Lynton and Barnstaple - Operations and Development

That is still on going I had hoped to get to some papers while I was in Devon next weekend but that will have to be on hold for now, I know of Hunslets who made a proposal and they look good but are more like LYN to look at, Brush are reported to have provided some details but not much has been found from them so far, I discussed this with the late Colin Pealling and he thinks others in the Leeds area would have also submitted proposals as the supposed cartel would not have been in operation at the time.

I am told there are some interesting loco designs around that time in the Bagnall records, but once again I have not seen them to make a comment on.

The comment about the L&B only being able to obtain three locos when they knew they needed four must have alerted a lot of the builders to some trade before they contacted Baldwin's.

 

Lyd is probably the limit of what you can do with the MW design before it becomes something else. Realistically increases in boiler pressure or changing the steam dryer to a full blown superheater are going to bring all sorts of problems.

To really evolve it you would need piston valves, different valve gear, bigger diameter but shorter boiler, swing link pony trucks, longer connecting rods etc etc. So essentially you are building a new engine but you've created some pointless constraints because you want it to look like the old one.

Realistically a loco like Lyd will be perfectly capable for most trains on the L&B, and it looks right too. The added bonus is there is a prototype running to iron out the bugs and you didn't have to pay for it.

Tim

 

I'm 90% behind Tim's assessment concerning how many mods could be made, yet still keep a straight face when describing the result as having anything to do with the original MW design.

Given that the original design of "Lyn" has been modified, in a reasonably unobtrusive manner, to incorporate piston valves (as has FR Hunslet "Blanche"), you've got to wonder whether the same approach would be beneficial, desirable (or, indeed, possible) for the 2-6-2t. Has Joy valve gear ever been adapted to drive piston valves? Would the distinctive MW chimney design be able to cope with the resultant exhaust without throttling gas flows? The balanced slide valves reportedly give "Lyd" a noticeably enhanced performance, but whether this can be (or needs to be) further improved, without completely changing the appearance, is one for the design teams. I have my suspicions that the geometry of the chimney will preclude any Lempor adaptation.

For what it's worth, my own feeling is that if, as seems likely, the L&B prioritise restoring the ambience of the old line, the result will be "Lyd" MKII and either a radically new design of shovel, or generations of L&B firemen with bad backs.

Over the longer term, I still feel a better solution will have to be found for a line which will be nearly 20 miles long and (hopefully) operating many more services than it's predecessor.

And four MWs? How are they going to explain that if someone actually goes and finds "Lew"? However unlikely, it might yet come to pass..... we live in hope!

 

On a recent visit to Woody Bay I was informed that, once Lyn has been successfully launched into service, the intention is to commission the FR to build a pair of MWs with some spare castings for Lyd manufactured at the same time.

 

Interesting idea, if it's fact and not wishful thinking.

 

A pedant writes: An 'intention' can itself be both fact and wishful thinking simultaneously.

 

I have it on good authority that piston valves were considered, but it is wasn't possible in the space available without changing the look of the front end. Hence the compromise that is balanced slide valves as they wanted it to look like the original.

Tim

 

Incidentally, MW were one of the companies approached by the Ffestiniog to quote for the construction of their first steam locos in 1862. Now there's an interesting might-have-been...

 

Can't help thinking if you put the valves between the frames, you could have piston valves along with a decent type of valve gear (also between the frames) without radically changing the overall outline of the loco, yes I'm sure some of the more anal enthusiasts would moan about the lack of external valve gear but does it really matter if a more workmanlike loco results. There is of course issues of maintainence of a set of stephensons gear in this position although there are plenty of examples which do have such an arrangement like indeed the most recent arrival?

 

It would be useful to compare the properties of piston valves and balanced slide valves on an otherwise identical engine design. No need to go crazy and build an entire loco, unless playing.... sorry, experimenting.... with exhaust arrangemets too. 'Spose these days, computer modelling would get you 75% of the way there, but something in to around 1:6 full size (for a 2ft-0" gauge prototype) or larger would put things beyond reasonable doubt. One for the SM&EE types, methinks.

 

Building a scale model could tell you about appearance etc. but won't tell you much about how such a redesign would work in practice, because the physical properties of steam don't scale in the same proportion. So you could build an exact scale model but then find the mass-flow rate of steam in and out of the valves would be completely to pot. (For example - if you built a 1/6 scale model, dimensionally accurate in all degrees, you'd have to get 1/216th the mass of steam in and out of cylinders on every stroke with 1/36th the area of valve opening, over a length between regulator and valve of 1/6th the original, but with steam having the same thermondynamic properties as the real thing. Different rates of heat loss, different frictional resistance to fluid flows in the steam pipes etc. It could be modelled analytically, but an actual scale working model would not simply scale up and give the same results.

Tom

 

Completely agree re:scaling, but a model of resonable size would be indicative of component behaviour. I'll grant you it's some way short of ideal, but coupled with the manner in which computer modelling is advancing, sufficient to at least rule out certain options or combinations. In an ideal world, resources would exist to carry out full scale evaluations (as conducted by Mr Bulleid, among others), but these were expensive then and remain so now.

There's another issue. Insofar as the bulk of steam age engineering was concerned, the finer points of thermodynamics remained, for the most part, a closed book. Was it ever, for instance, rocket science to suppose straight ported piston valves of adequate size will allow better steam flow than constricted and tortuous Z-ported designs?

How many potentially decent designs failed to acheive their potential through slavish adherence to outmoded thinking? How locos with short travel valves were still being designed, fully two decades after Churchward's work, is beyond me. Ditto provision of superheating in designs intended for mainline working. Why on earth did loco design have to wait over a century before Bulleid decided to place both injector controls in proximity to each other?

It's one thing to faithfully maintain a preserved loco, complete with all it's inherent design flaws. Quite another to wilfully include readily avoidable issues in a new build through some (IMO) misguided notion of 'authenticity'.

I'm in full agreement with the point made a few days ago that we're talking about obsolete technology here, but still don't think that's any reason to perpetuate the worst original design features of any recreation intended for regular service on heritage lines or on the big railway..... unless the intention is to be able to tell budding firemen that chronic back problems are a historically justified part of the job, or a future engineer that whatever glaring shortcoming they observe is why such-and-such a class went extinct in the first place.

 

I thought the public consultation period ended some time ago. I'm surprised that new items are still being considered, particularly of this quality!

 

I would imagine patents probably came into play over certain design features and a reluctance to cough up the dosh needed to use them, if it was even allowed.

 

That's certainly been an historic issue, which led to some 'creative' work arounds, some less successful than others, back in the day. I think the (extinct) SAR/ZASM "Modified Fairlies" came firmly into that category!

Anyone know if any of the later steam era patents are still in force?

 

Happy to be corrected but the example you quote sounds more like fluid dynamics, although limited superheat would indeed seem to indicate lesser importance placed on thermodynamics. Re Bulleid, didn't he dispense with an exhaust steam injector and eschew mechanical lubrication to the axleboxes? The main loco engineers all seemed to be somewhat idiosyncratic with their own idée fixes, which may indeed in some cases have been influenced by cost.

 

No great expert, me either! My understanding (quite possibly flawed!) was that fluid dynamics describes behaviour within fluids and thermodynamics specifically the point of interaction between fluid and a solid surface. I may, of course, be entirely incorrect, but it's that I believe was the crux of Tom's valid remark on the non-scalability of steam (or fire and water, for that matter) and which I was attempting to address regarding the usefullness scale modelling of components.

 

Probably the Authority are mortally scared of some possible Court ruling that their handling of the application was flawed and thus null and void.

PH

 

....or they just enjoy a good laugh!

 

Just like any other democratic decision the public are entitled to lobby their elected representatives until the day the decision is made (and often afterwards ). So you might as well continue to accept comments on line too.