34073 moved?

Is that temperature or element area?

 

Area Steve. Can only be shorter or different elements as I believe to flue count is the same.

 

At some undetermined date the elements for all the WC/BBs and MNs were shortened by 1ft. Ref Drawing No E31874.
Perhaps one of our Bulleid experts can give more details.

 

The boilers on original and detuned BB/WCs are identical. The smokebox is attached to the front of the boiler barrel in either case. They have the same number and size of smoke and flue tubes and superheater elements.
In practice, the round smokebox of the detuned version is actually better than the square original one. The detuned locos steam a little bit better than the originals, except the originals with air scoops, I suppose.
It's a shame that the front end of a detuned WC cannot use as much steam as it's boiler can produce!

 

Does any one have some numbers to hand for this? What was the range of superheat observed on the originals compared with the rebuilds? Shortening the elements would reduce the superheater area but it would also reduce the gas flow resistance through the flue tubes. I still do not understand why enthusiasts, in the cold light of day, feel the need to be lacking in appreciation for the work done during the rebuilding of these engines. As a shedmaster what would you rather have at your disposal the originals or the rebuilds? Then think about having to maintain the two types? And so on.

 

Winkworth in "Bulleid's Pacifics" quotes the superheating surfaces as follows: West Country : original 515 sq ft, rebuilt 488 sq ft. For the larger Merchant Navy the figures are more pronounced. Original 822 sq ft, rebuilt 612 sq ft.

46118

 

Interesting, DL Bradley gives 665 sq ft for a MN as built, and 545 sq ft for a WC/BB as built.

Tom

 

I suspect this has been mentioned in other "Bulleid Pacific" threads over time, but both Allen and Winkworth confirm that the chain drive was not Bulleid's first choice of valve gear. His original intention was a three-throw crankshaft driven by gears and a propeller shaft, as in a rotary cam poppet-valve motion, but due to wartime restrictions the gears were not obtainable.

 

Edit: Somewhat curiously, later on Bradley contradicts himself and gives the same values for a MN as given by 46118. The smaller figure he gives is for the first series MN boilers, which did differ in shape from the later MN boilers, though the two types were interchangeable and in time both types appeared on all three series of locos.

It seems the reduction occurred during rebuilding, when the superheater header was also changed to a new design, "in order to offer more convenient steam pipe connections and greater access". The same changes were made to the WC/BBs, though no figure is given for the changed superheater area, but presumably Winkworth is right.

Tom

 

A fleet allegedly consisting of 34067, 34016 and 35018 would make sense to have a source of spares in 34073.

any takers for the VSOE Contract when 35028 goes out for overhaul.. nice business if WCRC could get it.

 

Unless 34073 is there has a longterm project that will join the WCRC main line fleet in the future. Everyone seems to think the loco has gone to Carnforth to donate parts. Maybe there is a future for this loco and time will tell. From memory the loco comes will a long list of parts that have been made over the years and goes right down to cab window frames if my memory serves me right and isn't there a tender for this loco I seem to remember reading about when it was last put up for sale.

 

Tom: The answer is given in Fry, "Bulleid Power The Merchant Navy Class". Fry quotes superheating surface as 665 sq ft as built, and then clarifies as follows: "Usual figure given, 822 sq ft, is surface area on the outside of the elements. So one version is the surface area on the inside or steam side, and one is on the fire side.

46118

 

Interesting. So what is the normal convention when quoting heating area?

Tom

 

Its much more likely to be a source of a spare boiler and other parts. Anyway, we all know there will be not a word of this to breach the walls of the Kremlin, sorry Carnforth, until either 34067 appears with 34073's boiler or whatever else is planned!

 

VSOE's decision to use a particular TOC's is not necessarily all about the traction. Although EWS's ropey 37s couldn't have done them any favours when the Royal Scotsman TOC contract was won by WCR!

 

It is usually taken as the area in contact with the steam, or in the case of the boiler, the water. Therefore ID for superheater tubes and OD for boiler tubes. Gas areas use the opposite.

 

one problem, VSOE is air braked, WCR generally are vac at the moment only 34067 is duel fitted,so it would have to have at least 2 engines under its care .

 

Interesting business dealing with steam locomotives. So, we have some numbers for the superheater areas, it would be good to be more definite if only to address the anomaly. But nothing, so far, with regard to the degree of superheat achieved. Which is the more interesting part, since it is what these devices delivered that is the important part of the assessment of their design. Did the original superheaters raise steam to a temperature that was viewed as being too high?

 

This is indeed a rather interesting area when you come to dig a bit deeper. It appears most tube areas are quoted at you say. However with the MN's as-built, you can't get anywhere near the 822 sq ft superheater area by calculation unless you use the element OD, and the data I was given for the Kings only works if you take the mid-wall diameter. Conversely for WC's as-built the area pretty much equated to the element ID. So do we presume that the large difference on rebuilding is down to BR using the more normal ID dimension? All goes to show that trying to compare boiler designs using published heat transfer areas is proving to be very unreliable.

 

During 35028s last overhaul, 34067 covered almost all of the VSOE Steam jobs. After the saviour of steam locomotive "Flying Scotsman" wasn't all it was cracked up to be!