as you say it was frowned upon but it still happened.
I hope that someone from West Coast is reading this debate as it strikes me that notwithstanding the considerable expertise on LMS designs that must exist at Carnforth, there does seem to be plenty of food for thought here.
Let's set aside the possible issue of the coal quality used as it appears the Scot can handle it on a good day. Simply through observation, the recording of performance and the occasional comments made by those that drive and fire her, it appears all is not yet perfect with Galatea. Hopefully, over time, this can be sorted out or the Jubilee is likely to be destined for light main line duties for quite some time.
Heard of it being done with pieces of steel bar, or even chain, but I cannot imagine wood doing too well for too long.
Jimmy's were common enough in steam days a thick welding rod ore even two arranged as a cross would do it.
The jimmy led me to create a blower for our Fowler roller when I wanted to use better quality coal.
Most blowers on road engines if even fitted did not often work and so I took a different approach.
I made a ring of thick walled copper tube that vwould fit around the blast pipe and drilled holes around the ring directed up the chimney.
This device worked a treat and when using anthracite would quickly brighten the fire. The engine being a compound only generated a soft blast which was sufficient to keep[ the fire bright but not to get it going.
This worked a treat I could keep the boiler up to the mark (180psi) making the job of driving it a pleasant task, believe me a compound down the nick is not funny.
This is what got me interested in draughting after suffering with bad coal.
Merely comparing 5699 with 6115 tells us nothing apart from the obvious how could we tell if the coal was the same, the scots were well known for having a potent boiler and accordingly were overloaded, some have said power wise that they were not far short of being equal to a King.
I also think post #776 is probably right and it's not the first time this has happened.
Talking to the late Ray Tranter was interesting as he was of the opinion that the preservation runs of Manors on Talerddig could have been better, firing the loco all the way to the summit instead of closing the door at Llanbrynmair and letting her get on with it.
Ps to Jos wanted to learn more so I've ordered your book
Since I wasn't satisfied with the A/S results I have removed my earlier comment and recalculated with greater care for details like including the tube plate thicknesses(1,75 in. total?) for tube length. For the tubes it is 1/391 and for the flues 1/378, both different from Cox and Powell, but that is as it is. These are sufficiently different, but this does not explain the measured lower
superheat for the double chimney as reported by Powell and supported in my data.
As for the question on the consumptions, blast pressure should be compared with an identical amount of steam ejected, however, the effect of diminished blast pressure is to be found in the tractive effort/Hp. I made another graph from the WRHP power data (probably the waterbrake?) against the steam and for identical power, 1200, the steam consumption is 20.373 for the original, 20.203 for the modified single and 19.847 lbs/hr for the double, so yes, it appears quantifiable.
On the remark on "what to change", imho the flues should be left alone, replacing the 1.375 for 1.25 elements would be an option, but why not look at the tubes? Given Powells remark on the difference between the smokebox temperature in front of the tubes, some 800F, and in front of the flues, some 700, smaller tubes might enhance their heat transmission. It would improve the ratio between the area trough the large tubes to the total and increase superheat. Be not afraid of the decrease in evap. area, that is always sufficient!
Jos your mention of tube sizes takes me back to a journey behind 5690 in the 1980's when she was owned by the SVR.
After a day of delays and problems none of which were down to the engine we finally left Appleby in the late evening lierally hours late.
We made a good start from Appleby and were going really well when approaching Kirkby Stephen we got back boards we were catching the 47 hauled excursion in front of us probably due to long sections.
This seemed to be the last straw for our driver after a very trying day and he really went for it.
The sight must have been very similar to Terry Essery's run with 5699.
You would not dare to hang out of the window showers of sparks like tangerines were showeing down on the train I have never experienced anything like it I later found out that she was at 75% and full regulator.
A very special run.
I bet his mate on the shovel appreciated it lol!
Nah, just think how easy fire dropping would be.
He would have had TWO mates on the footplate!! Fairly normal in those days.
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