Draughting arrangements for Bulleid Pacifics including the Giesl ejector

Well, since this is about possible savings in consumption that should be a measurable quantity, so its either velocity
or length of travel with a given amount. If it is not possible that's how it is
Kind regards
Jos Koopmans

 

Since I have the principal layout anyway, here it is:
[/URL][/IMG] This is what S.O. Ell might have come up with if they had understood the continuity of a single, double
to multi-orifice layouts at the time. Apparently they were not aware of the Illinois tests by Everett Young which
gave proof of this as early as 1933.
The chimney is resized and the orifices positioned higher at the proper distance so that they do not become saturated by entrainment. The chimney now does what it should do- inhale/suck- and not act as a fluid valve against atmospheric pressure.
The total orifice area is equivalent to a 7 in. orifice
For those interested ask for the detailed info!
Have fun, kind regards
Jos Koopmans

 

Do you have similar information for a Light Pacific?

 

Sorry, I do not have the detailed differences between the two classes. What I have is from the book by Mannion
and I started from Ell's design for the single chimney as tested on 35019/35022. Since Nock (British Steam Railway Locomotive..) describes the "Lord Nelson" Bulleid Lemaitre as having five identical 2 5/8 in. orifices exhausting
in a 2ft 1 in. throat it appears as "one size fits all" to me. Anyone having better information is very welcome!
Kind regards
Jos Koopmans

 

Here's a photo of Sir Keith Park's. https://picasaweb.google.com/116839141471298057728/27Restoration2012#5737568832725585154

 

Thanks but I know what the draughting arrangements for a Light Pacific are. I was asking the Mr. Koopmans if he had drawings of his proposed modifications.

 

Of course you do; I thought others might appreciate a photo of the key item in the drawing.

 

Fair enough.

 

Yeah, but would you please enlighten me? So far I do not know whether the MN and BB/WC frontends are fully identical.
Thanks!
Jos Koopmans

 

thank you Jos for posting your drawing showing the modifications required to the MN class.

i can see clearly how the original petticoat pipe and chimney is of the wrong shape, and should instead be of more orthodox design with a smaller and much lower choke. i can also see clearly how the multiple blast nozzles need raising and be of different size etc.

as the original chimney is just a thin sheet metal fabrication, and the blast nozzle assembly bolts on, it should be relatively easy and cheap to carry out your modifications. the original chimney presumably only has a limited service life anyway and i expect gets replaced on the preserved examples much more often than a cast chimney and petticoat pipe.

cheers,
julian

 

My suggestion would be to cut the chimney entry from pipe bends. The blast pipe could be made from 5 plate sides mounted
on the bottom plate. The orifices are from 3.5 x .2 in. tube, so the lot isn't that difficult. Personally I would go for the
larger orifice area. If I see Tangmere struggling in the film that was recently posted, I can't help thinking that it could be a lot easier! A smaller orifice area is just a plain loss of power.
Kind regards
Jos Koopmans

 

The main arguments (from some people) against pursuing Jos's ideas in a trial installation seem to be concern about cost, plus the fear that it might all be a waste of time and effort. An unfavourable outcome seems to me very unlikely, given the expertise available, and anyway not really a valid concern if the work is paid for.

Can someone who knows about these things come up with a rough figure for the amount of cash that would be needed for materials and (paid-for) labour for a trial installation that could be fitted while one of the main-line locos is out of service for maintenance anyway? Then we can see whether enough of us are interested enough to provide that cash.

 

We at the 5AT only have costs for a Lempor, and they could be considered commercially sensitive. I'll update the team regarding all this though, just to see if there's any interest in Lemaitre development.

 

You may have missed this from an earlier thread:

in AE Durrant's book "Swindon Apprentice" he writes:

"Always eager to learn new techniques, I was most interested to discover how Bulleid's modified Lemaitre exhaust varied according to locomotive size, and extracted the relevant drawings for study. [he was seconded to Ashford at the time]. To my amazement they were all virtually the same, five jets of 2 5/8 inches diameter on closely similar pitch circle. Only much later did the significance of this emerge. The original design was probably prepared for the 'Nelsons' and worked well. On the Schools, it was really too big, which is why no definitive results were obtained in its favour. When these same sized jets were applied to the far larger 'Merchant Navy' class, they created too much back pressure, as confirmed with the tested high fuel consumption, but also created so much draught that the boilers were unbeatable! By coincidence the identical arrangement on the smaller Pacifics provided a less extravagant draught and back pressure, giving them their popular acceptance. It seems amazing that the jet and chimney dimensions were not varied according to locomotive size, this being one of those little mysteries which make locomotive history so rewarding."

 

Fine, thanks! That's what I thought. The Bulleid Lemaitre appears too small for the MN's and for the BB/WC just right.
Given their smaller heating surface and cylinders an expected outcome. For a light Pacific the above design might be reviewed with a smaller amount of steam.
Kind regards
Jos

 

I checked with the BB/WC heating surface data. For the light Pacific it is marginally different, equivalent orifice area goes to a 6.75 in. orifice and the diameter of the chimney is about an inch smaller. However that makes the length/diameter ratio a little better and might be regarded as an improvement. So no problem there.
Kind regards
Jos Koopmans

 

I think the issue is more fundamental - the benefits in coal/water savings and reduced spark emissions would not appear on the steam locomotive owner's balance sheet, but the railway/train operator who hires to the locomotive, therefore the owner won't see the benefit of the cost and effort.

Not many heritage railways own their own locomotives and the few that do tend to be narrow gauge or miniature railways - hence that is why these railways appear to be more interested in developments at present.

Kind regards,
Gareth

 

Si it would seem that the ideal candidates for a exhaust system tweak are the Merchant Navies, of which one will shortly be going for overhaul and one that is close to being restored; both may need said components renewing and both are intended for mainline use. So the oportunity presents itself

Wasnt it Bulleid who said 'Thermal Effieciency never sold a Locomotive'. And as Houghtonga says unless the users of Steam locomotives insist on certain levels of performance to be met by the loco's they hire ( whether thats power, efficiency, controlled emissions or even clean paint)... These things cost and the incentive is a little fuzzy and 'competition' isnt a clear cut factor...

 

Now that Bulleid has been brought in, would it be a wild guess that after proper explanation he would have accepted a
better front-end? It is not a guess anymore these days, fluid dynamics is 60 years more advanced, we understand front-end behaviour and we have computers of which Turing could only dream!
Kind regards
Jos Koopmans

 

No doubt some will tar loco owners with the "not invented here" brush but the case for improving the front end is not clear cut. As I and others have posted, the ones to reap any benefits on coal and water consumption will be the railways that foot the bill for these consumables and in many cases they are not the loco owners. I would argue that there has to be an incentive for a loco owner to spend money on the suggested modifications. If there is no gain, why bother?